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Sample records for event-related optical signal

  1. Event-related fast optical signal in a rapid object recognition task: improving detection by the independent component analysis.

    Science.gov (United States)

    Medvedev, Andrei V; Kainerstorfer, Jana; Borisov, Sergey V; Barbour, Randall L; VanMeter, John

    2008-10-21

    Noninvasive recording of fast optical signals presumably reflecting neuronal activity is a challenging task because of a relatively low signal-to-noise ratio. To improve detection of those signals in rapid object recognition tasks, we used the independent component analysis (ICA) to reduce "global interference" (heartbeat and contribution of superficial layers). We recorded optical signals from the left prefrontal cortex in 10 right-handed participants with a continuous-wave instrument (DYNOT, NIRx, Brooklyn, NY). Visual stimuli were pictures of urban, landscape and seashore scenes with various vehicles as targets (target-to-non-target ratio 1:6) presented at ISI=166 ms or 250 ms. Subjects mentally counted targets. Data were filtered at 2-30 Hz and artifactual components were identified visually (for heartbeat) and using the ICA weight matrix (for superficial layers). Optical signals were restored from the ICA components with artifactual components removed and then averaged over target and non-target epochs. After ICA processing, the event-related response was detected in 70%-100% of subjects. The refined signal showed a significant decrease from baseline within 200-300 ms after targets and a slight increase after non-targets. The temporal profile of the optical signal corresponded well to the profile of a "differential ERP response", the difference between targets and non-targets which peaks at 200 ms in similar object detection tasks. These results demonstrate that the detection of fast optical responses with continuous-wave instruments can be improved through the ICA method capable to remove noise, global interference and the activity of superficial layers. Fast optical signals may provide further information on brain processing during higher-order cognitive tasks such as rapid categorization of objects.

  2. Final Report on LDRD project 130784 : functional brain imaging by tunable multi-spectral Event-Related Optical Signal (EROS).

    Energy Technology Data Exchange (ETDEWEB)

    Speed, Ann Elizabeth; Spahn, Olga Blum; Hsu, Alan Yuan-Chun

    2009-09-01

    Functional brain imaging is of great interest for understanding correlations between specific cognitive processes and underlying neural activity. This understanding can provide the foundation for developing enhanced human-machine interfaces, decision aides, and enhanced cognition at the physiological level. The functional near infrared spectroscopy (fNIRS) based event-related optical signal (EROS) technique can provide direct, high-fidelity measures of temporal and spatial characteristics of neural networks underlying cognitive behavior. However, current EROS systems are hampered by poor signal-to-noise-ratio (SNR) and depth of measure, limiting areas of the brain and associated cognitive processes that can be investigated. We propose to investigate a flexible, tunable, multi-spectral fNIRS EROS system which will provide up to 10x greater SNR as well as improved spatial and temporal resolution through significant improvements in electronics, optoelectronics and optics, as well as contribute to the physiological foundation of higher-order cognitive processes and provide the technical foundation for miniaturized portable neuroimaging systems.

  3. Joint Maximum Likelihood Time Delay Estimation of Unknown Event-Related Potential Signals for EEG Sensor Signal Quality Enhancement

    Directory of Open Access Journals (Sweden)

    Kyungsoo Kim

    2016-06-01

    Full Text Available Electroencephalograms (EEGs measure a brain signal that contains abundant information about the human brain function and health. For this reason, recent clinical brain research and brain computer interface (BCI studies use EEG signals in many applications. Due to the significant noise in EEG traces, signal processing to enhance the signal to noise power ratio (SNR is necessary for EEG analysis, especially for non-invasive EEG. A typical method to improve the SNR is averaging many trials of event related potential (ERP signal that represents a brain’s response to a particular stimulus or a task. The averaging, however, is very sensitive to variable delays. In this study, we propose two time delay estimation (TDE schemes based on a joint maximum likelihood (ML criterion to compensate the uncertain delays which may be different in each trial. We evaluate the performance for different types of signals such as random, deterministic, and real EEG signals. The results show that the proposed schemes provide better performance than other conventional schemes employing averaged signal as a reference, e.g., up to 4 dB gain at the expected delay error of 10°.

  4. Brain Signals of Face Processing as Revealed by Event-Related Potentials.

    Science.gov (United States)

    Olivares, Ela I; Iglesias, Jaime; Saavedra, Cristina; Trujillo-Barreto, Nelson J; Valdés-Sosa, Mitchell

    2015-01-01

    We analyze the functional significance of different event-related potentials (ERPs) as electrophysiological indices of face perception and face recognition, according to cognitive and neurofunctional models of face processing. Initially, the processing of faces seems to be supported by early extrastriate occipital cortices and revealed by modulations of the occipital P1. This early response is thought to reflect the detection of certain primary structural aspects indicating the presence grosso modo of a face within the visual field. The posterior-temporal N170 is more sensitive to the detection of faces as complex-structured stimuli and, therefore, to the presence of its distinctive organizational characteristics prior to within-category identification. In turn, the relatively late and probably more rostrally generated N250r and N400-like responses might respectively indicate processes of access and retrieval of face-related information, which is stored in long-term memory (LTM). New methods of analysis of electrophysiological and neuroanatomical data, namely, dynamic causal modeling, single-trial and time-frequency analyses, are highly recommended to advance in the knowledge of those brain mechanisms concerning face processing.

  5. Development of a Method to Compensate for Signal Quality Variations in Repeated Auditory Event-Related Potential Recordings

    Science.gov (United States)

    Paukkunen, Antti K. O.; Leminen, Miika M.; Sepponen, Raimo

    2010-01-01

    Reliable measurements are mandatory in clinically relevant auditory event-related potential (AERP)-based tools and applications. The comparability of the results gets worse as a result of variations in the remaining measurement error. A potential method is studied that allows optimization of the length of the recording session according to the concurrent quality of the recorded data. In this way, the sufficiency of the trials can be better guaranteed, which enables control of the remaining measurement error. The suggested method is based on monitoring the signal-to-noise ratio (SNR) and remaining measurement error which are compared to predefined threshold values. The SNR test is well defined, but the criterion for the measurement error test still requires further empirical testing in practice. According to the results, the reproducibility of average AERPs in repeated experiments is improved in comparison to a case where the number of recorded trials is constant. The test-retest reliability is not significantly changed on average but the between-subject variation in the value is reduced by 33–35%. The optimization of the number of trials also prevents excessive recordings which might be of practical interest especially in the clinical context. The efficiency of the method may be further increased by implementing online tools that improve data consistency. PMID:20407635

  6. Neuroimaging measures of error-processing: Extracting reliable signals from event-related potentials and functional magnetic resonance imaging.

    Science.gov (United States)

    Steele, Vaughn R; Anderson, Nathaniel E; Claus, Eric D; Bernat, Edward M; Rao, Vikram; Assaf, Michal; Pearlson, Godfrey D; Calhoun, Vince D; Kiehl, Kent A

    2016-05-15

    Error-related brain activity has become an increasingly important focus of cognitive neuroscience research utilizing both event-related potentials (ERPs) and functional magnetic resonance imaging (fMRI). Given the significant time and resources required to collect these data, it is important for researchers to plan their experiments such that stable estimates of error-related processes can be achieved efficiently. Reliability of error-related brain measures will vary as a function of the number of error trials and the number of participants included in the averages. Unfortunately, systematic investigations of the number of events and participants required to achieve stability in error-related processing are sparse, and none have addressed variability in sample size. Our goal here is to provide data compiled from a large sample of healthy participants (n=180) performing a Go/NoGo task, resampled iteratively to demonstrate the relative stability of measures of error-related brain activity given a range of sample sizes and event numbers included in the averages. We examine ERP measures of error-related negativity (ERN/Ne) and error positivity (Pe), as well as event-related fMRI measures locked to False Alarms. We find that achieving stable estimates of ERP measures required four to six error trials and approximately 30 participants; fMRI measures required six to eight trials and approximately 40 participants. Fewer trials and participants were required for measures where additional data reduction techniques (i.e., principal component analysis and independent component analysis) were implemented. Ranges of reliability statistics for various sample sizes and numbers of trials are provided. We intend this to be a useful resource for those planning or evaluating ERP or fMRI investigations with tasks designed to measure error-processing. Copyright © 2016 Elsevier Inc. All rights reserved.

  7. Lamellar events related to insulin-like growth factor-1 receptor signalling in two models relevant to endocrinopathic laminitis.

    Science.gov (United States)

    Lane, H E; Burns, T A; Hegedus, O C; Watts, M R; Weber, P S; Woltman, K A; Geor, R J; McCutcheon, L J; Eades, S C; Mathes, L E; Belknap, J K

    2017-09-01

    Insulin dysregulation, obesity, and exposure to high-nonstructural carbohydrate (NSC) forage are risk factors for equine metabolic syndrome-associated laminitis (EMSAL); high systemic insulin concentrations in EMSAL are proposed to induce cellular dysregulation in the digital lamellae through activation of the insulin-like growth factor-1 receptor. To use a dietary challenge model (DCM) and a euglycaemic-hyperinsulinaemic clamp (EHC) model to assess lamellar growth factor-related signalling. Lamellar phospho (P)-protein concentrations of signalling proteins important in growth factor-related signalling were assessed in 2 models: 1) lean and obese ponies on a low- or high-NSC diet; and 2) EHC model using Standardbred horses. Ponies stratified for body condition (lean [LN, n = 11] and obese [OB, n = 11]) were exposed to a low-NSC diet (LO, n = 5 per group for LN LO and OB LO) or a high NSC diet (HI, n = 6 per group for LN HI and OB HI groups) for 7 days. For the EHC model, horses were administered insulin (constant rate infusion [6 mIU/kg bwt/min] combined with 50% dextrose, EHC group, n = 8)] or saline (0.57 mL/kg bwt/h, CON group, n = 8) for 48 h. Immunoblotting was employed to assess concentrations of activated/phosphorylated and total protein for members of the PI3K/Akt/mTORC1 and Ras/ERK pathways in lamellar samples from both models. In the DCM, lamellar P-(Ser 240/244) RPS6 was increased in OB HI ponies (vs. OB LO, P0.5) between Day 7 basal serum insulin concentrations and lamellar concentrations of P-p70S6K and P-(Ser 240/244) RPS6. In the EHC model, lamellar concentrations of P-Akt, P-p70S6K, P-ERK 1/2, P-p90RSK, and both P-(Ser 235/236) and P-(Ser 240/244) RPS6 were increased in the EHC group (vs. CON, Plaminitis as that was not the endpoint of either study. These results support further investigation of mTORC1/RPS6 signalling as a potential therapeutic target(s) in EMSAL. The Summary is available in Chinese - see Supporting Information. © 2017 EVJ Ltd.

  8. Hemodynamic and electrophysiological signals of conflict processing in the Chinese-character Stroop task: a simultaneous near-infrared spectroscopy and event-related potential study

    Science.gov (United States)

    Zhai, Jiahuan; Li, Ting; Zhang, Zhongxing; Gong, Hui

    2009-09-01

    A dual-modality method combining continuous-wave near-infrared spectroscopy (NIRS) and event-related potentials (ERPs) was developed for the Chinese-character color-word Stroop task, which included congruent, incongruent, and neutral stimuli. Sixteen native Chinese speakers participated in this study. Hemodynamic and electrophysiological signals in the prefrontal cortex (PFC) were monitored simultaneously by NIRS and ERP. The hemodynamic signals were represented by relative changes in oxy-, deoxy-, and total hemoglobin concentration, whereas the electrophysiological signals were characterized by the parameters P450, N500, and P600. Both types of signals measured at four regions of the PFC were analyzed and compared spatially and temporally among the three different stimuli. We found that P600 signals correlated significantly with the hemodynamic parameters, suggesting that the PFC executes conflict-solving function. Additionally, we observed that the change in deoxy-Hb concentration showed higher sensitivity in response to the Stroop task than other hemodynamic signals. Correlation between NIRS and ERP signals revealed that the vascular response reflects the cumulative effect of neural activities. Taken together, our findings demonstrate that this new dual-modality method is a useful approach to obtaining more information during cognitive and physiological studies.

  9. Optical time-lens signal processing

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2014-01-01

    This paper describes the use of optical time lenses for optical signal processing of advanced optical data signals. Examples given include 1.28 Tbaud Nyquist channel serial-to-parallel conversion and spectral magnification of OFDM signals.......This paper describes the use of optical time lenses for optical signal processing of advanced optical data signals. Examples given include 1.28 Tbaud Nyquist channel serial-to-parallel conversion and spectral magnification of OFDM signals....

  10. Fast optical signal not detected in awake behaving monkeys.

    Science.gov (United States)

    Radhakrishnan, Harsha; Vanduffel, Wim; Deng, Hong Ping; Ekstrom, Leeland; Boas, David A; Franceschini, Maria Angela

    2009-04-01

    While the ability of near-infrared spectroscopy (NIRS) to measure cerebral hemodynamic evoked responses (slow optical signal) is well established, its ability to measure non-invasively the 'fast optical signal' is still controversial. Here, we aim to determine the feasibility of performing NIRS measurements of the 'fast optical signal' or Event-Related Optical Signals (EROS) under optimal experimental conditions in awake behaving macaque monkeys. These monkeys were implanted with a 'recording well' to expose the dura above the primary visual cortex (V1). A custom-made optical probe was inserted and fixed into the well. The close proximity of the probe to the brain maximized the sensitivity to changes in optical properties in the cortex. Motion artifacts were minimized by physical restraint of the head. Full-field contrast-reversing checkerboard stimuli were presented to monkeys trained to perform a visual fixation task. In separate sessions, two NIRS systems (CW4 and ISS FD oximeter), which previously showed the ability to measure the fast signal in human, were used. In some sessions EEG was acquired simultaneously with the optical signal. The increased sensitivity to cortical optical changes with our experimental setup was quantified with 3D Monte Carlo simulations on a segmented MRI monkey head. Averages of thousands of stimuli in the same animal, or grand averages across the two animals and across repeated sessions, did not lead to detection of the fast optical signal using either amplitude or phase of the optical signal. Hemodynamic responses and visual evoked potentials were instead always detected with single trials or averages of a few stimuli. Based on these negative results, despite the optimal experimental conditions, we doubt the usefulness of non-invasive fast optical signal measurements with NIRS.

  11. Effects of wi-fi signals on the p300 component of event-related potentials during an auditory hayling task.

    Science.gov (United States)

    Papageorgiou, Charalabos C; Hountala, Chrissanthi D; Maganioti, Argiro E; Kyprianou, Miltiades A; Rabavilas, Andreas D; Papadimitriou, George N; Capsalis, Christos N

    2011-06-01

    The P300 component of event-related potentials (ERPs) is believed to index attention and working memory (WM) operation of the brain. The present study focused on the possible gender-related effects of Wi-Fi (Wireless Fidelity) electromagnetic fields (EMF) on these processes. Fifteen male and fifteen female subjects, matched for age and education level, were investigated while performing a modified version of the Hayling Sentence Completion test adjusted to induce WM. ERPs were recorded at 30 scalp electrodes, both without and with the exposure to a Wi-Fi signal. P300 amplitude values at 18 electrodes were found to be significantly lower in the response inhibition condition than in the response initiation and baseline conditions. Independent of the above effect, within the response inhibition condition there was also a significant gender X radiation interaction effect manifested at 15 leads by decreased P300 amplitudes of males in comparison to female subjects only at the presence of EMF. In conclusion, the present findings suggest that Wi-Fi exposure may exert gender-related alterations on neural activity associated with the amount of attentional resources engaged during a linguistic test adjusted to induce WM.

  12. The mixed block/event-related design.

    Science.gov (United States)

    Petersen, Steven E; Dubis, Joseph W

    2012-08-15

    Neuroimaging studies began using block design and event-related design experiments. While providing many insights into brain functions, these fMRI design types ignore components of the BOLD signal that can teach us additional elements. The development of the mixed block/event-related fMRI design allowed for a fuller characterization of nonlinear and time-sensitive neuronal responses: for example, the interaction between block and event related factors and the simultaneous extraction of transient activity related to trials and block transitions and sustained activity related to task-level processing. This review traces the origins of the mixed block/event-related design from conceptual precursors to a seminal paper and on to subsequent studies using the method. The review also comments on aspects of the experimental design that must be considered when attempting to use the mixed block/event-related design. When taking into account these considerations, the mixed block/event-related design allows fuller utilization of the BOLD signal allowing deeper interpretation of how regions of the brain function on multiple timescales. Copyright © 2011 Elsevier Inc. All rights reserved.

  13. Optical Performance Monitoring and Signal Optimization in Optical Networks

    DEFF Research Database (Denmark)

    Petersen, Martin Nordal

    2006-01-01

    The thesis studies performance monitoring for the next generation optical networks. The focus is on all-optical networks with bit-rates of 10 Gb/s or above. Next generation all-optical networks offer large challenges as the optical transmitted distance increases and the occurrence of electrical......-optical-electrical regeneration points decreases. This thesis evaluates the impact of signal degrading effects that are becoming of increasing concern in all-optical high-speed networks due to all-optical switching and higher bit-rates. Especially group-velocity-dispersion (GVD) and a number of nonlinear effects will require...... enhanced attention to avoid signal degradations. The requirements for optical performance monitoring features are discussed, and the thesis evaluates the advantages and necessity of increasing the level of performance monitoring parameters in the physical layer. In particular, methods for optical...

  14. All-optical signal processing for optical packet switching [Invited

    Science.gov (United States)

    Geldenhuys, R.; Liu, Y.; Calabretta, N.; Hill, M. T.; Huijskens, F. M.; Khoe, G. D.; Dorren, H. J. S.

    2004-12-01

    We present three optical signal processing functional blocks that enable 1×N optical packet switching. An ultrafast asynchronous multioutput all-optical header processor is demonstrated with a terahertz optical asymmetric demultiplexer in combination with a header preprocessor. It is shown that self-induced polarization rotation can be used for both the header processor and the header preprocessor. The second functional block is optical buffering. This is shown with both a laser neural network and a recirculating buffer. Related to this is a three-state all-optical memory based on coupled lasers, which increases the number of possible output states of an optical packet switch.

  15. Advanced optical signal processing of broadband parallel data signals

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Hu, Hao; Kjøller, Niels-Kristian

    2016-01-01

    Optical signal processing may aid in reducing the number of active components in communication systems with many parallel channels, by e.g. using telescopic time lens arrangements to perform format conversion and allow for WDM regeneration.......Optical signal processing may aid in reducing the number of active components in communication systems with many parallel channels, by e.g. using telescopic time lens arrangements to perform format conversion and allow for WDM regeneration....

  16. All-optical signal processing of OTDM and OFDM signals based on time-domain Optical Fourier Transformation

    DEFF Research Database (Denmark)

    Clausen, Anders; Guan, Pengyu; Mulvad, Hans Christian Hansen

    2014-01-01

    All-optical time-domain Optical Fourier Transformation utilised for signal processing of ultra-high-speed OTDM signals and OFDM signals will be presented.......All-optical time-domain Optical Fourier Transformation utilised for signal processing of ultra-high-speed OTDM signals and OFDM signals will be presented....

  17. Optical Processing of High Dimensionality Signals

    DEFF Research Database (Denmark)

    Da Ros, Francesco

    signal processing, including wavelength conversion, optical phase conjugation (OPC), and signal regeneration. This project focuses precisely on the applications of OPAs for all-optical signal processing with a two-fold focus: on the one hand, processing the advanced modulation formats required......) waveguides, are investigated. The limits of parametric amplification for 16-quadrature amplitude modulation (QAM) signals are first characterized. The acquired knowledge is then applied to the design of a black-box OPC-device used to provide Kerr nonlinearity compensation for a 5-channel polarization......-division multiplexing (PDM) 16-QAM signal at 1.12 Tbps with significant improvements in received signal quality. Furthermore, the first demonstration of phase regeneration for binary phase-shift keying (BPSK) signals using the silicon platform is presented. The silicon-based OPA relies on a novel design where a reverse...

  18. Serial optical communications and ultra-fast optical signal processing of Tbit/s data signals

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Hu, Hao

    2010-01-01

    This paper reviews our recent advances in ultra-high speed serial optical communications. It describes Tbit/s optical signal processing and various materials allowing for this, as well as network scenarios embracing this technology......This paper reviews our recent advances in ultra-high speed serial optical communications. It describes Tbit/s optical signal processing and various materials allowing for this, as well as network scenarios embracing this technology...

  19. Radio Science from an Optical Communications Signal

    Science.gov (United States)

    Moision, Bruce; Asmar, Sami; Oudrhiri, Kamal

    2013-01-01

    NASA is currently developing the capability to deploy deep space optical communications links. This creates the opportunity to utilize the optical link to obtain range, doppler, and signal intensity estimates. These may, in turn, be used to complement or extend the capabilities of current radio science. In this paper we illustrate the achievable precision in estimating range, doppler, and received signal intensity of an non-coherent optical link (the current state-of-the-art for a deep-space link). We provide a joint estimation algorithm with performance close to the bound. We draw comparisons to estimates based on a coherent radio frequency signal, illustrating that large gains in either precision or observation time are possible with an optical link.

  20. Optical Profilometers Using Adaptive Signal Processing

    Science.gov (United States)

    Hall, Gregory A.; Youngquist, Robert; Mikhael, Wasfy

    2006-01-01

    A method of adaptive signal processing has been proposed as the basis of a new generation of interferometric optical profilometers for measuring surfaces. The proposed profilometers would be portable, hand-held units. Sizes could be thus reduced because the adaptive-signal-processing method would make it possible to substitute lower-power coherent light sources (e.g., laser diodes) for white light sources and would eliminate the need for most of the optical components of current white-light profilometers. The adaptive-signal-processing method would make it possible to attain scanning ranges of the order of decimeters in the proposed profilometers.

  1. Moving Average Convergence Divergence filter preprocessing for real-time event-related peak activity onset detection : application to fNIRS signals.

    Science.gov (United States)

    Durantin, Gautier; Scannella, Sebastien; Gateau, Thibault; Delorme, Arnaud; Dehais, Frederic

    2014-01-01

    Real-time solutions for noise reduction and signal processing represent a central challenge for the development of Brain Computer Interfaces (BCI). In this paper, we introduce the Moving Average Convergence Divergence (MACD) filter, a tunable digital passband filter for online noise reduction and onset detection without preliminary learning phase, used in economic markets analysis. MACD performance was tested and benchmarked with other filters using data collected with functional Near Infrared Spectoscopy (fNIRS) during a digit sequence memorization task. This filter has a good performance on filtering and real-time peak activity onset detection, compared to other techniques. Therefore, MACD could be implemented for efficient BCI design using fNIRS.

  2. All-optical signal processing of OTDM and OFDM signals based on time-domain optical fourier transformation

    DEFF Research Database (Denmark)

    Galili, Michael; Guan, Pengyu; Lillieholm, Mads

    2017-01-01

    In the talk, we will review recent work on optical signal processing based on time lenses. Various applications of optical Fourier transformation for optical communications will be discussed.......In the talk, we will review recent work on optical signal processing based on time lenses. Various applications of optical Fourier transformation for optical communications will be discussed....

  3. Optical Bistability For Optical Signal Processing And Computing

    Science.gov (United States)

    Peyghambarian, N.; Gibbs, H. M.

    1985-02-01

    In this paper we present the basic principles of optical bistability and summarize the current advances in semiconductor optical switching, with emphasis on recent results in GaAs, CuCI, InAs, InSb, CdS, ZnS, and ZnSe etalons. These devices have great potential for applications involving optical signal processing and computing. As an example, we discuss the use of arrays of bistable devices for parallel optical processing and for addressable spatial light modulators. The use of nonlinear etalons as optical gates is also illustrated. To date, GaAs devices have shown the most favorable characteristics for practical applications. They operate at room temperature with a few milliwatts of power using a laser diode as the only light source. Quasi-cw operation and optical fiber signal regeneration have also been demonstrated. A GaAs NOR gate operates in 1 ps with <3 pJ incident energy; this, of course, implies a 1 ps switch-on time for a bistable etalon.

  4. Ultrafast Optical Signal Processing with Bragg Structures

    Directory of Open Access Journals (Sweden)

    Yikun Liu

    2017-05-01

    Full Text Available The phase, amplitude, speed, and polarization, in addition to many other properties of light, can be modulated by photonic Bragg structures. In conjunction with nonlinearity and quantum effects, a variety of ensuing micro- or nano-photonic applications can be realized. This paper reviews various optical phenomena in several exemplary 1D Bragg gratings. Important examples are resonantly absorbing photonic structures, chirped Bragg grating, and cholesteric liquid crystals; their unique operation capabilities and key issues are considered in detail. These Bragg structures are expected to be used in wide-spread applications involving light field modulations, especially in the rapidly advancing field of ultrafast optical signal processing.

  5. Photonic Applications Using Electrooptic Optical Signal Processors

    Science.gov (United States)

    2011-11-16

    metal deposition, BCB polymer coating, BCB dry-etching, and gold electrode plating. Standard optical ridge waveguide structures were fabricated in...and cross-section view of the phase modulator are shown in Fig. 2. A thick BCB polymer layer was used to isolate ground and signal electrodes and...modulators were fabricated with p-contact metal deposition, waveguide dry-etching, n-contact metal deposition, BCB polymer coating, BCB dry-etching

  6. Quantum Dot Devices for Optical Signal Processing

    DEFF Research Database (Denmark)

    Chen, Yaohui

    This thesis describes the physics and applications of quantum dot semiconductor optical ampliers through numerical simulations. As nano-structured materials with zero-dimensional quantum connement, semiconductor quantum dot material provides a number of unique physical properties compared...... with other semiconductor materials. The understanding of such properties is important in order to improve the performance of existing devices and to trigger the development of new semiconductor devices for dierent optical signal processing functionalities in the future. We present a detailed quantum dot...... semiconductor optical amplier model incorporating a carrier dynamics rate equation model for quantum dots with inhomogeneous broadening as well as equations describing propagation. A phenomenological description has been used to model the intradot electron scattering between discrete quantum dot states...

  7. Acousto-optic filtering of lidar signals

    Science.gov (United States)

    Kolarov, G.; Deleva, A.; Mitsev, TS.

    1992-01-01

    The predominant part of the noise in lidar receivers is created by the background radiation; therefore, one of the most important elements of the receiving optics is a spectrally selecting filter placed in front of the photodetector. Interference filters are usually used to transmit a given wavelength. Specific properties of the interference filters, such as simple design, reliability, small size, and large aperture, combined with high transmission coefficient and narrow spectral band, make them the preferred spectral device in many cases. However, problems arise in applications such as the Differential Absorption Lidar (DIAL) technique, where fast tuning within a wide spectral region is necessary. Tunable acousto-optical filters (TAOF), used recently in astrophysical observations to suppress the background radiation, can be employed with success in lidar sounding. They are attractive due to the possibility for fast spectral scanning with a narrow transmission band. The TAOF's advantages are fully evident in DIAL lidars where one must simultaneously receive signals at two laser frequencies.

  8. All-optical clock recovery of NRZ-DPSK signals using optical resonator-type filters

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Seoane, Jorge; Ji, Hua

    2009-01-01

    It is shown how introducing a limited rise time to the driving signal enables all-optical clock recovery of NRZ-DPSK signals generated using a phase modulator. A Fabry-Perot filter is used to generate the optical clock.......It is shown how introducing a limited rise time to the driving signal enables all-optical clock recovery of NRZ-DPSK signals generated using a phase modulator. A Fabry-Perot filter is used to generate the optical clock....

  9. Ultra-Fast Optical Signal Processing in Nonlinear Silicon Waveguides

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Pu, Minhao

    2011-01-01

    We describe recent demonstrations of exploiting highly nonlinear silicon nanowires for processing Tbit/s optical data signals. We perform demultiplexing and optical waveform sampling of 1.28 Tbit/s and wavelength conversion of 640 Gbit/s data signals.......We describe recent demonstrations of exploiting highly nonlinear silicon nanowires for processing Tbit/s optical data signals. We perform demultiplexing and optical waveform sampling of 1.28 Tbit/s and wavelength conversion of 640 Gbit/s data signals....

  10. Ultra-broadband and ultra-fast optical signal processing

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo

    2015-01-01

    We have recently seen that nanowires can provide unparalleled optical signal processing (OSP) bandwidth and provide ultra-fast operation as well. Utilising the ultra-broad OSP bandwidth for e.g. optical time lenses allows for energy-efficient optical switching. © 2015 OSA.......We have recently seen that nanowires can provide unparalleled optical signal processing (OSP) bandwidth and provide ultra-fast operation as well. Utilising the ultra-broad OSP bandwidth for e.g. optical time lenses allows for energy-efficient optical switching. © 2015 OSA....

  11. Reconfigurable Optical Signal Processing Based on a Distributed Feedback Semiconductor Optical Amplifier.

    Science.gov (United States)

    Li, Ming; Deng, Ye; Tang, Jian; Sun, Shuqian; Yao, Jianping; Azaña, José; Zhu, Ninghua

    2016-01-27

    All-optical signal processing has been considered a solution to overcome the bandwidth and speed limitations imposed by conventional electronic-based systems. Over the last few years, an impressive range of all-optical signal processors have been proposed, but few of them come with reconfigurability, a feature highly needed for practical signal processing applications. Here we propose and experimentally demonstrate an analog optical signal processor based on a phase-shifted distributed feedback semiconductor optical amplifier (DFB-SOA) and an optical filter. The proposed analog optical signal processor can be reconfigured to perform signal processing functions including ordinary differential equation solving and temporal intensity differentiation. The reconfigurability is achieved by controlling the injection currents. Our demonstration provitdes a simple and effective solution for all-optical signal processing and computing.

  12. Reconfigurable Optical Signal Processing Based on a Distributed Feedback Semiconductor Optical Amplifier

    Science.gov (United States)

    Li, Ming; Deng, Ye; Tang, Jian; Sun, Shuqian; Yao, Jianping; Azaña, José; Zhu, Ninghua

    2016-01-01

    All-optical signal processing has been considered a solution to overcome the bandwidth and speed limitations imposed by conventional electronic-based systems. Over the last few years, an impressive range of all-optical signal processors have been proposed, but few of them come with reconfigurability, a feature highly needed for practical signal processing applications. Here we propose and experimentally demonstrate an analog optical signal processor based on a phase-shifted distributed feedback semiconductor optical amplifier (DFB-SOA) and an optical filter. The proposed analog optical signal processor can be reconfigured to perform signal processing functions including ordinary differential equation solving and temporal intensity differentiation. The reconfigurability is achieved by controlling the injection currents. Our demonstration provitdes a simple and effective solution for all-optical signal processing and computing. PMID:26813252

  13. All-optical signal processing data communication and storage applications

    CERN Document Server

    Eggleton, Benjamin

    2015-01-01

    This book provides a comprehensive review of the state-of-the art of optical signal processing technologies and devices. It presents breakthrough solutions for enabling a pervasive use of optics in data communication and signal storage applications. It presents presents optical signal processing as solution to overcome the capacity crunch in communication networks. The book content ranges from the development of innovative materials and devices, such as graphene and slow light structures, to the use of nonlinear optics for secure quantum information processing and overcoming the classical Shannon limit on channel capacity and microwave signal processing. Although it holds the promise for a substantial speed improvement, today’s communication infrastructure optics remains largely confined to the signal transport layer, as it lags behind electronics as far as signal processing is concerned. This situation will change in the near future as the tremendous growth of data traffic requires energy efficient and ful...

  14. Ultra-high-speed optical signal processing of serial data signals

    DEFF Research Database (Denmark)

    Clausen, Anders; Mulvad, Hans Christian Hansen; Palushani, Evarist

    2012-01-01

    To ensure that ultra high-speed serial data signals can be utilised in future optical communication networks, it is indispensable to have all-optical signal processing elements at our disposal. In this paper, the most recent advances in our use of non-linear materials incorporated in different...... function blocks for high-speed signal processing are reviewed....

  15. Recent Advances in Ultra-High-Speed Optical Signal Processing

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Palushani, Evarist; Hu, Hao

    2012-01-01

    We review recent advances in the optical signal processing of ultra-high-speed serial data signals up to 1.28 Tbit/s, with focus on applications of time-domain optical Fourier transformation. Experimental methods for the generation of symbol rates up to 1.28 Tbaud are also described....

  16. High-speed signal processing using highly nonlinear optical fibres

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Oxenløwe, Leif Katsuo; Mulvad, Hans Christian Hansen

    2009-01-01

    We review recent progress in all-optical signal processing techniques making use of conventional silica-based highly nonlinear fibres. In particular, we focus on recent demonstrations of ultra-fast processing at 640 Gbit/s and above, as well as on signal processing of novel modulation formats...... relying on the phase of the optical field. Topics covered include all-optical switching of 640 Gbit/s and 1.28 Tbit/s serial data, wavelength conversion at 640 Gbit/s, optical amplitude regeneration of differential phase shift keying (DPSK) signals, as well as midspan spectral inversion for differential 8...

  17. Encoding an Optical Signal using a Wireless Radio-Freqency Signal

    DEFF Research Database (Denmark)

    2011-01-01

    Source: US2012148252A The present invention provides a method for modulating an optical signal in a semiconductor device. A wireless radio frequency modulation signal is used to provide a time-dependent electric field in a semiconductor nanostructure region, which causes a change in the absorption...... in the semiconductor device. An optical signal propagating in the semiconductor device will be modulated in accordance with the properties of the wireless radio frequency modulation signal, thus providing a method for encoding information from a wireless radio frequency signal onto an optical carrier....

  18. Advanced Optical Signal Processing using Time Lens based Optical Fourier Transformation

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Lillieholm, Mads

    2016-01-01

    An overview of recent progress on time lens based advanced optical signal processing is presented, with a special focus on all-optical ultrafast 640 Gbit/s all-channel serial-to-parallel conversion, and scalable WDM regeneration....

  19. Non-invasive Optical Biosensor for Probing Cell Signaling

    Directory of Open Access Journals (Sweden)

    Ye Fang

    2007-10-01

    Full Text Available Cell signaling mediated through a cellular target is encoded by spatial andtemporal dynamics of downstream signaling networks. The coupling of temporal dynamicswith spatial gradients of signaling activities guides cellular responses upon stimulation.Monitoring the integration of cell signaling in real time, if realized, would provide a newdimension for understanding cell biology and physiology. Optical biosensors includingresonant waveguide grating (RWG biosensor manifest a physiologically relevant andintegrated cellular response related to dynamic redistribution of cellular matters, thusproviding a non-invasive means for cell signaling study. This paper reviews recentprogresses in biosensor instrumentation, and theoretical considerations and potentialapplications of optical biosensors for whole cell sensing.

  20. Semiconductor quantum dot amplifiers for optical signal processing

    DEFF Research Database (Denmark)

    Berg, Tommy Winther; Uskov, A. V.; Bischoff, Svend

    2001-01-01

    The dynamics of quantum dot semiconductor amplifiers are investigated theoretically with respect to the potential for ultrafast signal processing. The high-speed signal processing capacity of these devices is found to be limited by the wetting layer dynamics in case of electrical pumping, while...... optical pumping partly removes this limitation. Also, the possibility of using spectral hole burning for signal processing is discussed....

  1. All-optical WDM Regeneration of DPSK Signals using Optical Fourier Transformation and Phase Sensitive Amplification

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Kjøller, Niels-Kristian

    2015-01-01

    We propose a novel all-optical WDM regeneration scheme for DPSK signals based on optical Fourier transformation and phase sensitive amplification. Phase regeneration of a WDM signal consisting of 4x10-Gbit/s phase noise degraded DPSK channels is demonstrated for the first time.......We propose a novel all-optical WDM regeneration scheme for DPSK signals based on optical Fourier transformation and phase sensitive amplification. Phase regeneration of a WDM signal consisting of 4x10-Gbit/s phase noise degraded DPSK channels is demonstrated for the first time....

  2. Optical unmasking of spectrally overlapping RF signals.

    Science.gov (United States)

    Loh, William; Yegnanarayanan, Siva; Kolodziej, Kenneth E; Juodawlkis, Paul W

    2017-10-30

    When two signals having overlapping frequency content are received at the same time, they interfere to obstruct detection of the information carried by each individual signal. We introduce here a new nonlinear optoelectronic filtering technique that enables the ability to individually detect two concurrent and spectrally overlapping signals, even when the amplitude ratio between the signals is as high as 100,000. We demonstrate our system for application in steganography where we unveil the information carried by a hidden desired RF signal, while a dominant interferer signal is intentionally transmitted nearby and at the same frequency. Our signal recovery technique, which operates assuming no a priori knowledge of either signal, presents an additional pathway that can be used to control how information can be processed and communicated.

  3. Energy-Efficient Optical Signal Processing Using Optical Time Lenses

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2015-01-01

    . Combining time lenses into telescopic arrangements allows for more advanced signal processing, such as temporal or spectral compression or magnification. A spectral telescope may for instance allow for conversion of OFDM signals to DWDM-like signals, which can be separated passively, i.e. without additional...

  4. Optical signal processing by silicon photonics

    CERN Document Server

    Ahmed, Jameel; Adeel, Freeha; Hussain, Ashiq

    2014-01-01

    The main objective of this book is to make respective graduate students understand the nonlinear effects inside SOI waveguide and possible applications of SOI waveguides in this emerging research area of optical fibre communication. This book focuses on achieving successful optical frequency shifting by Four Wave Mixing (FWM) in silicon-on-insulator (SOI) waveguide by exploiting a nonlinear phenomenon.

  5. Non-Invasive Optical Biosensor for Probing Cell Signaling

    OpenAIRE

    Fang, Ye

    2007-01-01

    Cell signaling mediated through a cellular target is encoded by spatial and temporal dynamics of downstream signaling networks. The coupling of temporal dynamics with spatial gradients of signaling activities guides cellular responses upon stimulation. Monitoring the integration of cell signaling in real time, if realized, would provide a new dimension for understanding cell biology and physiology. Optical biosensors including resonant waveguide grating (RWG) biosensor manifest a physiologica...

  6. Optical frequency upconversion technique for transmission of wireless MIMO-type signals over optical fiber.

    Science.gov (United States)

    Shaddad, R Q; Mohammad, A B; Al-Gailani, S A; Al-Hetar, A M

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

  7. Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber

    Directory of Open Access Journals (Sweden)

    R. Q. Shaddad

    2014-01-01

    Full Text Available The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO signals feeding multiple antennas in the fiber wireless (FiWi system. A novel optical frequency upconversion (OFU technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF. The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM. The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength.

  8. Optical Frequency Upconversion Technique for Transmission of Wireless MIMO-Type Signals over Optical Fiber

    Science.gov (United States)

    Shaddad, R. Q.; Mohammad, A. B.; Al-Gailani, S. A.; Al-Hetar, A. M.

    2014-01-01

    The optical fiber is well adapted to pass multiple wireless signals having different carrier frequencies by using radio-over-fiber (ROF) technique. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber, such as wireless multi-input multi-output (MIMO) signals feeding multiple antennas in the fiber wireless (FiWi) system. A novel optical frequency upconversion (OFU) technique is proposed to solve this problem. In this paper, the novel OFU approach is used to transmit three wireless MIMO signals over a 20 km standard single mode fiber (SMF). The OFU technique exploits one optical source to produce multiple wavelengths by delivering it to a LiNbO3 external optical modulator. The wireless MIMO signals are then modulated by LiNbO3 optical intensity modulators separately using the generated optical carriers from the OFU process. These modulators use the optical single-sideband with carrier (OSSB+C) modulation scheme to optimize the system performance against the fiber dispersion effect. Each wireless MIMO signal is with a 2.4 GHz or 5 GHz carrier frequency, 1 Gb/s data rate, and 16-quadrature amplitude modulation (QAM). The crosstalk between the wireless MIMO signals is highly suppressed, since each wireless MIMO signal is carried on a specific optical wavelength. PMID:24772009

  9. Optical signal processing using electro-absorption modulators

    DEFF Research Database (Denmark)

    Mørk, Jesper; Romstad, Francis Pascal; Højfeldt, Sune

    2003-01-01

    Reverse-biased semiconductor waveguides are efficient saturable absorbers and have a number of promising all-optical signal processing applications. Results on ultrafast modulator dynamics as well as demonstrations and investigations of wavelength conversion and regeneration are presented....

  10. All-optical microwave signal processing based on optical phase modulation

    Science.gov (United States)

    Zeng, Fei

    This thesis presents a theoretical and experimental study of optical phase modulation and its applications in all-optical microwave signal processing, which include all-optical microwave filtering, all-optical microwave mixing, optical code-division multiple-access (CDMA) coding, and ultrawideband (UWB) signal generation. All-optical microwave signal processing can be considered as the use of opto-electronic devices and systems to process microwave signals in the optical domain, which provides several significant advantages such as low loss, low dispersion, light weight, high time bandwidth products, and immunity to electromagnetic interference. In conventional approaches, the intensity of an optical carrier is modulated by a microwave signal based on direct modulation or external modulation. The intensity-modulated optical signal is then fed to a photonic circuit or system to achieve specific signal processing functionalities. The microwave signal being processed is usually obtained based on direct detection, i.e., an opto-electronic conversion by use of a photodiode. In this thesis, the research efforts are focused on the optical phase modulation and its applications in all-optical microwave signal processing. To avoid using coherent detection which is complicated and costly, simple and effective phase modulation to intensity modulation (PM-IM) conversion schemes are pursued. Based on a theoretical study of optical phase modulation, two approaches to achieving PM-IM conversions are proposed. In the first approach, the use of chromatic dispersion induced by a dispersive device to alter the phase relationships among the sidebands and the optical carrier of a phase-modulated optical signal to realize PM-IM conversion is investigated. In the second approach, instead of using a dispersive device, the PM-IM conversion is realized based on optical frequency discrimination implemented using an optical filter. We show that the proposed PM-IM conversion schemes can be

  11. Recent Advancements in Semiconductor-based Optical Signal Processing

    DEFF Research Database (Denmark)

    Nielsen, M L; Mørk, Jesper

    2006-01-01

    Significant advancements in technology and basic understanding of device physics are bringing optical signal processing closer to a commercial breakthrough. In this paper we describe the main challenges in high-speed SOA-based switching.......Significant advancements in technology and basic understanding of device physics are bringing optical signal processing closer to a commercial breakthrough. In this paper we describe the main challenges in high-speed SOA-based switching....

  12. High-speed optical signal processing using time lenses

    DEFF Research Database (Denmark)

    Galili, Michael; Hu, Hao; Guan, Pengyu

    2015-01-01

    This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

  13. Estimating the Spectral Width of a Narrowband Optical Signal

    DEFF Research Database (Denmark)

    Lading, Lars; Skov Jensen, A.

    1980-01-01

    Methods for estimating the spectral width of a narrowband optical signal are investigated. Spectral analysis and Fourier spectroscopy are compared. Optimum and close-to-optimum estimators are developed under the constraint of having only one photodetector.......Methods for estimating the spectral width of a narrowband optical signal are investigated. Spectral analysis and Fourier spectroscopy are compared. Optimum and close-to-optimum estimators are developed under the constraint of having only one photodetector....

  14. All-Optical Signal Processing using Silicon Devices

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Pu, Minhao; Ding, Yunhong

    2014-01-01

    This paper presents an overview of recent wo rk on the use of silicon waveguides for processing optical data signals. We will describe ultra-fast, ultra-broadband, polarisation-insensitive and phase-sensitive applications including processing of spectrally-efficient data formats and optical phase...

  15. Fast optical signal processing in high bit rate OTDM systems

    DEFF Research Database (Denmark)

    Poulsen, Henrik Nørskov; Jepsen, Kim Stokholm; Clausen, Anders

    1998-01-01

    As all-optical signal processing is maturing, optical time division multiplexing (OTDM) has also gained interest for simple networking in high capacity backbone networks. As an example of a network scenario we show an OTDM bus interconnecting another OTDM bus, a single high capacity user represen...

  16. Optical signal processing techniques and applications of optical phase modulation in high-speed communication systems

    Science.gov (United States)

    Deng, Ning

    In recent years, optical phase modulation has attracted much research attention in the field of fiber optic communications. Compared with the traditional optical intensity-modulated signal, one of the main merits of the optical phase-modulated signal is the better transmission performance. For optical phase modulation, in spite of the comprehensive study of its transmission performance, only a little research has been carried out in terms of its functions, applications and signal processing for future optical networks. These issues are systematically investigated in this thesis. The research findings suggest that optical phase modulation and its signal processing can greatly facilitate flexible network functions and high bandwidth which can be enjoyed by end users. In the thesis, the most important physical-layer technology, signal processing and multiplexing, are investigated with optical phase-modulated signals. Novel and advantageous signal processing and multiplexing approaches are proposed and studied. Experimental investigations are also reported and discussed in the thesis. Optical time-division multiplexing and demultiplexing. With the ever-increasing demand on communication bandwidth, optical time division multiplexing (OTDM) is an effective approach to upgrade the capacity of each wavelength channel in current optical systems. OTDM multiplexing can be simply realized, however, the demultiplexing requires relatively complicated signal processing and stringent timing control, and thus hinders its practicability. To tackle this problem, in this thesis a new OTDM scheme with hybrid DPSK and OOK signals is proposed. Experimental investigation shows this scheme can greatly enhance the demultiplexing timing misalignment and improve the demultiplexing performance, and thus make OTDM more practical and cost effective. All-optical signal processing. In current and future optical communication systems and networks, the data rate per wavelength has been approaching

  17. Nonlinear optical polymers for electro-optic signal processing

    Science.gov (United States)

    Lindsay, Geoffrey A.

    1991-01-01

    Photonics is an emerging technology, slated for rapid growth in communications systems, sensors, imagers, and computers. Its growth is driven by the need for speed, reliability, and low cost. New nonlinear polymeric materials will be a key technology in the new wave of photonics devices. Electron-conjubated polymeric materials offer large electro-optic figures of merit, ease of processing into films and fibers, ruggedness, low cost, and a plethora of design options. Several new broad classes of second-order nonlinear optical polymers were developed at the Navy's Michelson Laboratory at China Lake, California. Polar alignment in thin film waveguides was achieved by electric-field poling and Langmuir-Blodgett processing. Our polymers have high softening temperatures and good aging properties. While most of the films can be photobleached with ultraviolet (UV) light, some have excellent stability in the 500-1600 nm range, and UV stability in the 290-310 nm range. The optical nonlinear response of these polymers is subpicosecond. Electro-optic switches, frequency doublers, light modulators, and optical data storage media are some of the device applications anticipated for these polymers.

  18. Optical signal acquisition and processing in future accelerator diagnostics

    International Nuclear Information System (INIS)

    Jackson, G.P.; Elliott, A.

    1992-01-01

    Beam detectors such as striplines and wall current monitors rely on matched electrical networks to transmit and process beam information. Frequency bandwidth, noise immunity, reflections, and signal to noise ratio are considerations that require compromises limiting the quality of the measurement. Recent advances in fiber optics related technologies have made it possible to acquire and process beam signals in the optical domain. This paper describes recent developments in the application of these technologies to accelerator beam diagnostics. The design and construction of an optical notch filter used for a stochastic cooling system is used as an example. Conceptual ideas for future beam detectors are also presented

  19. SCOOP - Semiconductor COmponents for Optical signal Processing

    DEFF Research Database (Denmark)

    Mørk, Jesper; Yvind, Kresten; Oxenløwe, Leif Katsuo

    2001-01-01

    Opto-electronic semiconductor devices operating at very high bitrates play a central role in the continued expansion of the transmission capacity of optical communication systems. A number of different devices based on quantum well structures have been manufactured within the framework of the nat......Opto-electronic semiconductor devices operating at very high bitrates play a central role in the continued expansion of the transmission capacity of optical communication systems. A number of different devices based on quantum well structures have been manufactured within the framework...

  20. Sensing RF signals with the optical wideband converter

    Science.gov (United States)

    Valley, George C.; Sefler, George A.; Shaw, T. J.

    2013-01-01

    The optical wideband converter (OWC) is a system for measuring properties of RF signals in the GHz band without use of high speed electronics. In the OWC the RF signal is modulated on a repetitively pulsed optical field with a large wavelength chirp, the optical field is diffracted onto a spatial light modulator (SLM) whose pixels are modulated with a pseudo-random bit sequences (PRBSs), and finally the optical field is directed to a photodiode and the resulting current integrated for each PRBS. When the number of PRBSs and measurements equals the number of SLM pixels, the RF signal can be obtained in principle by multiplying the measurement vector by the inverse of the square matrix given by the PRBSs and the properties of the optics. When the number of measurements is smaller than the number of pixels, a compressive sensing (CS) measurement can be performed, and sparse RF signals can be obtained using one of the standard CS recovery algorithms such as the penalized l1 norm (also known as basis pursuit) or one of the variants of matching pursuit. Accurate reconstruction of RF signals requires good calibration of the OWC. In this paper, we present results using the OWC for RF signals consisting of 2 sinusoids recovered using 3 techniques (matrix inversion, basis pursuit, and matching pursuit). We compare results obtained with orthogonal matching pursuit with nonlinear least squares to basis pursuit with an over-complete dictionary.

  1. Digital Signal Processing for Optical Coherent Communication Systems

    DEFF Research Database (Denmark)

    Zhang, Xu

    In this thesis, digital signal processing (DSP) algorithms are studied to compensate for physical layer impairments in optical fiber coherent communication systems. The physical layer impairments investigated in this thesis include optical fiber chromatic dispersion, polarization demultiplexing......, light sources frequency and phase offset and phase noise. The studied DSP algorithms are considered as key building blocks in digital coherent receivers for the next generation of optical communication systems such as 112-Gb/s dual polarization (DP) quadrature phase shift keying (QPSK) optical...... spectrum narrowing tolerance 112-Gb/s DP-QPSK optical coherent systems using digital adaptive equalizer. The demonstrated results show that off-line DSP algorithms are able to reduce the bit error rate (BER) penalty induced by signal spectrum narrowing. Third, we also investigate bi...

  2. Nonlinear Silicon Photonic Signal Processing Devices for Future Optical Networks

    Directory of Open Access Journals (Sweden)

    Cosimo Lacava

    2017-01-01

    Full Text Available In this paper, we present a review on silicon-based nonlinear devices for all optical nonlinear processing of complex telecommunication signals. We discuss some recent developments achieved by our research group, through extensive collaborations with academic partners across Europe, on optical signal processing using silicon-germanium and amorphous silicon based waveguides as well as novel materials such as silicon rich silicon nitride and tantalum pentoxide. We review the performance of four wave mixing wavelength conversion applied on complex signals such as Differential Phase Shift Keying (DPSK, Quadrature Phase Shift Keying (QPSK, 16-Quadrature Amplitude Modulation (QAM and 64-QAM that dramatically enhance the telecom signal spectral efficiency, paving the way to next generation terabit all-optical networks.

  3. Radar signal transmission and switching over optical networks

    Science.gov (United States)

    Esmail, Maged A.; Ragheb, Amr; Seleem, Hussein; Fathallah, Habib; Alshebeili, Saleh

    2018-03-01

    In this paper, we experimentally demonstrate a radar signal distribution over optical networks. The use of fiber enables us to distribute radar signals to distant sites with a low power loss. Moreover, fiber networks can reduce the radar system cost, by sharing precise and expensive radar signal generation and processing equipment. In order to overcome the bandwidth challenges in electrical switches, a semiconductor optical amplifier (SOA) is used as an all-optical device for wavelength conversion to the desired port (or channel) of a wavelength division multiplexing (WDM) network. Moreover, the effect of chromatic dispersion in double sideband (DSB) signals is combated by generating optical single sideband (OSSB) signals. The optimal values of the SOA device parameters required to generate an OSSB with a high sideband suppression ratio (SSR) are determined. We considered various parameters such as injection current, pump power, and probe power. In addition, the effect of signal wavelength conversion and transmission over fiber are studied in terms of signal dynamic range.

  4. Demonstration of optical steganography transmission using temporal phase coded optical signals with spectral notch filtering.

    Science.gov (United States)

    Hong, Xuezhi; Wang, Dawei; Xu, Lei; He, Sailing

    2010-06-07

    A novel approach is proposed and experimentally demonstrated for optical steganography transmission in WDM networks using temporal phase coded optical signals with spectral notch filtering. A temporal phase coded stealth channel is temporally and spectrally overlaid onto a public WDM channel. Direct detection of the public channel is achieved in the presence of the stealth channel. The interference from the public channel is suppressed by spectral notching before the detection of the optical stealth signal. The approach is shown to have good compatibility and robustness to the existing WDM network for optical steganography transmission.

  5. Pulse shaping for all-optical signal processing of ultra-high bit rate serial data signals

    DEFF Research Database (Denmark)

    Palushani, Evarist

    The following thesis concerns pulse shaping and optical waveform manipulation for all-optical signal processing of ultra-high bit rate serial data signals, including generation of optical pulses in the femtosecond regime, serial-to-parallel conversion and terabaud coherent optical time division...

  6. Adaptive optics for enhanced signal in CARS microscopy.

    Science.gov (United States)

    Wright, A J; Poland, S P; Girkin, J M; Freudiger, C W; Evans, C L; Xie, X S

    2007-12-24

    We report the use of adaptive optics with coherent anti-Stokes Raman scattering (CARS) microscopy for label-free deep tissue imaging based on molecular vibrational spectroscopy. The setup employs a deformable membrane mirror and a random search optimization algorithm to improve signal intensity and image quality at large sample depths. We demonstrate the ability to correct for both system and sample-induced aberrations in test samples as well as in muscle tissue in order to enhance the CARS signal. The combined system and sample-induced aberration correction increased the signal by an average factor of approximately 3x for the test samples at a depth of 700 microm and approximately 6x for muscle tissue at a depth of 260 microm. The enhanced signal and higher penetration depth offered by adaptive optics will augment CARS microscopy as an in vivo and in situ biomedical imaging modality.

  7. Fiber fault location utilizing traffic signal in optical network.

    Science.gov (United States)

    Zhao, Tong; Wang, Anbang; Wang, Yuncai; Zhang, Mingjiang; Chang, Xiaoming; Xiong, Lijuan; Hao, Yi

    2013-10-07

    We propose and experimentally demonstrate a method for fault location in optical communication network. This method utilizes the traffic signal transmitted across the network as probe signal, and then locates the fault by correlation technique. Compared with conventional techniques, our method has a simple structure and low operation expenditure, because no additional device is used, such as light source, modulator and signal generator. The correlation detection in this method overcomes the tradeoff between spatial resolution and measurement range in pulse ranging technique. Moreover, signal extraction process can improve the location result considerably. Experimental results show that we achieve a spatial resolution of 8 cm and detection range of over 23 km with -8-dBm mean launched power in optical network based on synchronous digital hierarchy protocols.

  8. Nonlinear Optical Signal Processing for Tbit/s Ethernet Applications

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2012-01-01

    detection in a delay-interferometer-balanced detector-based receiver, yielding a BER less than 10−9. We also present subsystems making serial optical Tbit/s systems compatible with standard Ethernet data for data centre applications and present Tbit/s results using, for instance silicon nanowires.......We review recent experimental demonstrations of Tbaud optical signal processing. In particular, we describe a successful 1.28 Tbit/s serial data generation based on single polarization 1.28 Tbaud symbol rate pulses with binary data modulation (OOK) and subsequent all-optical demultiplexing. We also...

  9. Reconstruction of temporal signals from nonlinear-optical measurements

    International Nuclear Information System (INIS)

    Kuznetsova, Tatiana I; Walmsley, I A

    1998-01-01

    A novel approach is proposed for reconstruction of the temporal characteristics of radiation from the results of nonlinear-optical measurements. A description is given of an algorithm for the processing of a two-dimensional set of data, based on inversion of the Gabor transform. This algorithm makes it possible to reconstruct arbitrary temporal signals, including multipulse signals, in the absence of any a priori information on their profile. (laser applications and other topics in quantum electronics)

  10. Event-related functional MRI: implications for cognitive psychology.

    Science.gov (United States)

    D'Esposito, M; Zarahn, E; Aguirre, G K

    1999-01-01

    Functional magnetic resonance imaging (fMRI) has rapidly emerged as a powerful technique in cognitive neuroscience. We describe and critique a new class of imaging experimental designs called event-related fMRI that exploit the temporal resolution of fMRI by modeling fMRI signal changes associated with behavioral trials as opposed to blocks of behavioral trials. Advantages of this method over block designs include the ability to (a) randomize trial presentations, (b) test for functional correlates of behavioral measures with greater power, (c) directly examine the neural correlates of temporally dissociable components of behavioral trials (e.g., the delay period of a working memory task), and (d) test for differences in the onset time of neural activity evoked by different trial types. Consequently, event-related fMRI has the potential to address a number of cognitive psychology questions with a degree of inferential and statistical power not previously available.

  11. Studying overt word reading and speech production with event-related fMRI: a method for detecting, assessing, and correcting articulation-induced signal changes and for measuring onset time and duration of articulation.

    Science.gov (United States)

    Huang, Jie; Francis, Andrea P; Carr, Thomas H

    2008-01-01

    A quantitative method is introduced for detecting and correcting artifactual signal changes in BOLD time series data arising from the magnetic field warping caused by motion of the articulatory apparatus when speaking aloud, with extensions to detection of subvocal articulatory activity during silent reading. Whole-head images allow the large, spike-like signal changes from the moving tongue and other components of the articulatory apparatus to be detected and localized in time, providing a measure of the time of vocalization onset, the vocalization duration, and also an estimate of the magnitude and shape of the signal change resulting from motion. Data from brain voxels are then examined during the vocalization period, and statistical outliers corresponding to contamination from articulatory motion are removed and replaced by linear interpolation from adjacent, uncontaminated data points. This quantitative approach to cleansing brain time series data of articulatory-motion-induced artifact is combined with a pre-scanning training regimen that reduces gross head movement during reading aloud to the levels observed during reading silently, which can be corrected with available image registration techniques. The combination of quantitative analysis of articulatory motion artifacts and pre-scanning training makes possible a much wider range of tasks involving overt speech than are currently being used in fMRI studies of language and cognition, as well as characterization of subvocal movements of the articulatory apparatus that are relevant to theories of reading skill, verbal rehearsal in working memory, and problem solving.

  12. Optical Signal Processing; a novel approach to modifying digital information in optical domain

    NARCIS (Netherlands)

    Rijnders, J.M.

    1998-01-01

    It is concluded that the OSP offers a new and alternative method for manipulating and modifying data in the optical domain. Under certain circumstances during signal processing, a number of signal properties such as wavelength and modulation format can be preserved. Interesting applications can be

  13. Ultra-high-speed Optical Signal Processing using Silicon Photonics

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Ji, Hua; Jensen, Asger Sellerup

    with a photonic layer on top to interconnect them. For such systems, silicon is an attractive candidate enabling both electronic and photonic control. For some network scenarios, it may be beneficial to use optical on-chip packet switching, and for high data-density environments one may take advantage...... of the ultra-fast nonlinear response of silicon photonic waveguides. These chips offer ultra-broadband wavelength operation, ultra-high timing resolution and ultra-fast response, and when used appropriately offer energy-efficient switching. In this presentation we review some all-optical functionalities based...... on silicon photonics. In particular we use nano-engineered silicon waveguides (nanowires) [1] enabling efficient phasematched four-wave mixing (FWM), cross-phase modulation (XPM) or self-phase modulation (SPM) for ultra-high-speed optical signal processing of ultra-high bit rate serial data signals. We show...

  14. Demultiplexing of OTDM-DPSK signals based on a single semiconductor optical amplifier and optical filtering

    DEFF Research Database (Denmark)

    Xu, Jing; Ding, Yunhong; Peucheret, Christophe

    2011-01-01

    We propose and demonstrate the use of a single semiconductor optical amplifier (SOA) and optical filtering to time demultiplex tributaries from an optical time division multiplexing-differential phase shift keying (OTDM-DPSK) signal. The scheme takes advantage of the fact that phase variations...... added to the target channel by cross-phase modulation from the control signal are effectively subtracted in the differential demodulation scheme employed for DPSK signals. Demultiplexing from 80 to 40 Gbit=s is demonstrated with moderate power penalty using an SOA with recovery time twice as long...... as the bit period at 80 Gbit=s. Large dynamic ranges for the input power and SOA current are experimentally demonstrated. The scheme is expected to be scalable toward higher bit rates. © 2011 Optical Society of America....

  15. An integrated nonlinear optical loop mirror in silicon photonics for all-optical signal processing

    Directory of Open Access Journals (Sweden)

    Zifei Wang

    2018-02-01

    Full Text Available The nonlinear optical loop mirror (NOLM has been studied for several decades and has attracted considerable attention for applications in high data rate optical communications and all-optical signal processing. The majority of NOLM research has focused on silica fiber-based implementations. While various fiber designs have been considered to increase the nonlinearity and manage dispersion, several meters to hundreds of meters of fiber are still required. On the other hand, there is increasing interest in developing photonic integrated circuits for realizing signal processing functions. In this paper, we realize the first-ever passive integrated NOLM in silicon photonics and demonstrate its application for all-optical signal processing. In particular, we show wavelength conversion of 10 Gb/s return-to-zero on-off keying (RZ-OOK signals over a wavelength range of 30 nm with error-free operation and a power penalty of less than 2.5 dB, we achieve error-free nonreturn to zero (NRZ-to-RZ modulation format conversion at 10 Gb/s also with a power penalty of less than 2.8 dB, and we obtain error-free all-optical time-division demultiplexing of a 40 Gb/s RZ-OOK data signal into its 10 Gb/s tributary channels with a maximum power penalty of 3.5 dB.

  16. A comparison of signal processing techniques for Intrinsic Optical Signal imaging in mice.

    Science.gov (United States)

    Turley, Jordan A; Nilsson, Michael; Walker, Frederick Rohan; Johnson, Sarah J

    2015-01-01

    Intrinsic Optical Signal imaging is a technique which allows the visualisation and mapping of activity related changes within the brain with excellent spatial and temporal resolution. We analysed a variety of signal and image processing techniques applied to real mouse imaging data. The results were compared in an attempt to overcome the unique issues faced when performing the technique on mice and improve the understanding of post processing options available.

  17. Embodiment of Learning in Electro-Optical Signal Processors.

    Science.gov (United States)

    Hermans, Michiel; Antonik, Piotr; Haelterman, Marc; Massar, Serge

    2016-09-16

    Delay-coupled electro-optical systems have received much attention for their dynamical properties and their potential use in signal processing. In particular, it has recently been demonstrated, using the artificial intelligence algorithm known as reservoir computing, that photonic implementations of such systems solve complex tasks such as speech recognition. Here, we show how the backpropagation algorithm can be physically implemented on the same electro-optical delay-coupled architecture used for computation with only minor changes to the original design. We find that, compared to when the backpropagation algorithm is not used, the error rate of the resulting computing device, evaluated on three benchmark tasks, decreases considerably. This demonstrates that electro-optical analog computers can embody a large part of their own training process, allowing them to be applied to new, more difficult tasks.

  18. Event related potentials in children of alcoholics.

    Science.gov (United States)

    Naziel, B; Yavaş, G; Arikan, Z; Ozon, O; Aksoy Ozmenek, O; Irkeç, C

    2007-09-01

    Assessment of ERPs (Event Related Potentials) is a special area of interest in research on vulnerability to alcoholism in human subjects. ERP not only provide information about potential neurofunctional anomalies in healthy individuals, but also relate those neurofunctional characteristics to the cognitive process involved. The aim of the present study is to evaluate the effects of chronic alcoholism and alcoholism risk on children of alcoholic fathers by using ERP parameters. 24 children of alcoholic fathers (9 boys, 15 girls) with a mean age of 18 +/- 3 (range: 15-25) and 17 control subjects (children of non-alcoholic fathers with out a family history of alcoholism) were included to the study. The age range was from 15 to 25 (mean: 21 +/- 3). N200 potential latency recorded from the parietal electrode position was significantly prolonged (p = 0.032) and amplitudes of P200 potential also recorded from the parietal region was significantly low (p = 0.043) relative to controls. However, the rest of the event-related potential parameters including P300 latency and amplitudes recorded from FZ, CZ, PZ electrode positions did not differ significantly from the children of non-alcoholic fathers. The difference in our results from the previous studies may be due to various factors. Genetic, gender, environmental, educational and social factors may have an overall effect on ERP and we believe these factors may be the cause of the differences seen in our study when compared to the previous ones. We believe the gender differences in our group may have had effected the overall results. Consecutive studies with more subject participation are needed to confirm and settle this issue.

  19. Precise timing signal transmission by a new optical fiber cable

    International Nuclear Information System (INIS)

    Tanaka, Shigeru; Murakami, Yasunori; Sato, Yoshihiro; Urakawa, Junji.

    1990-05-01

    For the precise timing signal transmission, a new optical fiber cable system was developed and installed between the 2.5GeV LINAC gun room and the TRISTAN control room. This fiber cable showed the reduced thermal transmission delay change less than 10psec/km in the temperature range from -20 to 30degC (average 0.04ppm/degC), which is 100 times smaller than that of any other existing coaxial cables and conventional optical fiber cables. The developed optical to electrical (O/E) and electrical to optical (E/O) converters also achieved the timing accuracy within 11psec over the temperature range from 10 to 35degC. The installed cable system in KEK eliminated the necessity of adjusting the phase drift of the TRISTAN Accumulation Ring (AR) RF signal (508MHz), which was required with the former coaxial cable due to the temperature change in a year. Measured full width of jitter over the installed 1600m fiber link was 18.8psec. (author)

  20. Removal of pedestals and directional ambiguity of optical anemometer signals.

    Science.gov (United States)

    Durst, F; Zaré, M

    1974-11-01

    Laser Doppler anemometry permits, in principle, the measurement of both magnitude and direction of components of a particle's velocity vector. Most exiting anemometers, however, permit measurements only with a directional ambiguity of 180 degrees , resulting in errors in certain flow fields. Available methods of eliminating the directional ambiguity of Laser Doppler anemometers are reviewed, covering frequency shifting of the incident and scattered light beams, the use of beams with different polarization properties, and employment of multicolor laser beams. The advantages and disadvantages of existing methods are summarized, and suggestions for alterations are made. Different techniques used to remove the pedestal of laser Doppler anemometer signals are also reviewed. Optical techniques should be employed in any advanced optical anemometer system to avoid dynamic range limitations by electronic bandpass filters. Suggestions are made for advanced optical anemometers employing multielement avalanche photodiodes that can be used for simultaneous measurements of two velocity components. These anemometers incorporate devices to sense the direction of the velocity components and to eliminate optically the pedestal of laser Doppler signals.

  1. Ultra-broadband optical signal processing using AlGaAs-OI devices

    DEFF Research Database (Denmark)

    Galili, Michael; Da Ros, Francesco; Hu, Hao

    2017-01-01

    Aluminum Gallium Arsenide on insulator (AlGaAs-OI) has recently been developed into a very attractive platform for optical signal processing. This paper reviews key results of broadband optical signal processing using this platform.......Aluminum Gallium Arsenide on insulator (AlGaAs-OI) has recently been developed into a very attractive platform for optical signal processing. This paper reviews key results of broadband optical signal processing using this platform....

  2. Optical modulation techniques for analog signal processing and CMOS compatible electro-optic modulation

    Science.gov (United States)

    Gill, Douglas M.; Rasras, Mahmoud; Tu, Kun-Yii; Chen, Young-Kai; White, Alice E.; Patel, Sanjay S.; Carothers, Daniel; Pomerene, Andrew; Kamocsai, Robert; Beattie, James; Kopa, Anthony; Apsel, Alyssa; Beals, Mark; Mitchel, Jurgen; Liu, Jifeng; Kimerling, Lionel C.

    2008-02-01

    Integrating electronic and photonic functions onto a single silicon-based chip using techniques compatible with mass-production CMOS electronics will enable new design paradigms for existing system architectures and open new opportunities for electro-optic applications with the potential to dramatically change the management, cost, footprint, weight, and power consumption of today's communication systems. While broadband analog system applications represent a smaller volume market than that for digital data transmission, there are significant deployments of analog electro-optic systems for commercial and military applications. Broadband linear modulation is a critical building block in optical analog signal processing and also could have significant applications in digital communication systems. Recently, broadband electro-optic modulators on a silicon platform have been demonstrated based on the plasma dispersion effect. The use of the plasma dispersion effect within a CMOS compatible waveguide creates new challenges and opportunities for analog signal processing since the index and propagation loss change within the waveguide during modulation. We will review the current status of silicon-based electrooptic modulators and also linearization techniques for optical modulation.

  3. Improving Multi Access Interference Suppression in Optical CDMA by using all-Optical Signal Processing

    Directory of Open Access Journals (Sweden)

    T. B. Osadola

    2013-06-01

    Full Text Available This paper presents the study of a novel all-optical method for processing optical CDMA signals towards improving suppression of multi access interference. The main focus is on incoherent OCDMA systems using multiwavelength 2D-WH/TS codes generated using FBG based encoders and decoders. The MAI suppression capabilities based on its ability to eliminate selective wavelength pulse processing have been shown. A novel transmitter architecture that achieves up to 3dB power saving was also presented. As a result of hardware savings, processing cost will be significantly reduced and power budget improvement resulted in improved performance.

  4. Fiber-optic delay-line stabilization of heterodyne optical signal generator and method using same

    Science.gov (United States)

    Logan, Ronald T. (Inventor)

    1997-01-01

    The present invention is a laser heterodyne frequency generator system with a stabilizer for use in the microwave and millimeter-wave frequency ranges utilizing a photonic mixer as a photonic phase detector in a stable optical fiber delay-line. Phase and frequency fluctuations of the heterodyne laser signal generators are stabilized at microwave and millimeter wave frequencies by a delay line system operating as a frequency discriminator. The present invention is free from amplifier and mixer 1/.function. noise at microwave and millimeter-wave frequencies that typically limit phase noise performance in electronic cavity stabilized electronic oscillators. Thus, 1/.function. noise due to conventional mixers is eliminated and stable optical heterodyne generation of electrical signals is achieved.

  5. Silicon nanowires for ultra-fast and ultrabroadband optical signal processing

    DEFF Research Database (Denmark)

    Ji, Hua; Hu, Hao; Pu, Minhao

    2015-01-01

    In this paper, we present recent research on silicon nanowires for ultra-fast and ultra-broadband optical signal processing at DTU Fotonik. The advantages and limitations of using silicon nanowires for optical signal processing are revealed through experimental demonstrations of various optical s...

  6. Silicon Nanowires for All-Optical Signal Processing in Optical Communication

    DEFF Research Database (Denmark)

    Pu, Minhao; Hu, Hao; Ji, Hua

    2012-01-01

    and microelectronics. Silicon photonic nanowire waveguides fabricated on silicon-on-insulator (SOI) substrates are crucial elements in nano-photonic integrated circuits. The strong light confinement in nanowires induced by high index contrast SOI material enhances the nonlinear effects in the silicon nanowire core......Silicon (Si), the second most abundant element on earth, has dominated in microelectronics for many decades. It can also be used for photonic devices due to its transparency in the range of optical telecom wavelengths which will enable a platform for a monolithic integration of optics...... such as four-wave mixing (FWM) which is an imperative process for optical signal processing. Since the current mature silicon fabrication technology enables a precise dimension control on nanowires, dispersion engineering can be performed by tailoring nanowire dimensions to realize an efficient nonlinear...

  7. Cell swelling and ion redistribution assessed with intrinsic optical signals

    Directory of Open Access Journals (Sweden)

    WITTE OTTO W.

    2001-01-01

    Full Text Available Cell volume changes are associated with alterations of intrinsic optical signals (IOS. In submerged brain slices in vitro, afferent stimulation induces an increase in light transmission. As assessed by measurement of the largely membrane impermeant ion tetramethylammonium (TMA in the extracellular space, these IOS correlate with the extent and time course of the change of the extracellular space size. They have a high signal to noise ratio and allow measurements of IOS changes in the order of a few percent. Under conditions of reduced net KCl uptake (low Cl solution a directed spatial buffer mechanism (K syphoning can be demonstrated in the neocortex with widening of the extracellular space in superficial layers associated with a reduced light transmission and an increase of extracellular K concentration. The nature of the IOS under pathophysiological conditions is less clear. Spreading depressions first cause an increase of light transmission, then a decrease. Such a decrease has also been observed following application of NMDA where it was associated with structural damage. Pharmacological analyses suggest that under physiological conditions changes of extracellular space size are mainly caused by astrocytic volume changes while with strong stimuli and under pathophysiological conditions also neuronal swelling occurs. With reflected light usually signals opposite to those observed with transmitted light are seen. Recording of IOS from interface slices gives very complex signals since under these conditions an increase of light transmission has been reported to be superimposed by a decrease of the signal due to mechanical lensing effects of the slice surface. Depending on the method of measurement and the exact conditions, several mechanisms may contribute to IOS. Under well defined conditions IOS are a useful supplementary tool to monitor changes of extracellular volume both in space and time.

  8. Time Lens based Optical Fourier Transformation for All-Optical Signal Processing of Spectrally-Efficient Data

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Lillieholm, Mads

    2017-01-01

    We review recent progress in the use of time lens based optical Fourier transformation for advanced all-optical signal processing. A novel time lens based complete optical Fourier transformation (OFT) technique is introduced. This complete OFT is based on two quadratic phase-modulation stages using...

  9. Research of all-optical ultra-wideband triplet signal source based on a single semiconductor optical amplifier

    Science.gov (United States)

    Xue, Fei; Li, Pei-li; Zheng, Jia-jin; Wang, Li-li; Liang, Wei-kang

    2013-07-01

    A novel scheme for all-optical ultra-wideband triplet signal pulse generation based on the cross-gain modulation (XGM) in a single semiconductor optical amplifier (SOA) is demonstrated. In this scheme, only one optical source and one SOA are needed, so the configuration is simple. Due to only one wavelength is included in the generated triplet pulse, no time difference between output signal light and probe light is introduced during the transmission process. By using the software of Optisystem 7.0, the impacts of the input signal width, the optical power and the wavelength of the optical source on the generated triplet pulse are numerically simulated and studied. The results show that the proposed scheme has better triplet signal pulse when the input signal pulse width is larger, and it is insensitive to the wavelength change within a certain range.

  10. Detection and processing of phase modulated optical signals at 40 Gbit/s and beyond

    DEFF Research Database (Denmark)

    Geng, Yan

    This thesis addresses demodulation in direct detection systems and signal processing of high speed phase modulated signals in future all-optical wavelength division multiplexing (WDM) communication systems where differential phase shift keying (DPSK) or differential quadrature phase shift keying...... detection and all-optical signal processing -including optical labeling, wavelength conversion and signal regeneration- that already have been studied intensively for signals using conventional on-off keying (OOK) format, can also be successfully implemented for high-speed phase modulated signals...... (DQPSK) are used to transport information. All-optical network functionalities -such as optical labeling, wavelength conversion and signal regeneration- are experimentally investigated. Direct detection of phase modulated signals requires phase-to-intensity modulation conversion in a demodulator...

  11. Fiber optic signal amplifier using thermoelectric power generation

    Science.gov (United States)

    Hart, Mark M.

    1995-01-01

    A remote fiber optic signal amplifier for use as a repeater/amplifier, such as in transoceanic communications, powered by a Pu.sub.238 or Sr.sub.90 thermoelectric generator. The amplifier comprises a unit with connections on the receiving and sending sides of the communications system, and an erbium-doped fiber amplifier connecting each sending fiber to each receiving fiber. The thermoelectric generator, preferably a Pu.sub.238 or Sr.sub.90 thermoelectric generator delivers power to the amplifiers through a regulator. The heat exchange surfaces of the thermoelectric generator are made of materials resistant to corrosion and biological growth and are directly exposed to the outside, such as the ocean water in transoceanic communications.

  12. Time lens based optical fourier transformation for advanced processing of spectrally-efficient OFDM and N-WDM signals

    DEFF Research Database (Denmark)

    Guan, Pengyu; Røge, Kasper Meldgaard; Morioka, Toshio

    2016-01-01

    We review recent progress in the use of time lens based optical Fourier transformation for advanced optical signal processing, with focus on all-optical generation, detection and format conversion of spectrally-efficient OFDM and N-WDM signals.......We review recent progress in the use of time lens based optical Fourier transformation for advanced optical signal processing, with focus on all-optical generation, detection and format conversion of spectrally-efficient OFDM and N-WDM signals....

  13. Optical signal processing for enabling high-speed, highly spectrally efficient and high capacity optical systems

    Science.gov (United States)

    Fazal, Muhammad Irfan

    may be possible. Recently, interest has increased in exploring the spatial dimension of light to increase capacity, both in fiber as well as free-space communication channels. The orbital angular momentum (OAM) of light, carried by Laguerre-Gaussian (LG) beams have the interesting property that, in theory, an infinite number of OAMs can be transmitted; which due to its inherent orthogonality will not affect each other. Thus, in theory, one can increase the channel capacity arbitrarily. However, in practice, the device dimensions will reduce the number of OAMs used. In addition to advanced modulation formats, it is expected that optical signal processing may play a role in the future development of more efficient optical transmission systems. The hope is that performing signal processing in the optical domain may reduce optical-to-electronic conversion inefficiencies, eliminate bottlenecks and take advantage of the ultrahigh bandwidth inherent in optics. While 40 to 50 Gbit/s electronic components are the peak of commercial technology and 100 Gbit/s capable RF components are still in their infancy, optical signal processing of these high-speed data signals may provide a potential solution. Furthermore, any optical processing system or sub-system must be capable of handling the wide array of data formats and data rates that networks may employ. The work presented in this Ph.D. dissertation attempts at addressing the issue of optical processing for advanced optical modulation formats, and particularly explores the state of the art in increasing the capacity of an optical link by a combination of wavelength/phase/polarization/OAM dimensions of light. Spatial multiplexing and demultiplexing of both coherently and directly detected signals at the 100 Gbit/s Ethernet standard is addressed. The application of a continuously tunable all-optical delay for all-optical functionality like time-slot interchange at high data-rates is presented. Moreover the interplay of chirp

  14. Machine Learning Techniques for Optical Performance Monitoring from Directly Detected PDM-QAM Signals

    DEFF Research Database (Denmark)

    Thrane, Jakob; Wass, Jesper; Piels, Molly

    2017-01-01

    Linear signal processing algorithms are effective in dealing with linear transmission channel and linear signal detection, while the nonlinear signal processing algorithms, from the machine learning community, are effective in dealing with nonlinear transmission channel and nonlinear signal...... detection. In this paper, a brief overview of the various machine learning methods and their application in optical communication is presented and discussed. Moreover, supervised machine learning methods, such as neural networks and support vector machine, are experimentally demonstrated for in-band optical...

  15. Design and implementation of ATCA-based 100Gbps DP-QPSK optical signal test instrument

    Science.gov (United States)

    Su, Shaojing; Qin, Jiangyi; Huang, Zhiping; Liu, Chenwu

    2014-11-01

    In order to achieve the receiving task of 100Gbps Dual Polarization-Quadrature Phase Shift Keying (DP-QPSK) optical signal acquisition instrument, improve acquisition performance of the instrument, this paper has deeply researched DP-QPSK modulation principles, demodulation techniques and the key technologies of optical signal acquisition. The theories of DP-QPSK optical signal transmission are researched. The DP-QPSK optical signal transmission model is deduced. And the clock and data recovery in high-speed data acquisition and offset correction of multi-channel data are researched. By reasonable hardware circuit design and software system construction, the utilization of high performance Advanced Telecom Computing Architecture (ATCA), this paper proposes a 100Gbps DP-QPSK optical signal acquisition instrument which is based on ATCA. The implementations of key modules are presented by comparison and argumentation. According to the modularization idea, the instrument can be divided into eight modules. Each module performs the following functions. (1) DP-QPSK coherent detection demodulation module; (2) deceleration module; (3) FPGA (Field Programmable Gate Array); (4) storage module; (5) data transmission module; (6) clock module; (7) power module; (8) JTAG debugging, configuration module; What is more, this paper has put forward two solutions to test optical signal acquisition instrument performance. The first scenario is based on a standard STM-256 optical signal format and exploits the SignalTap of QuartusII software to monitor the optical signal data. Another scenario is to use a pseudo-random signal series to generate data, acquisition module acquires a certain amount of data signals, and then the signals are transferred to a computer by the Gigabit Ethernet to analyze. Two testing results show that the bit error rate of optical signal acquisition instrument is low. And the instrument fully meets the requirements of signal receiving system. At the same time

  16. Comparison of the properties of various optically stimulated luminescence signals from potassium feldspar

    International Nuclear Information System (INIS)

    Fu Xiao; Zhang Jiafu; Zhou Liping

    2012-01-01

    Various optically stimulated luminescence signals from K-feldspar have been used to determine the equivalent doses of sediment samples. Understanding the properties of these optical signals is critical to evaluate their applicability and limitations to optical dating. In this paper, some properties of IRSL, post-IR OSL and post-IR IRSL signals (detected in the UV region using U-340 filters) from a museum sample of K-feldspar were investigated by analyzing the relationships between optical and TL signals, and the effect of optical bleaching and heating on optical signals. The trap parameters of the different optical signals were calculated using the pulse annealing method. The results show that this sample exhibits two regenerated TL peaks at ∼140 and ∼330 °C. Corresponding to the low temperature TL peak, the OSL and post-IR OSL signals appear to be more associated with lower temperature TL than the IRSL signal measured at 50 °C. Corresponding to the high temperature TL peak, the post-IR IRSL signals mainly originate from the more thermally stable traps associated with the high temperature TL, compared with the IRSL and post-IR OSL signals. However, the post-IR IRSL 225°C signal is shown to be hard to be bleached by blue light and simulated sunlight, compared with the IRSL 50°C and low temperature post-IR IRSL signals. The implication for optical dating is that the elevated temperature post-IR IRSL signals can be preferentially applied over other signals from K-feldspar, but it is desirable that the effectiveness of the pre-depositional zeroing of these signals is assessed.

  17. Optically envelope detected QAM and QPSK RF modulated signals in hybrid wireless-fiber systems

    DEFF Research Database (Denmark)

    Tafur Monroy, Idelfonso; Prince, Kamau; Seoane, Jorge

    2009-01-01

    We experimentally demonstrate optical envelope detection of 40 Mbaud 16-QAM and QPSK RF modulated signals. The proposed system employs an electro-absorption modulator performing the function of an optical halfwave rectifier. In this experiment, the QAM and QPSK signals are frequency down converted...

  18. Optical signal inverter of erbium-doped yttrium aluminum garnet with red shift of laser diodes.

    Science.gov (United States)

    Maeda, Y

    1994-08-10

    An optical signal inverter was demonstrated in a simple structure that combined a laser diode with Er-doped YAG crystal. The optical signal inversion occurred at a response time of 7 ns and was caused by the decrease of transmission of Er:YAG against the red shift of the wavelength of the laser diode.

  19. Encryption and validation of multiple signals for optical identification systems

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Cabre, E [Universitat PoliteGcnica de Catalunya, Department Optica i Optometria, Violinista Vellsola 37, 08222 Terrassa (Spain); Millan, M S [Universitat PoliteGcnica de Catalunya, Department Optica i Optometria, Violinista Vellsola 37, 08222 Terrassa (Spain); Javidi, B [University of Connecticut, Electrical and Computer Engineering Department, 371 Fairfield Road, CT 06269 Storrs (United States)

    2007-07-15

    Multifactor encryption-authentication technique reinforces optical security by allowing the simultaneous A N D-verification of more than one primary image. Instead of basing the identification on a unique signature or piece of information, our goal is to authenticate a given person, object, vehicle by the simultaneous recognition of several factors. Some of them are intrinsic to the person and object or vehicle under control. Other factors, act as keys of the authentication step. Such a system is proposed for situations such as the access control to restricted areas, where the demand of security is high. The multifactor identification method involves double random-phase encoding, fully phase-based encryption and a combined nonlinear joint transform correlator and a classical 4f-correlator for simultaneous recognition and authentication of multiple images. The encoded signal fulfils the general requirements of invisible content, extreme difficulty in counterfeiting and real-time automatic verification. Four reference double-phase encoded images are compared with the retrieved input images obtained in situ from the person or the vehicle whose authentication is wanted and from a database. A recognition step based on the correlation between the signatures and the stored references determines the authentication or rejection of the person and object under surveillance.

  20. About the effects of polarising optics on lidar signals and the Δ90 calibration

    OpenAIRE

    V. Freudenthaler

    2016-01-01

    This paper provides a model for assessing the effects of polarising optics on the signals of typical lidar systems, which is based on the description of the individual optical elements of the lidar and of the state of polarisation of the light by means of the Muller-Stokes formalism. General analytical equations are derived for the dependence of the lidar signals on polarisation parameters, for the linear depolarisation ratio, and for the signals of different polarisation calibration setups. ...

  1. Harnessing mode-selective nonlinear optics for on-chip multi-channel all-optical signal processing

    Directory of Open Access Journals (Sweden)

    Ming Ma

    2016-11-01

    Full Text Available All-optical signal processing based on nonlinear optical effects allows for the realization of important functions in telecommunications including wavelength conversion, optical multiplexing/demultiplexing, Fourier transformation, and regeneration, amongst others, on ultrafast time scales to support high data rate transmission. In integrated photonic subsystems, the majority of all-optical signal processing systems demonstrated to date typically process only a single channel at a time or perform a single processing function, which imposes a serious limitation on the functionality of integrated solutions. Here, we demonstrate how nonlinear optical effects can be harnessed in a mode-selective manner to perform simultaneous multi-channel (two and multi-functional optical signal processing (i.e., regenerative wavelength conversion in an integrated silicon photonic device. This approach, which can be scaled to a higher number of channels, opens up a new degree of freedom for performing a broad range of multi-channel nonlinear optical signal processing functions using a single integrated photonic device.

  2. Suppression of phase-induced intensity noise in fibre optic delay line signal processors using an optical phase modulation technique.

    Science.gov (United States)

    Chan, Erwin H W

    2010-10-11

    A technique that can suppress the dominant phase-induced intensity noise in fibre optic delay line signal processors is presented. It is based on phase modulation of the optical carrier to distribute the phase noise at the information band into a high frequency band which can be filtered out. This technique is suitable for suppressing the phase noise in various delay line structures and for integrating in the conventional fibre optic links. It can also suppress the coherent interference effect at the same time. A model for predicting the amount of phase noise reduction in various delay line structures using the optical phase modulation technique is presented for the first time and is experimentally verified. Experimental results demonstrate the technique can achieve a large phase noise reduction in various fibre optic delay line signal processors.

  3. Quality Monitoring of Infrared Optics Using Ultrasound Signals

    Science.gov (United States)

    Neumeier, Benedikt; Schmitt-Landsiedel, Doris

    During laser processing with beam powers in the multi-kilowatt range a fraction of the emission is absorbed in optical elements, leading to thermal loading on the optics. This temperature rise of the optics results in thermal lensing, impairing the power density at the processing location. In a number of niche applications, the CO2 laser still is preferred over solid-state lasers due to its unrivaled features in processing materials like fused silica, glasses, wood, ceramics or plastics. Applying existing techniques to monitor the temperature of CO2 laser optics using pyrometers prove to be unreliable due to the transmissivity in the infrared of the optical materials used. The object of this study is experimental identification of temperature increase of ZnSe optics during use for processing in a laser cutting machine, and development of a method utilizing ultrasound to measure the temperature of the infrared optics. The method enables the testing of the absorption properties of infrared optics as well as solid-state laser optics.

  4. Asynchronous monitoring of the quality of multilevel optical PAM signals

    Science.gov (United States)

    Siuzdak, J.

    2017-08-01

    In the paper, there is analyzed the signal quality assessment method based on delay tap asynchronous sampling, both for binary and multilevel PAM signals. The obtained multilevel phase diagrams are far more complicated than binary ones. The phase diagrams are affected by the signal distortions but it is difficult to relate reliably the phase diagram form to the distortion type and its influence on the signal quality.

  5. Modeling of semiconductor devices for high-speed all-optical signal processing

    DEFF Research Database (Denmark)

    Bischoff, Svend; Højfeldt, Sune; Mørk, Jesper

    2001-01-01

    The all-optical signal processing performance of devices based on active semiconductor waveguides is investigated. A large signal model is used to analyse the physical mechanisms limiting the high-speed performance of both semiconductor optical amplifiers (SOAs) and electro-absorption modulators...... (EAMs). Wavelength conversion and signal regeneration in EAMs is discussed at 10 and 40 Gbit/s. The finite carrier sweep-out time is shown to limit the EAM performance. Four-wave mixing (FWM) in SOAs is almost instantaneous. However, with increasing bit rates and advanced processing functionalities some...... limitations arise. These limitations are elucidated by studying bi-directional simultaneous clear and drop (de-multiplexing) for a 4x40 Gbit/s signal. The simultaneous clearing and de-multiplexing (drop) of an optical time division multiplexing signal channel for an 8x40 Gbit/s signal is investigated...

  6. Modeling of semiconductor devices for high-speed all-optical signal processing

    DEFF Research Database (Denmark)

    Bischoff, Svend; Højfeldt, Sune; Mørk, Jesper

    2001-01-01

    limitations arise. These limitations are elucidated by studying bi-directional simultaneous clear and drop (de-multiplexing) for a 4x40 Gbit/s signal. The simultaneous clearing and de-multiplexing (drop) of an optical time division multiplexing signal channel for an 8x40 Gbit/s signal is investigated......The all-optical signal processing performance of devices based on active semiconductor waveguides is investigated. A large signal model is used to analyse the physical mechanisms limiting the high-speed performance of both semiconductor optical amplifiers (SOAs) and electro-absorption modulators...... (EAMs). Wavelength conversion and signal regeneration in EAMs is discussed at 10 and 40 Gbit/s. The finite carrier sweep-out time is shown to limit the EAM performance. Four-wave mixing (FWM) in SOAs is almost instantaneous. However, with increasing bit rates and advanced processing functionalities some...

  7. Optical interferometric synthesis of PAM4 signals based on dual-drive Mach-Zehnder modulation

    Science.gov (United States)

    Xu, Jianfeng; Du, Jiangbing; Ren, Rongrong; Ruan, Zhengshang; He, Zuyuan

    2017-11-01

    In this work, optical interferometric synthesis and demodulation of four-level pulse amplitude modulation (PAM4) signals by using commercial dual-drive Mach-Zehnder Modulator (DD-MZM) is proposed and studied. Simulations are carried out and signal quality is evaluated in terms of eye jitter, linearity and so on for the PAM4 signals generated by the proposed DD-MZM with improved performance unfolded. Experimental generation of the optically synthesized PAM4 signals up to 50 Gbaud (100 Gbps) is achieved. The transmission of the PAM4 signals over 5-Km standard single mode fiber (SSMF) is carried out with error-free below the FEC limit (3.8E-3) without digital equalization at 90 Gbps. The linear-amplifier-free configuration by DD-MZM leads to simplified implementation and improved performance for high speed PAM4 signal generation, which would be of great significance for short reach optical interconnection.

  8. Efficient trigger signal generation from wasted backward amplified stimulated emission at optical amplifiers for optical coherence tomography

    Directory of Open Access Journals (Sweden)

    Kim Seung Taek

    2015-01-01

    Full Text Available This paper propose an optical structure to generate trigger signals for optical coherence tomography (OCT using backward light which is usually disposed. The backward light is called backward amplified stimulated emission generated from semiconductor optical amplifier (SOA when using swept wavelength tunable laser (SWTL. A circulator is applied to block undesirable lights in the SWTL instead of an isolator in common SWTL. The circulator also diverts backward amplified spontaneous lights, which finally bring out trigger signals for a high speed digitizer. The spectra of the forward lights at SOA and the waveform of the backward lights were measured to check the procedure of the trigger formation in the experiment. The results showed that the trigger signals from the proposed SWTL with the circulator was quite usable in OCT.

  9. Machine Learning for Optical Performance Monitoring from Directly Detected PDM-QAM Signals

    DEFF Research Database (Denmark)

    Wass, J.; Thrane, Jakob; Piels, Molly

    2016-01-01

    Supervised machine learning methods are applied and demonstrated experimentally for inband OSNR estimation and modulation format classification in optical communication systems. The proposed methods accurately evaluate coherent signals up to 64QAM using only intensity information....

  10. An ultra-efficient nonlinear planar integrated platform for optical signal processing and generation

    DEFF Research Database (Denmark)

    Pu, Minhao; Ottaviano, Luisa; Semenova, Elizaveta

    2017-01-01

    This paper will discuss the recently developed integrated platform: AlGaAs-oninsulator and its broad range of nonlinear applications. Recent demonstrations of broadband optical signal processing and efficient frequency comb generations in this platform will be reviewed....

  11. Dispersion management for two-level optically labeled signals in IP-over-WDM networks 4

    DEFF Research Database (Denmark)

    Chi, Nan; Carlsson, Birger; Holm-Nielsen, Pablo Villanueva

    2002-01-01

    The transmission characteristics of a two-level optically labeled signal with ASK/DPSK modulation are investigated under varying dispersion management. A limitation of extinction ratio and the resilience of fiber span, compensation ratio, and power level are obtained...

  12. Microwave vector signal transmission over an optical fiber based on IQ modulation and coherent detection.

    Science.gov (United States)

    Chen, Yang; Shao, Tong; Wen, Aijun; Yao, Jianping

    2014-03-15

    A novel approach to transmitting two vector signals using a single optical carrier based on IQ modulation and coherent detection is proposed and demonstrated. In the proposed system, two quadrature phase-shift keying (QPSK) signals are IQ modulated on an optical carrier with one polarization state using a dual-parallel Mach-Zehnder modulator (DP-MZM). The optical carrier with an orthogonal polarization state is not modulated but transmitted with the modulated optical wave. At the receiver, the two orthogonally polarized light waves are separated and sent to a coherent detector, where the two QPSK signals are separated and demodulated. An experiment is performed. The transmission of two QPSK signals at 2 GHz with a data rate of 1 Gbps is implemented over a 25 km single-mode fiber. The performance of the transmission in terms of error vector magnitude is evaluated.

  13. Blind Source Separation of Event-Related EEG/MEG.

    Science.gov (United States)

    Metsomaa, Johanna; Sarvas, Jukka; Ilmoniemi, Risto Juhani

    2017-09-01

    Blind source separation (BSS) can be used to decompose complex electroencephalography (EEG) or magnetoencephalography data into simpler components based on statistical assumptions without using a physical model. Applications include brain-computer interfaces, artifact removal, and identifying parallel neural processes. We wish to address the issue of applying BSS to event-related responses, which is challenging because of nonstationary data. We introduce a new BSS approach called momentary-uncorrelated component analysis (MUCA), which is tailored for event-related multitrial data. The method is based on approximate joint diagonalization of multiple covariance matrices estimated from the data at separate latencies. We further show how to extend the methodology for autocovariance matrices and how to apply BSS methods suitable for piecewise stationary data to event-related responses. We compared several BSS approaches by using simulated EEG as well as measured somatosensory and transcranial magnetic stimulation (TMS) evoked EEG. Among the compared methods, MUCA was the most tolerant one to noise, TMS artifacts, and other challenges in the data. With measured somatosensory data, over half of the estimated components were found to be similar by MUCA and independent component analysis. MUCA was also stable when tested with several input datasets. MUCA is based on simple assumptions, and the results suggest that MUCA is robust with nonideal data. Event-related responses and BSS are valuable and popular tools in neuroscience. Correctly designed BSS is an efficient way of identifying artifactual and neural processes from nonstationary event-related data.

  14. Training-based Channel Estimation for Signal Equalization and OPM in 16-QAM Optical Transmission Systems

    DEFF Research Database (Denmark)

    Pittalà, Fabio; Hauske, Fabian N.; Ye, Yabin

    2012-01-01

    Efficient channel estimation for signal equalization and OPM based on short CAZAC sequences with QPSK and 8PSK constellation formats is demonstrated in a 224-Gb/s PDM 16-QAM optical linear transmission system.......Efficient channel estimation for signal equalization and OPM based on short CAZAC sequences with QPSK and 8PSK constellation formats is demonstrated in a 224-Gb/s PDM 16-QAM optical linear transmission system....

  15. Converged wireline and wireless signal transport over optical fibre access links

    DEFF Research Database (Denmark)

    Tafur Monroy, Idelfonso; Prince, Kamau; Osadchiy, Alexey Vladimirovich

    2009-01-01

    This article reviews emerging trends in converged optical-wireless communication systems and outline the role that photonic technologies are playing in making the vision of a wireline-wireless converged signal transport network a reality.......This article reviews emerging trends in converged optical-wireless communication systems and outline the role that photonic technologies are playing in making the vision of a wireline-wireless converged signal transport network a reality....

  16. Development of an imaging modality utilizing 2D optical signals during an EPI-fluorescent optical mapping experiment

    Energy Technology Data Exchange (ETDEWEB)

    Prior, Phillip; Roth, Bradley J [Department of Physics, Oakland University, Rochester, MI 48309 (United States)], E-mail: phil.prior@gmail.com

    2009-05-21

    Optical mapping is a commonly used technique to visualize the electrical activity in the heart. Recently, several groups have attempted to use the signals acquired in optical mapping to image the transmembrane potential in the heart, which would be particularly advantageous when studying the effects of defibrillation-type shocks throughout the wall of the heart. Our work presents an alternative imaging method that makes use of data obtained using multiple wavelengths and therefore multiple optical decay constants. A modified form of the diffusion equation Green's function for a semi-infinite slab of tissue is derived and used to relate the detected optical signals to the source of emission photons. Images using the optical signals are reconstructed using Gaussian quadrature and matrix inversion. Our results show that images can be obtained for source terms located below the tissue surface. Furthermore, we demonstrate that our reconstruction method's susceptibility to noise can be alleviated using sophisticated matrix inverse techniques, such as singular value decomposition. Sources that rapidly decay with depth or are highly localized in the image plane require more sophisticated techniques (e.g., regularization methods) to image the electrical activity in the heart. The work presented here demonstrates the feasibility of a new imaging technique of cardiac electrical activity using optical mapping.

  17. Impact of Signal-Conjugate Wavelength Shift on Optical Phase Conjugation-based Transmission of QAM Signals

    DEFF Research Database (Denmark)

    Da Ros, Francesco; Lillieholm, Mads; Yankov, Metodi Plamenov

    2017-01-01

    The impact of signal-conjugate wavelength shift on nonlinearity compensation through optical phase conjugation is investigated for 64- and 256-QAM. Wavelength-shift independent achievable rate improvements between 0.2 and 0.3 bit/symbol are reported for shifts up to 30 nm in 500-km transmission....

  18. Thermally tuneable optical modulator adapted for differential signaling

    Science.gov (United States)

    Zortman, William A.

    2016-01-12

    An apparatus for optical modulation is provided. The apparatus includes a modulator structure and a heater structure. The modulator structure comprises a ring or disk optical resonator having a closed curvilinear periphery and a pair of oppositely doped semiconductor regions within and/or adjacent to the optical resonator and conformed to modify the optical length of the optical resonator upon application of a bias voltage. The heater structure comprises a relatively resistive annulus of semiconductor material enclosed between an inner disk and an outer annulus of relatively conductive semiconductor material. The inner disk and the outer annulus are adapted as contact regions for a heater activation current. The heater structure is situated within the periphery of the optical resonator such that in operation, at least a portion of the resonator is heated by radial conductive heat flow from the heater structure. The apparatus further includes a substantially annular isolation region of dielectric or relatively resistive semiconductor material interposed between the heater structure and the modulator structure. The isolation region is effective to electrically isolate the bias voltage from the heater activation current.

  19. Method and apparatus for the electro-optic convolution of a one-dimensional signal

    International Nuclear Information System (INIS)

    1979-01-01

    Procedure for the electro-optic convolution of a signal and a filter function, whereby the one dimensional electro-optical signal would be portrayed as a line along which the clarity varies and whereby filter function is determined by one or more masks, whilst after each mask is placed a light detector, with which the light passing through the masks may be detected, whilst a one-dimensional portrayal of the signal along the masks will be developed, characterised in that a one dimensional portrayal of the signal, with the aid of an optical system in a direction across the line, will be enlarged, and that this enlarged signal in the direction of the line along the masks will be affected which the masks closing fields will contain, which are either fully transparent or are fully non-transparent. (Auth.)

  20. Simultaneous all-optical AND and NOR gates for NRZ differential phase-shift-keying signals

    DEFF Research Database (Denmark)

    Xu, Jing; Zhang, X.; Dong, J.

    2008-01-01

    A scheme for realizing all-optical logic AND and NOR gates simultaneously for nonreturn-to-zero differential phase-shift-keying signals is proposed and demonstrated based on a delayed interferometer and two semiconductor optical amplifiers. Experimental demonstration at 20 Gb/s verifies the logic...

  1. Converged wireline and wireless signal distribution in optical fiber access networks

    DEFF Research Database (Denmark)

    Prince, Kamau

    This thesis presents results obtained during the course of my doctoral studies into the transport of fixed and wireless signaling over a converged otpical access infrastructure. In the formulation, development and assessment of a converged paradigma for multiple-services delivery via optical access...... networking infrastructure, I have demonstrated increased functionalities with existing optical technologies and commercially available optoelectronic devices. I have developed novel systems for extending the range of optical access systems, and have demonstrated the repurposing of standard digital devices...

  2. Universal Michelson Gires-Tournois interferometer optical interleaver based on digital signal processing.

    Science.gov (United States)

    Zhang, Juan; Yang, Xiaowei

    2010-03-01

    Optical interleavers based on Michelson Gires-Tournois interferometer (MGTI) with arbitrary cascaded reflectors for symmetrical or asymmetrical periodic frequency response with arbitrary duty cycles are defined as universal MGTI optical interleaver (UMGTIOI). It can significantly enhance flexibility and applicability of optical networks. A novel and simple method based on digital signal processing is proposed for the design of UMGTIOI. Different kinds of design examples are given to confirm effectiveness of the method.

  3. Paired SSB optical OFDM channels for high spectral efficient signal transmission over DWDM networks

    Science.gov (United States)

    Chicharro, Francisco I.; Ortega, Beatriz; Mora, José

    2016-07-01

    A new high spectral efficient SSB-OOFDM DWDM transmission system has been experimentally demonstrated. The proposed transmitter employs paired optical channels consisting of two SSB modulated OFDM signals using opposite sidebands in order to allow an efficient use of the spectrum with optical carriers separation under 10 GHz. Moreover, different paired channels are multiplexed into the 25 GHz grid DWDM fiber transmission link. Optical carrier spacing of 8.75 GHz in paired channels has been demonstrated allowing 40.8 Gb/s signal transmission rate over a 25 GHz paired channel bandwidth.

  4. Analyzing Influence of the Transmission Medium on Timing Signals Transmitted by Hybrid Optical Transport Technologies

    Directory of Open Access Journals (Sweden)

    Rastislav Róka

    2017-01-01

    Full Text Available The contribution deals with synchronization aspects in SDH and Synchronous Ethernet timing networks utilizing optical transmission medium. First, it explains a hierarchical configuration of timing network elements, characterizes transmission features of the optical fiber, particularly its main negative influences influencing transmitted information signals. The main part is dedicated to the evaluation program created for analyzing influences of the optical transmission path on timing signals transmitted by SDH and SyncE transport technologies. At last, resultant values from the introduced evaluation program are presented and evaluated.

  5. Integration of Optically Generated Impulse Radio UWB Signals into Baseband WDM-PON

    DEFF Research Database (Denmark)

    Pham, Tien Thang; Yu, Xianbin; Dittmann, Lars

    2011-01-01

    We propose a compact integration system to simultaneously provide wireline and wireless (baseband and ultra-wide band (UWB)) services to end-users in a WDM-PON. A 1-Gbps UWB signal is optically generated and shares the same wavelength with the baseband signal. Error-free performance was achieved...

  6. Amplitude regeneration of RZ-DPSK signals in single-pump fiber-optic parametric amplifiers

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Lorenzen, Michael Rodas; Seoane, Jorge

    2009-01-01

    to demonstrate amplitude regeneration of a distorted RZ-DPSK signal in a gain-saturated FOPA. An optical signal-to-noise ratio penalty of 3.5 dB after amplitude distortion is shown to be reduced to 0.2 dB after the FOPA, thus clearly demonstrating the regenerative nature of saturated FOPAs for RZ-DPSK modulation....

  7. Single-trial normalization for event-related spectral decomposition reduces sensitivity to noisy trials

    Directory of Open Access Journals (Sweden)

    Romain eGrandchamp

    2011-09-01

    Full Text Available In EEG research, the classical Event-Related Potential (ERP model often proves to be a limited method when studying complex brain dynamics. For this reason, spectral techniques adapted from signal processing such as Event-Related Spectral Perturbation (ERSP – and its variant ERS (Event-Related Synchronization and ERD (Event-Related Desynchronization – have been used over the past 20-years. They represent average spectral changes in response to a stimulus.These spectral methods do not have strong consensus for comparing pre and post-stimulus activity. When computing ERSP, pre-stimulus baseline removal is usually performed after averaging the spectral estimate of multiple trials. Correcting the baseline of each single-trial prior to averaging spectral estimates is an alternative baseline correction method. However, we show that this method leads to positively skewed post-stimulus ERSP values. We eventually present new single-trial based ERSP baseline correction methods that perform trial normalization or centering prior to applying classical baseline correction methods. We show that single-trial correction methods minimize the contribution of artifactual data trials with high-amplitude spectral estimates and are robust to outliers when performing statistical inference testing. We then characterize these methods in terms of their time-frequency responses and behavior when performing statistical inference testing compared to classical ERSP methods.

  8. Low-frequency analog signal distribution on digital photonic networks by optical delta-sigma modulation

    Science.gov (United States)

    Kanno, Atsushi; Kawanishi, Tetsuya

    2013-12-01

    We propose a delta-sigma modulation scheme for low- and medium-frequency signal transmission in a digital photonic network system. A 10-Gb/s-class optical transceiver with a delta-sigma modulator utilized as a high-speed analog-to-digital converter (ADC) provides a binary optical signal. On the signal reception side, a low-cost and slow-speed photonic receiver directly converts the binary signal into an analog signal at frequencies from several hundreds of kilohertz several tens of megahertz. Further, by using a clock and data recovery circuit at the receiver to reduce jitters, the single-sideband phase noise of the generated signals can be significantly reduced.

  9. Theoretical and Experimental Study of Optical Coherence Tomography (OCT) Signals Using an Analytical Transport Model

    International Nuclear Information System (INIS)

    Vazquez Villa, A.; Delgado Atencio, J. A.; Vazquez y Montiel, S.; Cunill Rodriguez, M.; Martinez Rodriguez, A. E.; Ramos, J. Castro; Villanueva, A.

    2010-01-01

    Optical coherence tomography (OCT) is a non-invasive low coherent interferometric technique that provides cross-sectional images of turbid media. OCT is based on the classical Michelson interferometer where the mirror of the reference arm is oscillating and the signal arm contains a biological sample. In this work, we analyzed theoretically the heterodyne optical signal adopting the so called extended Huygens-Fresnel principle (EHFP). We use simulated OCT images with known optical properties to test an algorithm developed by ourselves to recover the scattering coefficient and we recovered the scattering coefficient with a relative error less than 5% for noisy signals. In addition, we applied this algorithm to OCT images from phantoms of known optical properties; in this case curves were indistinguishable. A revision of the validity of the analytical model applied to our system should be done.

  10. Intracerebral Event-related Potentials to Subthreshold Target Stimuli

    Czech Academy of Sciences Publication Activity Database

    Brázdil, M.; Rektor, I.; Daniel, P.; Dufek, M.; Jurák, Pavel

    2001-01-01

    Roč. 112, č. 4 (2001), s. 650-661 ISSN 1388-2457 R&D Projects: GA ČR GA309/98/0490 Institutional research plan: CEZ:AV0Z2065902 Keywords : event-related potentials * intracerebral recordings * oddball paradigm Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 1.922, year: 2001

  11. Event-Related Potentials and the Stroop Effect.

    Science.gov (United States)

    Sahinoglu, Babur; Dogan, Gamze

    2016-02-01

    In this manuscript, the researches on the Event-Related Potentials (ERP) elicited by the standard Stroop effect were reviewed. For the sake of clarity, only the parts of the manuscripts that reported the standard Stroop effect - ERPs relation were taken into consideration.

  12. Event-Related Potentials and the Stroop Effect

    OpenAIRE

    Sahinoglu, Babur; Dogan, Gamze

    2016-01-01

    In this manuscript, the researches on the Event-Related Potentials (ERP) elicited by the standard Stroop effect were reviewed. For the sake of clarity, only the parts of the manuscripts that reported the standard Stroop effect - ERPs relation were taken into consideration.

  13. Influence of Stimuled Raman Scattering on Transmitted Optical Signal in WDM System

    Directory of Open Access Journals (Sweden)

    Ján Ružbarský

    2015-12-01

    Full Text Available Paper is focused on simulations behavior of signals in high-speed networks. Huge amount of transmitted information and increase in transmission speed create unwanted events in optical fiber. The main influences comprise effects such as: stimulated Raman scattering and stimulated Brillouin scattering. This paper is focused only on Raman scattering. For transmitting a signal through optical fiber one needs to select an appropriate wavelength. This is one of goals the experiment in this article. Signals were transmitted accordance with Dense Wavelength Division Multiplexing (DWDM and spacing among channels 100GHz.

  14. An analog modulation and demodulation method employing LVDT signal conditioner for fiber-optic interferometric sensors

    Science.gov (United States)

    Zhou, Kejiang; Rao, Qi; Zhang, Minjie; Hu, Keke; Ruan, Yefeng

    2017-09-01

    An analog method to modulate and demodulate fiber-optic interferometric sensors employing a linear variable differential transformer signal conditioner to generate sine modulation wave and demodulate phase-modulated signal from the photodetector’s output is presented in this letter. No external lock-in amplifiers or digital components are used in this design. All the necessary components for signal processing are integrated in a single analog electronic microchip AD698, which reduces the system’s complexity significantly. After implementation on an interferometric fiber-optic gyroscope as an example, this method demonstrates a bias stability of 0.063 deg h-1 (i.e. 0.220 µrad).

  15. Optical recognition of one-dimensional signals represented on the phase plane

    Science.gov (United States)

    Kurashov, Vitalij N.; Dan'ko, Volodymir P.; Kisil, Alexandr V.; Kovalenko, Andry V.; Podanchuk, Dmitrij V.

    1997-12-01

    Structural correlation analysis is carried out for 1D signals, represented as phase images. For LFM signals, mapped into generalized phase plane with coordinates x equals S, y equals S"/S, sensitivity of correlation analysis to staggering of deviation frequency is invariant to impulse duration and increase with increase of carrier frequency and decrease of initial deviation. Phase representation of LFM signals essentially improves the sensitivity of coherent optical processing in comparison with binary raster representation.

  16. Monte Carlo simulation of an optical coherence tomography signal in homogeneous turbid media

    OpenAIRE

    Yao, Gang; Wang, Lihong V.

    1999-01-01

    The Monte Carlo technique with angle biasing is used to simulate the optical coherence tomography (OCT) signal from homogeneous turbid media. The OCT signal is divided into two categories: one is from a target imaging layer in the medium (Class I); the other is from the rest of the medium (Class II). These two classes of signal are very different in their spatial distributions, angular distributions and the numbers of experienced scattering events. Multiply scattered light contributes to the ...

  17. Process-specific analysis in episodic memory retrieval using fast optical signals and hemodynamic signals in the right prefrontal cortex

    Science.gov (United States)

    Dong, Sunghee; Jeong, Jichai

    2018-02-01

    Objective. Memory is formed by the interaction of various brain functions at the item and task level. Revealing individual and combined effects of item- and task-related processes on retrieving episodic memory is an unsolved problem because of limitations in existing neuroimaging techniques. To investigate these issues, we analyze fast and slow optical signals measured from a custom-built continuous wave functional near-infrared spectroscopy (CW-fNIRS) system. Approach. In our work, we visually encode the words to the subjects and let them recall the words after a short rest. The hemodynamic responses evoked by the episodic memory are compared with those evoked by the semantic memory in retrieval blocks. In the fast optical signal, we compare the effects of old and new items (previously seen and not seen) to investigate the item-related process in episodic memory. The Kalman filter is simultaneously applied to slow and fast optical signals in different time windows. Main results. A significant task-related HbR decrease was observed in the episodic memory retrieval blocks. Mean amplitude and peak latency of a fast optical signal are dependent upon item types and reaction time, respectively. Moreover, task-related hemodynamic and item-related fast optical responses are correlated in the right prefrontal cortex. Significance. We demonstrate that episodic memory is retrieved from the right frontal area by a functional connectivity between the maintained mental state through retrieval and item-related transient activity. To the best of our knowledge, this demonstration of functional NIRS research is the first to examine the relationship between item- and task-related memory processes in the prefrontal area using single modality.

  18. Generating arbitrary optical signal constellations using microring resonators.

    Science.gov (United States)

    Ehrlichman, Yossef; Amrani, Ofer; Ruschin, Shlomo

    2013-02-11

    It is shown that two mutually uncoupled microresonators in series can adequately cover the entire I-Q space and render the realization of QAM signals possible. This approach is based on the independent optimization of each microresonator for amplitude and phase modulation respectively. Generation of 16 quadrature amplitude modulation is demonstrated by means of simulation.

  19. Generation of synchronized signal and pump pulses for an optical ...

    Indian Academy of Sciences (India)

    parametric amplification (OPA) utilizes instantaneous non-linear interaction of the signal and the pump beams, the performance of OPCPA system is expected to be highly sensitive to the temporal synchronization errors between them (required to be less than ~100 ps). One way to eliminate this problem is to derive the ...

  20. Analog CMOS design for optical coherence tomography signal detection and processing.

    Science.gov (United States)

    Xu, Wei; Mathine, David L; Barton, Jennifer K

    2008-02-01

    A CMOS circuit was designed and fabricated for optical coherence tomography (OCT) signal detection and processing. The circuit includes a photoreceiver, differential gain stage and lock-in amplifier based demodulator. The photoreceiver consists of a CMOS photodetector and low noise differential transimpedance amplifier which converts the optical interference signal into a voltage. The differential gain stage further amplifies the signal. The in-phase and quadrature channels of the lock-in amplifier each include an analog mixer and switched-capacitor low-pass filter with an external mixer reference signal. The interferogram envelope and phase can be extracted with this configuration, enabling Doppler OCT measurements. A sensitivity of -80 dB is achieved with faithful reproduction of the interferometric signal envelope. A sample image of finger tip is presented.

  1. Development of linear and nonlinear components for integrated optical signal processing

    Science.gov (United States)

    Tseng, Shuo-Yen

    Optical processors have potentially a major advantage over electronic processors because of their tremendous bandwidth. Massive parallelism is another inherent advantage of optical processors. However, it is traditionally demonstrated with free space components and seldom used for integrated optical signal processing. In this thesis, we consider spatial domain signal processing in guided wave structures, which brings a new dimension to the existing serial signal processing architecture and takes advantage of the parallelism in optics. A novel class of devices using holograms in multimode channel waveguides is developed in this work. Linear optical signal processing using multimode waveguide holograms (MWHs) is analyzed. We focus on discrete unitary transformations to take advantage of the discrete nature of modes in multimode waveguides. We prove that arbitrary unitary transformations can be performed using holograms in multimode waveguides. A model using the wide-angle beam propagation method (WA-BPM) is developed to simulate the devices and shows good agreement with the theory. The design principle of MWH devices is introduced. Based on the design principle, BPM models are used to design several devices including a mode-order converter, a Hadamard transformer, and an optical pattern generator/correlator. Optical pattern generators are fabricated to verify the theory and the model. Also, the bandwidth and fabrication tolerance of MWH devices are also analyzed. Also, we examine the nonlinear optical switches which allow the integration of MWHs into modern optical communication networks. A simple optical setup using an imaged 2-D phase grating is developed for characterization of the complex third-order nonlinearity chi(3) to identify suitable nonlinear materials for integrated optical switches. This technique provides a reliable way to characterize chi(3) as new materials are constantly being developed. Finally, we demonstrate the concept of optical switching using

  2. Simultaneous functional near-infrared brain imaging and event-related potential studies of Stroop effect

    Science.gov (United States)

    Zhai, Jiahuan; Li, Ting; Zhang, Zhongxing; Gong, Hui

    2009-02-01

    Functional near-infrared brain imaging (fNIRI) and event-related potential (ERP) were used simultaneous to detect the prefrontal cortex (PFC) which is considered to execute cognitive control of the subjects while performing the Chinese characters color-word matching Stroop task with event-related design. The fNIRI instrument is a portable system operating at three wavelengths (735nm & 805nm &850nm) with continuous-wave. The event-related potentials were acquired by Neuroscan system. The locations of optodes corresponding to the electrodes were defined four areas symmetrically. In nine native Chinese-speaking fit volunteers, fNIRI measured the hemodynamic parameters (involving oxy-/deoxy- hemoglobin) changes when the characteristic waveforms (N500/P600) were recorded by ERP. The interference effect was obvious as a longer reaction time for incongruent than congruent and neutral stimulus. The responses of hemodynamic and electrophysiology were also stronger during incongruent compared to congruent and neutral trials, and these results are similar to those obtained with fNIRI or ERP separately. There are high correlations, even linear relationship, in the two kinds of signals. In conclusion, the multi-modality approach combining of fNIRI and ERP is feasible and could obtain more cognitive function information with hemodynamic and electrophysiology signals. It also provides a perspective to prove the neurovascular coupling mechanism.

  3. An analysis of signal processing algorithm performance for cortical intrinsic optical signal imaging and strategies for algorithm selection.

    Science.gov (United States)

    Turley, J A; Zalewska, K; Nilsson, M; Walker, F R; Johnson, S J

    2017-08-03

    Intrinsic Optical Signal (IOS) imaging has been used extensively to examine activity-related changes within the cerebral cortex. A significant technical challenge with IOS imaging is the presence of large noise, artefact components and periodic interference. Signal processing is therefore important in obtaining quality IOS imaging results. Several signal processing techniques have been deployed, however, the performance of these approaches for IOS imaging has never been directly compared. The current study aims to compare signal processing techniques that can be used when quantifying stimuli-response IOS imaging data. Data were gathered from the somatosensory cortex of mice following piezoelectric stimulation of the hindlimb. The effectiveness of each technique to remove noise and extract the IOS signal was compared for both spatial and temporal responses. Careful analysis of the advantages and disadvantages of each method were carried out to inform the choice of signal processing for IOS imaging. We conclude that spatial Gaussian filtering is the most effective choices for improving the spatial IOS response, whilst temporal low pass and bandpass filtering produce the best results for producing temporal responses when periodic stimuli are an option. Global signal regression and truncated difference also work well and do not require periodic stimuli.

  4. On-chip photonic microsystem for optical signal processing based on silicon and silicon nitride platforms

    Science.gov (United States)

    Li, Yu; Li, Jiachen; Yu, Hongchen; Yu, Hai; Chen, Hongwei; Yang, Sigang; Chen, Minghua

    2018-04-01

    The explosive growth of data centers, cloud computing and various smart devices is limited by the current state of microelectronics, both in terms of speed and heat generation. Benefiting from the large bandwidth, promising low power consumption and passive calculation capability, experts believe that the integrated photonics-based signal processing and transmission technologies can break the bottleneck of microelectronics technology. In recent years, integrated photonics has become increasingly reliable and access to the advanced fabrication process has been offered by various foundries. In this paper, we review our recent works on the integrated optical signal processing system. We study three different kinds of on-chip signal processors and use these devices to build microsystems for the fields of microwave photonics, optical communications and spectrum sensing. The microwave photonics front receiver was demonstrated with a signal processing range of a full-band (L-band to W-band). A fully integrated microwave photonics transceiver without the on-chip laser was realized on silicon photonics covering the signal frequency of up 10 GHz. An all-optical orthogonal frequency division multiplexing (OFDM) de-multiplier was also demonstrated and used for an OFDM communication system with the rate of 64 Gbps. Finally, we show our work on the monolithic integrated spectrometer with a high resolution of about 20 pm at the central wavelength of 1550 nm. These proposed on-chip signal processing systems potential applications in the fields of radar, 5G wireless communication, wearable devices and optical access networks.

  5. Measurement of event-related potentials and placebo

    Directory of Open Access Journals (Sweden)

    Sovilj Platon

    2014-01-01

    Full Text Available ERP is common abbreviation for event-related brain potentials, which are measured and used in clinical practice as well as in research practice. Contemporary studies of placebo effect are often based on functional neuromagnetic resonance (fMRI, positron emission tomography (PET, and event related potentials (ERP. This paper considers an ERP instrumentation system used in experimental researches of placebo effect. This instrumentation system can be divided into four modules: electrodes and cables, conditioning module, digital measurement module, and PC module for stimulations, presentations, acquisition and data processing. The experimental oddball paradigm is supported by the software of the instrumentation. [Projekat Ministarstva nauke Republike Srbije, br. TR32019 and Provincial Secretariat for Science and Technological Development of Autonomous Province of Vojvodina (Republic of Serbia under research grant No. 114-451-2723

  6. Generation of synchronized signal and pump pulses for an optical ...

    Indian Academy of Sciences (India)

    30%T beam, with an average power of 80 mW, with pulse duration of 650 ps, is reflected by a pickup mirror. This signal beam with 1 nJ energy will be amplified in various OPA stages for making the multi-terawatt laser system. The reflected laser pulses (180 mW power) that are redirected into the pulse stretcher are allowed ...

  7. Linear and nonlinear optical signals in probability and phase-space representations

    International Nuclear Information System (INIS)

    Man'ko, Margarita A

    2006-01-01

    Review of different representations of signals including the phase-space representations and tomographic representations is presented. The signals under consideration are either linear or nonlinear ones. The linear signals satisfy linear quantumlike Schroedinger and von Neumann equations. Nonlinear signals satisfy nonlinear Schroedinger equations as well as Gross-Pitaevskii equation describing solitons in Bose-Einstein condensate. The Ville-Wigner distributions for solitons are considered in comparison with tomographic-probability densities describing solitons completely. different kinds of tomographies - symplectic tomography, optical tomography and Fresnel tomography are reviewed. New kind of map of the signals onto probability distributions of discrete photon number-like variable is discussed. Mutual relations between different transformations of signal functions are established in explicit form. Such characteristics of the signal-probability distribution as entropy is discussed

  8. Proprioceptive event related potentials: gating and task effects

    DEFF Research Database (Denmark)

    Arnfred, Sidse M

    2005-01-01

    The integration of proprioception with vision, touch or audition is considered basic to the developmental formation of perceptions, conceptual objects and the creation of cognitive schemes. Thus, mapping of proprioceptive information processing is important in cognitive research. A stimulus...... of a brisk change of weight on a hand held load elicit a proprioceptive evoked potential (PEP). Here this is used to examine early and late information processing related to weight discrimination by event related potentials (ERP)....

  9. [The use of event related potentials in psychiatric research].

    Science.gov (United States)

    Wichniak, Adam; Ciołkiewicz, Agnieszka; Waliniowska, Elzbieta; Wołkow, Lidia; Wierzbicka, Aleksandra; Jakubczyk, Tomasz; Jernajczyk, Wojciech

    2010-01-01

    Event related potentials (ERPs) originate predominantly from cortical structures in response to information processing. In contrast to evoked potentials of short latency (psychiatric research. ERPs can be also useful in clinic related questions: identification of subject at high-risk of psychosis, assessment of attention deficits or selective attention problems in anxiety disorders, evaluation of early response to psychopharmacological treatment and efficacy of psychotherapeutic interventions.

  10. Event-related potential response to auditory social stimuli, parent-reported social communicative deficits and autism risk in school-aged children with congenital visual impairment

    Directory of Open Access Journals (Sweden)

    Joe Bathelt

    2017-10-01

    Full Text Available Communication with visual signals, like facial expression, is important in early social development, but the question if these signals are necessary for typical social development remains to be addressed. The potential impact on social development of being born with no or very low levels of vision is therefore of high theoretical and clinical interest. The current study investigated event-related potential responses to basic social stimuli in a rare group of school-aged children with congenital visual disorders of the anterior visual system (globe of the eye, retina, anterior optic nerve. Early-latency event-related potential responses showed no difference between the VI and control group, suggesting similar initial auditory processing. However, the mean amplitude over central and right frontal channels between 280 and 320 ms was reduced in response to own-name stimuli, but not control stimuli, in children with VI suggesting differences in social processing. Children with VI also showed an increased rate of autistic-related behaviours, pragmatic language deficits, as well as peer relationship and emotional problems on standard parent questionnaires. These findings suggest that vision may be necessary for the typical development of social processing across modalities.

  11. Event-related potential response to auditory social stimuli, parent-reported social communicative deficits and autism risk in school-aged children with congenital visual impairment.

    Science.gov (United States)

    Bathelt, Joe; Dale, Naomi; de Haan, Michelle

    2017-10-01

    Communication with visual signals, like facial expression, is important in early social development, but the question if these signals are necessary for typical social development remains to be addressed. The potential impact on social development of being born with no or very low levels of vision is therefore of high theoretical and clinical interest. The current study investigated event-related potential responses to basic social stimuli in a rare group of school-aged children with congenital visual disorders of the anterior visual system (globe of the eye, retina, anterior optic nerve). Early-latency event-related potential responses showed no difference between the VI and control group, suggesting similar initial auditory processing. However, the mean amplitude over central and right frontal channels between 280 and 320ms was reduced in response to own-name stimuli, but not control stimuli, in children with VI suggesting differences in social processing. Children with VI also showed an increased rate of autistic-related behaviours, pragmatic language deficits, as well as peer relationship and emotional problems on standard parent questionnaires. These findings suggest that vision may be necessary for the typical development of social processing across modalities. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  12. Equalizer design for clock recovery based on multi-level optical disk using signal waveform modulation

    Science.gov (United States)

    Shao, Meng; Pei, Jing; Yang, Bo

    2013-12-01

    With smaller pits and lands in multi-level optical disks using signal waveform modulation than those in DVD disks, the ISI and nonlinear attenuation of the read-out signal become more serious. One ordinary way is using an equalizer at sample rate 1/T, we proposed one method of designing the equalizer in fixed sample rate with digital interpolation. According to the analysis of the multi-level optical disk channel, we get the target frequency-response cure and implement it with seven order FIR filter. From the result of the read out experiment with multi-level optical disk, the clock of the RF signal could be recovered with the proposed equalizer.

  13. Kalman filtering to suppress spurious signals in Adaptive Optics control

    Energy Technology Data Exchange (ETDEWEB)

    Poyneer, L; Veran, J P

    2010-03-29

    In many scenarios, an Adaptive Optics (AO) control system operates in the presence of temporally non-white noise. We use a Kalman filter with a state space formulation that allows suppression of this colored noise, hence improving residual error over the case where the noise is assumed to be white. We demonstrate the effectiveness of this new filter in the case of the estimated Gemini Planet Imager tip-tilt environment, where there are both common-path and non-common path vibrations. We discuss how this same framework can also be used to suppress spatial aliasing during predictive wavefront control assuming frozen flow in a low-order AO system without a spatially filtered wavefront sensor, and present experimental measurements from Altair that clearly reveal these aliased components.

  14. Improving the All-Optical Response of SOAs Using a Modulated Holding Signal

    DEFF Research Database (Denmark)

    Bischoff, Svend; Nielsen, Mads Lønstrup; Mørk, Jesper

    2004-01-01

    A method for increasing the all-optical modulation bandwidth of semiconductor optical amplifiers (SOAs) by use of a cross-gain-modulated (XGM) holding signal is suggested and analyzed. The bandwidth improvement is numerically demonstrated by studying wavelength conversion in an SOA-based Mach......-Zehnder interferometer (MZI) at 160 and 40 Gb/s. The new scheme is predicted to improve the extinction ratio and the minimum mark output power, as well as to reduce the amplitude jitter of the wavelength converted signal....

  15. Exchange transfusion with fluorocarbon for studying synaptically evoked optical signal in rat cortex.

    Science.gov (United States)

    Nomura, Y; Fujii, F; Sato, C; Nemoto, M; Tamura, M

    2000-02-01

    Optical imaging of intrinsic signal is a powerful technique for studying the functional organization of the brain [T. Bonhoeffer, D. S. Kim, D. Malonek, D. Shoham, A. Grinvald, Optical imaging of the layout of functional domains in area 17 and across the area 17/18 border in cat visual cortex, Eur. J. Neurosci. 7 (1995) 1973-1988; M. Hubener, D. Shoham, A. Grinvald, T. Bonhoeffer, Spatial relationships among three columnar systems in cat area 17, J. Neurosci. 17 (1997) 9270-9284; D. Malonek, A. Grinvald, Interactions between electrical activity and cortical microcirculation revealed by imaging spectroscopy: implications for functional brain mapping, Science 272 (1996) 551-554; A. Shmuel, A. Grinvald, Functional organization for direction of motion and its relationship to orientation maps in cat area 18, J. Neurosci. 16 (1996) 6945-6964] [1] [10] [14] [22]. Three components of intrinsic optical signal can be distinguished. Two of these components can be attributed either to changes in blood volume or to changes in oxygen consumption [R.D. Frostig, E.E. Lieke, D.Y. Ts'o, A. Grinvald, Cortical functional architecture and local coupling between neuronal activity and the microcirculation revealed by in vivo high resolution optical imaging of intrinsic signals, Proc. Natl. Acad. Sci. U. S. A. 87 (1990) 6082-6086] [7]. The origin of the third component is not yet clear but the component seems to be based on scattered light [H.U. Dodt, G. D'Arcangelo, E. Pestel, W. Zieglgansberger, The spread of excitation in neocortical columns visualized with infrared-dark field videomicroscopy, NeuroReport 7 (1996) 1553-1558; K. Holthoff, O.W. Witte, Intrinsic optical signals in rat neocortical slices measured with near-infrared dark-field microscopy reveal changes in extracellular space, J. Neurosci. 16 (1996) 2740-2749; B.A. MacVicar, D. Hochman, Imaging of synaptically evoked intrinsic optical signals in hippocampal slices, J. Neurosci. 11 (1991) 1458-1469; L. Trachsel, H.U. Dodt, W

  16. Stabilization of Phase of a Sinusoidal Signal Transmitted Over Optical Fiber

    Science.gov (United States)

    DAddario, Larry R.; Trink, Joseph T.

    2010-01-01

    In the process of connecting widely distributed antennas into a coherent array, it is necessary to synchronize the timing of signals at the various locations. This can be accomplished by distributing a common reference signal from a central source, usually over optical fiber. A high-frequency (RF or microwave) tone is a good choice for the reference. One difficulty is that the effective length of the optical fiber changes with temperature and mechanical stress, leading to phase instability in the received tone. This innovation provides a new way to stabilize the phase of the received tone, in spite of variations in the electrical length of the fiber. Stabilization is accomplished by two-way transmission in which part of the received signal is returned to the transmitting end over an identical fiber. The returned signal is detected and used to close an electrical servo loop whose effect is to keep constant the phase of the tone at the receiving end.

  17. Fibre-optic metadevice for all-optical signal modulation based on coherent absorption.

    Science.gov (United States)

    Xomalis, Angelos; Demirtzioglou, Iosif; Plum, Eric; Jung, Yongmin; Nalla, Venkatram; Lacava, Cosimo; MacDonald, Kevin F; Petropoulos, Periklis; Richardson, David J; Zheludev, Nikolay I

    2018-01-12

    Recently, coherent control of the optical response of thin films in standing waves has attracted considerable attention, ranging from applications in excitation-selective spectroscopy and nonlinear optics to all-optical image processing. Here, we show that integration of metamaterial and optical fibre technologies allows the use of coherently controlled absorption in a fully fiberized and packaged switching metadevice. With this metadevice, which controls light with light in a nanoscale plasmonic metamaterial film on an optical fibre tip, we provide proof-of-principle demonstrations of logical functions XOR, NOT and AND that are performed within a coherent fibre network at wavelengths between 1530 and 1565 nm. The metadevice has been tested at up to 40 gigabits per second and sub-milliwatt power levels. Since coherent absorption can operate at the single-photon level and with 100 THz bandwidth, we argue that the demonstrated all-optical switch concept has potential applications in coherent and quantum information networks.

  18. Brain Specificity of Diffuse Optical Imaging: Improvements from Superficial Signal Regression and Tomography

    OpenAIRE

    Gregg, Nicholas M.; White, Brian R.; Zeff, Benjamin W.; Berger, Andrew J.; Culver, Joseph P.

    2010-01-01

    Functional near infrared spectroscopy (fNIRS) is a portable monitor of cerebral hemodynamics with wide clinical potential. However, in fNIRS, the vascular signal from the brain is often obscured by vascular signals present in the scalp and skull. In this paper, we evaluate two methods for improving in vivo data from adult human subjects through the use of high-density diffuse optical tomography (DOT). First, we test whether we can extend superficial regression methods (which utilize the multi...

  19. All-optical encryption/decryption for nonreturn-to-zero differential phase-shift keying signals using four-wave mixing in semiconductor optical amplifier

    Science.gov (United States)

    Yang, Xuelin; Zhou, Peng; Hu, Xiaonan; Hu, Weisheng

    2015-04-01

    By experiment we demonstrate an all-optical encryption/decryption scheme for nonreturn-to-zero differential phase-shift keying (NRZ-DPSK) signals at 10 Gbit/s using all-optical exclusive-OR (XOR) logic. The key bit stream is performed by a pseudorandom bit stream. The all-optical XOR logic is achieved by nondegenerate four-wave mixing (FWM) in a semiconductor optical amplifier (SOA), which allows high data rate operation and asymmetric optical powers of the two input bit streams. The gain dynamics and pattern effect associated with the SOA carrier lifetime are alleviated due to the constant envelope of the NRZ-DPSK signals.

  20. The effect of jogging on P300 event related potentials.

    Science.gov (United States)

    Nakamura, Y; Nishimoto, K; Akamatu, M; Takahashi, M; Maruyama, A

    1999-03-01

    Physical exercise has beneficial effects not only on cardiovascular system and fat metabolism, may also directly effect the cognitive process. We studied the effect of physical exercise on cognitive processes by measuring the P300 event related-potential (ERP) after jogging. Seven well-trained joggers were enrolled in this study and the P300 potentials using auditory oddball paradigm. ERPs were measured before and after 30 minutes of jogging. The amplitude of the P300 significantly increased after jogging compared to values recorded before jogging. These findings suggest that jogging has the effect of facilitating cognitive processes involved in generation of the P300.

  1. Analog signals transmission of up to 100 khz though optical fiber

    International Nuclear Information System (INIS)

    Cremy, C.

    1996-12-01

    Around TJ-II device, potential problems may arise as a consequence of an adverse electromagnetic environment, presence of strong DC and AC currents, motors, coils, power supplies, magnetic fields and so on. Consequently, signal transmission towards monitoring or data acquisition systems may be affected due to induced noise, ground loops and other undesirable effects. Trying to avoid such problems, signals may be translated in a proper way in order to be routed through optical fiber. The present report shows a method to solve the difficulty, by means of a galvanic isolation between the signal source and the measurement circuit. (Author)

  2. Optical signal processing up to 1.28 Tbits/s

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen; Oxenløwe, Leif Katsuo; Galili, Michael

    2009-01-01

    Techniques for 640 Gbit/s optical signal processing are described, including demultiplexing, clock recovery, transmission, wavelength conversion, add-drop multiplexing, and timing-jitter tolerance. Demultiplexing at 1.28 Tbit/s is presented, with preliminary results for 1.28 Tbit/s transmission....

  3. Linear all-optical signal processing using silicon micro-ring resonators

    DEFF Research Database (Denmark)

    Ding, Yunhong; Ou, Haiyan; Xu, Jing

    2016-01-01

    Silicon micro-ring resonators (MRRs) are compact and versatile devices whose periodic frequency response can be exploited for a wide range of applications. In this paper, we review our recent work on linear all-optical signal processing applications using silicon MRRs as passive filters. We focus...

  4. All-optical wavelength conversion and signal regeneration using an electroabsorption modulator

    DEFF Research Database (Denmark)

    Højfeldt, Sune; Bischoff, Svend; Mørk, Jesper

    2000-01-01

    All-optical wavelength conversion and signal regeneration based on cross-absorption modulation in an InGaAsP quantum well electroabsorption modulator (EAM) is studied at different bit rates. We present theoretical results showing wavelength conversion efficiency in agreement with existing...

  5. All-optical wavelength conversion and signal regeneration using an electroabsorption modulator

    DEFF Research Database (Denmark)

    Højfeldt, Sune; Bischoff, Svend; Mørk, Jesper

    1999-01-01

    All-optical wavelength conversion in an InGaAsP quantum well electroabsorption modulator is studied at different bit-rates. We present theoretical results showing wavelength conversion efficiency in agreement with existing experimental results, and signal regeneration capability is demonstrated....

  6. Signal Processing Algorithm for Controlling Dynamic Bandwidth of Fiber Optic Accelerometer

    International Nuclear Information System (INIS)

    Kim, Dae Hyun

    2007-01-01

    This paper presents a signal processing algorithm to control the dynamic bandwidth of a single-degree-of-freedom (SDF) dynamic sensor system. An accelerometer is a representative SDF sensor system. In this paper, a moire-fringe-based fiber optic accelerometer is newly used for the test of the algorithm. The accelerometer is composed of one mass, one damper and one spring as a SDF dynamic system. In order to increase the dynamic bandwidth of the accelerometer, it is needed to increase the spring constant or decrease the mass. However, there are mechanical difficulties of this adjustment. Therefore, the presented signal processing algorithm is very effective to overcome the difficulties because it is just adjustment in the signal processing software. In this paper, the novel fiber optic accelerometer is introduced shortly, and the algorithm is applied to the fiber optic accelerometer to control its natural frequency and damping ratio. Several simulations and experiments are carried out to prove the performance of the algorithm. As a result, it is shown that the presented signal processing algorithm is a good way to broaden the dynamic bandwidth of the fiber optic accelerometer

  7. Optical coherence tomography signal analysis: LIDAR like equation and inverse methods

    International Nuclear Information System (INIS)

    Amaral, Marcello Magri

    2012-01-01

    Optical Coherence Tomography (OCT) is based on the media backscattering properties in order to obtain tomographic images. In a similar way, LIDAR (Light Detection and Range) technique uses these properties to determine atmospheric characteristics, specially the signal extinction coefficient. Exploring this similarity allowed the application of signal inversion methods to the OCT images, allowing to construct images based in the extinction coefficient, original result until now. The goal of this work was to study, propose, develop and implement algorithms based on OCT signal inversion methodologies with the aim of determine the extinction coefficient as a function of depth. Three inversion methods were used and implemented in LABView R : slope, boundary point and optical depth. Associated errors were studied and real samples (homogeneous and stratified) were used for two and three dimension analysis. The extinction coefficient images obtained from the optical depth method were capable to differentiate air from the sample. The images were studied applying PCA and cluster analysis that established the methodology strength in determining the sample's extinction coefficient value. Moreover, the optical depth methodology was applied to study the hypothesis that there is some correlation between signal extinction coefficient and the enamel teeth demineralization during a cariogenic process. By applying this methodology, it was possible to observe the variation of the extinction coefficient as depth function and its correlation with microhardness variation, showing that in deeper layers its values tends to a healthy tooth values, behaving as the same way that the microhardness. (author)

  8. All-Optical Signal Processing for 640 Gbit/s Applications

    DEFF Research Database (Denmark)

    Mulvad, Hans Christian Hansen

    2008-01-01

    This thesis concerns all-optical signal processing technologies for ultra-high serial data rates up to 640 Gbit/s. Firstly, time-division add-drop multiplexing at 640 Gbit/s is demonstrated for the first time using two different fibre-based switching techniques. Secondly, a novel principle for po...

  9. Transmission and transparent wavelength conversion of an optically labeled signal using ASK/DPSK orthogonal modulation

    DEFF Research Database (Denmark)

    Chi, Nan; Zhang, Jianfeng; Holm-Nielsen, Pablo Villanueva

    2003-01-01

    We report an experimental investigation of transmission and transparent wavelength conversion properties of a two-level optically labeled signal using amplitude-shift-keying/differential-phase-shift-keying orthogonal modulation. Error-free transmission of a 10-Gb/s payload and 2.5-Gb/s label over...

  10. Optical Switching for Dynamic Distribution of Wireless-Over-Fiber Signals in Active Optical Networks

    DEFF Research Database (Denmark)

    Vegas Olmos, Juan José; Rodes, Guillermo; Tafur Monroy, Idelfonso

    2012-01-01

    of a four wavelength-division-multiplexed channel system operating on a WiMax frequency band and employing an orthogonal-frequency-division-multiplexing modulation at 625 Mbits/s per channel, transmission of the data over 20 km of optical fiber, and active switching in a 1 × 16 active optical switch....... The results show a negligible power penalty on each channel for both the best and the worst case in terms of inter-channel crosstalk. The presented system is highly scalable both in terms of port count and throughput, a desirable feature in highly branched access networks, and is modulation- and frequency...

  11. Classification of Event-Related Potentials Associated with Response Errors in Actors and Observers Based on Autoregressive Modeling

    NARCIS (Netherlands)

    Vasios, C.E.; Ventouras, E.M.; Matsopoulos, G.K.; Karanasiou, I.; Asvestas, P.; Uzunoglu, N.K.; Schie, H.T. van; Bruijn, E.R.A. de

    2009-01-01

    Event-Related Potentials (ERPs) provide non-invasive measurements of the electrical activity on the scalp related to the processing of stimuli and preparation of responses by the brain. In this paper an ERP-signal classification method is proposed for discriminating between ERPs of correct and

  12. Auto-adaptive averaging: Detecting artifacts in event-related potential data using a fully automated procedure

    NARCIS (Netherlands)

    Talsma, D.

    2008-01-01

    The auto-adaptive averaging procedure proposed here classifies artifacts in event-related potential data by optimizing the signal-to-noise ratio. This method rank orders single trials according to the impact of each trial on the ERP average. Then, the minimum residual background noise level in the

  13. Auto-adaptive averaging: Detecting artifacts in event-related potential data using a fully automated procedure.

    NARCIS (Netherlands)

    Talsma, D.

    2008-01-01

    The auto-adaptive averaging procedure proposed here classifies artifacts in event-related potential data by optimizing the signal-to-noise ratio. This method rank orders single trials according to the impact of each trial on the ERP average. Then, the minimum residual background noise level in the

  14. Adaptive coded spreading OFDM signal for dynamic-λ optical access network

    Science.gov (United States)

    Liu, Bo; Zhang, Lijia; Xin, Xiangjun

    2015-12-01

    This paper proposes and experimentally demonstrates a novel adaptive coded spreading (ACS) orthogonal frequency division multiplexing (OFDM) signal for dynamic distributed optical ring-based access network. The wavelength can be assigned to different remote nodes (RNs) according to the traffic demand of optical network unit (ONU). The ACS can provide dynamic spreading gain to different signals according to the split ratio or transmission length, which offers flexible power budget for the network. A 10×13.12 Gb/s OFDM access with ACS is successfully demonstrated over two RNs and 120 km transmission in the experiment. The demonstrated method may be viewed as one promising for future optical metro access network.

  15. Transmission of multi-dimensional signals for next generation optical communication systems

    Science.gov (United States)

    Yi, Anlin; Yan, Lianshan; Pan, Yan; Jiang, Lin; Chen, Zhiyu; Pan, Wei; Luo, Bin

    2018-02-01

    Over the past several decades, the data-carrying capacity of a single optical fiber have been increased significantly by fully exploring and optimizing physical dimensions of the light. Generally there are five major candidates of dimensions, including time, wavelength, polarization, space and quadrature (phase and amplitude). Multi-dimension, utilizing more than two dimensions of the light simultaneously, is one of the essential characteristics of next generation optical communication systems. We review recent advances in transmission of multi-dimensional signals, and highlight innovative ways of exploring the polarization dimension to further increase the capacity or spectral efficiency of a single optical fiber, a so-called pseudo-polarization-division-multiplexing (PPDM) technique. Related demonstrations include non-orthogonal PDM, PPDM of three and four states (PPDM-3 and PPDM-4). Brief discussions on trends of multi-dimensional signal transmission technologies are also presented.

  16. P300- like event related potential amplitude in rats is a correlate of conditioned reinforcement

    OpenAIRE

    William D. Klipec; Steven Faux

    2012-01-01

    We have developed a methodology for recording a robust P300 event related potential (ERP) in rats. In these experiments a contingency shaped model of the human “oddball’ paradigm was employed in which rats were shaped to press a lever for food reinforcement signaled by the click of the pellet dispenser. A target tone cued the insertion of the lever that retracted after 1­sec or immediately following a single reinforced response, while a non­target tone was randomly ...

  17. Dread of uncertain pain: An event-related potential study.

    Science.gov (United States)

    Huang, Yujing; Shang, Qian; Dai, Shenyi; Ma, Qingguo

    2017-01-01

    Humans experience more stress about uncertain situations than certain situations. However, the neural mechanism underlying the uncertainty of a negative stimulus has not been determined. In the present study, event-related potential was recorded to examine neural responses during the dread of unpredictable pain. We used a cueing paradigm in which predictable cues were always followed by electric shocks, unpredictable cues by electric shocks at a 50/50 ratio and safe cues by no electric shock. Visual analogue scales following electric shocks were presented to quantify subjective anxiety levels. The behavioral results showed that unpredictable cues evoked high-level anxiety compared with predictable cues in both painful and unpainful stimulation conditions. More importantly, the ERPs results revealed that unpredictable cues elicited a larger P200 at parietal sites than predictable cues. In addition, unpredictable cues evoked larger P200 compared with safe cues at frontal electrodes and compared with predictable cues at parietal electrodes. In addition, larger P3b and LPP were observed during perception of safe cues compared with predictable cues at frontal and central electrodes. The similar P3b effect was also revealed in the left sites. The present study underlined that the uncertain dread of pain was associated with threat appraisal process in pain system. These findings on early event-related potentials were significant for a neural marker and development of therapeutic interventions.

  18. Dread of uncertain pain: An event-related potential study.

    Directory of Open Access Journals (Sweden)

    Yujing Huang

    Full Text Available Humans experience more stress about uncertain situations than certain situations. However, the neural mechanism underlying the uncertainty of a negative stimulus has not been determined. In the present study, event-related potential was recorded to examine neural responses during the dread of unpredictable pain. We used a cueing paradigm in which predictable cues were always followed by electric shocks, unpredictable cues by electric shocks at a 50/50 ratio and safe cues by no electric shock. Visual analogue scales following electric shocks were presented to quantify subjective anxiety levels. The behavioral results showed that unpredictable cues evoked high-level anxiety compared with predictable cues in both painful and unpainful stimulation conditions. More importantly, the ERPs results revealed that unpredictable cues elicited a larger P200 at parietal sites than predictable cues. In addition, unpredictable cues evoked larger P200 compared with safe cues at frontal electrodes and compared with predictable cues at parietal electrodes. In addition, larger P3b and LPP were observed during perception of safe cues compared with predictable cues at frontal and central electrodes. The similar P3b effect was also revealed in the left sites. The present study underlined that the uncertain dread of pain was associated with threat appraisal process in pain system. These findings on early event-related potentials were significant for a neural marker and development of therapeutic interventions.

  19. Fractals properties of EEG during event-related desynchronization of motor imagery.

    Science.gov (United States)

    Nguyen, Ngoc Quang; Truong, Quang Dang Khoa; Kondo, Toshiyuki

    2015-01-01

    Chaos and fractal dimension are emerging modalities for the research of electroencephalogram (EEG) signal processing. The capability of measuring non-linear characteristics of the fractal dimension enables new methodologies to identify distinct brain activities. Recent studies on the topic focus on utilizing various types of fractals as features in order to design better brain state classification system. However, we have little insight about the EEG signals projected in fractal dimension. In this paper, we investigate the relationship between the non-linear characteristics of ongoing EEG signals and event-related desynchronization (ERD) during motor imagery. We observed a considerable synchronization between ERD and fractal dimension. This finding suggests further usage of chaos and fractal theory in investigating brain activities.

  20. Measurement of splanchnic photoplethysmographic signals using a new reflectance fiber optic sensor

    Science.gov (United States)

    Hickey, Michelle; Samuels, Neal; Randive, Nilesh; Langford, Richard M.; Kyriacou, Panayiotis A.

    2010-03-01

    Splanchnic organs are particularly vulnerable to hypoperfusion. Currently, there is no technique that allows for the continuous estimation of splanchnic blood oxygen saturation (SpO2). As a preliminary to developing a suitable splanchnic SpO2 sensor, a new reflectance fiber optic photoplethysmographic (PPG) sensor and processing system are developed. An experimental procedure to examine the effect of fiber source detector separation distance on acquired PPG signals is carried out before finalizing the sensor design. PPG signals are acquired from four volunteers for separation distances of 1 to 8 mm. The separation range of 3 to 6 mm provides the best quality PPG signals with large amplitudes and the highest signal-to-noise ratios (SNRs). Preliminary calculation of SpO2 shows that distances of 3 and 4 mm provide the most realistic values. Therefore, it is suggested that the separation distance in the design of a fiber optic reflectance pulse oximeter be in the range of 3 to 4 mm. Preliminary PPG signals from various splanchnic organs and the periphery are obtained from six anaesthetized patients. The normalized amplitudes of the splanchnic PPGs are, on average, approximately the same as those obtained simultaneously from the periphery. These observations suggest that fiber optic pulse oximetry may be a valid monitoring technique for splanchnic organs.

  1. Optical single sideband millimeter-wave signal generation and transmission using 120° hybrid coupler

    Science.gov (United States)

    Zheng, Zhiwei; Peng, Miao; Zhou, Hui; Chen, Ming; Jiang, Leyong; Tan, Li; Dai, Xiaoyu; Xiang, Yuanjiang

    2018-03-01

    We propose a novel 60 GHz optical single sideband (OSSB) millimeter-wave (mm-wave) signal generation scheme using 120° hybrid coupler based on external integrated Mach-Zehnder modulator (MZM). The proposed scheme shows that the bit error ratio (BER) performance is improved by suppressing the +2nd-order sideband. Meanwhile, the transmission distance is extended as only the optical +1st-order sideband is modulated by using 5 Gbit/s baseband signal while the carrier is blank, owing to the elimination of walk-off effect suffered from fiber dispersion. The simulation results demonstrated that the eye diagrams of the generated 60 GHz OSSB signal keep open and clear after 100 km standard single-mode fiber (SSMF). In addition, the proposed scheme can achieve 2 dB receiver sensitivity improvements than the conventional 90° hybrid coupler when transmitted over 100 km SSMF at a BER of 10-9.

  2. All-Optical envelope detection and fiber transmission of wireless signals by external injection of a DFB laser

    DEFF Research Database (Denmark)

    Prince, Kamau; Tafur Monroy, Idelfonso

    2008-01-01

    We outline a novel method for all-optical envelope detection of wireless signals by exploiting cross-gain modulation effects in a distributed feedback laser operating with optical injection. We successfully demonstrate envelope detection of a 20-GHz carrier amplitude-shift-keying modulated signal...

  3. The use of balanced homodyne and squeezed states for detecting weak optical signals in a Michelson interferometer

    International Nuclear Information System (INIS)

    Ben-Aryeh, Y.

    2011-01-01

    The possibility of using squeezed states and balanced homodyne detection of optical signals in a Michelson interferometer is discussed. The present analysis describes photon statistics measurements effects related to quadrature balanced homodyne detection showing the advantage of using this scheme for detecting weak optical signals.

  4. Remote sensing of the energetic status of plants and ecosystems: optical and odorous signals

    Science.gov (United States)

    Penuelas, J.; Bartrons, M.; Llusia, J.; Filella, I.

    2016-12-01

    The optical and odorous signals emitted by plants and ecosystems present consistent relationships. They offer promising prospects for continuous local and global monitoring of the energetic status of plants and ecosystems, and therefore of their processing of energy and matter. We will discuss how the energetic status of plants (and ecosystems) resulting from the balance between the supply and demand of reducing power can be assessed biochemically, by the cellular NADPH/NADP ratio, optically, by using the photochemical reflectance index and sun-induced fluorescence as indicators of the dissipation of excess energy and associated physiological processes, and "odorously", by the emission of volatile organic compounds such as isoprenoids, as indicators of an excess of reducing equivalents and also of enhancement of protective converging physiological processes. These signals thus provide information on the energetic status, associated health status, and the functioning of plants and ecosystems. We will present the links among the three signals and will especially discuss the possibility of remotely sense the optical signals linked to carbon uptake and VOCs exchange by plants and ecosystems. These signals and their integration may have multiple applications for environmental and agricultural monitoring, for example, by extending the spatial coverage of carbon-flux and VOCs emission observations to most places and times, and/or for improving the process-based modeling of carbon fixation and isoprenoid emissions from terrestrial vegetation on plant, ecosystemic and global scales. Considerable challenges remain for a wide-scale and routine implementation of these biochemical, optical, and odorous signals for ecosystemic and/or agronomic monitoring and modeling, but its interest for making further steps forward in global ecology, agricultural applications, global carbon cycle, atmospheric science, and earth science warrants further research efforts in this line.

  5. Linear and Nonlinear Impairment Compensation in Coherent Optical Transmission with Digital Signal Processing

    DEFF Research Database (Denmark)

    Porto da Silva, Edson

    Digital signal processing (DSP) has become one of the main enabling technologies for the physical layer of coherent optical communication networks. The DSP subsystems are used to implement several functionalities in the digital domain, from synchronization to channel equalization. Flexibility...... and effectiveness of DSP contribute to reducing costs and increase reliability of optical communications systems. The work presented in this thesis focuses on DSP subsystems for coherent optical communication systems. In particular, the contributions presented in this thesis relate to the following topics: (I) Kerr...... are performed to evaluate the proposed methods. In conclusion, the results presented in this thesis contribute to the state-of-the-art of DSP for coherent optical communication over single-mode fibers (SMFs). The techniques investigated have the potential to improve performance and reliability of such systems...

  6. Optical technology for microwave applications VI and optoelectronic signal processing for phased-array antennas III; Proceedings of the Meeting, Orlando, FL, Apr. 20-23, 1992

    Science.gov (United States)

    Yao, Shi-Kay; Hendrickson, Brian M.

    The following topics related to optical technology for microwave applications are discussed: advanced acoustooptic devices, signal processing device technologies, optical signal processor technologies, microwave and optomicrowave devices, advanced lasers and sources, wideband electrooptic modulators, and wideband optical communications. The topics considered in the discussion of optoelectronic signal processing for phased-array antennas include devices, signal processing, and antenna systems.

  7. All-optical ultra-wideband doublet signal source based on the cross-gain modulation in a semiconductor optical amplifier

    Science.gov (United States)

    Zhao, Zan-shan; Li, Pei-li; Zheng, Jia-jin; Pan, Ting-ting; Huang, Shi-jie; Luo, You-hong

    2012-03-01

    We propose a novel scheme to generate the ultra-wideband (UWB) doublet signal pulse based on the cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA). In the scheme, only an optical source and an SOA are needed. As there is only one wavelength included in the output doublet signal pulse, no time difference between the upper and down pulses is introduced during the transmission process. By using the software of Optisystem 7.0, the impacts of the optical power, the SOA current, the wavelength and the input signal pulse width on the generated doublet pulse are simulated and tudied numerically. The results show that when the pulse width of the input signal pulse is larger, the output signal pulse is better, and is insensitive to the change of wavelength. In addition, the ultra-wideband positive and negative monocycles can be generated by choosing suitable optical source power and SOA current.

  8. A 2-10 GHz GaAs MMIC opto-electronic phase detector for optical microwave signal generators

    DEFF Research Database (Denmark)

    Bruun, Marlene; Gliese, Ulrik Bo; Petersen, Anders Kongstad

    1994-01-01

    Optical transmission of microwave signals becomes increasingly important. Techniques using beat between optical carriers of semiconductor lasers are promising if efficient optical phase locked loops are realized. A highly efficient GaAs MMIC optoelectronic phase detector for a 2-10 GHz OPLL...

  9. Proprioceptive event related potentials: gating and task effects

    DEFF Research Database (Denmark)

    Arnfred, Sidse Marie

    2005-01-01

    OBJECTIVE: The integration of proprioception with vision, touch or audition is considered basic to the developmental formation of perceptions, conceptual objects and the creation of cognitive schemes. Thus, mapping of proprioceptive information processing is important in cognitive research....... A stimulus of a brisk change of weight on a hand held load elicit a proprioceptive evoked potential (PEP). Here this is used to examine early and late information processing related to weight discrimination by event related potentials (ERP). METHODS: A gating paradigm having 1s between the proprioceptive...... stimuli of 100 g weight increase was recorded in 12 runs of 40 pairs and an 1:4 oddball task of discriminating between 40 and 100 g weight increase was both recorded in 24 healthy men. The subjects were stratified in 3 groups according to their discrimination errors. RESULTS: The proprioceptive event...

  10. Event-Related Potentials and Emotion Processing in Child Psychopathology

    Directory of Open Access Journals (Sweden)

    Georgia eChronaki

    2016-04-01

    Full Text Available In recent years there has been increasing interest in the neural mechanisms underlying altered emotional processes in children and adolescents with psychopathology. This review provides a brief overview of the most up-to-date findings in the field of Event-Related Potentials (ERPs to facial and vocal emotional expressions in the most common child psychopathological conditions. In regards to externalising behaviour (i.e. ADHD, CD, ERP studies show enhanced early components to anger, reflecting enhanced sensory processing, followed by reductions in later components to anger, reflecting reduced cognitive-evaluative processing. In regards to internalising behaviour, research supports models of increased processing of threat stimuli especially at later more elaborate and effortful stages. Finally, in autism spectrum disorders abnormalities have been observed at early visual-perceptual stages of processing. An affective neuroscience framework for understanding child psychopathology can be valuable in elucidating underlying mechanisms and inform preventive intervention.

  11. Re-configurable digital receiver for optically envelope detected half cycle BPSK and MSK radio-on-fiber signals

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Prince, Kamau; Zibar, Darko

    2011-01-01

    We present the first known integration of a digital receiver into optically envelope detection radio-on-fiber systems. We also present a re-configurable scheme for two different types of optically envelope detected wireless signals while keeping the complexity of used optical components low. Our ......-shift-keying and 104.17 Mbit/s minimum-shift-keying radio-frequency modulated signals after 30 km of fiber transmission....

  12. Squeezed-input, optical-spring, signal-recycled gravitational-wave detectors

    International Nuclear Information System (INIS)

    Harms, Jan; Chelkowski, Simon; Franzen, Alexander; Vahlbruch, Henning; Danzmann, Karsten; Schnabel, Roman; Chen Yanbei

    2003-01-01

    We theoretically analyze the quantum noise of signal-recycled laser interferometric gravitational-wave detectors with additional input and output optics, namely, frequency-dependent squeezing of the vacuum state of light entering the dark port and frequency-dependent homodyne detection. We combine the work of Buonanno and Chen on the quantum noise of signal-recycled interferometers with ordinary input and output optics, and the work of Kimble et al. on frequency-dependent input and output optics with conventional interferometers. Analytical formulas for the optimal input and output frequency dependencies are obtained. It is shown that injecting squeezed light with the optimal frequency-dependent squeezing angle into the dark port yields an improvement in the noise spectral density by a factor of e -2r (in power) over the entire squeezing bandwidth, where r is the squeezing parameter. It is further shown that a frequency-dependent (variational) homodyne readout leads to an additional increase in sensitivity which is significant in the wings of the doubly resonant structure. The optimal variational input squeezing in the case of an ordinary output homodyne detection is shown to be realizable by applying two optical filters on a frequency-independent squeezed vacuum. Throughout this paper, we take as an example the signal-recycled topology currently being completed at the GEO 600 site. However, theoretical results obtained here are also applicable to the proposed topology of the Advanced LIGO

  13. Threshold-Based Multiple Optical Signal Selection Scheme for Free-Space Optical Wavelength Division Multiplexing Systems

    KAUST Repository

    Nam, Sung Sik

    2017-11-13

    We propose a threshold-based multiple optical signal selection scheme (TMOS) for free-space optical wavelength division multiplexing systems. With this scheme, we can obtain higher spectral efficiency while reducing the possible complexity of implementation caused by the beam-selection scheme and without a considerable performance loss. To characterize the performance of our scheme, we statistically analyze the operation characteristics under conventional detection conditions (i.e., heterodyne detection and intensity modulation/direct detection techniques) with log-normal turbulence while taking into consideration the impact of pointing error. More specifically, we derive exact closed-form expressions for the outage probability, the average bit error rate, and the average spectral efficiency while adopting an adaptive modulation. Some selected results show that TMOS increases the average spectral efficiency while maintaining a minimum average bit error rate requirement.

  14. Network coding based joint signaling and dynamic bandwidth allocation scheme for inter optical network unit communication in passive optical networks

    Science.gov (United States)

    Wei, Pei; Gu, Rentao; Ji, Yuefeng

    2014-06-01

    As an innovative and promising technology, network coding has been introduced to passive optical networks (PON) in recent years to support inter optical network unit (ONU) communication, yet the signaling process and dynamic bandwidth allocation (DBA) in PON with network coding (NC-PON) still need further study. Thus, we propose a joint signaling and DBA scheme for efficiently supporting differentiated services of inter ONU communication in NC-PON. In the proposed joint scheme, the signaling process lays the foundation to fulfill network coding in PON, and it can not only avoid the potential threat to downstream security in previous schemes but also be suitable for the proposed hybrid dynamic bandwidth allocation (HDBA) scheme. In HDBA, a DBA cycle is divided into two sub-cycles for applying different coding, scheduling and bandwidth allocation strategies to differentiated classes of services. Besides, as network traffic load varies, the entire upstream transmission window for all REPORT messages slides accordingly, leaving the transmission time of one or two sub-cycles to overlap with the bandwidth allocation calculation time at the optical line terminal (the OLT), so that the upstream idle time can be efficiently eliminated. Performance evaluation results validate that compared with the existing two DBA algorithms deployed in NC-PON, HDBA demonstrates the best quality of service (QoS) support in terms of delay for all classes of services, especially guarantees the end-to-end delay bound of high class services. Specifically, HDBA can eliminate queuing delay and scheduling delay of high class services, reduce those of lower class services by at least 20%, and reduce the average end-to-end delay of all services over 50%. Moreover, HDBA also achieves the maximum delay fairness between coded and uncoded lower class services, and medium delay fairness for high class services.

  15. Ultrafast all-optical switching using signal flow graph for PANDA resonator.

    Science.gov (United States)

    Bahadoran, Mahdi; Ali, Jalil; Yupapin, Preecha P

    2013-04-20

    In this paper, the bifurcation behavior of light in the PANDA ring resonator is investigated using the signal flow graph (SFG) method, where the optical transfer function for the through and drop ports of the PANDA Vernier system are derived. The optical nonlinear phenomena, such as bistability, Ikeda instability, and dynamics of light in the silicon-on-insulator (SOI) PANDA ring resonator with four couplers are studied. The transmission curves for bistability and instability as a function of the resonant mode numbers and coupling coefficients for the coupler are derived by the SFG method and simulated. The proposed system has an advantage as no optical pumping component is required. Simulated results show that closed-loop bistable switching can be generated and achieved by varying mode resonant numbers in the SOI-PANDA Vernier resonator, where a smooth and closed-loop bistable switching with low relative output/input power can be obtained and realized. The minimum through-port switching time of 1.1 ps for resonant mode numbers of 5;4;4 and minimum drop port switching time of 1.96 ps for resonant mode numbers of 9;7;7 of the PANDA Vernier resonator are achieved, which makes the PANDA Vernier resonator an operative component for optical applications, such as optical signal processing and a fast switching key in photonics integrated circuits.

  16. Remote controlled signal conditioner and fiber optic data link system development CPRF (Confinement Physics Research Facility)

    International Nuclear Information System (INIS)

    Schrank, L.S.; Caudill, L.D.; Haberstich, A.; Klare, K.A.; Reass, W.A.

    1989-01-01

    The ZTH reversed-field pinch to be installed in the Confinement Physics Research Facility (CPRF) will produce a significant ambient magnetic field. To avoid ground-loop and other electrical problems, the diagnostics in direct or possible contact with the experiment will be accessed through a fiber optic data way. The frequency-modulated analog links developed for this system have a bandwidth of dc to 100 kHz and a signal-to-noise ratio of better than 60 dB. The fiber optic transmitter units include a signal conditioner and a microprocessor controller. The conditioners can be configured as dc-coupled, low-noise differential amplifiers, or as high-gain, low-drift differential integrators with a very long droop time constant. Magnetic field pickup is minimized by balancing sensitive circuit areas to within 5 mm 2 in all three planes of the PC boards. The gain, offset, and integrator reset are controlled and monitored by the microprocessor, and their status is displayed on the front panel of the transmitter unit. The signal conditioner can be controlled locally, or by way of a fiber optic coupled control network. The system allows fast, convenient, noise-immune control of a large number of signal conditioners from a central host computer. By varying the offset, the computer can verify the operational integrity of the data links. 2 refs., 6 figs

  17. Digital nonlinearity compensation in high-capacity optical communication systems considering signal spectral broadening effect.

    Science.gov (United States)

    Xu, Tianhua; Karanov, Boris; Shevchenko, Nikita A; Lavery, Domaniç; Liga, Gabriele; Killey, Robert I; Bayvel, Polina

    2017-10-11

    Nyquist-spaced transmission and digital signal processing have proved effective in maximising the spectral efficiency and reach of optical communication systems. In these systems, Kerr nonlinearity determines the performance limits, and leads to spectral broadening of the signals propagating in the fibre. Although digital nonlinearity compensation was validated to be promising for mitigating Kerr nonlinearities, the impact of spectral broadening on nonlinearity compensation has never been quantified. In this paper, the performance of multi-channel digital back-propagation (MC-DBP) for compensating fibre nonlinearities in Nyquist-spaced optical communication systems is investigated, when the effect of signal spectral broadening is considered. It is found that accounting for the spectral broadening effect is crucial for achieving the best performance of DBP in both single-channel and multi-channel communication systems, independent of modulation formats used. For multi-channel systems, the degradation of DBP performance due to neglecting the spectral broadening effect in the compensation is more significant for outer channels. Our work also quantified the minimum bandwidths of optical receivers and signal processing devices to ensure the optimal compensation of deterministic nonlinear distortions.

  18. Effect of red blood cell aggregation and sedimentation on optical coherence tomography signals from blood samples

    International Nuclear Information System (INIS)

    Kirillin, M Yu; Priezzhev, A V; Tuchin, V V; Wang, R K; Myllylae, R

    2005-01-01

    In this work, Monte Carlo simulation is used to obtain model optical coherence tomography (OCT) signals from a horizontally orientated blood layer at different stages of red blood cell (RBC) aggregation and sedimentation processes. The parameters for aggregating and sedimenting blood cells were chosen based on the data available from the literature and our earlier experimental studies. We consider two different cases: a suspension of washed RBCs in physiological solution (where aggregation does not take place) and RBCs in blood plasma (which provides necessary conditions for aggregation). Good agreement of the simulation results with the available experimental data shows that the chosen optical parameters are reasonable. The dependence of the numbers of photons contributing to the OCT signal on the number of experienced scattering events was analysed for each simulated signal. It was shown that the maxima of these dependences correspond to the peaks in the OCT signals related to the interfaces between the layers of blood plasma and blood cells. Their positions can be calculated from the optical thicknesses of the layers, and the absorption and scattering coefficients of the media

  19. Event-related brain responses while listening to entire pieces of music

    DEFF Research Database (Denmark)

    Poikonen, Hanna; Alluri, Vinoo; Brattico, Elvira

    2017-01-01

    ERPs in human elicited by continuous music. The ERPs were recorded during listening to a Tango Nuevo piece, a deep techno track and an acoustic lullaby. Acoustic features related to timbre, harmony, and dynamics of the audio signal were computationally extracted from the musical pieces. Negative......Brain responses to discrete short sounds have been studied intensively using the event-related potential (ERP) method, in which the electroencephalogram (EEG) signal is divided into epochs time-locked to stimuli of interest. Here we introduce and apply a novel technique which enables one to isolate...... changes in these musical features, long phases of low values that precede a rapid increase – and that we will call Preceding Low-Feature Phases – followed by a rapid increase enhanced the amplitudes of N100 and P200 responses. These ERP responses resembled those to simpler sounds, making it possible...

  20. Signal Generation for Radio Over Fibre Systems Based on Optical Combination

    Directory of Open Access Journals (Sweden)

    Muñoz-Ortiz Rafael Oswaldo

    2015-09-01

    Full Text Available This paper presents a comparative study of the signal generation techniques for the transport of information in Radio over Fiber (RoF systems by using optical combination techniques. In these systems, the radio frequency carriers are conveyed as optical subcarriers over a link in a point-to-point or point-to-multipoint connectivity paradigm. This study is focused on three different generation techniques: double arm, parallel and serial generation. An analytical model to describe the elements, the configuration and the processes involved in the RoF signal generation is defined for each one of them. Subsequently, a modeling of the obtained electrical field functions allows assessing the quality of the generated signals based on the modulation depth. Results show that while there is a trade-off between the modulation depths of both signals for the double arm and serial configuration, the parallel technique relaxes the establishment of different modulation depths. An optimum configuration that guarantees a good quality for the generated signals is found for each generation technique.

  1. Effect of input signal and filter parameters on patterning effect in a semiconductor optical amplifier

    Science.gov (United States)

    Hussain, Kamal; Pratap Singh, Satya; Kumar Datta, Prasanta

    2013-11-01

    A numerical investigation is presented to show the dependence of patterning effect (PE) of an amplified signal in a bulk semiconductor optical amplifier (SOA) and an optical bandpass filter based amplifier on various input signal and filter parameters considering both the cases of including and excluding intraband effects in the SOA model. The simulation shows that the variation of PE with input energy has a characteristic nature which is similar for both the cases. However the variation of PE with pulse width is quite different for the two cases, PE being independent of the pulse width when intraband effects are neglected in the model. We find a simple relationship between the PE and the signal pulse width. Using a simple treatment we study the effect of the amplified spontaneous emission (ASE) on PE and find that the ASE has almost no effect on the PE in the range of energy considered here. The optimum filter parameters are determined to obtain an acceptable extinction ratio greater than 10 dB and a PE less than 1 dB for the amplified signal over a wide range of input signal energy and bit-rate.

  2. Development of Optical Molecular Imaging System for the Acquisition of Bioluminescence Signals from Small Animals

    International Nuclear Information System (INIS)

    Lee, Byeong Il; Kim, Hyeon Sik; Jeong, Hye Jin; Lee, Hyung Jae; Moon, Seung Min; Kwon, Seung Young; Jeong, Shin Young; Bom, Hee Seung; Min, Jung Joon; Choi, Eun Seo

    2009-01-01

    Optical imaging is providing great advance and improvement in genetic and molecular imaging of animals and humans. Optical imaging system consists of optical imaging devices, which carry out major function for monitoring, tracing, and imaging in most of molecular in-vivo researches. In bio-luminescent imaging, small animals containing luciferase gene locally irradiate light, and emitted photons transmitted through skin of the small animals are imaged by using a high sensitive charged coupled device (CCD) camera. In this paper, we introduced optical imaging system for the image acquisition of bio-luminescent signals emitted from small animals. In the system, Nikon lens and four LED light sources were mounted at the inside of a dark box. A cooled CCD camera equipped with a control module was used. We tested the performance of the optical imaging system using effendorf tube and light emitting bacteria which injected intravenously into CT26 tumor bearing nude mouse. The performance of implemented optical imaging system for bio-luminescence imaging was demonstrated and the feasibility of the system in small animal imaging application was proved. We anticipate this system could be a useful tool for the molecular imaging of small animals adaptable for various experimental conditions in future

  3. Optical spectral reshaping for directly modulated 4-pulse amplitude modulation signals

    DEFF Research Database (Denmark)

    Ozolins, Oskars; Da Ros, Francesco; Cristofori, Valentina

    2017-01-01

    (PAM) [3] signals. However, moving to 4-PAM,many of the impressive demonstrations reported so far rely heavily on off-line digital signal processing (DSP), which increases latency, power consumption and cost. In this talk, we report on (i) a detailed numerical analysis on the complex transfer function...... to their low dispersion tolerance and limited achievable extinction ratio (ER). A promising solution to this problem is optical spectral reshaping (OSR) since it is possible to increase the dispersion tolerance as well as to enhance the achievable ER for both on-of-keying [2] and 4-pulse amplitude modulation...

  4. Acousto-optics bandwidth broadening in a Bragg cell based on arbitrary synthesized signal methods.

    Science.gov (United States)

    Peled, Itay; Kaminsky, Ron; Kotler, Zvi

    2015-06-01

    In this work, we present the advantages of driving a multichannel acousto-optical deflector (AOD) with a digitally synthesized multifrequency RF signal. We demonstrate a significant bandwidth broadening of ∼40% by providing well-tuned phase control of the array transducers. Moreover, using a multifrequency, complex signal, we manage to suppress the harmonic deflections and return most of the spurious energy to the main beam. This method allows us to operate the AOD with more than an octave of bandwidth with negligible spurious energy going to the harmonic beams and a total bandwidth broadening of over 70%.

  5. High-Capacity Wireless Signal Generation and Demodulation in 75- to 110-GHz Band Employing All-Optical OFDM

    DEFF Research Database (Denmark)

    Zibar, Darko; Sambaraju, Rakesh; Caballero Jambrina, Antonio

    2011-01-01

    We present a radio-frequency (RF) and bit-rate scalable technique for multigigabit wireless signal generation based on all-optical orthogonal frequency-division multiplexing (OFDM) and photonic up-conversion. Coherent detection supported by digital signal processing is used for signal demodulation...

  6. Linearized Optically Phase-Modulated Fiber Optic Links for Microwave Signal Transport

    Science.gov (United States)

    2009-03-03

    detectors (with internal 50- Ohm resistors) capable of 40-mA dc current per detector. With this link, the linearized SFDR would improve to 133 dB/Hz4/5...the IF) limitation on the signal. All calculations consider the 3dB power loss from the hybrid combiner and 6dB loss from parallel 50- Ohm resistors...283. [25] M. Nazarathy, J. Berger, A. Ley , I. Levi, and Y. Kagan, “Externally Modulated 80 Channel Am Catv Fiber-to-feeder Distribution System Over

  7. Signal of microstrip scanning near-field optical microscope in far- and near-field zones.

    Science.gov (United States)

    Morozov, Yevhenii M; Lapchuk, Anatoliy S

    2016-05-01

    An analytical model of interference between an electromagnetic field of fundamental quasi-TM(EH)00-mode and an electromagnetic field of background radiation at the apex of a near-field probe based on an optical plasmon microstrip line (microstrip probe) has been proposed. The condition of the occurrence of electromagnetic energy reverse flux at the apex of the microstrip probe was obtained. It has been shown that the nature of the interference depends on the length of the probe. Numerical simulation of the sample scanning process was conducted in illumination-reflection and illumination-collection modes. Results of numerical simulation have shown that interference affects the scanning signal in both modes. However, in illumination-collection mode (pure near-field mode), the signal shape and its polarity are practically insensible to probe length change; only signal amplitude (contrast) is slightly changed. However, changing the probe length strongly affects the signal amplitude and shape in the illumination-reflection mode (the signal formed in the far-field zone). Thus, we can conclude that even small background radiation can significantly influence the signal in the far-field zone and has practically no influence on a pure near-field signal.

  8. Investigation of optical current transformer signal processing method based on an improved Kalman algorithm

    Science.gov (United States)

    Shen, Yan; Ge, Jin-ming; Zhang, Guo-qing; Yu, Wen-bin; Liu, Rui-tong; Fan, Wei; Yang, Ying-xuan

    2018-01-01

    This paper explores the problem of signal processing in optical current transformers (OCTs). Based on the noise characteristics of OCTs, such as overlapping signals, noise frequency bands, low signal-to-noise ratios, and difficulties in acquiring statistical features of noise power, an improved standard Kalman filtering algorithm was proposed for direct current (DC) signal processing. The state-space model of the OCT DC measurement system is first established, and then mixed noise can be processed by adding mixed noise into measurement and state parameters. According to the minimum mean squared error criterion, state predictions and update equations of the improved Kalman algorithm could be deduced based on the established model. An improved central difference Kalman filter was proposed for alternating current (AC) signal processing, which improved the sampling strategy and noise processing of colored noise. Real-time estimation and correction of noise were achieved by designing AC and DC noise recursive filters. Experimental results show that the improved signal processing algorithms had a good filtering effect on the AC and DC signals with mixed noise of OCT. Furthermore, the proposed algorithm was able to achieve real-time correction of noise during the OCT filtering process.

  9. Advanced signaling technologies for high-speed digital fiber-optic links.

    Science.gov (United States)

    Stark, Andrew J; Isautier, Pierre; Pan, Jie; Pavan, Sriharsha Kota; Filer, Mark; Tibuleac, Sorin; Lingle, Robert; de Salvo, Richard; Ralph, Stephen E

    2014-09-01

    We summarize the most recent research of the Georgia Tech Terabit Optical Networking Consortium and the state-of-the-art in fiber telecommunications. These results comprise high-capacity single-mode fiber systems with digital coherent receivers and shorter-reach multimode fiber links with vertical cavity surface emitting lasers. We strongly emphasize the capabilities that sophisticated digital signal processing and electronics add to these fiber-based data transport links.

  10. An Expectation-Maximization Algorithm for Amplitude Estimation of Saturated Optical Transient Signals.

    Energy Technology Data Exchange (ETDEWEB)

    Kagie, Matthew J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lanterman, Aaron D. [Georgia Inst. of Technology, Atlanta, GA (United States)

    2017-12-01

    This paper addresses parameter estimation for an optical transient signal when the received data has been right-censored. We develop an expectation-maximization (EM) algorithm to estimate the amplitude of a Poisson intensity with a known shape in the presence of additive background counts, where the measurements are subject to saturation effects. We compare the results of our algorithm with those of an EM algorithm that is unaware of the censoring.

  11. Measurement of gas phase characteristics using new monofiber optical probes and real time signal processing

    International Nuclear Information System (INIS)

    Cartellier, A.

    1998-01-01

    Single optical or impedance phase detection probes are able to measure gas velocities provided that their sensitive length L is accurately known. In this paper, it is shown that L can be controlled during the manufacture of optical probes. Beside, for a probe geometry in the form of a cone + a cylinder + a cone, the corresponding rise time / velocity correlation becomes weakly sensitive to uncontrollable parameter such as the angle of impact on the interface. A real time signal processing performing phase detection as well as velocity measurements is described. Since its sensitivity to the operator inputs is less than the reproducibility of measurements, it is a fairly objective tool. Qualifications achieved in air/water flows with various optical probes demonstrate that the void fraction is detected with a relative error less than 10 %. For bubbly flows, the gas flux is accurate within ±10%, but this uncertainty increases when large bubbles are present in the flow. (author)

  12. Influence of the stem effect on radioluminescence signals from optical fibre Al2O3:C dosemeters

    DEFF Research Database (Denmark)

    Marckmann, C.J.; Aznar, M.C.; Andersen, C.E.

    2006-01-01

    This paper analyses the influence of the Cerenkov radiation and other noise sources, the so-called stem effect, on radioluminescence (RL) signals generated in optical fibre Al2O3:C dosemeters used in medical dosimetry. The optical fibre dosemeter consists of a sensitive Al2O3:C crystal coupled...... to an optical fibre cable that carries the RL and optically stimulated luminescence (OSL) signals generated in the Al2O3:C crystal. During irradiation of the dosemeter, the real-time dose rate can be determined from the RL signal and after irradiation the total dose absorbed is determined from the OSL signal...... stimulated using a focused green solid-state laser. In particular, the components of the stem effect generated in the fibres were analysed to determine their impact on the RL signal....

  13. Auditory P300 event-related potential in tobacco smokers.

    Science.gov (United States)

    Guney, Figen; Genc, Bulent Oguz; Kutlu, Ruhusen; Ilhan, Bilge Cetin

    2009-10-01

    The aim of this study was to elucidate the chronic effects of tobacco smoking on the P300, a neurophysiological index of cognitive function. Prospective study participants were recruited from a family medicine polyclinic. We selected 32 right-handed smokers who had smoked more than 15 cigarettes per day, by inhalation, for more than 2 years. The control population consisted of 32 right-handed, age-matched healthy individuals who had never smoked. Event-related potentials (ERPs) were recorded with the auditory "oddball" two-tone discrimination task. The data from the central (Cz) and frontal (Fz) electrodes were analyzed. The P300 and N1 amplitudes at Fz were lower in the study population compared to the control group. The early component of ERP, the measure of mental speed (N1) latency at Fz was prolonged in the study group compared to the controls, possibly because early cognitive processes such as sensory input or initial encoding of sensory information were delayed in this group. For those who smoke, a decreased N1 amplitude might indicate delayed information processing and possibly short-term memory disturbance. Thus, chronic tobacco smoking may produce prefrontal cognitive dysfunction.

  14. Social Comparison Manifests in Event-related Potentials.

    Science.gov (United States)

    Luo, Yi; Feng, Chunliang; Wu, Tingting; Broster, Lucas S; Cai, Huajian; Gu, Ruolei; Luo, Yue-jia

    2015-07-17

    Social comparison, a widespread phenomenon in human society, has been found to affect outcome evaluation. The need to belong to a social group may result in distinct neural responses to diverse social comparison outcomes. To extend previous studies by examining how social comparison with hierarchical characteristics is temporally processed, electroencephalography responses were recorded in the current study. Participants played a lottery game with two pseudo-players simultaneously and received both their own and the other two players' outcomes. Results of three event-related potential components, including the P2, the feedback-related negativity (FRN), and the late positive component (LPC), indicate that social comparison manifests in three stages. First, outcomes indicating a different performance from others elicited a larger P2 than evenness. Second, the FRN showed hierarchical sensitivity to social comparison outcomes. This effect manifested asymmetrically. Finally, large difference between the participant's outcome and the other two players' evoked a larger LPC than the medium difference and the even condition. We suggest that during social comparison, people detect if there is any difference between self and others, and then evaluate the information of this difference hierarchically, and finally interpret the situations in which oneself deviates from the group as most motivationally salient.

  15. Acute low-level alcohol consumption reduces phase locking of event-related oscillations in rodents.

    Science.gov (United States)

    Amodeo, Leslie R; Wills, Derek N; Ehlers, Cindy L

    2017-07-14

    Event-related oscillations (EROs) are rhythmic changes that are evoked by a sensory and/or cognitive stimulus that can influence the dynamics of the EEG. EROs are defined by the decomposition of the EEG signal into magnitude (energy) and phase information and can be elicited in both humans and animals. EROs have been linked to several relevant genes associated with ethanol dependence phenotypes in humans and are altered in selectively bred alcohol-preferring rats. However, pharmacological studies are only beginning to emerge investigating the impact low intoxicating doses of ethanol can have on event-related neural oscillations. The main goal of this study was to investigate the effects of low levels of voluntary consumption of ethanol, in rats, on phase locking of EROs in order to give further insight into the acute intoxicating effects of ethanol on the brain. To this end, we allow rats to self-administer unsweetened 20% ethanol over 15 intermittent sessions. This method results in a stable low-dose consumption of ethanol. Using an auditory event-related potential "oddball" paradigm, we investigated the effects of alcohol on the phase variability of EROs from electrodes implanted into the frontal cortex, dorsal hippocampus, and amygdala. We found that intermittent ethanol self-administration was sufficient to produce a significant reduction in overall intraregional synchrony across all targeted regions. These data suggest that phase locking of EROs within brain regions known to be impacted by alcohol may represent a sensitive biomarker of low levels of alcohol intoxication. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. A high-resolution optical rangefinder using tunable focus optics and spatial photonic signal processing

    Science.gov (United States)

    Khwaja, Tariq S.; Mazhar, Mohsin Ali; Niazi, Haris Khan; Reza, Syed Azer

    2017-06-01

    In this paper, we present the design of a proposed optical rangefinder to determine the distance of a semi-reflective target from the sensor module. The sensor module deploys a simple Tunable Focus Lens (TFL), a Laser Source (LS) with a Gaussian Beam profile and a digital beam profiler/imager to achieve its desired operation. We show that, owing to the nature of existing measurement methodologies, previous attempts to use a simple TFL in prior art to estimate target distance mostly deliver "one-shot" distance measurement estimates instead of obtaining and using a larger dataset which can significantly reduce the effect of some largely incorrect individual data points on the final distance estimate. Using a measurement dataset and calculating averages also helps smooth out measurement errors in individual data points through effectively low-pass filtering unexpectedly odd measurement offsets in individual data points. In this paper, we show that a simple setup deploying an LS, a TFL and a beam profiler or imager is capable of delivering an entire measurement dataset thus effectively mitigating the effects on measurement accuracy which are associated with "one-shot" measurement techniques. The technique we propose allows a Gaussian Beam from an LS to pass through the TFL. Tuning the focal length of the TFL results in altering the spot size of the beam at the beam imager plane. Recording these different spot radii at the plane of the beam profiler for each unique setting of the TFL provides us with a means to use this measurement dataset to obtain a significantly improved estimate of the target distance as opposed to relying on a single measurement. We show that an iterative least-squares curve-fit on the recorded data allows us to estimate distances of remote objects very precisely. We also show that using some basic ray-optics-based approximations, we also obtain an initial seed value for distance estimate and subsequently use this value to obtain a more precise

  17. Impact of amplitude jitter and signal-to-noise ratio on the nonlinear spectral compression in optical fibres

    Science.gov (United States)

    Boscolo, Sonia; Fatome, Julien; Finot, Christophe

    2017-04-01

    We numerically study the effects of amplitude fluctuations and signal-to-noise ratio degradation of the seed pulses on the spectral compression process arising from nonlinear propagation in an optical fibre. The unveiled quite good stability of the process against these pulse degradation factors is assessed in the context of optical regeneration of intensity-modulated signals, by combining nonlinear spectral compression with centered bandpass optical filtering. The results show that the proposed nonlinear processing scheme indeed achieves mitigation of the signal's amplitude noise. However, in the presence of a jitter of the temporal duration of the pulses, the performance of the device deteriorates. © 2016 Elsevier

  18. Adaptive Integrated Optical Bragg Grating in Semiconductor Waveguide Suitable for Optical Signal Processing

    Science.gov (United States)

    Moniem, T. A.

    2016-05-01

    This article presents a methodology for an integrated Bragg grating using an alloy of GaAs, AlGaAs, and InGaAs with a controllable refractive index to obtain an adaptive Bragg grating suitable for many applications on optical processing and adaptive control systems, such as limitation and filtering. The refractive index of a Bragg grating is controlled by using an external electric field for controlling periodic modulation of the refractive index of the active waveguide region. The designed Bragg grating has refractive indices programmed by using that external electric field. This article presents two approaches for designing the controllable refractive indices active region of a Bragg grating. The first approach is based on the modification of a planar micro-strip structure of the iGaAs traveling wave as the active region, and the second is based on the modification of self-assembled InAs/GaAs quantum dots of an alloy from GaAs and InGaAs with a GaP traveling wave. The overall design and results are discussed through numerical simulation by using the finite-difference time-domain, plane wave expansion, and opto-wave simulation methods to confirm its operation and feasibility.

  19. Detection and Correction of Under-/Overexposed Optical Soundtracks by Coupling Image and Audio Signal Processing

    Science.gov (United States)

    Taquet, Jonathan; Besserer, Bernard; Hassaine, Abdelali; Decenciere, Etienne

    2008-12-01

    Film restoration using image processing, has been an active research field during the last years. However, the restoration of the soundtrack has been mainly performed in the sound domain, using signal processing methods, despite the fact that it is recorded as a continuous image between the images of the film and the perforations. While the very few published approaches focus on removing dust particles or concealing larger corrupted areas, no published works are devoted to the restoration of soundtracks degraded by substantial underexposure or overexposure. Digital restoration of optical soundtracks is an unexploited application field and, besides, scientifically rich, because it allows mixing both image and signal processing approaches. After introducing the principles of optical soundtrack recording and playback, this contribution focuses on our first approaches to detect and cancel the effects of under and overexposure. We intentionally choose to get a quantification of the effect of bad exposure in the 1D audio signal domain instead of 2D image domain. Our measurement is sent as feedback value to an image processing stage where the correction takes place, building up a "digital image and audio signal" closed loop processing. The approach is validated on both simulated alterations and real data.

  20. Research and Analysis Laser Target Optics Characteristics and Signal Recognition Processing in Detection Screen System

    Directory of Open Access Journals (Sweden)

    Hanshan LI

    2014-02-01

    Full Text Available In order to improve the measurement accuracy of the laser measurement distance system, this paper study the laser target optics characteristics based on the laser detection principle in the laser measurement distance system. A calculation model of laser reflective echo signal is put forward by analyzing the influence factors on the detector output value, and discuss the relationship between the distance from the detector to the target, the laser wavelength, the Transmission power of laser and the detector output power, the radiation intensity, and use the Fisher identification and modulus maxima method based on wavelet analysis to distinguish and identify the received echo signals. By the theoretical calculation and experimentation, the result shows the laser target optics characteristics are consistent with the calculation method of radiation. The real reflective signal can be identified by using wavelet transform, and the numerical value of the distance between the target and the detector is larger, the numerical value of echo signal will be smaller.

  1. Detection and Correction of Under-/Overexposed Optical Soundtracks by Coupling Image and Audio Signal Processing

    Directory of Open Access Journals (Sweden)

    Etienne Decenciere

    2008-10-01

    Full Text Available Film restoration using image processing, has been an active research field during the last years. However, the restoration of the soundtrack has been mainly performed in the sound domain, using signal processing methods, despite the fact that it is recorded as a continuous image between the images of the film and the perforations. While the very few published approaches focus on removing dust particles or concealing larger corrupted areas, no published works are devoted to the restoration of soundtracks degraded by substantial underexposure or overexposure. Digital restoration of optical soundtracks is an unexploited application field and, besides, scientifically rich, because it allows mixing both image and signal processing approaches. After introducing the principles of optical soundtrack recording and playback, this contribution focuses on our first approaches to detect and cancel the effects of under and overexposure. We intentionally choose to get a quantification of the effect of bad exposure in the 1D audio signal domain instead of 2D image domain. Our measurement is sent as feedback value to an image processing stage where the correction takes place, building up a “digital image and audio signal” closed loop processing. The approach is validated on both simulated alterations and real data.

  2. A Review on Successive Interference Cancellation-Based Optical PPM-CDMA Signaling

    Science.gov (United States)

    Alsowaidi, Naif; Eltaif, Tawfig; Mokhtar, Mohd Ridzuan

    2017-06-01

    This paper presents a comprehensive review of successive interference cancellation (SIC) scheme using pulse position modulation (PPM) for optical code division multiple access (OCDMA) systems. SIC scheme focuses on high-intensity signal, which will be selected after all users were detected, and then it will be subtracted from the overall received signal, hence, generating a new received signal. This process continues till all users eliminated one by one have been detected. It is shown that the random location of the sequences due to PPM encoding can reduce the probability of concentrated buildup of the pulse overlap in any one-slot time, and support SIC to easily remove the effect of the strongest signal at each stage of the cancellation process. The system bit error rate (BER) performance with modified quadratic congruence (MQC) codes used as signature sequence has been investigated. A detailed theoretical analysis of proposed system taking into account the impact of imperfect interference cancellation, the loss produced from the splitting during encoding and decoding, the channel loss and multiple access interference is presented. Results show that under average effective power constraint optical CDMA system using SIC scheme with M-ary PPM modulation outperforms conventional correlator detector and SIC scheme with on-off keying (OOK) modulation.

  3. ``Seeing'' electroencephalogram through the skull: imaging prefrontal cortex with fast optical signal

    Science.gov (United States)

    Medvedev, Andrei V.; Kainerstorfer, Jana M.; Borisov, Sergey V.; Gandjbakhche, Amir H.; Vanmeter, John

    2010-11-01

    Near-infrared spectroscopy is a novel imaging technique potentially sensitive to both brain hemodynamics (slow signal) and neuronal activity (fast optical signal, FOS). The big challenge of measuring FOS noninvasively lies in the presumably low signal-to-noise ratio. Thus, detectability of the FOS has been controversially discussed. We present reliable detection of FOS from 11 individuals concurrently with electroencephalogram (EEG) during a Go-NoGo task. Probes were placed bilaterally over prefrontal cortex. Independent component analysis (ICA) was used for artifact removal. Correlation coefficient in the best correlated FOS-EEG ICA pairs was highly significant (p prefrontal cortex in rapid object recognition. EROS is highly localized and can provide cost-effective imaging tools for cortical mapping of cognitive processes.

  4. Multi-stage optical FDM of 12-channel 10-Gb/s data with 20-GHz exact channel spacing using fiber cross-phase modulation with optical subcarrier signals.

    Science.gov (United States)

    Kato, Tomoyuki; Okabe, Ryo; Ludwig, Reinhold; Elschner, Robert; Schubert, Colja; Watanabe, Shigeki

    2011-12-12

    A sequential optical frequency-division multiplexing technique using cross-phase modulation in fibers with exactly frequency-controlled optical subcarrier signals is proposed and demonstrated. 12 channels of 10-Gb/s ASK/DPSK signals with 20-GHz exact channel spacing are successfully multiplexed all-optically at 12 stages with 1-km intervals. © 2011 Optical Society of America

  5. Event-related potential correlates of mindfulness meditation competence

    Science.gov (United States)

    Atchley, Rachel; Klee, Dan; Memmott, Tabatha; Goodrich, Elena; Wahbeh, Helané; Oken, Barry

    2016-01-01

    Objective This cross-sectional study evaluated event-related potentials (ERPs) across three groups: naïve, novice, and experienced meditators as potential physiological markers of mindfulness meditation competence. Methods Electroencephalographic (EEG) data was collected during a target tone detection task and a Breath Counting task. The Breath Counting task served as the mindfulness meditation condition for the novice and experienced meditator groups. Participants were instructed to respond to target tones with a button press in the first task (Tones), and then ignore the primed tones while breath counting. The primary outcomes were ERP responses to target tones, namely the N2 and P3, as markers of stimulus discrimination and attention, respectively. Results As expected, P3 amplitudes elicited by target tones were attenuated within groups during the Breath Counting task in comparison to the Tones task (p meditator groups displayed greater change in peak-to-trough P3 amplitudes, with higher amplitudes during the Tones condition and more pronounced reductions in P3 amplitudes during the Breath Counting meditation task in comparison to the naïve group. Conclusions Meditators had stronger P3 amplitude responses to target tones when instructed to attend to the tones, and a greater attenuation of P3 amplitudes when instructed to ignore the same tones during the Breath Counting task. This study introduces the idea of identifying ERP markers as a means of measuring mindfulness meditation competence, and results suggest this may be a valid approach. This information has the potential to improve mindfulness meditation interventions by allowing objective assessment of mindfulness meditation quality. PMID:26850995

  6. Iconic Meaning in Music: An Event-Related Potential Study

    Science.gov (United States)

    Luo, Qiuling; Huang, Hong; Mo, Lei

    2015-01-01

    Although there has been extensive research on the processing of the emotional meaning of music, little is known about other aspects of listeners’ experience of music. The present study investigated the neural correlates of the iconic meaning of music. Event-related potentials (ERP) were recorded while a group of 20 music majors and a group of 20 non-music majors performed a lexical decision task in the context of implicit musical iconic meaning priming. ERP analysis revealed a significant N400 effect of congruency in time window 260-510 ms following the onset of the target word only in the group of music majors. Time-course analysis using 50 ms windows indicated significant N400 effects both within the time window 410-460 ms and 460-510 ms for music majors, whereas only a partial N400 effect during time window 410-460 ms was observed for non-music majors. There was also a trend for the N400 effects in the music major group to be stronger than those in the non-major group in the sub-windows of 310-360ms and 410-460ms. Especially in the sub-window of 410-460 ms, the topographical map of the difference waveforms between congruent and incongruent conditions revealed different N400 distribution between groups; the effect was concentrated in bilateral frontal areas for music majors, but in central-parietal areas for non-music majors. These results imply probable neural mechanism differences underlying automatic iconic meaning priming of music. Our findings suggest that processing of the iconic meaning of music can be accomplished automatically and that musical training may facilitate the understanding of the iconic meaning of music. PMID:26161561

  7. Event-related potential correlates of mindfulness meditation competence.

    Science.gov (United States)

    Atchley, R; Klee, D; Memmott, T; Goodrich, E; Wahbeh, H; Oken, B

    2016-04-21

    This cross-sectional study evaluated event-related potentials (ERPs) across three groups: naïve, novice, and experienced meditators as potential physiological markers of mindfulness meditation competence. Electroencephalographic (EEG) data were collected during a target tone detection task and a Breath Counting task. The Breath Counting task served as the mindfulness meditation condition for the novice and experienced meditator groups. Participants were instructed to respond to target tones with a button press in the first task (Tones), and then ignore the primed tones while Breath Counting. The primary outcomes were ERP responses to target tones, namely the N2 and P3, as markers of stimulus discrimination and attention, respectively. As expected, P3 amplitudes elicited by target tones were attenuated within groups during the Breath Counting task in comparison to the Tones task (pmeditator groups displayed greater change in peak-to-trough P3 amplitudes, with higher amplitudes during the Tones condition and more pronounced reductions in P3 amplitudes during the Breath Counting meditation task in comparison to the naïve group. Meditators had stronger P3 amplitude responses to target tones when instructed to attend to the tones, and a greater attenuation of P3 amplitudes when instructed to ignore the same tones during the Breath Counting task. This study introduces the idea of identifying ERP markers as a means of measuring mindfulness meditation competence, and results suggest this may be a valid approach. This information has the potential to improve mindfulness meditation interventions by allowing objective assessment of mindfulness meditation quality. Published by Elsevier Ltd.

  8. Accounting for Laser Extinction, Signal Attenuation, and Secondary Emission While Performing Optical Patternation in a Single Plane

    National Research Council Canada - National Science Library

    Brown, C

    2002-01-01

    An optical patternation method is described where the effects of laser extinction and signal attenuation can be corrected for, and where secondary scattering effects are reduced by probing the spray...

  9. Coherent demodulation of microwave signals by using optical heterodyne technique with applications to point to point indoor wireless communications systems

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Juarez, A; Gomez-Colin, M R; Rojas-Hernandez, A G [Universidad de Sonora (Mexico); Zaldivar-Huerta, I E; Aguayo-Rodriguez, G [Instituto Nacional de Astrofisica, Optica y Electronica (Mexico); Rodriguez-Asomoza, J, E-mail: agarcia@cifus.uson.mx [Universidad de las Americas-Puebla (Mexico)

    2011-01-01

    An optical communications system using a couple microstrip antennas for distributing point to point analog TV with coherent demodulation based on optical heterodyne in close vicinity is reported in this paper. In the proposed experimental setup, two optical waves at different wavelengths are mixed and applied to a photodetector. Then a beat signal with a frequency equivalent to the spacing of the two wavelengths is obtained at the output of the photodetector. This signal corresponds to a microwave signal located at 1.25 GHz, which it is used as a microwave carrier in the transmitter and as a local oscillator in the receiver of our optical communication system. The feasibility of this technique is demonstrated transmitting a TV signal of 66-72 MHz.

  10. Parametric Phase-sensitive and Phase-insensitive All-optical Signal Processing on Multiple Nonlinear Platforms - Invited talk

    DEFF Research Database (Denmark)

    Peucheret, Christophe; Da Ros, Francesco; Vukovic, Dragana

    -optical signal processing. In this presentation, we will review our recent results on the demonstration of all-optical para- metric signal processing using dierent nonlinear platforms, including highly nonlinear optical bers (HNLFs), silicon nanowires, and periodically-poled lithium niobate (PPLN) waveguides......Parametric processes in materials presenting a second- or third-order nonlinearity have been widely used to demonstrate a wide range of all-optical signal processing functionalities, including amplication, wavelength conversion, regeneration, sampling, switching, modulation format conver- sion....... In particu- lar, we will show how phase-sensitive processes can be engineered to demonstrate phase-quadrature separation, which we have recently demonstrated in HNLFs [1] and PPLN waveguides [2]. Silicon nanowires are particularly attractive for signal processing thanks to their compact size, CMOS...

  11. Wide bandwidth fiber-optic ultrasound probe in MOMS technology: Preliminary signal processing results.

    Science.gov (United States)

    Vannacci, E; Granchi, S; Belsito, L; Roncaglia, A; Biagi, E

    2017-03-01

    An ultrasonic probe consisting of two optical fiber-based miniaturized transducers for wideband ultrasound emission and detection is employed for the characterization of in vitro biological tissues. In the probe, ultrasound generation is obtained by thermoelastic emission from patterned carbon films in Micro-Opto-Mechanical-System (MOMS) devices mounted on the tip of an optical fiber, whereas acousto-optical detection is performed in a similar way by a miniaturized polymeric interferometer. The microprobe presents a wide, flat bandwidth that is a very attractive feature for ultrasonic investigation, especially for tissue characterization. Thanks to the very high ultrasonic frequencies obtained, the probe is able to reveal different details of the object under investigation by analyzing the ultrasonic signal within different frequencies ranges, as shown by specific experiments performed on a patterned cornstarch flour sample in vitro. This is confirmed by measurements executed to determine the lateral resolution of the microprobe at different frequencies of about 70μm at 120MHz. Moreover, measurements performed with the wideband probe in pulsed-echo mode on a histological finding of porcine kidney are presented, on which two different spectral signal processing algorithms are applied. After processing, the ultrasonic spectral features show a peculiar spatial distribution on the sample, which is expected to depend on different ultrasonic backscattering properties of the analyzed tissues. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Analysis of Optical CDMA Signal Transmission: Capacity Limits and Simulation Results

    Directory of Open Access Journals (Sweden)

    Lawrence R. Chen

    2005-06-01

    Full Text Available We present performance limits of the optical code-division multiple-access (OCDMA networks. In particular, we evaluate the information-theoretical capacity of the OCDMA transmission when single-user detection (SUD is used by the receiver. First, we model the OCDMA transmission as a discrete memoryless channel, evaluate its capacity when binary modulation is used in the interference-limited (noiseless case, and extend this analysis to the case when additive white Gaussian noise (AWGN is corrupting the received signals. Next, we analyze the benefits of using nonbinary signaling for increasing the throughput of optical CDMA transmission. It turns out that up to a fourfold increase in the network throughput can be achieved with practical numbers of modulation levels in comparison to the traditionally considered binary case. Finally, we present BER simulation results for channel coded binary and M-ary OCDMA transmission systems. In particular, we apply turbo codes concatenated with Reed-Solomon codes so that up to several hundred concurrent optical CDMA users can be supported at low target bit error rates. We observe that unlike conventional OCDMA systems, turbo-empowered OCDMA can allow overloading (more active users than is the length of the spreading sequences with good bit error rate system performance.

  13. Analysis of Optical CDMA Signal Transmission: Capacity Limits and Simulation Results

    Science.gov (United States)

    Garba, Aminata A.; Yim, Raymond M. H.; Bajcsy, Jan; Chen, Lawrence R.

    2005-12-01

    We present performance limits of the optical code-division multiple-access (OCDMA) networks. In particular, we evaluate the information-theoretical capacity of the OCDMA transmission when single-user detection (SUD) is used by the receiver. First, we model the OCDMA transmission as a discrete memoryless channel, evaluate its capacity when binary modulation is used in the interference-limited (noiseless) case, and extend this analysis to the case when additive white Gaussian noise (AWGN) is corrupting the received signals. Next, we analyze the benefits of using nonbinary signaling for increasing the throughput of optical CDMA transmission. It turns out that up to a fourfold increase in the network throughput can be achieved with practical numbers of modulation levels in comparison to the traditionally considered binary case. Finally, we present BER simulation results for channel coded binary and[InlineEquation not available: see fulltext.]-ary OCDMA transmission systems. In particular, we apply turbo codes concatenated with Reed-Solomon codes so that up to several hundred concurrent optical CDMA users can be supported at low target bit error rates. We observe that unlike conventional OCDMA systems, turbo-empowered OCDMA can allow overloading (more active users than is the length of the spreading sequences) with good bit error rate system performance.

  14. Relationship of Event-Related Potentials to the Vigilance Decrement

    Directory of Open Access Journals (Sweden)

    Ashley Haubert

    2018-03-01

    Full Text Available Cognitive fatigue emerges in wide-ranging tasks and domains, but traditional vigilance tasks provide a well-studied context in which to explore the mechanisms underlying it. Though a variety of experimental methodologies have been used to investigate cognitive fatigue in vigilance, relatively little research has utilized electroencephalography (EEG, specifically event-related potentials (ERPs, to explore the nature of cognitive fatigue, also known as the vigilance decrement. Moreover, much of the research that has been done on vigilance and ERPs uses non-traditional vigilance paradigms, limiting generalizability to the established body of behavioral results and corresponding theories. In this study, we address concerns with prior research by (1 investigating the vigilance decrement using a well-established visual vigilance task, (2 utilizing a task designed to attenuate possible confounding ERP components present within a vigilance paradigm, and (3 informing our interpretations with recent findings from ERP research. We averaged data across electrodes located over the frontal, central, and parietal scalp. Then, we generated waveforms locked to the onset of critical low-frequency or non-critical high-frequency events during a 40 min task that was segregated into time blocks for data analysis. There were three primary findings from the analyses of these data. First, mean amplitude of N1 was greater during later blocks for both low-frequency and high-frequency events, a contradictory finding compared to past visual vigilance studies that is further discussed with respect to current interpretations of the N1 in visual attention tasks. Second, P3b mean amplitude following low-frequency events was reduced during later blocks, with a later onset latency. Third and finally, the decrease in P3b amplitude correlated with individual differences in the magnitude of the vigilance decrement, assessed using d′. The results provide evidence for degradations

  15. An energy ratio feature extraction method for optical fiber vibration signal

    Science.gov (United States)

    Sheng, Zhiyong; Zhang, Xinyan; Wang, Yanping; Hou, Weiming; Yang, Dan

    2017-12-01

    The intrusion events in the optical fiber pre-warning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of these two types of events are usually designed from the view of the time domain. However, the differences of time-domain characteristics for different harmful intrusion events are not obvious, which cannot reflect the diversity of them in detail. We find that the spectrum distribution of different intrusion signals has obvious differences. For this reason, the intrusion signal is transformed into the frequency domain. In this paper, an energy ratio feature extraction method of harmful intrusion event is drawn on. Firstly, the intrusion signals are pre-processed and the power spectral density (PSD) is calculated. Then, the energy ratio of different frequency bands is calculated, and the corresponding feature vector of each type of intrusion event is further formed. The linear discriminant analysis (LDA) classifier is used to identify the harmful intrusion events in the paper. Experimental results show that the algorithm improves the recognition rate of the intrusion signal, and further verifies the feasibility and validity of the algorithm.

  16. AMA- and RWE- Based Adaptive Kalman Filter for Denoising Fiber Optic Gyroscope Drift Signal.

    Science.gov (United States)

    Yang, Gongliu; Liu, Yuanyuan; Li, Ming; Song, Shunguang

    2015-10-23

    An improved double-factor adaptive Kalman filter called AMA-RWE-DFAKF is proposed to denoise fiber optic gyroscope (FOG) drift signal in both static and dynamic conditions. The first factor is Kalman gain updated by random weighting estimation (RWE) of the covariance matrix of innovation sequence at any time to ensure the lowest noise level of output, but the inertia of KF response increases in dynamic condition. To decrease the inertia, the second factor is the covariance matrix of predicted state vector adjusted by RWE only when discontinuities are detected by adaptive moving average (AMA).The AMA-RWE-DFAKF is applied for denoising FOG static and dynamic signals, its performance is compared with conventional KF (CKF), RWE-based adaptive KF with gain correction (RWE-AKFG), AMA- and RWE- based dual mode adaptive KF (AMA-RWE-DMAKF). Results of Allan variance on static signal and root mean square error (RMSE) on dynamic signal show that this proposed algorithm outperforms all the considered methods in denoising FOG signal.

  17. An energy ratio feature extraction method for optical fiber vibration signal

    Science.gov (United States)

    Sheng, Zhiyong; Zhang, Xinyan; Wang, Yanping; Hou, Weiming; Yang, Dan

    2018-03-01

    The intrusion events in the optical fiber pre-warning system (OFPS) are divided into two types which are harmful intrusion event and harmless interference event. At present, the signal feature extraction methods of these two types of events are usually designed from the view of the time domain. However, the differences of time-domain characteristics for different harmful intrusion events are not obvious, which cannot reflect the diversity of them in detail. We find that the spectrum distribution of different intrusion signals has obvious differences. For this reason, the intrusion signal is transformed into the frequency domain. In this paper, an energy ratio feature extraction method of harmful intrusion event is drawn on. Firstly, the intrusion signals are pre-processed and the power spectral density (PSD) is calculated. Then, the energy ratio of different frequency bands is calculated, and the corresponding feature vector of each type of intrusion event is further formed. The linear discriminant analysis (LDA) classifier is used to identify the harmful intrusion events in the paper. Experimental results show that the algorithm improves the recognition rate of the intrusion signal, and further verifies the feasibility and validity of the algorithm.

  18. Event-related potential evidence suggesting voters remember political events that never happened.

    Science.gov (United States)

    Coronel, Jason C; Federmeier, Kara D; Gonsalves, Brian D

    2014-03-01

    Voters tend to misattribute issue positions to political candidates that are consistent with their partisan affiliation, even though these candidates have never explicitly stated or endorsed such stances. The prevailing explanation in political science is that voters misattribute candidates' issue positions because they use their political knowledge to make educated but incorrect guesses. We suggest that voter errors can also stem from a different source: false memories. The current study examined event-related potential (ERP) responses to misattributed and accurately remembered candidate issue information. We report here that ERP responses to misattributed information can elicit memory signals similar to that of correctly remembered old information--a pattern consistent with a false memory rather than educated guessing interpretation of these misattributions. These results suggest that some types of voter misinformation about candidates may be harder to correct than previously thought.

  19. All-optical characterization of large-signal modulation bandwidth of a monolithically integrated DFB-EA

    DEFF Research Database (Denmark)

    Blaaberg, Søren; Mulvad, Hans Christian Hansen; Oxenløwe, Leif Katsuo

    2009-01-01

    We use an all-optical method to characterize the modulation bandwidth of a DFB-EA designed for 100 Gb/s Ethernet. In a large-signal wavelength conversion set-up, we show the device has an all-optical bandwidth of 83 GHz....

  20. Electroabsorption modulators used for all-optical signal processing and labelling

    DEFF Research Database (Denmark)

    Xu, Lin

    2004-01-01

    This thesis concerns the applications of semiconductor components, primarily electroabsorption modulators (EAMs), in optical signal processing and labelling for future all optical communication networks. An introduction to electroabsorption modulators is given and several mechanisms that form...... encoding are –25.6/-28.1 dBm and –23.7/-21 dBm, respectively. Using an EAM for optical label insertion and a MZ-SOA for optical label erasure and payload regeneration in the ASK(10 Gb/s)/ Frequency Shift Keying (312 Mb/s) orthogonal modulation format, the complete functionality of a network node including...... in the return-to-zero (RZ)-DPSK/ASK and non-return-to-zero (NRZ)-DPSK/ASK format. We experimentally demonstrated label encoding, transmission over a 50 km SMF link, and label erasure of a 40 Gb/s RZDPSK modulated payload with an orthogonal 2.5 Gb/s ASK label. The penalties for the payload and label due...

  1. De-noising with a SOCK can improve the performance of event-related ICA

    Directory of Open Access Journals (Sweden)

    Kaushik eBhaganagarapu

    2014-09-01

    Full Text Available Event-related ICA (eICA is a partially data-driven analysis method for event-related fMRI that is particularly suited to analysis of simultaneous EEG-fMRI of patients with epilepsy. EEG-fMRI studies in epileptic patients are typically analyzed using the general linear model (GLM, often with assumption that the onset and o□set of neuronal activity match EEG event onset and o□set, the neuronal activation is sustained at a constant level throughout the epileptiform event and that associated fMRI signal changes follow the canonical HRF. The eICA method allows for less constrained analyses capable of detecting early, non-canonical responses. A key step of eICA is the initial deconvolution which can be confounded by various sources of structured noise present in the fMRI signal. To help overcome this, we have extend the eICA procedure by utilizing a fully standalone and automated fMRI de-noising procedure to process the fMRI data from an EEG-fMRI acquisition prior to running eICA. Specifically we first apply ICA to the entire fMRI time-series and use a classifier to remove noise-related components. The automated objective de-noiser, Spatially Organised Component Klassificator (SOCK is used; it has previously been shown to distinguish a substantial fraction of noise from true activation, without rejecting the latter, in resting-state fMRI. A second ICA is then performed, this time on the event-related response estimates derived from the denoised data (according to the usual eICA procedure. We hypothesize that SOCK + eICA has the potential to be more sensitive than eICA alone. We test the e□effectiveness of SOCK by comparing activation obtained in an eICA analysis of EEG-fMRI data with and without the use of SOCK for 14 patients with rolandic epilepsy who exhibited stereotypical IEDs arising from a focus in the rolandic fissure.

  2. Fuzzy control of optical PPM CDMA with M-ary orthogonal signaling

    Science.gov (United States)

    Cui, K.; Leeson, M. S.; Hines, E. L.

    2008-06-01

    This paper introduces an incorporated spectral-amplitude coding (SAC) optical code-division multiple-access (OCDMA) scheme. One novel class of optical signature codes based on combinatorial designs is employed with M-ary pulse-position modulation (PPM) signaling to improve the system performance beyond the interference limit. A union upper bound on the bit error rate (BER) is derived and the performance characteristics are then discussed with a variety of system parameters. Furthermore, fuzzy logic (FL) control is proposed to provide tolerance of different degrees of reliability in multirate transmission and to achieve distinct service differentiation for multimedia applications. It is shown that the proposed system can effectively suppress noise effects and offer improved adaptation capabilities for multi-quality network requirements in comparison with systems without optimization.

  3. A threshold-based multiple optical signal selection scheme for WDM FSO systems

    KAUST Repository

    Nam, Sung Sik

    2017-07-20

    In this paper, we propose a threshold-based-multiple optical signal selection scheme (TMOS) for free-space optical systems based on wavelength division multiplexing. With the proposed TMOS, we can obtain higher spectral efficiency while reducing the potential increase in complexity of implementation caused by applying a selection-based beam selection scheme without a considerable performance loss. Here, to accurately characterize the performance of the proposed TMOS, we statistically analyze the characteristics with heterodyne detection technique over independent and identically distributed Log-normal turbulence conditions taking into considerations the impact of pointing error. Specifically, we derive exact closed-form expressions for the average bit error rate, and the average spectral efficiency by adopting an adaptive modulation. Some selected results shows that the average spectral efficiency can be increased with TMOS while the system requirement is satisfied.

  4. Signal Processing using Nonlinear Optical Eects in Single- and Few-Mode Fibers

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk

    The stagnating increase in data transmission capacity in optical communication systems combined with the ever growing demand of transmission bandwidth is leading to an impending capacity crunch, referring to the point in time after which the available bandwidth of the individual user starts...... accounts for multiple effects present in nonlinear fibers such as four-wave mixing, Raman scattering, distributed loss, and dispersion, and it is valid in the depleted pump regime. After validating the model against well-known results of quantum models, the model is used to predict the impacts of Raman...... noise, loss, and pump depletion on the noise properties of parametric frequency conversion and phase-insensitive and phase-sensitive parametric amplification. An important part of realizing space-division multiplexing is the ability of optical signal processing so the second part of this thesis...

  5. Enhanced signaling scheme with admission control in the hybrid optical wireless (HOW) networks

    DEFF Research Database (Denmark)

    Yan, Ying; Yu, Hao; Wessing, Henrik

    2009-01-01

    that it can support stringent Quality of Service (QoS) requirements. In this paper, we describe and evaluate a resource management framework designed for the HOW networks. There are two parts in the resource management framework The first part is the Enhanced MPCP (E-MPCP) scheme aiming at improving signaling......The hybrid optical wireless (HOW) network has been viewed as a promising solution to meet the increasing user bandwidth and mobility demands. Due to the basic differences in the optical and wireless technologies, a challenging problem lies in the Media Access Control (MAC) protocol design so...... dropping probability depend on several factors. These factors include the frame duration, the traffic load and the total number of shared users. The results also highlight that our proposed system achieves significant improvements over the traditional approach in terms of user QoS guarantee and network...

  6. Spatiotemporal changes of optical signals in the somatosensory cortex of neuropathic rats after electroacupuncture stimulation.

    Science.gov (United States)

    Cha, Myeounghoon; Chae, Younbyoung; Bai, Sun Joon; Lee, Bae Hwan

    2017-01-10

    Peripheral nerve injury causes physiological changes in primary afferent neurons. Neuropathic pain associated with peripheral nerve injuries may reflect changes in the excitability of the nervous system, including the spinothalamic tract. Current alternative medical research indicates that acupuncture stimulation has analgesic effects in various pain symptoms. However, activation changes in the somatosensory cortex of the brain by acupuncture stimulation remain poorly understood. The present study was conducted to monitor the changes in cortical excitability, using optical imaging with voltage-sensitive dye (VSD) in neuropathic rats after electroacupuncture (EA) stimulation. Male Sprague-Dawley rats were divided into three groups: control (intact), sham injury, and neuropathic pain rats. Under pentobarbital anesthesia, rats were subjected to nerve injury with tight ligation and incision of the tibial and sural nerves in the left hind paw. For optical imaging, the rats were re-anesthetized with urethane, and followed by craniotomy. The exposed primary somatosensory cortex (S1) was stained with VSD for one hour. Optical signals were recorded from the S1 cortex, before and after EA stimulation on Zusanli (ST36) and Yinlingquan (SP9). After peripheral stimulation, control and sham injury rats did not show significant signal changes in the S1 cortex. However, inflamed and amplified neural activities were observed in the S1 cortex of nerve-injured rats. Furthermore, the optical signals and region of activation in the S1 cortex were reduced substantially after EA stimulation, and recovered in a time-dependent manner. The peak fluorescence intensity was significantly reduced until 90 min after EA stimulation (Pre-EA: 0.25 ± 0.04 and Post-EA 0 min: 0.01 ± 0.01), and maximum activated area was also significantly attenuated until 60 min after EA stimulation (Pre-EA: 37.2 ± 1.79 and Post-EA 0 min: 0.01 ± 0.10). Our results indicate that EA stimulation

  7. Multilayered optical bit memory with a high signal-to-noise ratio in fluorescent polymethylmethacrylate

    Science.gov (United States)

    Nie, Zhaogang; Lee, Heungyeol; Yoo, Hyeonggeun; Lee, Youlee; Kim, Younshil; Lim, Ki-Soo; Lee, Myeongkyu

    2009-03-01

    We report on the three-dimensional optical memory utilizing a photoluminescence (PL) change in polymethylmethacrylate. Irradiation with a femtosecond pulsed laser (800 nm, 1 kHz, 100 fs) induced a strong PL spectrum in the visible range, which may result from the photogeneration of emissive radicals. Multilayered patterns were recorded inside the bulk sample by tightly focusing a pulsed laser beam. The pattern images were read out by a reflection-type fluorescent confocal microscope which detected the blue-green emission at 410-510 nm. The stored bits were retrieved with a high signal-to-noise ratio in the absence of any cross-talk.

  8. Electro-optical techniques for the investigation of photoplethysmographic signals in human abdominal organs

    International Nuclear Information System (INIS)

    Kyriacou, P A; Crerar-Gilber, A; Langford, R M; Jones, D P

    2006-01-01

    There is a need for reliable continuous monitoring of abdominal organ oxygen saturation (SpO 2 ). Splanchnic ischaemia may ultimately lead to cellular hypoxia and necrosis and may well contribute to the development of multiple organ failures and increased mortality. A new reflectance electro-optical photoplethysmographic (PPG) probe and signal processing system were developed. PPG signals from abdominal organs (bowel, liver, and kidney) and the finger were obtained from 12 anaesthetised patients. The amplitudes of the abdominal organ PPGs were, on average, approximately the same as those obtained simultaneously from the finger. These observations suggest that pulse oximetry may be a valid monitoring technique for abdominal organs such as the bowel liver and kidney

  9. Integration of micromirror and mixed-signal ICs for optical information processing

    Science.gov (United States)

    Lin, Tseng-Hwang

    1995-05-01

    The Texas Instruments flexure beam micromirror represents one of the most promising structures for production because of its reproducibility, which results from its symmetrical supporting structure. Flexure beam micromirrors modulate light in phase with a piston-flap motion that changes the length of the optical path. The device allows us to perform analog phase modulation by balancing spring and electrostatic forces. To fully use the analog phase capability, we need a mixed-signal circuit to drive it, but fortunately, micro-mirror technology is compatible with IC processes. Texas Instruments owns not only this unique micromirror design, but also a world-class mixed-signal production line. The main issue in production is maintaining the hinge strength to overcome stress caused by nonuniformity while staying within the range of analog CMOS driver compliance restrictions.

  10. Gigabit Ethernet signal transmission using asynchronous optical code division multiple access.

    Science.gov (United States)

    Ma, Philip Y; Fok, Mable P; Shastri, Bhavin J; Wu, Ben; Prucnal, Paul R

    2015-12-15

    We propose and experimentally demonstrate a novel architecture for interfacing and transmitting a Gigabit Ethernet (GbE) signal using asynchronous incoherent optical code division multiple access (OCDMA). This is the first such asynchronous incoherent OCDMA system carrying GbE data being demonstrated to be working among multi-users where each user is operating with an independent clock/data rate and is granted random access to the network. Three major components, the GbE interface, the OCDMA transmitter, and the OCDMA receiver are discussed in detail. The performance of the system is studied and characterized through measuring eye diagrams, bit-error rate and packet loss rate in real-time file transfer. Our Letter also addresses the near-far problem and realizes asynchronous transmission and detection of signal.

  11. Frequency-agile vector signal generation based on optical frequency comb and pre-coding

    Science.gov (United States)

    Qu, Kun; Zhao, ShangHong; Tan, QingGui; Liang, DanYa

    2017-06-01

    In this paper, we experimentally demonstrate the generation of frequency-agile vector signals based on an optical frequency comb (OFC) and unbalanced pre-coding technology by employing a dual-driven Mach-Zehnder Modulator (DD-MZM) and an intensity modulator (IM). The OFC is generated by the DD-MZM and sent to the IM as a carrier. The IM is driven by a 5 GHz 2 Gbaud quadrature phase-shift keying (QPSK) vector signal with unbalanced pre-coding. The -1st order sideband of one OFC line and the +1st order sideband of another OFC line are selected by a programmable pulse shaper (PPS), after square-low photodiode detection, the frequency-agile vector signal can be obtained. The results show that the 2 Gbaud QPSK vector signals at 30 GHz, 50 GHz, 70 GHz and 90 GHz can be generated by only pre-coding once. It is possible to achieve a bit-error-rate (BER) below 1e-3 for wireless transmissions over 0.5 m using this method.

  12. Modeling borehole microseismic and strain signals measured by a distributed fiber optic sensor

    Science.gov (United States)

    Mellors, R. J.; Sherman, C. S.; Ryerson, F. J.; Morris, J.; Allen, G. S.; Messerly, M. J.; Carr, T.; Kavousi, P.

    2017-12-01

    The advent of distributed fiber optic sensors installed in boreholes provides a new and data-rich perspective on the subsurface environment. This includes the long-term capability for vertical seismic profiles, monitoring of active borehole processes such as well stimulation, and measuring of microseismic signals. The distributed fiber sensor, which measures strain (or strain-rate), is an active sensor with highest sensitivity parallel to the fiber and subject to varying types of noise, both external and internal. We take a systems approach and include the response of the electronics, fiber/cable, and subsurface to improve interpretation of the signals. This aids in understanding noise sources, assessing error bounds on amplitudes, and developing appropriate algorithms for improving the image. Ultimately, a robust understanding will allow identification of areas for future improvement and possible optimization in fiber and cable design. The subsurface signals are simulated in two ways: 1) a massively parallel multi-physics code that is capable of modeling hydraulic stimulation of heterogeneous reservoir with a pre-existing discrete fracture network, and 2) a parallelized 3D finite difference code for high-frequency seismic signals. Geometry and parameters for the simulations are derived from fiber deployments, including the Marcellus Shale Energy and Environment Laboratory (MSEEL) project in West Virginia. The combination mimics both the low-frequency strain signals generated during the fracture process and high-frequency signals from microseismic and perforation shots. Results are compared with available fiber data and demonstrate that quantitative interpretation of the fiber data provides valuable constraints on the fracture geometry and microseismic activity. These constraints appear difficult, if not impossible, to obtain otherwise.

  13. Wavelength reused bidirectional transmission of adaptively modulated optical OFDM signals in WDM-PONs incorporating SOA and RSOA intensity modulators.

    Science.gov (United States)

    Wei, J L; Hugues-Salas, E; Giddings, R P; Jin, X Q; Zheng, X; Mansoor, S; Tang, J M

    2010-05-10

    Detailed numerical investigations are undertaken of wavelength reused bidirectional transmission of adaptively modulated optical OFDM (AMOOFDM) signals over a single SMF in a colorless WDM-PON incorporating a semiconductor optical amplifier (SOA) intensity modulator and a reflective SOA (RSOA) intensity modulator in the optical line termination and optical network unit, respectively. A comprehensive theoretical model describing the performance of such network scenarios is, for the first time, developed, taking into account dynamic optical characteristics of SOA and RSOA intensity modulators as well as the effects of Rayleigh backscattering (RB) and residual downstream signal-induced crosstalk. The developed model is rigorously verified experimentally in RSOA-based real-time end-to-end OOFDM systems at 7.5 Gb/s. It is shown that the RB noise and crosstalk effects are dominant factors limiting the maximum achievable downstream and upstream transmission performance. Under optimum SOA and RSOA operating conditions as well as practical downstream and upstream optical launch powers, 10 Gb/s downstream and 6 Gb/s upstream over 40 km SMF transmissions of conventional double sideband AMOOFDM signals are feasible without utilizing in-line optical amplification and chromatic dispersion compensation. In particular, the aforementioned transmission performance can be improved to 23 Gb/s downstream and 8 Gb/s upstream over 40 km SMFs when single sideband subcarrier modulation is adopted in the downstream systems. (c) 2010 Optical Society of America.

  14. All-optical simultaneous multichannel quadrature phase shift keying signal regeneration based on phase-sensitive amplification

    Science.gov (United States)

    Wang, Hongxiang; Wang, Qi; Bai, Lin; Ji, Yuefeng

    2018-01-01

    A scheme is proposed to realize the all-optical phase regeneration of four-channel quadrature phase shift keying (QPSK) signal based on phase-sensitive amplification. By utilizing conjugate pump and common pump in a highly nonlinear optical fiber, degenerate four-wave mixing process is observed, and QPSK signals are regenerated. The number of waves is reduced to decrease the cross talk caused by undesired nonlinear interaction during the coherent superposition process. In addition, to avoid the effect of overlapping frequency, frequency spans between pumps and signals are set to be nonintegral multiples. Optical signal-to-noise ratio improvement is validated by bit error rate measurements. Compared with single-channel regeneration, multichannel regeneration brings 0.4-dB OSNR penalty when the value of BER is 10-3, which shows the cross talk in regeneration process is negligible.

  15. Converged Wireless and Wireline Access System Based on Optical Phase Modulation for Both Radio-Over-Fiber and Baseband Signals

    DEFF Research Database (Denmark)

    Yu, Xianbin; Jensen, Jesper Bevensee; Zibar, Darko

    2008-01-01

    -to-zero differential quaternary phase-shift keyed signal and a 5.25-GHz RoF carrying 1.25 Gb/s, enables the use of identical optical receiver structures. The experimental results show that both receivers achieve error-free operation after 80-km standard single-mode fiber transmission. The proposed scheme has potential......We propose and experimentally investigate a scheme for transmitting a phase-modulated radio-over-fiber (RoF) signal along an existing fiber infrastructure without degradation of the existing baseband signal. Optical phase encoding of both signals, namely a baseband 21.4-Gb/s nonreturn...... applications for converged wireless and wireline optical access networks....

  16. In vivo optical modulation of neural signals using monolithically integrated two-dimensional neural probe arrays

    Science.gov (United States)

    Son, Yoojin; Jenny Lee, Hyunjoo; Kim, Jeongyeon; Shin, Hyogeun; Choi, Nakwon; Justin Lee, C.; Yoon, Eui-Sung; Yoon, Euisik; Wise, Kensall D.; Geun Kim, Tae; Cho, Il-Joo

    2015-10-01

    Integration of stimulation modalities (e.g. electrical, optical, and chemical) on a large array of neural probes can enable an investigation of important underlying mechanisms of brain disorders that is not possible through neural recordings alone. Furthermore, it is important to achieve this integration of multiple functionalities in a compact structure to utilize a large number of the mouse models. Here we present a successful optical modulation of in vivo neural signals of a transgenic mouse through our compact 2D MEMS neural array (optrodes). Using a novel fabrication method that embeds a lower cladding layer in a silicon substrate, we achieved a thin silicon 2D optrode array that is capable of delivering light to multiple sites using SU-8 as a waveguide core. Without additional modification to the microelectrodes, the measured impedance of the multiple microelectrodes was below 1 MΩ at 1 kHz. In addition, with a low background noise level (±25 μV), neural spikes from different individual neurons were recorded on each microelectrode. Lastly, we successfully used our optrodes to modulate the neural activity of a transgenic mouse through optical stimulation. These results demonstrate the functionality of the 2D optrode array and its potential as a next-generation tool for optogenetic applications.

  17. Numerical investigations of signal-spectrum shaping based on conformal profile theory in optical parametric chirped pulse amplification

    Science.gov (United States)

    Li, Wenqi; Yu, Lianghong; Peng, Chun; Liang, Xiaoyan

    2017-11-01

    We proposed a theoretical description and numerical model of signal-spectrum shaping based on conformal profile theory and the three-dimensional coupling wave equations for improving the performance of optical parametric chirped pulse amplification (OPCPA). Using our model, we executed quantitative simulations of signal-spectrum shaping and compared the differences of spatiotemporal amplification characteristics between a shaped signal-spectrum and Gaussian signal-spectrum of an OPCPA based on LiB3O5 near 800 nm. By comparison, we found that the conversion efficiency from pump to signal can be dramatically boosted via signal-spectrum shaping. Meanwhile the amplified-spectrum profile, as well as the Fourier-limited pulse, can be improved significantly. We also found that the spatial spot profiles, for injecting a shaped signal or a Gaussian signal in OPCPA, are nearly the same before the saturation regime and at the maximum conversion efficiency or output energy.

  18. Optical transmission of low-level signals with high dynamic range using the optically-coupled current-mirror architecture

    International Nuclear Information System (INIS)

    Camin, Daniel V.; Grassi, Valerio; De Donato, Cinzia

    2007-01-01

    In this paper we illustrate the application of a novel circuit architecture, the Optically-Coupled Current-Mirror (OCCM), conceived for the linear transmission of analogue signals via fibre optics. We installed 880 OCCMs in the PMTs of the first two telescopes of the cosmic-ray experiment Pierre Auger. The Pierre Auger Observatory (PAO) has been designed to increase the statistics of cosmic-rays with energies above 10 18 eV. Two different techniques have been adopted: the Surface Detector (SD) modules that comprise 1600 tanks spaced each other by 1.5km within an area of 3000km 2 . On the other side there are four buildings, the Optical Stations (OS), in which six telescopes are installed in each one of the four OS, at the periphery of the site, looking inwards. The telescopes are sensitive to the UV light created at the moment a high-energy shower develops in the atmosphere and is within the field-of-view (FOV) of the telescopes. The PAO is located in the Northern Patagonia, not far from the Cordillera de Los Andes, in Argentina. Both detector types, FD telescopes and SD modules, are sensitive to the UV light resulting from the interaction of high-energy particles and the nitrogen molecules in the atmosphere. The UV-sensitive telescopes operate only at night when the sky is completely dark. Otherwise, the light collected by the telescopes may give origin to severe damage in particular if those telescopes point at twilight or to artificial light sources. The duty cycle of the telescope's operation is therefore limited to about 10% or slightly more than that, if data are taken also when there is a partial presence of the Moon. The SD modules establish, independently of the telescopes, the geometry of the event. At the same time a shower reconstruction is performed using the telescope's data, independently of the SD modules. Use of both sets of data, taken by the FD telescopes and by the SD modules, allows the hybrid reconstruction that significantly improves the data

  19. Correlating optical, microwave and thermal remote sensing signals with groundwater head measurement time series

    Science.gov (United States)

    Sutanudjaja, E. H.; de Jong, S.; van Geer, F.; Bierkens, M. F.

    2010-12-01

    Due to global climate change, population growth and an ever increasing demand for fresh water, monitoring groundwater changes over large areas becomes very important. Current groundwater monitoring still heavily depends on groundwater head data that are often not available for large parts of the non-western world. Consequently, groundwater assessment, especially for large areas comprising several aquifers and basins, is very complex and not very accurate. The main research question of this study is to check whether optical, microwave and thermal remote sensing signals carry information on groundwater levels. The advantage of remote sensing data is that it provides synoptic overview of semi-quantitative maps of surface properties, such as vegetation, surface temperature, and soil moisture signals, where we seek the relation with shallow groundwater tables. In this study, we analyze and compare groundwater head measurement data and various remote sensing signals. Our datasets comprise over 5000 groundwater head measurement points in the Rhine-Meuse basin. These groundwater head data are compared to the signals of soil moisture (AMSR-E and ERS), thermal (MODIS land surface temperature) and vegetation (MODIS NDVI, LAI and FPAR). We investigated the correlation among these variables by performing straightforward statistical analyses, such as scatter-plots, multiple regression techniques and analyses of temporal variability between the variables. Results show that particularly the soil moisture demonstrates significant relations with groundwater depth, specifically for shallow water table depths and areas with sparse vegetation. We argue that remote sensing signals should be considered as important information for groundwater assessment in data-poor environments.

  20. A novel optical single-sideband frequency translation technique for transmission of wireless MIMO signals over fiber-wireless system

    Science.gov (United States)

    Shaddad, Redhwan Q.; Mohammad, Abu Bakar; Al-Hetar, Abdulaziz M.; Al-Gailani, Samir A.

    2013-04-01

    The fiber-wireless (FiWi) access network is a powerful hybrid architecture of optical backhaul and wireless front-end to support high data rates and throughput with minimal time delay. By using radio over fiber (ROF) technique, the optical fiber is well adapted to propagate multiple wireless services having different carrier frequencies. However, multiple wireless signals which have the same carrier frequency cannot propagate over a single optical fiber on the same wavelength, such as multi-input multi-output (MIMO) signals. A novel optical single-sideband frequency translation technique is designed and simulated to solve this problem. 240 Mb/s 802.11n MIMO signals are proposed to transport over FiWi system using the proposed approach at 2.4 GHz and 5.0 GHz carrier frequencies. The crosstalk between MIMO signals with the same carrier frequency is excluded, since each MIMO signal is carried on a specific optical wavelength. Error vector magnitude (EVM) values of -29.83 dB (for 2.4 GHz) and -28.41 dB (for 5.0 GHz) have been achieved for bit error rate (BER) 10-5 in the proposed FiWi system.

  1. Novel Signal-Enhancing Approaches for Optical Detection of Nucleic Acids—Going beyond Target Amplification

    Directory of Open Access Journals (Sweden)

    Laura Miotke

    2015-09-01

    Full Text Available Detection of low-abundance nucleic acids is a challenging task, which over the last two decades has been solved using enzymatic target amplification. Enzymatic synthesis enhances the signal so that diverse, scientifically and clinically relevant molecules can be identified and studied, including cancer DNA, viral nucleic acids, and regulatory RNAs. However, using enzymes increases the detection time and cost, not to mention the high risk of mistakes with amplification and data alignment. These limitations have stimulated a growing interest in enzyme-free methods within researchers and industry. In this review we discuss recent advances in signal-enhancing approaches aimed at nucleic acid diagnostics that do not require target amplification. Regardless of enzyme usage, signal enhancement is crucial for the reliable detection of nucleic acids at low concentrations. We pay special attention to novel nanomaterials, fluorescence microscopy, and technical advances in detectors for optical assessment. We summarize sensitivity parameters of the currently available assays and devices which makes this review relevant to the broad spectrum of researchers working in fields from biophysics, to engineering, to synthetic biology and bioorganic chemistry.

  2. Feature extraction of event-related potentials using wavelets: an application to human performance monitoring

    Science.gov (United States)

    Trejo, L. J.; Shensa, M. J.

    1999-01-01

    This report describes the development and evaluation of mathematical models for predicting human performance from discrete wavelet transforms (DWT) of event-related potentials (ERP) elicited by task-relevant stimuli. The DWT was compared to principal components analysis (PCA) for representation of ERPs in linear regression and neural network models developed to predict a composite measure of human signal detection performance. Linear regression models based on coefficients of the decimated DWT predicted signal detection performance with half as many free parameters as comparable models based on PCA scores. In addition, the DWT-based models were more resistant to model degradation due to over-fitting than PCA-based models. Feed-forward neural networks were trained using the backpropagation algorithm to predict signal detection performance based on raw ERPs, PCA scores, or high-power coefficients of the DWT. Neural networks based on high-power DWT coefficients trained with fewer iterations, generalized to new data better, and were more resistant to overfitting than networks based on raw ERPs. Networks based on PCA scores did not generalize to new data as well as either the DWT network or the raw ERP network. The results show that wavelet expansions represent the ERP efficiently and extract behaviorally important features for use in linear regression or neural network models of human performance. The efficiency of the DWT is discussed in terms of its decorrelation and energy compaction properties. In addition, the DWT models provided evidence that a pattern of low-frequency activity (1 to 3.5 Hz) occurring at specific times and scalp locations is a reliable correlate of human signal detection performance. Copyright 1999 Academic Press.

  3. Single-trial event-related potential extraction through one-unit ICA-with-reference

    Science.gov (United States)

    Lih Lee, Wee; Tan, Tele; Falkmer, Torbjörn; Leung, Yee Hong

    2016-12-01

    Objective. In recent years, ICA has been one of the more popular methods for extracting event-related potential (ERP) at the single-trial level. It is a blind source separation technique that allows the extraction of an ERP without making strong assumptions on the temporal and spatial characteristics of an ERP. However, the problem with traditional ICA is that the extraction is not direct and is time-consuming due to the need for source selection processing. In this paper, the application of an one-unit ICA-with-Reference (ICA-R), a constrained ICA method, is proposed. Approach. In cases where the time-region of the desired ERP is known a priori, this time information is utilized to generate a reference signal, which is then used for guiding the one-unit ICA-R to extract the source signal of the desired ERP directly. Main results. Our results showed that, as compared to traditional ICA, ICA-R is a more effective method for analysing ERP because it avoids manual source selection and it requires less computation thus resulting in faster ERP extraction. Significance. In addition to that, since the method is automated, it reduces the risks of any subjective bias in the ERP analysis. It is also a potential tool for extracting the ERP in online application.

  4. Optimal weighted averaging of event related activity from acquisitions with artifacts.

    Science.gov (United States)

    Vollero, Luca; Petrichella, Sara; Innello, Giulio

    2016-08-01

    In several biomedical applications that require the signal processing of biological data, the starting procedure for noise reduction is the ensemble averaging of multiple repeated acquisitions (trials). This method is based on the assumption that each trial is composed of two additive components: (i) a time-locked activity related to some sensitive/stimulation phenomenon (ERA, Event Related Activity in the following) and (ii) a sum of several other non time-locked background activities. The averaging aims at estimating the ERA activity under very low Signal to Noise and Interference Ratio (SNIR). Although averaging is a well established tool, its performance can be improved in the presence of high-power disturbances (artifacts) by a trials classification and removal stage. In this paper we propose, model and evaluate a new approach that avoids trials removal, managing trials classified as artifact-free and artifact-prone with two different weights. Based on the model, a weights tuning is possible and through modeling and simulations we show that, when optimally configured, the proposed solution outperforms classical approaches.

  5. Event-related brain responses while listening to entire pieces of music.

    Science.gov (United States)

    Poikonen, H; Alluri, V; Brattico, E; Lartillot, O; Tervaniemi, M; Huotilainen, M

    2016-01-15

    Brain responses to discrete short sounds have been studied intensively using the event-related potential (ERP) method, in which the electroencephalogram (EEG) signal is divided into epochs time-locked to stimuli of interest. Here we introduce and apply a novel technique which enables one to isolate ERPs in human elicited by continuous music. The ERPs were recorded during listening to a Tango Nuevo piece, a deep techno track and an acoustic lullaby. Acoustic features related to timbre, harmony, and dynamics of the audio signal were computationally extracted from the musical pieces. Negative deflation occurring around 100 milliseconds after the stimulus onset (N100) and positive deflation occurring around 200 milliseconds after the stimulus onset (P200) ERP responses to peak changes in the acoustic features were distinguishable and were often largest for Tango Nuevo. In addition to large changes in these musical features, long phases of low values that precede a rapid increase - and that we will call Preceding Low-Feature Phases - followed by a rapid increase enhanced the amplitudes of N100 and P200 responses. These ERP responses resembled those to simpler sounds, making it possible to utilize the tradition of ERP research with naturalistic paradigms. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

  6. All-optical OTDM-to-WDM signal-format translation and OTDM add-drop functionality using bidirectional four wave mixing in semiconductor optical amplifier

    DEFF Research Database (Denmark)

    Buxens Azcoaga, Alvaro Juan; Poulsen, Henrik Nørskov; Clausen, Anders

    2000-01-01

    The authors report simultaneous demultiplexing and wavelength conversion of two 10Gbit/s channels from a 40Gbit/s OTDM signal using bidirectional four wave mixing in a single semiconductor optical amplifier. Simultaneous demultiplexing and clearing of a 10Gbit/s channel from the 40Gbit/s OTDM dat...

  7. High speed all-optical PRBS generation using binary phase shift keyed signal based on QD-SOA

    Science.gov (United States)

    Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.

    2014-09-01

    A scheme to generate return-to-zero on-off keying (RZ-OOK) high speed all-optical pseudo random bit sequence (PRBS) using binary phase shift keyed (BPSK) signal based on quantum-dot semiconductor optical amplifiers (QD-SOA) has been designed and studied. The PRBS is generated by a linear feedback shift register (LFSR) composed of all-optical logic XOR and AND gates. The XOR gate is composed of a pair of QD SOA Mach-Zehnder interferometers, which can generate BSPK signal to realize all-optical logic XOR gate. Results show that this scheme can mitigate the patterning effects and increase the operation speed to ~250Gb/s.

  8. Extending the upper age limit for luminescence dating using the thermally transferred optically stimulated luminescence signal from quartz

    Science.gov (United States)

    Duller, Geoff A. T.; Wintle, Ann G.

    2010-05-01

    The optically stimulated luminescence (OSL) signal from quartz has been exploited for the last 20 years to date heated and unheated materials. While methods based on this signal have been extremely successful and are now widely adopted in laboratories around the world, growth of the signal with dose is affected by saturation and this commonly limits application to samples with equivalent doses of ~100 to 300 Gy. In most environments this limits application of the method to the last 100-150 ka. Studies of OSL from quartz in the late 1980's showed that if the OSL signal from a sample was reduced to background level by measurement, and the sample then heated, further optical stimulation gave a significant signal. This recuperated OSL was viewed as a problem to be avoided, particularly for young samples. Three years ago papers were published showing that this recuperated signal has the potential to be valuable in dosimetry, and in particular that the signal continues to grow to doses in excess of 10,000 Gy offering the possibility of extending the age range over which quartz can be used to as much as 1 Ma. The first work on this signal was undertaken on fine grain quartz extracted from Chinese loess, and ages back to the Brunhes-Matuyama boundary were obtained. The signal is now commonly referred to as thermally transferred optically stimulated luminescence (TT-OSL). Intense research on the signal has focussed on a number of areas, including, (a) understanding the origin of the charge measured in TT-OSL, (b) improving methods for measuring the TT-OSL signal, and (c) developing protocols for using TT-OSL in dose estimation, and these are reviewed in this presentation.

  9. Biomedical signals and sensors II linking acoustic and optic biosignals and biomedical sensors

    CERN Document Server

    Kaniusas, Eugenijus

    2015-01-01

    The book set develops a bridge between physiologic mechanisms and diagnostic human engineering. While the first volume is focused on the interface between physiologic mechanisms and the resultant biosignals, this second volume is devoted to the interface between biosignals and biomedical sensors. That is, in the first volume, the physiologic mechanisms determining biosignals are described from the basic cellular level up to their advanced mutual coordination level. This second volume, considers the genesis of acoustic and optic biosignals and the associated sensing technology from a strategic point of view. As a novelty, this book discusses heterogeneous biosignals within a common frame. This frame comprises both the biosignal formation path from the biosignal source at the physiological level to biosignal propagation in the body, and the biosignal sensing path from the biosignal transmission in the sensor applied on the body up to its conversion to a, usually electric, signal. Some biosignals arise in the co...

  10. Optical diversity transmission using WDM signal and phase-conjugate lights through multi-core fiber.

    Science.gov (United States)

    Koga, Masafumi; Moroi, Mitsuki; Takara, Hidehiko

    2016-05-02

    This paper proposes a maximum-ratio combining (MRC) scheme for a WDM signal and phase-conjugate pair (PCP) diversity transmission to cancel nonlinear phase-shift. A transfer function approximation for nonlinear phase-shift cancellation is formulated. It shows, with the help of a numerical calculation, that span-by-span chromatic dispersion compensation is more effective than the lumped equivalent at the receiver. This is confirmed in a 2-core diversity 5 channel WDM transmission experiment over 3-spans of 60km MCF with 25 Gbit/s-QPSK PCP. The peak Q-value was enhanced by 3.6dB through MRC, resulting in superior bitrate-distance product and optical power density limit, compared to twice the single core transmission.

  11. Optical signal demultiplexing and conversion in the fullerene–oligothiophene–CdS system

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowska, Kornelia [Polish Academy of Science, Institute of Molecular Physics, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Podborska, Agnieszka; Kwolek, Przemysław [AGH University of Science and Technology, Faculty of Non-Ferrous Metals, al. A. Mickiewicza 30, 30-059 Kraków (Poland); Kim, Tae-Dong; Lee, Kwang-Sup [Department of Advanced Materials, Hannam University, Daejeon 305-811 (Korea, Republic of); Szaciłowski, Konrad, E-mail: szacilow@agh.edu.pl [AGH University of Science and Technology, Faculty of Non-Ferrous Metals, al. A. Mickiewicza 30, 30-059 Kraków (Poland); Jagiellonian University, Faculty of Chemistry, ul. R. Ingardena 3, 30-60 Kraków (Poland)

    2014-11-15

    Graphical abstract: - Highlights: • Photoelectrochemical photocurrent switching (PEPS) effect in the C{sub 60} derivatives system. • Systems for optical-to-electrical signal conversion. • Fullerene–oligothiophene dyad system as 1:2-demultiplexer. - Abstract: We report the photoelectrochemical photocurrent switching (PEPS) effect in the system based on a C{sub 60} derivatives and nanostructured cadmium sulfide. Rapid and efficient photocurrent switching upon changes of the electrode potential was observed. This process relies on the photocurrent generation by semiconducting particles and interfacial electron transfer reactions governed by the redox chemistry of fullerene derivatives (fullerene–oligothiophene dyads) with molecular oxygen as a final electron acceptor. Surprisingly, fullerene derivatives without thiophene moieties were much less efficient as CdS modifiers. These peculiar photoelectrochemical properties were applied for construction of an optoelectronic logic device.

  12. Optical Time-Division Multiplexing of 10 Gbit/s Ethernet Signals Synchronized by All-Optical Signal Processing Based on a Time-Lens

    DEFF Research Database (Denmark)

    Areal, Janaina Laguardia

    This Thesis presents 3 years work of an optical circuit that performs both pulse compression and frame synchronization and retiming. Our design aims at directly multiplexing several 10G Ethernet data packets (frames) to a high-speed OTDM link. This scheme is optically transparent and does...... pulse compression, as well. The overall design is: (1) Pulses are converted from NRZ to RZ; (2) pulses are synchronized, retimed and further compressed at the specially designed time-lens; and (3) with adequate optical delays, frames from different input interfaces are added, with a simple optical...

  13. Functional structure of the cryogenic optical sensor and mathematical models of signal

    Science.gov (United States)

    Yatsenko, Vitaliy A.

    2003-10-01

    Today, remote sensing is one of the fastest growing technologies around. It is a multibillion-dollar industry and remote thematic images are routinely used in an increasing number of fields. The solution of many important practical problems depends on a large-scale usage of the measurement systems and underlying physical principles. These problems include monitoring of the natural resources based on the analysis of the gravity anomalies, studying of global geodynamic processes and evolution of the Earth gravity field, analysis of movement of the Earth poles, etc. In spite of the existence of the considerable achievements in the area of gravity measurements, some important aspects of the problem have not been solved yet due to the absence of appropriate sensitive elements (SE) and sensors with the relevant parameters. The author of the report has proposed a functional structure of the cryogenic-optical sensor based on magnetic bearing phenomenon. A functional structure of the sensitive element consists of a controlled magnetic suspension, a high-precision optical system for registration of levitating body mechanical coordinates, and a signal processing toolbox. This toolbox contents the adaptive compensator, digital filters, inverse mathematical models of the SE, the Kalman filter, the control system, the dynamical analysis system, the mathematical modeling system, the simulation system, the information statistical system, the wavelet analysis system, a neural network, and data base. Mathematical models of the signal and noise are conventionally based on the principles of nonlinear electro-mechanics. Such models explains most basic features of the superconducting sensitive element. We will also discuss a new theoretical framework for adaptive estimation of gravitation perturbations and compare program models to conventional robust estimation models.

  14. Manipulating and detecting the chirpiness of spatial chirp signals via fractional Fourier lenses designed by transformation optics.

    Science.gov (United States)

    Chen, Jing; Hu, Jin; Yang, Xiao-Bo; Lu, Xiang-Yang

    2017-11-10

    Estimating the chirpiness of a spatial chirp signal is important in many optical engineering applications. With the help of transformation optics, a new kind of fractional Fourier transform lens is designed by deforming the conventional graded index lens through conformal mapping, which can manipulate the chirpiness of the input chirp signal. The low-input chirpiness is magnified by the transformation material, and the error of the detection is kept approximately the same; thus, the designed lens has enhanced chirpiness detection precision and distinguishability for low chirpiness. The design is validated by numerical simulations.

  15. All-optical logic gates for 40 Gb/s NRZ signals using complementary data in SOA-MZIs

    Science.gov (United States)

    Wang, Gang; Yang, Xuelin; Hu, Weisheng

    2013-03-01

    All-optical AND/XOR gates are proposed for non-return-to-zero (NRZ) data using semiconductor optical amplifier-based Mach-Zehnder interferometers (SOA-MZIs). For AND/XOR gates, the complementary data is applied as input to SOA-MZIs to enhance the operation data rate for NRZ signal up to 40 Gb/s. Numerical simulations show that the novel scheme can effectively mitigate the patterning effect in SOAs via shortening the rising/falling transition times. The high quality of the output signal (Q>6) are numerically evaluated for both AND/XOR gates.

  16. All-optical phase-preserving amplitude regeneration of a 640 Gbit/s RZ-DPSK signal

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Galili, Michael; Mulvad, Hans Christian Hansen

    2013-01-01

    Phase-preserving amplitude regeneration based on optical parametric amplification has been experimentally demonstrated for a 640 Gbit/s RZ-DPSK signal. Improvement of 2.2 dB in receiver sensitivity at a BER of 10-9 together with 13.3 dB net gain have been successfully achieved.......Phase-preserving amplitude regeneration based on optical parametric amplification has been experimentally demonstrated for a 640 Gbit/s RZ-DPSK signal. Improvement of 2.2 dB in receiver sensitivity at a BER of 10-9 together with 13.3 dB net gain have been successfully achieved....

  17. Effect of confounding variables on hemodynamic response function estimation using averaging and deconvolution analysis: An event-related NIRS study.

    Science.gov (United States)

    Aarabi, Ardalan; Osharina, Victoria; Wallois, Fabrice

    2017-07-15

    Slow and rapid event-related designs are used in fMRI and functional near-infrared spectroscopy (fNIRS) experiments to temporally characterize the brain hemodynamic response to discrete events. Conventional averaging (CA) and the deconvolution method (DM) are the two techniques commonly used to estimate the Hemodynamic Response Function (HRF) profile in event-related designs. In this study, we conducted a series of simulations using synthetic and real NIRS data to examine the effect of the main confounding factors, including event sequence timing parameters, different types of noise, signal-to-noise ratio (SNR), temporal autocorrelation and temporal filtering on the performance of these techniques in slow and rapid event-related designs. We also compared systematic errors in the estimates of the fitted HRF amplitude, latency and duration for both techniques. We further compared the performance of deconvolution methods based on Finite Impulse Response (FIR) basis functions and gamma basis sets. Our results demonstrate that DM was much less sensitive to confounding factors than CA. Event timing was the main parameter largely affecting the accuracy of CA. In slow event-related designs, deconvolution methods provided similar results to those obtained by CA. In rapid event-related designs, our results showed that DM outperformed CA for all SNR, especially above -5 dB regardless of the event sequence timing and the dynamics of background NIRS activity. Our results also show that periodic low-frequency systemic hemodynamic fluctuations as well as phase-locked noise can markedly obscure hemodynamic evoked responses. Temporal autocorrelation also affected the performance of both techniques by inducing distortions in the time profile of the estimated hemodynamic response with inflated t-statistics, especially at low SNRs. We also found that high-pass temporal filtering could substantially affect the performance of both techniques by removing the low-frequency components of

  18. Statistical analysis of event-related potential elicited by verb-complement merge in Brazilian Portuguese

    Directory of Open Access Journals (Sweden)

    M. Cagy

    2006-11-01

    Full Text Available An interesting fact about language cognition is that stimulation involving incongruence in the merge operation between verb and complement has often been related to a negative event-related potential (ERP of augmented amplitude and latency of ca. 400 ms - the N400. Using an automatic ERP latency and amplitude estimator to facilitate the recognition of waves with a low signal-to-noise ratio, the objective of the present study was to study the N400 statistically in 24 volunteers. Stimulation consisted of 80 experimental sentences (40 congruous and 40 incongruous, generated in Brazilian Portuguese, involving two distinct local verb-argument combinations (nominal object and pronominal object series. For each volunteer, the EEG was simultaneously acquired at 20 derivations, topographically localized according to the 10-20 International System. A computerized routine for automatic N400-peak marking (based on the ascendant zero-cross of the first waveform derivative was applied to the estimated individual ERP waveform for congruous and incongruous sentences in both series for all ERP topographic derivations. Peak-to-peak N400 amplitude was significantly augmented (P < 0.05; one-sided Wilcoxon signed-rank test due to incongruence in derivations F3, T3, C3, Cz, T5, P3, Pz, and P4 for nominal object series and in P3, Pz and P4 for pronominal object series. The results also indicated high inter-individual variability in ERP waveforms, suggesting that the usual procedure of grand averaging might not be considered a generally adequate approach. Hence, signal processing statistical techniques should be applied in neurolinguistic ERP studies allowing waveform analysis with low signal-to-noise ratio.

  19. Influence of analyzed signals fiber-optic transmission system on spread function of the diffraction grating spectral device

    Science.gov (United States)

    Kazakov, Vasily I.; Moskaletz, Oleg D.; Paraskun, Arthur S.; Zhdanov, Arseny Yu.

    2017-08-01

    Fiber-optic transmission system of analyzed signal is considered to allow signals transmission from optical sources with either impossible or undesirable contact. Diffraction grating spectral device is chosen as investigation system. It should be noted that diffraction grating operates with transmitted light but not reflected. Influence of optical fiber consists in the distortion of wave front incident on the spectral device. Front distortion leads to a broadening of the device spread function in all diffraction orders, and as a consequence, to a deterioration in the device resolution. In this case, the complex spread function is a reaction of the device to the homogeneous plane monochromatic wave which clearly links the input-output of spectral device. Fiber-optic system influence is determined by introducing a fictitious transparency located directly in front of the diffraction grating. Research of the effect the fiber-optic system has on the spread function of the diffraction grating spectral device is made in two ways. On one hand, mathematical model is proposed to describe the influence of a single-mode optical fiber to a spread function of the diffraction grating spectral device. We performed computer simulations of the analyzed signal transmission from the end of the optical fiber to the photodetector based on the proposed model. The calculations are performed for a single-mode optical fiber with a core diameter of 8 microns. On the other hand, experimental laboratory set up of the diffraction grating spectral device with a fiber optic transmission system is created. Theoretical calculations are compared with the experimental results.

  20. A Mixed L2 Norm Regularized HRF Estimation Method for Rapid Event-Related fMRI Experiments

    Directory of Open Access Journals (Sweden)

    Yu Lei

    2013-01-01

    Full Text Available Brain state decoding or “mind reading” via multivoxel pattern analysis (MVPA has become a popular focus of functional magnetic resonance imaging (fMRI studies. In brain decoding, stimulus presentation rate is increased as fast as possible to collect many training samples and obtain an effective and reliable classifier or computational model. However, for extremely rapid event-related experiments, the blood-oxygen-level-dependent (BOLD signals evoked by adjacent trials are heavily overlapped in the time domain. Thus, identifying trial-specific BOLD responses is difficult. In addition, voxel-specific hemodynamic response function (HRF, which is useful in MVPA, should be used in estimation to decrease the loss of weak information across voxels and obtain fine-grained spatial information. Regularization methods have been widely used to increase the efficiency of HRF estimates. In this study, we propose a regularization framework called mixed L2 norm regularization. This framework involves Tikhonov regularization and an additional L2 norm regularization term to calculate reliable HRF estimates. This technique improves the accuracy of HRF estimates and significantly increases the classification accuracy of the brain decoding task when applied to a rapid event-related four-category object classification experiment. At last, some essential issues such as the impact of low-frequency fluctuation (LFF and the influence of smoothing are discussed for rapid event-related experiments.

  1. Simultaneous transmission of the IEEE 802.11 radio signal and optical Gbit Ethernet over the multimode fiber link

    Science.gov (United States)

    Maksymiuk, L.; Podziewski, A.

    2015-09-01

    In the paper we present a successful joint transmission of the IEEE 802.11 signal and an optical Gbit Ethernet over a multimode fiber based link. Most importantly, the multiplexation of both signals was performed in the optical domain. Due to the utilization of the multimode fiber the OBI noise was avoided and both channels were able to operate at the same wavelength. We prove that potential RoF link for IEEE 802.11 signal distribution may be used to additionally transmit other signals as Gbit Ethernet and therefore utilize the fiber infrastructure installed more effectively. The qualities of both the IEEE 802.11 and Ethernet transmissions fulfilled the requirements imposed by appropriate standards.

  2. Characterization and mitigation of coherent-optical-transition-radiation signals from a compressed electron beam

    Directory of Open Access Journals (Sweden)

    A. H. Lumpkin

    2009-08-01

    Full Text Available The Advanced Photon Source (APS injector complex includes an option for rf photocathode (PC gun beam injection into the 450-MeV S-band linac. At the 150-MeV point, a four-dipole chicane was used to compress the micropulse bunch length from a few ps to sub-0.5 ps (FWHM. Noticeable enhancements of the optical transition radiation (OTR signal sampled after the APS chicane were then observed as has been reported in the Linac Coherent Light Source (LCLS injector commissioning. A far-infrared (FIR coherent transition radiation detector and interferometer were used to monitor the bunch compression process and correlate the appearance of localized spikes of OTR signal (5 to 10 times brighter than adjacent areas within the beam-image footprint. We have performed spectral-dependency measurements at 375 MeV with a series of bandpass filters centered in 50-nm increments from 400 to 700 nm and with an imaging spectrometer and observed a broadband enhancement in these spikes. Mitigation concepts of the observed coherent OTR, which exhibits an intensity enhancement in the red part of the visible spectrum as compared to incoherent OTR, are described.

  3. Dynamic full field optical coherence tomography: subcellular metabolic contrast revealed in tissues by interferometric signals temporal analysis

    OpenAIRE

    Apelian, Clement; Harms, Fabrice; Thouvenin, Olivier; Boccara, A. Claude

    2016-01-01

    We developed a new endogenous approach to reveal subcellular metabolic contrast in fresh ex vivo tissues taking advantage of the time dependence of the full field optical coherence tomography interferometric signals. This method reveals signals linked with local activity of the endogenous scattering elements which can reveal cells where other OCT-based techniques fail or need exogenous contrast agents. We benefit from the micrometric transverse resolution of full field OCT to image intracellu...

  4. Dynamic full field optical coherence tomography: subcellular metabolic contrast revealed in tissues by temporal analysis of interferometric signals

    OpenAIRE

    Apelian, Clement; Harms, Fabrice; Thouvenin, Olivier; Boccara, A. Claude

    2016-01-01

    We developed a new endogenous approach to reveal subcellular metabolic contrast in fresh ex vivo tissues taking advantage of the time dependence of the full field optical coherence tomography interferometric signals. This method reveals signals linked with local activity of the endogenous scattering elements which can reveal cells where other imaging techniques fail or need exogenous contrast agents. We benefit from the micrometric transverse resolution of full field OCT to image intracellula...

  5. Reduction of pattern effects in SOA-based all-optical switches by using cross-gain modulated holding signal

    DEFF Research Database (Denmark)

    Bischoff, Svend; Mørk, Jesper

    2002-01-01

    , and reduces the fluctuations of the total energy injected into the interferometer within a bit-slot. Thus, we demonstrate a technique for reducing pattern effects in SOAs by employing a partially inverted holding beam. The method should be useful for increasing the data rates of all-optical switches.......The effective carrier lifetime of SOAs is typically shortened by an intense Continuous Wave (CW) holding signal. However, the SOA gain is reduced by the holding signal resulting in smaller gain and refractive index changes induced by the data signal. Accordingly, an optimum exists for the CW...... and data signal power. Here, we demonstrate that the modulation bandwidth (amplitude jitter) is significantly improved (reduced) by replacing the CW holding beam with a signal, which is low-pass filtered and inverted with respect to the data signal. Such a holding beam can be generated by XGM WC in an SOA...

  6. Multivariate Bayesian decoding of single-trial event-related fMRI responses for memory retrieval of voluntary actions.

    Directory of Open Access Journals (Sweden)

    Dongha Lee

    Full Text Available This study proposes a method for classifying event-related fMRI responses in a specialized setting of many known but few unknown stimuli presented in a rapid event-related design. Compared to block design fMRI signals, classification of the response to a single or a few stimulus trial(s is not a trivial problem due to contamination by preceding events as well as the low signal-to-noise ratio. To overcome such problems, we proposed a single trial-based classification method of rapid event-related fMRI signals utilizing sparse multivariate Bayesian decoding of spatio-temporal fMRI responses. We applied the proposed method to classification of memory retrieval processes for two different classes of episodic memories: a voluntarily conducted experience and a passive experience induced by watching a video of others' actions. A cross-validation showed higher classification performance of the proposed method compared to that of a support vector machine or of a classifier based on the general linear model. Evaluation of classification performances for one, two, and three stimuli from the same class and a correlation analysis between classification accuracy and target stimulus positions among trials suggest that presenting two target stimuli at longer inter-stimulus intervals is optimal in the design of classification experiments to identify the target stimuli. The proposed method for decoding subject-specific memory retrieval of voluntary behavior using fMRI would be useful in forensic applications in a natural environment, where many known trials can be extracted from a simulation of everyday tasks and few target stimuli from a crime scene.

  7. Multisensory integration and attention in autism spectrum disorder: evidence from event-related potentials.

    Directory of Open Access Journals (Sweden)

    Maurice J C M Magnée

    Full Text Available Successful integration of various simultaneously perceived perceptual signals is crucial for social behavior. Recent findings indicate that this multisensory integration (MSI can be modulated by attention. Theories of Autism Spectrum Disorders (ASDs suggest that MSI is affected in this population while it remains unclear to what extent this is related to impairments in attentional capacity. In the present study Event-related potentials (ERPs following emotionally congruent and incongruent face-voice pairs were measured in 23 high-functioning, adult ASD individuals and 24 age- and IQ-matched controls. MSI was studied while the attention of the participants was manipulated. ERPs were measured at typical auditory and visual processing peaks, namely, P2 and N170. While controls showed MSI during divided attention and easy selective attention tasks, individuals with ASD showed MSI during easy selective attention tasks only. It was concluded that individuals with ASD are able to process multisensory emotional stimuli, but this is differently modulated by attention mechanisms in these participants, especially those associated with divided attention. This atypical interaction between attention and MSI is also relevant to treatment strategies, with training of multisensory attentional control possibly being more beneficial than conventional sensory integration therapy.

  8. Kernel PLS Estimation of Single-trial Event-related Potentials

    Science.gov (United States)

    Rosipal, Roman; Trejo, Leonard J.

    2004-01-01

    Nonlinear kernel partial least squaes (KPLS) regressior, is a novel smoothing approach to nonparametric regression curve fitting. We have developed a KPLS approach to the estimation of single-trial event related potentials (ERPs). For improved accuracy of estimation, we also developed a local KPLS method for situations in which there exists prior knowledge about the approximate latency of individual ERP components. To assess the utility of the KPLS approach, we compared non-local KPLS and local KPLS smoothing with other nonparametric signal processing and smoothing methods. In particular, we examined wavelet denoising, smoothing splines, and localized smoothing splines. We applied these methods to the estimation of simulated mixtures of human ERPs and ongoing electroencephalogram (EEG) activity using a dipole simulator (BESA). In this scenario we considered ongoing EEG to represent spatially and temporally correlated noise added to the ERPs. This simulation provided a reasonable but simplified model of real-world ERP measurements. For estimation of the simulated single-trial ERPs, local KPLS provided a level of accuracy that was comparable with or better than the other methods. We also applied the local KPLS method to the estimation of human ERPs recorded in an experiment on co,onitive fatigue. For these data, the local KPLS method provided a clear improvement in visualization of single-trial ERPs as well as their averages. The local KPLS method may serve as a new alternative to the estimation of single-trial ERPs and improvement of ERP averages.

  9. Nicotine enhances an auditory Event-Related Potential component which is inversely related to habituation.

    Science.gov (United States)

    Veltri, Theresa; Taroyan, Naira; Overton, Paul G

    2017-07-01

    Nicotine is a psychoactive substance that is commonly consumed in the context of music. However, the reason why music and nicotine are co-consumed is uncertain. One possibility is that nicotine affects cognitive processes relevant to aspects of music appreciation in a beneficial way. Here we investigated this possibility using Event-Related Potentials. Participants underwent a simple decision-making task (to maintain attentional focus), responses to which were signalled by auditory stimuli. Unlike previous research looking at the effects of nicotine on auditory processing, we used complex tones that varied in pitch, a fundamental element of music. In addition, unlike most other studies, we tested non-smoking subjects to avoid withdrawal-related complications. We found that nicotine (4.0 mg, administered as gum) increased P2 amplitude in the frontal region. Since a decrease in P2 amplitude and latency is related to habituation processes, and an enhanced ability to disengage from irrelevant stimuli, our findings suggest that nicotine may cause a reduction in habituation, resulting in non-smokers being less able to adapt to repeated stimuli. A corollary of that decrease in adaptation may be that nicotine extends the temporal window during which a listener is able and willing to engage with a piece of music.

  10. [Event-related EEG potentials associated with error detection in psychiatric disorder: literature review].

    Science.gov (United States)

    Balogh, Lívia; Czobor, Pál

    2010-01-01

    Error-related bioelectric signals constitute a special subgroup of event-related potentials. Researchers have identified two evoked potential components to be closely related to error processing, namely error-related negativity (ERN) and error-positivity (Pe), and they linked these to specific cognitive functions. In our article first we give a brief description of these components, then based on the available literature, we review differences in error-related evoked potentials observed in patients across psychiatric disorders. The PubMed and Medline search engines were used in order to identify all relevant articles, published between 2000 and 2009. For the purpose of the current paper we reviewed publications summarizing results of clinical trials. Patients suffering from schizophrenia, anorexia nervosa or borderline personality disorder exhibited a decrease in the amplitude of error-negativity when compared with healthy controls, while in cases of depression and anxiety an increase in the amplitude has been observed. Some of the articles suggest specific personality variables, such as impulsivity, perfectionism, negative emotions or sensitivity to punishment to underlie these electrophysiological differences. Research in the field of error-related electric activity has come to the focus of psychiatry research only recently, thus the amount of available data is significantly limited. However, since this is a relatively new field of research, the results available at present are noteworthy and promising for future electrophysiological investigations in psychiatric disorders.

  11. Trial latencies estimation of event-related potentials in EEG by means of genetic algorithms

    Science.gov (United States)

    Da Pelo, P.; De Tommaso, M.; Monaco, A.; Stramaglia, S.; Bellotti, R.; Tangaro, S.

    2018-04-01

    Objective. Event-related potentials (ERPs) are usually obtained by averaging thus neglecting the trial-to-trial latency variability in cognitive electroencephalography (EEG) responses. As a consequence the shape and the peak amplitude of the averaged ERP are smeared and reduced, respectively, when the single-trial latencies show a relevant variability. To date, the majority of the methodologies for single-trial latencies inference are iterative schemes providing suboptimal solutions, the most commonly used being the Woody’s algorithm. Approach. In this study, a global approach is developed by introducing a fitness function whose global maximum corresponds to the set of latencies which renders the trial signals most aligned as possible. A suitable genetic algorithm has been implemented to solve the optimization problem, characterized by new genetic operators tailored to the present problem. Main results. The results, on simulated trials, showed that the proposed algorithm performs better than Woody’s algorithm in all conditions, at the cost of an increased computational complexity (justified by the improved quality of the solution). Application of the proposed approach on real data trials, resulted in an increased correlation between latencies and reaction times w.r.t. the output from RIDE method. Significance. The above mentioned results on simulated and real data indicate that the proposed method, providing a better estimate of single-trial latencies, will open the way to more accurate study of neural responses as well as to the issue of relating the variability of latencies to the proper cognitive and behavioural correlates.

  12. From sensation to percept: the neural signature of auditory event-related potentials.

    Science.gov (United States)

    Joos, Kathleen; Gilles, Annick; Van de Heyning, Paul; De Ridder, Dirk; Vanneste, Sven

    2014-05-01

    An external auditory stimulus induces an auditory sensation which may lead to a conscious auditory perception. Although the sensory aspect is well known, it is still a question how an auditory stimulus results in an individual's conscious percept. To unravel the uncertainties concerning the neural correlates of a conscious auditory percept, event-related potentials may serve as a useful tool. In the current review we mainly wanted to shed light on the perceptual aspects of auditory processing and therefore we mainly focused on the auditory late-latency responses. Moreover, there is increasing evidence that perception is an active process in which the brain searches for the information it expects to be present, suggesting that auditory perception requires the presence of both bottom-up, i.e. sensory and top-down, i.e. prediction-driven processing. Therefore, the auditory evoked potentials will be interpreted in the context of the Bayesian brain model, in which the brain predicts which information it expects and when this will happen. The internal representation of the auditory environment will be verified by sensation samples of the environment (P50, N100). When this incoming information violates the expectation, it will induce the emission of a prediction error signal (Mismatch Negativity), activating higher-order neural networks and inducing the update of prior internal representations of the environment (P300). Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Single-Trial Event-Related Potential Based Rapid Image Triage System

    Directory of Open Access Journals (Sweden)

    Ke Yu

    2011-06-01

    Full Text Available Searching for points of interest (POI in large-volume imagery is a challenging problem with few good solutions. In this work, a neural engineering approach called rapid image triage (RIT which could offer about a ten-fold speed up in POI searching is developed. It is essentially a cortically-coupled computer vision technique, whereby the user is presented bursts of images at a speed of 6–15 images per second and then neural signals called event-related potential (ERP is used as the ‘cue’ for user seeing images of high relevance likelihood. Compared to past efforts, the implemented system has several unique features: (1 it applies overlapping frames in image chip preparation, to ensure rapid image triage performance; (2 a novel common spatial-temporal pattern (CSTP algorithm that makes use of both spatial and temporal patterns of ERP topography is proposed for high-accuracy single-trial ERP detection; (3 a weighted version of probabilistic support-vector-machine (SVM is used to address the inherent unbalanced nature of single-trial ERP detection for RIT. High accuracy, fast learning, and real-time capability of the developed system shown on 20 subjects demonstrate the feasibility of a brainmachine integrated rapid image triage system for fast detection of POI from large-volume imagery.

  14. Evidence for Attentional Gradient in the Serial Position Memory Curve from Event-related Potentials

    Science.gov (United States)

    Azizian, Allen; Polich, John

    2009-01-01

    The occurrence of primacy versus recency effects in free recall is suggested to reflect either two distinct memory systems, or the operation of a single system that is modulated by allocation of attention and less vulnerable to interference. Behavioral and event-related brain potential (ERPs) measures were used to investigate the encoding substrates of the serial position curve and subsequent recall in young adults. Participants were instructed to remember lists of words consisting of 12 common nouns each presented once every 1.5 sec, with a recall signal following the last word to indicate that all remembered items should be written on paper. This procedure was repeated for 20 different word lists. Both performance and late ERP amplitudes reflected classic recall serial position effects. Greater recall and larger late positive component amplitudes were obtained for the primacy and recency items, with less recall and smaller amplitudes for the middle words. The late positive component was larger for recalled compared to unrecalled primacy items, but it did not differ between memory performance outcomes for the recency items. The close relationship between the enhanced amplitude and primacy retrieval supports the view that this positive component reflects one of a process series related to attentional gradient and encoding of events for storage in memory. Recency effects appear to index operations determined by the anticipation of the last stimulus presentation, which occurred for both recalled and unrecalled memory items. Theoretical implications are discussed. PMID:17892393

  15. The application of particle filters in single trial event-related potential estimation

    International Nuclear Information System (INIS)

    Mohseni, Hamid R; Nazarpour, Kianoush; Sanei, Saeid; Wilding, Edward L

    2009-01-01

    In this paper, an approach for the estimation of single trial event-related potentials (ST-ERPs) using particle filters (PFs) is presented. The method is based on recursive Bayesian mean square estimation of ERP wavelet coefficients using their previous estimates as prior information. To enable a performance evaluation of the approach in the Gaussian and non-Gaussian distributed noise conditions, we added Gaussian white noise (GWN) and real electroencephalogram (EEG) signals recorded during rest to the simulated ERPs. The results were compared to that of the Kalman filtering (KF) approach demonstrating the robustness of the PF over the KF to the added GWN noise. The proposed method also outperforms the KF when the assumption about the Gaussianity of the noise is violated. We also applied this technique to real EEG potentials recorded in an odd-ball paradigm and investigated the correlation between the amplitude and the latency of the estimated ERP components. Unlike the KF method, for the PF there was a statistically significant negative correlation between amplitude and latency of the estimated ERPs, matching previous neurophysiological findings

  16. EEG Channel Selection Using Particle Swarm Optimization for the Classification of Auditory Event-Related Potentials

    Directory of Open Access Journals (Sweden)

    Alejandro Gonzalez

    2014-01-01

    Full Text Available Brain-machine interfaces (BMI rely on the accurate classification of event-related potentials (ERPs and their performance greatly depends on the appropriate selection of classifier parameters and features from dense-array electroencephalography (EEG signals. Moreover, in order to achieve a portable and more compact BMI for practical applications, it is also desirable to use a system capable of accurate classification using information from as few EEG channels as possible. In the present work, we propose a method for classifying P300 ERPs using a combination of Fisher Discriminant Analysis (FDA and a multiobjective hybrid real-binary Particle Swarm Optimization (MHPSO algorithm. Specifically, the algorithm searches for the set of EEG channels and classifier parameters that simultaneously maximize the classification accuracy and minimize the number of used channels. The performance of the method is assessed through offline analyses on datasets of auditory ERPs from sound discrimination experiments. The proposed method achieved a higher classification accuracy than that achieved by traditional methods while also using fewer channels. It was also found that the number of channels used for classification can be significantly reduced without greatly compromising the classification accuracy.

  17. An Event-Related Study for Dynamic Analysis of Corticomuscular Connectivity

    Directory of Open Access Journals (Sweden)

    Ou Bai

    2010-01-01

    Full Text Available Corticomuscular coupling estimated by EEG-EMG coherence may reveal functional cortical driving of peripheral muscular activity. EEG-EMG coherence in the beta band (15–30 Hz has been extensively studied under isometric muscle contraction tasks. We attempted to study the time-course of corticomuscular connectivity under a dynamic target tracking task. A new device was developed for the real-time measurement of dynamic force created by pinching thumb and index fingers. Four healthy subjects who participated in this study were asked to track visual targets with the feedback forces. Spectral parameters using FFT and complex wavelet were explored for reliable estimation of event-related coherence and EEG-EMG correlogram for representing corticomuscular connectivity. Clearly distinguishable FFT-based coherence and cross-correlogram during the visual target tracking were observed with appropriate hyper-parameters for spectral estimation. The system design and the exploration of signal processing methods in this study supports further exploration of corticomuscular connectivity associated with human motor control.

  18. Low-loss, silicon integrated, aluminum nitride photonic circuits and their use for electro-optic signal processing.

    Science.gov (United States)

    Xiong, Chi; Pernice, Wolfram H P; Tang, Hong X

    2012-07-11

    Photonic miniaturization requires seamless integration of linear and nonlinear optical components to achieve passive and active functions simultaneously. Among the available material systems, silicon photonics holds immense promise for optical signal processing and on-chip optical networks. However, silicon is limited to wavelengths above 1.1 μm and does not provide the desired lowest order optical nonlinearity for active signal processing. Here we report the integration of aluminum nitride (AlN) films on silicon substrates to bring active functionalities to chip-scale photonics. Using CMOS-compatible sputtered thin films we fabricate AlN-on-insulator waveguides that exhibit low propagation loss (0.6 dB/cm). Exploiting AlN's inherent Pockels effect we demonstrate electro-optic modulation up to 4.5 Gb/s with very low energy consumption (down to 10 fJ/bit). The ultrawide transparency window of AlN devices also enables high speed modulation at visible wavelengths. Our low cost, wideband, carrier-free photonic circuits hold promise for ultralow power and high-speed signal processing at the microprocessor chip level.

  19. Experimental Investigation of transmission properties of all-optical label swapping of orthogonal IM/FSK labeled signals

    DEFF Research Database (Denmark)

    Holm-Nielsen, Pablo Villanueva; Chi, Nan; Zhang, Jianfeng

    2003-01-01

    Optically labeled IM/FSK signal saretran smitte dover 50km of SMF under different compensation schemes.All-opticallabel swapping based on MZ-SOA and EAM is presented. Transmission followed by label swapping shows a 2dB overall power penalty....

  20. All-optical 40Gbit/s OTDM to 2x20Gbit/s WDM signal-format translation

    DEFF Research Database (Denmark)

    Jørgensen, Carsten; Danielsen, Søren Lykke; Mikkelsen, Benny

    1996-01-01

    40Gbit/s OTDM to 2 x 20 Gbit/s WDM signal-format translation is demonstrated using a cross-gain modulation in a semiconductor optical amplifier designed for high-speed operation. Excellent performance is demonstrated by polarisation-independent operation, showing clear eye diagrams and high...... extinction ratios for the translated WDM-channels....

  1. Development of event related negativity together with an internal model of audio-motor associations

    Directory of Open Access Journals (Sweden)

    Kai eLutz

    2013-09-01

    Full Text Available The brain’s reactions to error are manifested in several event related potentials (ERP components, derived from electroencephalographic (EEG signals. Although these components have been known for decades, their interpretation is still controversial. A current hypothesis (first indicator hypothesis claims that the first indication of an action being erroneous leads to a negative deflection of the EEG signal over frontal midline areas. In some cases this requires sensory feedback in the form of knowledge of results (KR. If KR is given, then the first negative deflection can be found around 250 ms after feedback presentation (feedback related negativity, FRN. When KR is not required, a negative deflection is found already around 100 ms after action onset (ERN. This deflection may be evoked when a mismatch between required and actually executed actions is detected. To detect such a mismatch, however, necessitates knowledge about which action is required. To test this assumption, the current study monitored EEG error components during acquisition of an internal model, i.e., acquisition of the knowledge of which actions are needed to reach certain goals. Actions consisted of finger presses on a piano keyboard and goals were tones of a certain pitch to be generated, thus the internal model represented audio-motor mapping. Results show that with increasing proficiency in mapping goals to appropriate actions, the amplitude of the ERN increased, whereas the amplitude of the FRN remained unchanged. Thus, when knowledge is present about which action is required, this supports generation of an ERN around 100ms, likely by detecting a mismatch between required and performed actions. This is in accordance with the first indicator hypothesis. The present study furthermore lends support to the notion that FRN mainly relies on comparison of sensory targets with sensory feedback.

  2. Localizing Event-Related Potentials Using Multi-source Minimum Variance Beamformers: A Validation Study.

    Science.gov (United States)

    Herdman, Anthony T; Moiseev, Alexander; Ribary, Urs

    2018-02-15

    Adaptive and non-adaptive beamformers have become a prominent neuroimaging tool for localizing neural sources of electroencephalographic (EEG) and magnetoencephalographic (MEG) data. In this study, we investigated single-source and multi-source scalar beamformers with respect to their performances in localizing and reconstructing source activity for simulated and real EEG data. We compared a new multi-source search approach (multi-step iterative approach; MIA) to our previous multi-source search approach (single-step iterative approach; SIA) and a single-source search approach (single-step peak approach; SPA). In order to compare performances across these beamformer approaches, we manipulated various simulated source parameters, such as the amount of signal-to-noise ratio (0.1-0.9), inter-source correlations (0.3-0.9), number of simultaneously active sources (2-8), and source locations. Results showed that localization performance followed the order of MIA > SIA > SPA regardless of the number of sources, source correlations, and single-to-noise ratios. In addition, SIA and MIA were significantly better than SPA at localizing four or more sources. Moreover, MIA was better than SIA and SPA at identifying the true source locations when signal characteristics were at their poorest. Source waveform reconstructions were similar between MIA and SIA but were significantly better than that for SPA. A similar trend was also found when applying these beamformer approaches to a real EEG dataset. Based on our findings, we conclude that multi-source beamformers (MIA and SIA) are an improvement over single-source beamformers for localizing EEG. Importantly, our new search method, MIA, had better localization performance, localization precision, and source waveform reconstruction as compared to SIA or SPA. We therefore recommend its use for improved source localization and waveform reconstruction of event-related potentials.

  3. A modular, low-cost, digital signal processor-based lock-in card for measuring optical attenuation

    Science.gov (United States)

    Barragán, L. A.; Artigas, J. I.; Alonso, R.; Villuendas, F.

    2001-01-01

    A modular, low-cost, digital signal processor (DSP)-based lock-in card is described for measuring optical attenuation. By transferring the lock-in operation from the analog domain to the digital domain, the nonlinearities gain, and offset errors and drifts are virtually eliminated. The dual phase lock-in operation has been implemented on the low-cost DSP56002 evaluation module (DSP56002EVM) of Motorola that is widely used in audio signal processing. This evaluation board contains a 24 bit DSP56002 DSP and a stereo CD-quality audio codec that makes the board ideal for implementing signal processing algorithms. Due to the maximum sampling rate of the codec embedded on the DSP56002EVM, the frequencies of the processed signals must be below 20 kHz. This specification is enough for the most common applications in the field of optics, where low or very low frequency (<1 kHz) references are frequent. The software algorithm implementing the lock-in amplifier can be particularized by the user on the basis of the needed performances. The effects of finite word length in the digital filter implementation are analyzed. This analysis reveals that a 24 bit word length is not enough to ensure the filter stability and the required frequency response. To overcome this problem, the double precision multiply mode must be used. When the DSP56002 enters this mode, double precision 48 bit by 48 bit multiplication can be performed. The lock-in performance has been tested. The measured amplitude variations of the reference sine signal are about 0.003%, which do not affect the signal measurement. The lock-in behaves like a band-pass filter centered on the reference frequency whose bandwidth is related to the low-pass filter cutoff frequency. The measured frequency response shows that the lock-in performs as theoretically predicted. The DSP56002EVM can be used as a lock-in for electrical signals in stand-alone operation. Besides, we have designed a card that interconnects to the DSP56002EVM

  4. Nematicons and Their Electro-Optic Control: Light Localization and Signal Readdressing via Reorientation in Liquid Crystals

    Directory of Open Access Journals (Sweden)

    Armando Piccardi

    2013-10-01

    Full Text Available Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely “nematicons”. Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing.

  5. Nematicons and their electro-optic control: light localization and signal readdressing via reorientation in liquid crystals.

    Science.gov (United States)

    Piccardi, Armando; Alberucci, Alessandro; Assanto, Gaetano

    2013-10-08

    Liquid crystals in the nematic phase exhibit substantial reorientation when the molecules are driven by electric fields of any frequencies. Exploiting such a response at optical frequencies, self-focusing supports transverse localization of light and the propagation of self-confined beams and waveguides, namely "nematicons". Nematicons can guide other light signals and interact with inhomogeneities and other beams. Moreover, they can be effectively deviated by using the electro-optic response of the medium, leading to several strategies for voltage-controlled reconfiguration of light-induced guided-wave circuits and signal readdressing. Hereby, we outline the main features of nematicons and review the outstanding progress achieved in the last twelve years on beam self-trapping and electro-optic readdressing.

  6. Event-related potential response to auditory social stimuli, parent-reported social communicative deficits and autism risk in school-aged children with congenital visual impairment

    OpenAIRE

    Bathelt, J.; Dale, N.; de Haan, M.

    2017-01-01

    Communication with visual signals, like facial expression, is important in early social development, but the question if these signals are necessary for typical social development remains to be addressed. The potential impact on social development of being born with no or very low levels of vision is therefore of high theoretical and clinical interest. The current study investigated event-related potential responses to basic social stimuli in a rare group of school-aged children with congenit...

  7. Optical Synchronization of a 10-G Ethernet Packet and Time-Division Multiplexing to a 50-Gb/s Signal Using an Optical Time Lens

    DEFF Research Database (Denmark)

    Hu, Hao; Laguardia Areal, Janaina; Palushani, Evarist

    2010-01-01

    A 10-G Ethernet packet with maximum packet size of 1518 bytes is synchronized to a master clock with 200-kHz frequency offset using a time lens. The input 10-Gb/s non-return-to-zero packet is at the same time converted into a return-to-zero (RZ) packet with a pulsewidth of 10 ps and then time......-division multiplexed with four 10-Gb/s optical time-division-multiplexing (OTDM) channels, thus constituting a 50-Gb/s OTDM serial signal. Error-free performances of the synchronized RZ packet and demultiplexed packet from the aggregated 50-Gb/s OTDM signal are achieved....

  8. Amplification of the Signal Intensity of Fluorescence-Based Fiber-Optic Biosensors Using a Fabry-Perot Resonator Structure

    Directory of Open Access Journals (Sweden)

    Meng-Chang Hsieh

    2015-02-01

    Full Text Available Fluorescent biosensors have been widely used in biomedical applications. To amplify the intensity of fluorescence signals, this study developed a novel structure for an evanescent wave fiber-optic biosensor by using a Fabry-Perot resonator structure. An excitation light was coupled into the optical fiber through a laser-drilled hole on the proximal end of the resonator. After entering the resonator, the excitation light was reflected back and forth inside the resonator, thereby amplifying the intensity of the light in the fiber. Subsequently, the light was used to excite the fluorescent molecules in the reactive region of the sensor. The experimental results showed that the biosensor signal was amplified eight-fold when the resonator reflector was formed using a 92% reflective coating. Furthermore, in a simulation, the biosensor signal could be amplified 20-fold by using a 99% reflector.

  9. Increasing signal-to-noise ratio of swept-source optical coherence tomography by oversampling in k-space

    Science.gov (United States)

    Nagib, Karim; Mezgebo, Biniyam; Thakur, Rahul; Fernando, Namal; Kordi, Behzad; Sherif, Sherif

    2018-03-01

    Optical coherence tomography systems suffer from noise that could reduce ability to interpret reconstructed images correctly. We describe a method to increase the signal-to-noise ratio of swept-source optical coherence tomography (SSOCT) using oversampling in k-space. Due to this oversampling, information redundancy would be introduced in the measured interferogram that could be used to reduce white noise in the reconstructed A-scan. We applied our novel scaled nonuniform discrete Fourier transform to oversampled SS-OCT interferograms to reconstruct images of a salamander egg. The peak-signal-to-noise (PSNR) between the reconstructed images using interferograms sampled at 250MS/s andz50MS/s demonstrate that this oversampling increased the signal-to-noise ratio by 25.22 dB.

  10. Changes in fMRI magnitude data and phase data observed in block-design and event-related tasks.

    Science.gov (United States)

    Arja, Sunil Kumar; Feng, Zhaomei; Chen, Zikuan; Caprihan, Arvind; Kiehl, Kent A; Adali, Tülay; Calhoun, Vince D

    2010-02-15

    Functional magnetic resonance imaging (fMRI) data are acquired as a complex image pair including magnitude and phase information. The vast majority of fMRI experiments do not attempt to take advantage of the time varying phase information. The phase of the MRI signal is related to the local magnetic field changes, suggesting it may contain useful information about the source of hemodynamic activity. Analysis of phase data acquired from different fMRI experiments has shown the presence of activity in response to various stimuli. However, there have been no studies that have examined phase data in a larger group of subjects for multiple types of fMRI tasks nor have studies examined phase changes due to event-related stimuli. In this paper, we evaluate the correspondence between the magnitude and phase changes at a group level in a block-design motor tapping task and in an event-related auditory oddball task. The results for both block-design and event-related tasks indicate the presence of task-related information in the phase data with phase-only and magnitude-only approaches showing signal changes in the expected brain regions. Although there is more overall activity detected with magnitude data, the phase-only analysis also reveals activity in regions expected to be involved in the task, some of which were not significantly activated in the magnitude-only analysis, suggesting that the phase might provide some unique information. In addition, the phase can potentially increase sensitivity within regions also showing magnitude changes. Future work should focus on additional methods for combining the magnitude and phase data. Copyright 2009 Elsevier Inc. All rights reserved.

  11. Fiber nonlinearity mitigation of WDM-PDM QPSK/16-QAM signals using fiber-optic parametric amplifiers based multiple optical phase conjugations

    DEFF Research Database (Denmark)

    Hu, Hao; Jopson, Robert M.; Gnauck, Alan H.

    2017-01-01

    We demonstrate fiber nonlinearity mitigation by using multiple optical phase conjugations (OPCs) in the WDM transmission systems of both 8 x 32-Gbaud PDM QPSK channels and 8 x 32-Gbaud PDM 16-QAM channels, showing improved performance over a single mid-span OPC and no OPC in terms of nonlinear...... threshold and a best achievable Q(2) factor after transmission. In addition, after an even number of OPCs, the signal wavelength can be preserved after transmission. The performance of multiple OPCs for fiber nonlinearity mitigation was evaluated independently for WDM PDM QPSK signals and WDM PDM 16QAM...... to 1 dB compared to the case of mid-span OPC. The improvements in the best achievable Q(2) factors were more modest, ranging from 0.2 dB to 1.1 dB for the results presented. (C) 2017 Optical Society of America...

  12. Optical signal response pf the alanine gel solution for photons and electrons clinical beams

    International Nuclear Information System (INIS)

    Silva, Cleber Feijo; Campos, Leticia Lucente

    2009-01-01

    Alanine gel dosimeter is a new gel material developed at IPEN that presents significant improvement on previous alanine systems developed by Costa (1994). The measure technique is based on the transformation of ferrous ions (Fe 2+ ) in ferric ions (Fe 3+ ) after irradiation. The DL-Alanine (C 3 H 7 NO 2 ) is an aminoacid tissue equivalent that improves the production of ferric ions in the solution. This work aims to study the comparison of optical signal response of the alanine gel solution for photons and electrons clinical beams. It was observed that the calibration factor can be considered independent of quality of the radiation for photons and electrons clinical beams. Therefore, it can be used the same calibration factor for evaluating the absorbed dose in photons and electrons fields in the energy of 6 MeV. Alanine Gel Dosimeter presents good performance and can be useful as alternative dosimeter in the radiotherapy area using MRI technique for 3D dose distribution evaluation. (author)

  13. The impact of relative intensity noise on the signal in multiple reference optical coherence tomography

    Science.gov (United States)

    Neuhaus, Kai; Subhash, Hrebesh; Alexandrov, Sergey; Dsouza, Roshan; Hogan, Josh; Wilson, Carol; Leahy, Martin; Slepneva, Svetlana; Huyet, Guillaume

    2016-03-01

    Multiple reference optical coherence tomography (MR-OCT) applies a unique low-cost solution to enhance the scanning depth of standard time domain OCT by inserting an partial mirror into the reference arm of the interferometric system. This novel approach achieves multiple reflections for different layers and depths of an sample with minimal effort of engineering and provides an excellent platform for low-cost OCT systems based on well understood production methods for micro-mechanical systems such as CD/DVD pick-up systems. The direct integration of a superluminescent light-emitting diode (SLED) is a preferable solution to reduce the form- factor of an MR-OCT system. Such direct integration exposes the light source to environmental conditions that can increase fluctuations in heat dissipation and vibrations and affect the noise characteristics of the output spectrum. This work describes the impact of relative intensity noise (RIN) on the quality of the interference signal of MR-OCT related to a variety of environmental conditions, such as temperature.

  14. Extreme temperature robust optical sensor designs and fault-tolerant signal processing

    Science.gov (United States)

    Riza, Nabeel Agha [Oviedo, FL; Perez, Frank [Tujunga, CA

    2012-01-17

    Silicon Carbide (SiC) probe designs for extreme temperature and pressure sensing uses a single crystal SiC optical chip encased in a sintered SiC material probe. The SiC chip may be protected for high temperature only use or exposed for both temperature and pressure sensing. Hybrid signal processing techniques allow fault-tolerant extreme temperature sensing. Wavelength peak-to-peak (or null-to-null) collective spectrum spread measurement to detect wavelength peak/null shift measurement forms a coarse-fine temperature measurement using broadband spectrum monitoring. The SiC probe frontend acts as a stable emissivity Black-body radiator and monitoring the shift in radiation spectrum enables a pyrometer. This application combines all-SiC pyrometry with thick SiC etalon laser interferometry within a free-spectral range to form a coarse-fine temperature measurement sensor. RF notch filtering techniques improve the sensitivity of the temperature measurement where fine spectral shift or spectrum measurements are needed to deduce temperature.

  15. Analysis of behavior of focusing error signals generated by astigmatic method when a focused spot moves beyond the radius of a land-groove-type optical disk

    Science.gov (United States)

    Shinoda, Masahisa; Nakatani, Hidehiko; Nakai, Kenya; Ohmaki, Masayuki

    2015-09-01

    We theoretically calculate behaviors of focusing error signals generated by an astigmatic method in a land-groove-type optical disk. The focusing error signal from the land does not coincide with that from the groove. This behavior is enhanced when a focused spot of an optical pickup moves beyond the radius of the optical disk. A gain difference between the slope sensitivities of focusing error signals from the land and the groove is an important factor with respect to stable focusing servo control. In our calculation, the format of digital versatile disc-random access memory (DVD-RAM) is adopted as the land-groove-type optical disk model, and the dependences of the gain difference on various factors are investigated. The gain difference strongly depends on the optical intensity distribution of the laser beam in the optical pickup. The calculation method and results in this paper will be reflected in newly developed land-groove-type optical disks.

  16. An event-related potential study on memory search for color

    OpenAIRE

    Miyatani, Makoto; Nakao, Takasi; Ohkawa, Kaori; Sanderson, Nicholas S. R.; Takumi, Ken

    2002-01-01

    The present study focused on memory search processes in nonverbal working memory. Event-related potentials (ERPs) were recorded while subjects engaged in two memory search tasks. Effects of memory set size on event-related potentials were compared between when memory sets consisted of one or four alphabets and when one to three unvocable color patches composed memory sets. In a letter search task, increase of memory set size caused the enlargement of negativities of ERPs between 250 and 450 m...

  17. Markov Switching Model for Quick Detection of Event Related Desynchronization in EEG

    Directory of Open Access Journals (Sweden)

    Giuseppe Lisi

    2018-02-01

    Full Text Available Quick detection of motor intentions is critical in order to minimize the time required to activate a neuroprosthesis. We propose a Markov Switching Model (MSM to achieve quick detection of an event related desynchronization (ERD elicited by motor imagery (MI and recorded by electroencephalography (EEG. Conventional brain computer interfaces (BCI rely on sliding window classifiers in order to perform online continuous classification of the rest vs. MI classes. Based on this approach, the detection of abrupt changes in the sensorimotor power suffers from an intrinsic delay caused by the necessity of computing an estimate of variance across several tenths of a second. Here we propose to avoid explicitly computing the EEG signal variance, and estimate the ERD state directly from the voltage information, in order to reduce the detection latency. This is achieved by using a model suitable in situations characterized by abrupt changes of state, the MSM. In our implementation, the model takes the form of a Gaussian observation model whose variance is governed by two latent discrete states with Markovian dynamics. Its objective is to estimate the brain state (i.e., rest vs. ERD given the EEG voltage, spatially filtered by common spatial pattern (CSP, as observation. The two variances associated with the two latent states are calibrated using the variance of the CSP projection during rest and MI, respectively. The transition matrix of the latent states is optimized by the “quickest detection” strategy that minimizes a cost function of detection latency and false positive rate. Data collected by a dry EEG system from 50 healthy subjects, was used to assess performance and compare the MSM with several logistic regression classifiers of different sliding window lengths. As a result, the MSM achieves a significantly better tradeoff between latency, false positive and true positive rates. The proposed model could be used to achieve a more reactive and

  18. Maintenance of glia in the optic lamina is mediated by EGFR signaling by photoreceptors in adult Drosophila.

    Science.gov (United States)

    Lee, Yuan-Ming; Sun, Y Henry

    2015-04-01

    The late onset of neurodegeneration in humans indicates that the survival and function of cells in the nervous system must be maintained throughout adulthood. In the optic lamina of the adult Drosophila, the photoreceptor axons are surrounded by multiple types of glia. We demonstrated that the adult photoreceptors actively contribute to glia maintenance in their target field within the optic lamina. This effect is dependent on the epidermal growth factor receptor (EGFR) ligands produced by the R1-6 photoreceptors and transported to the optic lamina to act on EGFR in the lamina glia. EGFR signaling is necessary and sufficient to act in a cell-autonomous manner in the lamina glia. Our results suggest that EGFR signaling is required for the trafficking of the autophagosome/endosome to the lysosome. The loss of EGFR signaling results in cell degeneration most likely because of the accumulation of autophagosomes. Our findings provide in vivo evidence for the role of adult neurons in the maintenance of glia and a novel role for EGFR signaling in the autophagic flux.

  19. Harmful intrusion detection algorithm of optical fiber pre-warning system based on correlation of orthogonal polarization signals

    Science.gov (United States)

    Bi, Fukun; Feng, Chong; Qu, Hongquan; Zheng, Tong; Wang, Chonglei

    2017-09-01

    At present, advanced researches of optical fiber intrusion measurement are based on the constant false alarm rate (CFAR) algorithm. Although these conventional methods overcome the interference of non-stationary random signals, there are still a large number of false alarms in practical applications. This is because there is no specific study on orthogonal polarization signals of false alarm and intrusion. In order to further reduce false alarms, we analyze the correlation of optical fiber signals using birefringence of single-mode fiber. This paper proposes the harmful intrusion detection algorithm based on the correlation of two orthogonal polarization signals. The proposed method uses correlation coefficient to distinguish false alarms and intrusions, which can decrease false alarms. Experiments on real data, which are collected from the practical environment, demonstrate that the difference in correlation is a robust feature. Furthermore, the results show that the proposed algorithm can reduce the false alarms and ensure the detection performance when it is used in optical fiber pre-warning system (OFPS).

  20. Optical Frequency Division for Low Noise RF to W Band Signal Generation

    Science.gov (United States)

    Quinlan, Franklyn

    Modern optical frequency references have extraordinary spectral purity, with lasers stabilized to passive optical reference cavities reaching fractional frequency instabilities below 10-16 at 1 second, and optical atomic clocks approaching 10-18 at 104 seconds. Both the short- and long-term stability providing by ultrastable optical references can find new utility after high fidelity conversion to the electrical domain, including precision microwave spectroscopy, navigation and radar systems, and an optical clock-based redefinition of the SI second. Frequency division from an optical reference at 100s of THz to RF and microwave frequencies is performed by phase locking an optical frequency comb to the optical reference, followed by optical-to-electrical conversion with a high-speed photodetector. This process generates RF and microwave carriers at the harmonics of the repetition rate of the optical frequency comb, all of which ideally maintain the fractional stability of the optical reference. This talk will cover the performance of current and next-generation optical references, as well as the current and required performance of optical frequency combs and optical-to-electrical conversion needed to support the exquisite performance available in the optical domain. To date, 1 second instability state-of-the-art optical references, with added noise at a level of 10-17 at 1 second, and <10-19 at 103 seconds. Techniques to extend the frequency range into the millimeter-wave domain while maintaining 10-15 fractional instability, as well as arbitrary frequency generation with sub-millihertz precision tuning, will also be discussed.

  1. Wave onset in central gray matter - its intrinsic optical signal and phase transitions in extracellular polymers

    Directory of Open Access Journals (Sweden)

    VERA M. FERNANDES-DE-LIMA

    2001-09-01

    Full Text Available The brain is an excitable media in which excitation waves propagate at several scales of time and space. ''One-dimensional'' action potentials (millisecond scale along the axon membrane, and spreading depression waves (seconds to minutes at the three dimensions of the gray matter neuropil (complex of interacting membranes are examples of excitation waves. In the retina, excitation waves have a prominent intrinsic optical signal (IOS. This optical signal is created by light scatter and has different components at the red and blue end of the spectrum. We could observe the wave onset in the retina, and measure the optical changes at the critical transition from quiescence to propagating wave. The results demonstrated the presence of fluctuations preceding propagation and suggested a phase transition. We have interpreted these results based on an extrapolation from Tasaki's experiments with action potentials and volume phase transitions of polymers. Thus, the scatter of red light appeared to be a volume phase transition in the extracellular matrix that was caused by the interactions between the cellular membrane cell coat and the extracellular sugar and protein complexes. If this hypothesis were correct, then forcing extracellular current flow should create a similar signal in another tissue, provided that this tissue was also transparent to light and with a similarly narrow extracellular space. This control tissue exists and it is the crystalline lens. We performed the experiments and confirmed the optical changes. Phase transitions in the extracellular polymers could be an important part of the long-range correlations found during wave propagation in central nervous tissue.O encéfalo é um meio excitável no qual ondas de excitação se propagam em várias escalas de tempo e espaço. Potenciais de axônios ''unidimensionais'' (escala de milisegundos ao longo da membrana axonal e ondas de depressão alastrante (segundos a minutos nas três dimens

  2. Examining Event-Related Potential (ERP correlates of decision bias in recognition memory judgments.

    Directory of Open Access Journals (Sweden)

    Holger Hill

    Full Text Available Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure. Event related potentials (ERP correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias. In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320 that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500-700 ms poststimulus, bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions.

  3. Distinct modulation of event-related potentials during motor preparation in patients with motor conversion disorder.

    Directory of Open Access Journals (Sweden)

    Rebekah L Blakemore

    Full Text Available OBJECTIVE: Conversion paresis patients and healthy people feigning weakness both exhibit weak voluntary movement without detectable neuropathology. Uniquely, conversion patients lack a sense of conscious awareness of the origin of their impairment. We investigated whether conversion paresis patients show distinct electroencephalographic (EEG markers associated with their unconscious movement deficits. METHODS: Six unilateral upper limb conversion paresis patients, 12 feigning participants asked to mimic weakness and 12 control participants performed a precued reaction time task, requiring movements of either hand, depending on precue information. Performance measures (force, reaction and movement time, and event-related EEG potentials (ERP were compared, between groups and across hands or hemisphere, using linear mixed models. RESULTS: Feigners generated the same inter-hand difference in reaction and movement time as expressed by patients, even though no specific targets were set nor feedback given on these measures. We found novel ERP signatures specific to patients. When the symptomatic hand was precued, the P3 ERP component accompanying the precue was dramatically larger in patients than in feigning participants. Additionally, in patients the earlier N1 ERP component was diminished when the precue signalled either the symptomatic or asymptomatic hand. CONCLUSIONS: These results are consistent with previous suggestions that lack of awareness of the origin of their symptoms in conversion disorder patients may result from suppression of brain activity normally related to self-agency. In patients the diminished N1 to all precues is consistent with a generalised reduction in cognitive processing of movement-related precues. The P3 enhancement in patients is unlikely to simply reflect changes required for generation of impaired movements, because it was not seen in feigners showing the same behavioural deficits. Rather, this P3 enhancement in

  4. Examining Event-Related Potential (ERP) Correlates of Decision Bias in Recognition Memory Judgments

    Science.gov (United States)

    Hill, Holger; Windmann, Sabine

    2014-01-01

    Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure). Event related potentials (ERP) correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias) and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias). In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied) items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320) that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500–700 ms poststimulus), bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions. PMID

  5. Using event related potentials to identify a user's behavioural intention aroused by product form design.

    Science.gov (United States)

    Ding, Yi; Guo, Fu; Zhang, Xuefeng; Qu, Qingxing; Liu, Weilin

    2016-07-01

    The capacity of product form to arouse user's behavioural intention plays a decisive role in further user experience, even in purchase decision, while traditional methods rarely give a fully understanding of user experience evoked by product form, especially the feeling of anticipated use of product. Behavioural intention aroused by product form designs has not yet been investigated electrophysiologically. Hence event related potentials (ERPs) were applied to explore the process of behavioural intention when users browsed different smart phone form designs with brand and price not taken into account for mainly studying the brain activity evoked by variety of product forms. Smart phone pictures with different anticipated user experience were displayed with equiprobability randomly. Participants were asked to click the left mouse button when certain picture gave them a feeling of behavioural intention to interact with. The brain signal of each participant was recorded by Curry 7.0. The results show that pictures with an ability to arouse participants' behavioural intention for further experience can evoke enhanced N300 and LPPs (late positive potentials) in central-parietal, parietal and occipital regions. The scalp topography shows that central-parietal, parietal and occipital regions are more activated. The results indicate that the discrepancy of ERPs can reflect the neural activities of behavioural intention formed or not. Moreover, amplitude of ERPs occurred in corresponding brain areas can be used to measure user experience. The exploring of neural correlated with behavioural intention provide an accurate measurement method of user's perception and help marketers to know which product can arouse users' behavioural intention, maybe taken as an evaluating indicator of product design. Copyright © 2016 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  6. Examining Event-Related Potential (ERP) correlates of decision bias in recognition memory judgments.

    Science.gov (United States)

    Hill, Holger; Windmann, Sabine

    2014-01-01

    Memory judgments can be based on accurate memory information or on decision bias (the tendency to report that an event is part of episodic memory when one is in fact unsure). Event related potentials (ERP) correlates are important research tools for elucidating the dynamics underlying memory judgments but so far have been established only for investigations of accurate old/new discrimination. To identify the ERP correlates of bias, and observe how these interact with ERP correlates of memory, we conducted three experiments that manipulated decision bias within participants via instructions during recognition memory tests while their ERPs were recorded. In Experiment 1, the bias manipulation was performed between blocks of trials (automatized bias) and compared to trial-by-trial shifts of bias in accord with an external cue (flexibly controlled bias). In Experiment 2, the bias manipulation was performed at two different levels of accurate old/new discrimination as the memory strength of old (studied) items was varied. In Experiment 3, the bias manipulation was added to another, bottom-up driven manipulation of bias induced via familiarity. In the first two Experiments, and in the low familiarity condition of Experiment 3, we found evidence of an early frontocentral ERP component at 320 ms poststimulus (the FN320) that was sensitive to the manipulation of bias via instruction, with more negative amplitudes indexing more liberal bias. By contrast, later during the trial (500-700 ms poststimulus), bias effects interacted with old/new effects across all three experiments. Results suggest that the decision criterion is typically activated early during recognition memory trials, and is integrated with retrieved memory signals and task-specific processing demands later during the trial. More generally, the findings demonstrate how ERPs can help to specify the dynamics of recognition memory processes under top-down and bottom-up controlled retrieval conditions.

  7. An efficient optimization method to improve the measuring accuracy of oxygen saturation by using triangular wave optical signal

    Science.gov (United States)

    Li, Gang; Yu, Yue; Zhang, Cui; Lin, Ling

    2017-09-01

    The oxygen saturation is one of the important parameters to evaluate human health. This paper presents an efficient optimization method that can improve the accuracy of oxygen saturation measurement, which employs an optical frequency division triangular wave signal as the excitation signal to obtain dynamic spectrum and calculate oxygen saturation. In comparison to the traditional method measured RMSE (root mean square error) of SpO2 which is 0.1705, this proposed method significantly reduced the measured RMSE which is 0.0965. It is notable that the accuracy of oxygen saturation measurement has been improved significantly. The method can simplify the circuit and bring down the demand of elements. Furthermore, it has a great reference value on improving the signal to noise ratio of other physiological signals.

  8. Rod-like plasmonic nanoparticles as optical building blocks: how differences in particle shape and structural geometry influence optical signal

    Energy Technology Data Exchange (ETDEWEB)

    Stender, Anthony [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    Gold nanoparticles, particularly those with an anisotropic shape, have become a popular optical probe for experiments involving work on the nanoscale. However, to carry out such delicate and intricate experiments, it is first necessary to understand the detailed behavior of individual nanoparticles. In this series of experiments, optical and electron microscopy were utilized for the characterization of individual nanoparticles and small assemblies of nanoparticles. In the first experiment, gold nanorods were investigated. Single, isolated nanorods exhibit two maxima of localized surface plasmon resonance (LSPR), which are associated with the two nanorod axes. Upon the physical rotation of a nanorod at one of its LSPR wavelengths under polarized illumination, the optical behavior varies in a sinusoidal fashion. A dimer of nanorods exhibits optical behavior quite similar to a nanorod, except the LSPR maxima are shifted and broader. Under differential interference contrast (DIC) microscopy, a pair of nanorods separated by a distance below the diffraction limit can be distinguished from a single nanorod due to its optical behavior upon rotation. Dark field microscopy is unable to distinguish the two geometries. For the second set of experiments, the optical behavior of single gold nanorods at non-plasmonic wavelengths was investigated. The same nanorod was rotated with respect to a polarized light source under DIC, dark field, and polarized light microscopy. DIC microscopy was found to produce diffraction pattern peaks at non-plasmonic wavelengths, which could be altered by adjusting the setting of the polarizer. In the third set of experiments, the optical behavior of a single gold dumbbell and several simple dumbbell geometries were investigated with microscopy and simulations. The single dumbbell displayed behavior quite similar to that of a nanorod, but dumbbells exhibit a shift in both LSPR wavebands. Moreover, the shape of dumbbell particles allows them to

  9. Real-time monitoring of intracellular signal transduction in PC12 cells by non-adiabatic tapered optical fiber biosensor

    Science.gov (United States)

    Zibaii, M. I.; Latifi, H.; Asadollahi, A.; Noraeipoor, Z.; Dargahi, L.

    2014-05-01

    Real-time observation of intracellular process of signal transduction is very useful for biomedical and pharmaceutical applications as well as for basic research work of cell biology. For feasible and reagentless observation of intracellular alterations in real time, we examined the use of a nonadiabatic tapered optical fiber (NATOF) biosensor for monitoring of intracellular signal transduction that was mainly translocation of protein kinase C via refractive index change in PC12 cells adhered on tapered fiber sensor without any indicator reagent. PC12 cells were stimulated with KCl . Our results suggest that complex intracellular reactions could be real-time monitored and characterized by NATOF biosensor.

  10. Dynamic full field optical coherence tomography: subcellular metabolic contrast revealed in tissues by interferometric signals temporal analysis.

    Science.gov (United States)

    Apelian, Clement; Harms, Fabrice; Thouvenin, Olivier; Boccara, A Claude

    2016-04-01

    We developed a new endogenous approach to reveal subcellular metabolic contrast in fresh ex vivo tissues taking advantage of the time dependence of the full field optical coherence tomography interferometric signals. This method reveals signals linked with local activity of the endogenous scattering elements which can reveal cells where other OCT-based techniques fail or need exogenous contrast agents. We benefit from the micrometric transverse resolution of full field OCT to image intracellular features. We used this time dependence to identify different dynamics at the millisecond scale on a wide range of organs in normal or pathological conditions.

  11. Optical signal processing for a smart vehicle lighting system using a-SiCH technology

    Science.gov (United States)

    Vieira, M. A.; Vieira, M.; Vieira, P.; Louro, P.

    2017-05-01

    We propose the use of Visible Light Communication (VLC) for vehicle safety applications, creating a smart vehicle lighting system that combines the functions of illumination and signaling, communications, and positioning. The feasibility of VLC is demonstrated by employing trichromatic Red-Green-Blue (RGB) LEDs as transmitters, since they offer the possibility of Wavelength Division Multiplexing (WDM), which can greatly increase the transmission data rate, when using SiC double p-i-n receivers to encode/decode the information. Trichromatic RGB Light Emitting Diodes (LED)s (RGB-LED) are used together for illumination proposes (headlamps) and individually, each chip, to transmit the driving range distance and data information. An on-off code is used to transmit the data. Free space is the transmission medium. The receivers consist of two stacked amorphous a-H:SiC cells. They combine the simultaneous demultiplexing operation with the photodetection and self-amplification. The proposed coding is based on SiC technology. Multiple Input Multi Output (MIMO) architecture is used. For data transmission, we propose the use of two headlights based on commercially available modulated white RGB-LEDs. For data receiving and decoding we use three a-SiC:H double pin/pin optical processors symmetrically distributed at the vehicle tail Moreover, we present a way to achieve vehicular communication using the parity bits. A representation with a 4 bit original string color message and the transmitted 7 bit string, the encoding and decoding accurate positional information processes and the design of SiC navigation system are discussed and tested. A visible multilateration method estimates the drive distance range by using the decoded information received from several non-collinear transmitters.

  12. An imaging system for intraoperative functional imaging of optical intrinsic signals

    Science.gov (United States)

    Wong, Gregory Kai

    This dissertation focuses on the research, design, and implementation of a Neurosurgical Imaging System (NIS), having the principle characteristics of modularity, mobility, multispectral imaging capabilities, and an open software architecture. The NIS will enable functional imaging of humans and animals by implementing innovative hardware and software enhancements. The NIS is tightly integrated with data acquisition hardware and software for simultaneous measurements of real-time, physiological parameters and Optical Intrinsic Signals (OIS). The NIS provides a portable, versatile imaging system. High speed ``off the shelf'' hardware has been implemented and refined to reduce overall cost and maintenance of the NIS. Implementation of new, enhanced charge coupled device technology, such as, Electron Bombardment Charge Coupled Devices (EBCCD) dramatically increases sensitivity and multi-spectral image acquisition capabilities. Utilization of efficient calibration and testing protocols provides advanced trouble shooting and standard performance metrics for the NIS. The NIS was experimentally tested and validated on LED ``phantoms'' and a variety of mammalian brain models throughout its design phases. Implementation of an innovative imaging system such as the NIS provides a powerful research and clinical diagnostic tool that will enhance our current understanding of the various physiologic underpinnings of neurovascular coupling in normal and diseased brains. The development of this type of portable imaging instrumentation controlled by a robust software architecture that provides command and control, real time data acquisition, data analysis, auto calibration, and performance metrics lay the foundations for a comprehensive neurosurgical guidance tool, as well as, a powerful experimental research tool for mapping activity-related changes in cerebral perfusion and neuronal activity.

  13. Event-related cortical processing in neuropathic pain under long-term spinal cord stimulation.

    Science.gov (United States)

    Weigel, Ralf; Capelle, H Holger; Flor, Herta; Krauss, Joachim K

    2015-01-01

    Several mechanisms were suggested in the past to explain the beneficial effect of spinal cord stimulation (SCS) in patients suffering from neuropathic pain. Little is known about potential supraspinal mechanisms. In this study cortical signaling of patients with neuropathic pain and successful long-term treatment with SCS was analyzed. Observational study. University hospital, neurosurgical department, outpatient clinic for movement disorders and pain, institute for cognitive and clinical neuroscience. Nine patients with neuropathic pain of a lower extremity with a lasting response to chronic SCS were included. Cortical activity was analyzed using event-related potentials of the electroencephalogram after non-painful and painful stimulation. Each patient was tested under the effect of long-term SCS and 24 hours after cessation of SCS. Cortical areas involved in the peaks of evoked potentials were localized using a source localization method based on a fixed dipole model. Detection threshold and intensity of non-painful stimulation did not differ significantly on both sides. Pain threshold was significantly lower on the neuropathic side under the effect of SCS (P = 0.03). Bilateral pain thresholds were significantly lower (P = 0.03 healthy side, P = 0.003 neuropathic side) in 5 patients with increased pain after cessation of SCS. Under the effect of SCS cortical negativities (N1, N2, N3) and positivities (P1) demonstrated bilaterally comparable amplitudes. After cessation of SCS, decreased threshold for peripheral stimulation resulted in lowered negativities on both sides. The positivity P1 was differentially regulated and was reduced more contralateral to the unaffected side. N2 was localized at the sensory representation of the leg within the homunculus. The main vector of P1 was localized within the cingular cortex (CC) and moved more anteriorly under the effect of SCS. The exact time span that SCS continues to have an effect is not known. However, due to patient

  14. Spatial-Temporal Feature Analysis on Single-Trial Event Related Potential for Rapid Face Identification

    Directory of Open Access Journals (Sweden)

    Lei Jiang

    2017-11-01

    Full Text Available The event-related potential (ERP is the brain response measured in electroencephalography (EEG, which reflects the process of human cognitive activity. ERP has been introduced into brain computer interfaces (BCIs to communicate the computer with the subject's intention. Due to the low signal-to-noise ratio of EEG, most ERP studies are based on grand-averaging over many trials. Recently single-trial ERP detection attracts more attention, which enables real time processing tasks as rapid face identification. All the targets needed to be retrieved may appear only once, and there is no knowledge of target label for averaging. More interestingly, how the features contribute temporally and spatially to single-trial ERP detection has not been fully investigated. In this paper, we propose to implement a local-learning-based (LLB feature extraction method to investigate the importance of spatial-temporal components of ERP in a task of rapid face identification using single-trial detection. Comparing to previous methods, LLB method preserves the nonlinear structure of EEG signal distribution, and analyze the importance of original spatial-temporal components via optimization in feature space. As a data-driven methods, the weighting of the spatial-temporal component does not depend on the ERP detection method. The importance weights are optimized by making the targets more different from non-targets in feature space, and regularization penalty is introduced in optimization for sparse weights. This spatial-temporal feature extraction method is evaluated on the EEG data of 15 participants in performing a face identification task using rapid serial visual presentation paradigm. Comparing with other methods, the proposed spatial-temporal analysis method uses sparser (only 10% of the total features, and could achieve comparable performance (98% of single-trial ERP detection as the whole features across different detection methods. The interesting finding is

  15. Transmission of 112 Gb/s PM-QPSK signals over up to 635 km of multimode optical fiber.

    Science.gov (United States)

    Downie, John D; Hurley, Jason E; Kuksenkov, Dmitri V; Lynn, Christopher M; Korolev, Andrey E; Nazarov, Vladimir N

    2011-12-12

    We investigate transmission of 112 Gb/s PM-QPSK signals over 50 μm core diameter OM3 multimode fiber using the center launch approach. We demonstrate successful transmission of 16 DWDM channels over a distance of 635 km for a capacity-distance product of 1016 Tb/s-km. The limiting impairment appears due to mode coupling and multipath interference effects. © 2011 Optical Society of America

  16. Single Particle Differentiation through 2D Optical Fiber Trapping and Back-Scattered Signal Statistical Analysis: An Exploratory Approach.

    Science.gov (United States)

    Paiva, Joana S; Ribeiro, Rita S R; Cunha, João P S; Rosa, Carla C; Jorge, Pedro A S

    2018-02-27

    Recent trends on microbiology point out the urge to develop optical micro-tools with multifunctionalities such as simultaneous manipulation and sensing. Considering that miniaturization has been recognized as one of the most important paradigms of emerging sensing biotechnologies, optical fiber tools, including Optical Fiber Tweezers (OFTs), are suitable candidates for developing multifunctional small sensors for Medicine and Biology. OFTs are flexible and versatile optotools based on fibers with one extremity patterned to form a micro-lens. These are able to focus laser beams and exert forces onto microparticles strong enough (piconewtons) to trap and manipulate them. In this paper, through an exploratory analysis of a 45 features set, including time and frequency-domain parameters of the back-scattered signal of particles trapped by a polymeric lens, we created a novel single feature able to differentiate synthetic particles (PMMA and Polystyrene) from living yeasts cells. This single statistical feature can be useful for the development of label-free hybrid optical fiber sensors with applications in infectious diseases detection or cells sorting. It can also contribute, by revealing the most significant information that can be extracted from the scattered signal, to the development of a simpler method for particles characterization (in terms of composition, heterogeneity degree) than existent technologies.

  17. Rare-earth-doped materials with application to optical signal processing, quantum information science, and medical imaging technology

    Science.gov (United States)

    Cone, R. L.; Thiel, C. W.; Sun, Y.; Böttger, Thomas; Macfarlane, R. M.

    2012-02-01

    Unique spectroscopic properties of isolated rare earth ions in solids offer optical linewidths rivaling those of trapped single atoms and enable a variety of recent applications. We design rare-earth-doped crystals, ceramics, and fibers with persistent or transient "spectral hole" recording properties for applications including high-bandwidth optical signal processing where light and our solids replace the high-bandwidth portion of the electronics; quantum cryptography and information science including the goal of storage and recall of single photons; and medical imaging technology for the 700-900 nm therapeutic window. Ease of optically manipulating rare-earth ions in solids enables capturing complex spectral information in 105 to 108 frequency bins. Combining spatial holography and spectral hole burning provides a capability for processing high-bandwidth RF and optical signals with sub-MHz spectral resolution and bandwidths of tens to hundreds of GHz for applications including range-Doppler radar and high bandwidth RF spectral analysis. Simply stated, one can think of these crystals as holographic recording media capable of distinguishing up to 108 different colors. Ultra-narrow spectral holes also serve as a vibration-insensitive sub-kHz frequency reference for laser frequency stabilization to a part in 1013 over tens of milliseconds. The unusual properties and applications of spectral hole burning of rare earth ions in optical materials are reviewed. Experimental results on the promising Tm3+:LiNbO3 material system are presented and discussed for medical imaging applications. Finally, a new application of these materials as dynamic optical filters for laser noise suppression is discussed along with experimental demonstrations and theoretical modeling of the process.

  18. Simultaneous measurement of patterns in the signal and idler near and far fields from a confocal optical parametrical oscillator with applications in quantum optics

    DEFF Research Database (Denmark)

    Lassen, Mikael Østergaard; Tidemand-Lichtenberg, Peter; Buchhave, Preben

    2005-01-01

    We present the results of an experimental investigation of multimode intensity patterns from an optical parametric oscillator operating above threshold and show that it oscillates in 10-15 transverse modes strongly coupled through the nonlinear crystal, which makes this setup useful for future in...... also show that the oscillator can be stabilized by optical feedback, indicating a possible route for controlling the generated intensity patterns....... investigation of quantum correlations in the transverse plane. We describe the experimental setup for simultaneous measurements of signal and idler near- and far-field patterns and analyze the effects of various experimental complications such as walk-off and thermal index changes on the generated patterns. We...

  19. Application of signal detection theory to optics. [image evaluation and restoration

    Science.gov (United States)

    Helstrom, C. W.

    1973-01-01

    Basic quantum detection and estimation theory, applications to optics, photon counting, and filtering theory are studied. Recent work on the restoration of degraded optical images received at photoelectrically emissive surfaces is also reported, the data used by the method are the numbers of electrons ejected from various parts of the surface.

  20. The influence of event-related knowledge on verb-argument processing in aphasia.

    Science.gov (United States)

    Dickey, Michael Walsh; Warren, Tessa

    2015-01-01

    Event-related conceptual knowledge outside the language system rapidly affects verb-argument processing in unimpaired adults (McRae and Matsuki, 2009). Some have argued that verb-argument processing is in fact reducible to the activation of such event-related knowledge. However, data favoring this conclusion have come primarily from college-aged healthy adults, for whom both linguistic and conceptual semantic processing is fast and automatic. This study examined the influence of event-related knowledge on verb-argument processing among adults with aphasia (n = 8) and older unimpaired controls (n = 60), in two self-paced reading studies. Participants read sentences containing a plausible verb-argument combination (Mary used a knife to chop the large carrots before dinner), a combination that violated event-related world knowledge (Mary used some bleach to clean the large carrots before dinner), or a combination that violated the verb's selectional restrictions (Mary used a pump to inflate the large carrots before dinner). The participants with aphasia naturally split into two groups: Group 1 (n = 4) had conceptual-semantic impairments (evidenced by poor performance on tasks like Pyramids & Palm Trees) but reasonably intact language processing (higher Western Aphasia Battery Aphasia Quotients), while Group 2 (n = 4) had intact conceptual semantics but poorer language processing. Older unimpaired controls and aphasic Group 1 showed rapid on-line disruption for sentences with selectional-restriction violations (SRVs) and event-related knowledge violations, and also showed SRV-specific penalties in sentence-final acceptability judgments (Experiment 1) and comprehension questions (Experiment 2). In contrast, Group 2 showed very few reliable differences across conditions in either on-line or off-line measures. This difference between aphasic groups suggests that verb-related information and event-related knowledge may be dissociated in aphasia. Furthermore, it suggests

  1. Cortical light scattering during interictal epileptic spikes in frontal lobe epilepsy in children: A fast optical signal and electroencephalographic study.

    Science.gov (United States)

    Manoochehri, Mana; Mahmoudzadeh, Mahdi; Bourel-Ponchel, Emilie; Wallois, Fabrice

    2017-12-01

    Interictal epileptic spikes (IES) represent a signature of the transient synchronous and excessive discharge of a large ensemble of cortical heterogeneous neurons. Epilepsy cannot be reduced to a hypersynchronous activation of neurons whose functioning is impaired, resulting on electroencephalogram (EEG) in epileptic seizures or IES. The complex pathophysiological mechanisms require a global approach to the interactions between neural synaptic and nonsynaptic, vascular, and metabolic systems. In the present study, we focused on the interaction between synaptic and nonsynaptic mechanisms through the simultaneous noninvasive multimodal multiscale recording of high-density EEG (HD-EEG; synaptic) and fast optical signal (FOS; nonsynaptic), which evaluate rapid changes in light scattering related to changes in membrane configuration occurring during neuronal activation of IES. To evaluate changes in light scattering occurring around IES, three children with frontal IES were simultaneously recorded with HD-EEG and FOS. To evaluate change in synchronization, time-frequency representation analysis of the HD-EEG was performed simultaneously around the IES. To independently evaluate our multimodal method, a control experiment with somatosensory stimuli was designed and applied to five healthy volunteers. Alternating increase-decrease-increase in optical signals occurred 200 ms before to 180 ms after the IES peak. These changes started before any changes in EEG signal. In addition, time-frequency domain EEG analysis revealed alternating decrease-increase-decrease in the EEG spectral power concomitantly with changes in the optical signal during IES. These results suggest a relationship between (de)synchronization and neuronal volume changes in frontal lobe epilepsy during IES. These changes in the neuronal environment around IES in frontal lobe epilepsy observed in children, as they have been in rats, raise new questions about the synaptic/nonsynaptic mechanisms that propel

  2. Analysis of focusing error signals by differential astigmatic method under off-center tracking in the land-groove-type optical disk

    Science.gov (United States)

    Shinoda, Masahisa; Nakatani, Hidehiko

    2015-04-01

    We theoretically calculate the behavior of the focusing error signal in the land-groove-type optical disk when the objective lens traverses on out of the radius of the optical disk. The differential astigmatic method is employed instead of the conventional astigmatic method for generating the focusing error signals. The signal behaviors are compared and analyzed in terms of the gain difference of the slope sensitivity of the focusing error signals from the land and the groove. In our calculation, the format of digital versatile disc-random access memory (DVD-RAM) is adopted as the land-groove-type optical disk model, and advantageous conditions for suppressing the gain difference are investigated. The calculation method and results described in this paper will be reflected in the next generation land-groove-type optical disks.

  3. Digital Signal Processing for a Sliceable Transceiver for Optical Access Networks

    DEFF Research Database (Denmark)

    Saldaña Cercos, Silvia; Wagner, Christoph; Vegas Olmos, Juan José

    2015-01-01

    Methods to upgrade the network infrastructure to cope with current traffic demands has attracted increasing research efforts. A promising alternative is signal slicing. Signal slicing aims at re-using low bandwidth equipment to satisfy high bandwidth traffic demands. This technique has been used ...... penalty is reported for 10 Gbps. Power savings of the order of hundreds of Watts can be obtained when using signal slicing as an alternative to 10 Gbps implemented access networks....

  4. Hardware-efficient signal generation of layered/enhanced ACO-OFDM for short-haul fiber-optic links.

    Science.gov (United States)

    Wang, Qibing; Song, Binhuang; Corcoran, Bill; Boland, David; Zhu, Chen; Zhuang, Leimeng; Lowery, Arthur J

    2017-06-12

    Layered/enhanced ACO-OFDM is a promising candidate for intensity modulation and direct-detection based short-haul fiber-optic links due to its both power and spectral efficiency. In this paper, we firstly demonstrate a hardware-efficient real-time 9.375 Gb/s QPSK-encoded layered/enhanced asymmetrical clipped optical OFDM (L/E-ACO-OFDM) transmitter using a Virtex-6 FPGA. This L/E-ACO-OFDM signal is successfully transmitted over 20-km uncompensated standard single-mode fiber (S-SMF) using a directly modulated laser. Several methods are explored to reduce the FPGA's logic resource utilization by taking advantage of the L/E-ACO-OFDM's signal characteristics. We show that the logic resource occupation of L/E-ACO-OFDM transmitter is almost the same as that of DC-biased OFDM transmitter when they achieve the same spectral efficiency, proving its great potential to be used in a real-time short-haul optical transmission link.

  5. Optical interconnects for in-plane high-speed signal distribution at 10 Gb/s: Analysis and demonstration

    Science.gov (United States)

    Chang, Yin-Jung

    With decreasing transistor size, increasing chip speed, and larger numbers of processors in a system, the performance of a module/system is being limited by the off-chip and off-module bandwidth-distance products. Optical links have moved from fiber-based long distance communications to the cabinet level of 1m--100m, and recently to the backplane-level (10cm--1m). Board-level inter-chip parallel optical interconnects have been demonstrated recently by researchers from Intel, IBM, Fujitsu, NTT and a few research groups in universities. However, the board-level signal/clock distribution function using optical interconnects, the lightwave circuits, the system design, a practically convenient integration scheme committed to the implementation of a system prototype have not been explored or carefully investigated. In this dissertation, the development of a board-level 1 x 4 optical-to-electrical signal distribution at 10Gb/s is presented. In contrast to other prototypes demonstrating board-level parallel optical interconnects that have been drawing much attention for the past decade, the optical link design for the high-speed signal broadcasting is even more complicated and the pitch between receivers could be varying as opposed to fixed-pitch design that has been widely-used in the parallel optical interconnects. New challenges for the board-level high-speed signal broadcasting include, but are not limited to, a new optical link design, a lightwave circuit as a distribution network, and a novel integration scheme that can be a complete radical departure from the traditional assembly method. One of the key building blocks in the lightwave circuit is the distribution network in which a 1 x 4 multimode interference (MMI) splitter is employed. MMI devices operating at high data rates are important in board-level optical interconnects and need to be characterized in the application of board-level signal broadcasting. To determine the speed limitations of MMI devices, the

  6. Colorless detection of NRZ-DPSK signals using electro-optic clock re-modulation

    DEFF Research Database (Denmark)

    Zsigri, Beata; Tokle, Torger; Peucheret, Christophe

    2010-01-01

    Wavelength-independent detection of NRZ-DPSK signals is proposed and demonstrated at 43 Gbit/s. The scheme relies on re-modulation of the incoming NRZ-DPSK signal with a recovered electrical clock. Good performance is obtained after dispersion managed transmission.......Wavelength-independent detection of NRZ-DPSK signals is proposed and demonstrated at 43 Gbit/s. The scheme relies on re-modulation of the incoming NRZ-DPSK signal with a recovered electrical clock. Good performance is obtained after dispersion managed transmission....

  7. Attentional Mechanisms in Sports via Brain-Electrical Event-Related Potentials

    Science.gov (United States)

    Hack, Johannes; Memmert, Daniel; Rup, Andre

    2009-01-01

    In this study, we examined attention processes in complex, sport-specific decision-making tasks without interdependencies from anticipation. Psychophysiological and performance data recorded from advanced and intermediate level basketball referees were compared. Event-related potentials obtained while judging game situations in foul recognition…

  8. Snake scales, partial exposure, and the Snake Detection Theory: A human event-related potentials study

    NARCIS (Netherlands)

    J.W. van Strien (Jan); L.A. Isbell (Lynne A.)

    2017-01-01

    textabstractStudies of event-related potentials in humans have established larger early posterior negativity (EPN) in response to pictures depicting snakes than to pictures depicting other creatures. Ethological research has recently shown that macaques and wild vervet monkeys respond strongly to

  9. Effects of Experience and Task Difficulty on Event-Related Potentials

    Science.gov (United States)

    1989-10-13

    indexing performance. In K. Atsumi, T. Katila, H. Kotani, S. G. Williamson, & K. Ueno (Eds.) Biomagnetism 198y7,Proceedings of the oth International...Conference on Biomagnetism . To y, Japan. --- Lindholm, E. & Koriath, J. J. (1985). Analysis of multiple event-related potential components in a tone

  10. Event-related EEG changes preceding saccadic eye movements before and after dry immersion.

    Science.gov (United States)

    Tomilovskaya, E S; Kirenskaya, A V; Novototski-Vlasov, V Yu; Kozlovskaya, I B

    2004-07-01

    Objectives of this work were to quantify antisaccade characteristics, presaccadic slow negative EEG-potentials, and event-related EEG frequency band power (theta, alpha1, alpha2, beta1, beta2 and beta3) changes (ERD) in healthy volunteers before and after 6-day simulated weightlessness (dry immersion).

  11. Event-Related Potentials and Consonant Differentiation in Newborns with Familial Risk for Dyslexia.

    Science.gov (United States)

    Guttorm, Tomi K.; Leppanen, Paavo H. T.; Richardson, Ulla; Lyytinen, Heikki

    2001-01-01

    This study examined event-related potentials (ERPs) to synthetic consonant-vowel syllables from 26 newborns with familial risk for dyslexia and 23 control infants participating in a longitudinal study of dyslexia. Results indicated that the cortical electric activation evoked by speech elements differed between children with and without risk for…

  12. Two Languages, One Developing Brain: Event-Related Potentials to Words in Bilingual Toddlers

    Science.gov (United States)

    Conboy, Barbara T.; Mills, Debra L.

    2006-01-01

    Infant bilingualism offers a unique opportunity to study the relative effects of language experience and maturation on brain development, with each child serving as his or her own control. Event-related potentials (ERPs) to words were examined in 19- to 22-month-old English-Spanish bilingual toddlers. The children's dominant vs. nondominant…

  13. Atypical Brain Responses to Reward Cues in Autism as Revealed by Event-Related Potentials

    Science.gov (United States)

    Kohls, Gregor; Peltzer, Judith; Schulte-Ruther, Martin; Kamp-Becker, Inge; Remschmidt, Helmut; Herpertz-Dahlmann, Beate; Konrad, Kerstin

    2011-01-01

    Social motivation deficit theories suggest that children with autism do not properly anticipate and appreciate the pleasure of social stimuli. In this study, we investigated event-related brain potentials evoked by cues that triggered social versus monetary reward anticipation in children with autism. Children with autism showed attenuated P3…

  14. Temporal evolution of event-related desynchronization in acute stroke: A pilot study

    NARCIS (Netherlands)

    Tangwiriyasakul, Chayanin; Verhagen, Rens; Rutten, Wim; van Putten, Michel Johannes Antonius Maria

    2014-01-01

    Objective Assessment of event-related desynchronization (ERD) may assist in predicting recovery from stroke and rehabilitation, for instance in BCI applications. Here, we explore the temporal evolution of ERD during stroke recovery. Methods Ten stroke patients and eleven healthy controls were

  15. Complement Set Reference after Implicitly Small Quantities: An Event-Related Potentials Study

    Science.gov (United States)

    Ingram, Joanne; Ferguson, Heather J.

    2018-01-01

    An anaphoric reference to the complement-set is a reference to the set that does not fulfil the predicate of the preceding sentence. Preferred reference to the complement-set has been found in eye movements when a character's implicit desire for a high amount has been denied using a negative emotion. We recorded event-related potentials to examine…

  16. MODULATION OF EVENT-RELATED POTENTIALS BY WORD REPETITION - THE ROLE OF VISUAL SELECTIVE ATTENTION

    NARCIS (Netherlands)

    OTTEN, LJ; RUGG, MD; DOYLE, MC

    1993-01-01

    Event-related potentials (ERPs) were recorded while subjects viewed visually presented words, some of which occurred twice. Each trial consisted of two colored letter strings, the requirement being to attend to and make a word/nonword discrimination for one of the strings. Attention was manipulated

  17. Auditory Processing in Dyslexia: Middle Latency Event-Related Potentials and Temporal Sequencing.

    Science.gov (United States)

    Krull, Kevin R.

    Behavioral and electrophysiological processing of sequential tones were investigated in reading delayed (RD) and non-reading delayed (NRD) children matched on intelligence and reading level. NRD children performed consistently better on sequencing of tonal patterns. Middle latency event-related potentials from the RD group indicated reduced…

  18. Event-related Potentials Reflecting the Processing of Phonological Constraint Violations

    NARCIS (Netherlands)

    Domahs, Ulrike; Kehrein, Wolfgang; Knaus, Johannes; Wiese, Richard; Schlesewsky, Matthias

    2009-01-01

    Flow are violations of phonological constraints processed in word comprehension? The present article reports the results of ail event-related potentials (ERP) Study oil a phonological constraint of German that disallows identical segments within it syllable or word (CC(i)VC(i)). We examined three

  19. Event-related potentials reflecting the processing of phonological constraint violations

    NARCIS (Netherlands)

    Domahs, U.; Kehrein, W.; Knaus, J.; Wiese, R.; Schlesewsky, M.

    2009-01-01

    How are violations of phonological constraints processed in word comprehension? The present article reports the results of an event-related potentials (ERP) study on a phonological constraint of German that disallows identical segments within a syllable or word (CC iVCi). We examined three types of

  20. Effects of sleep deprivation on event-related fields and alpha activity during rhythmic force production

    NARCIS (Netherlands)

    Boonstra, T.W.; Daffertshofer, A.; Beek, P.J.

    2005-01-01

    The influence of sleep deprivation (SD) on event-related fields and the distribution of power over the scalp of MEG imaged brain activity was studied during acoustically paced rhythmic force production. At the behavioral level, SD resulted in a reduction of the lag (negative asynchrony) between

  1. Gender Differences in Memory Processing: Evidence from Event-Related Potentials to Faces

    Science.gov (United States)

    Guillem, F.; Mograss, M.

    2005-01-01

    This study investigated gender differences on memory processing using event-related potentials (ERPs). Behavioral data and ERPs were recorded in 16 males and 10 females during a recognition memory task for faces. The behavioral data results showed that females performed better than males. Gender differences on ERPs were evidenced over anterior…

  2. Representations in human visual short-term memory : an event-related brain potential study

    NARCIS (Netherlands)

    Klaver, P; Smid, HGOM; Heinze, HJ

    1999-01-01

    Behavioral measures and event-related potentials (ERPs) were recorded from 12 subjects while performing three delayed matching-to-sample tasks. The task instructions indicated whether stimulus locations, shapes or conjunctions of locations and shapes had to be memorized and matched against a probe.

  3. An event-related brain potential correlate of visual short-term memory

    NARCIS (Netherlands)

    Klaver, Peter; Talsma, D.; Wijers, Albertus; Heinze, Hans-Jochen; Mulder, Gijsbertus

    1999-01-01

    EVENT-RELATED potentials (ERPs) were recorded as 12 subjects performed a delayed matching to sample task. We presented two bilateral abstract shapes and cued spatially which had to be memorized for a subsequent matching task: left, right or both. During memorization a posterior slow negative ERP

  4. Pitch Discrimination without Awareness in Congenital Amusia: Evidence from Event-Related Potentials

    Science.gov (United States)

    Moreau, Patricia; Jolicoeur, Pierre; Peretz, Isabelle

    2013-01-01

    Congenital amusia is a lifelong disorder characterized by a difficulty in perceiving and producing music despite normal intelligence and hearing. Behavioral data have indicated that it originates from a deficit in fine-grained pitch discrimination, and is expressed by the absence of a P3b event-related brain response for pitch differences smaller…

  5. Priming prepositional phrase attachment: Evidence from eye-tracking and event-related potentials

    NARCIS (Netherlands)

    Boudewyn, M.A.; Zirnstein, M.; Swaab, T.Y.; Traxler, M.J.

    2014-01-01

    Three syntactic-priming experiments investigated the effect of structurally similar or dissimilar prime sentences on the processing of target sentences, using eye tracking (Experiment 1) and event-related potentials (ERPs) (Experiments 2 and 3) All three experiments tested readers' response to

  6. Optics

    CERN Document Server

    Mathieu, Jean Paul

    1975-01-01

    Optics, Parts 1 and 2 covers electromagnetic optics and quantum optics. The first part of the book examines the various of the important properties common to all electromagnetic radiation. This part also studies electromagnetic waves; electromagnetic optics of transparent isotropic and anisotropic media; diffraction; and two-wave and multi-wave interference. The polarization states of light, the velocity of light, and the special theory of relativity are also examined in this part. The second part is devoted to quantum optics, specifically discussing the classical molecular theory of optical p

  7. Pulse shaping using the optical Fourier transform technique - for ultra-high-speed signal processing

    DEFF Research Database (Denmark)

    Palushani, Evarist; Oxenløwe, Leif Katsuo; Galili, Michael

    2009-01-01

    This paper reports on the generation of a 1.6 ps FWHM flat-top pulse using the optical Fourier transform technique. The pulse is validated in a 320 Gbit/s demultiplexing experiment.......This paper reports on the generation of a 1.6 ps FWHM flat-top pulse using the optical Fourier transform technique. The pulse is validated in a 320 Gbit/s demultiplexing experiment....

  8. Added soft tissue contrast using signal attenuation and the fractal dimension for optical coherence tomography images of porcine arterial tissue

    International Nuclear Information System (INIS)

    Flueraru, C; Mao, Y; Chang, S; Popescu, D P; Sowa, M G

    2010-01-01

    Optical coherence tomography (OCT) images of left-descending coronary tissues harvested from three porcine specimens were acquired with a home-build swept-source OCT setup. Despite the fact that OCT is capable of acquiring high resolution circumferential images of vessels, many distinct histological features of a vessel have comparable optical properties leading to poor contrast in OCT images. Two classification methods were tested in this report for the purpose of enhancing contrast between soft-tissue components of porcine coronary vessels. One method involved analyzing the attenuation of the OCT signal as a function of light penetration into the tissue. We demonstrated that by analyzing the signal attenuation in this manner we were able to differentiate two media sub-layers with different orientations of the smooth muscle cells. The other classification method used in our study was fractal analysis. Fractal analysis was implemented in a box-counting (fractal dimension) image-processing code and was used as a tool to differentiate and quantify variations in tissue texture at various locations in the OCT images. The calculated average fractal dimensions had different values in distinct regions of interest (ROI) within the imaged coronary samples. When compared to the results obtained by using the attenuation of the OCT signal, the method of fractal analysis demonstrated better classification potential for distinguishing amongst the tissue ROI.

  9. PRECISE MEASUREMENT OF THE REIONIZATION OPTICAL DEPTH FROM THE GLOBAL 21 cm SIGNAL ACCOUNTING FOR COSMIC HEATING

    International Nuclear Information System (INIS)

    Fialkov, Anastasia; Loeb, Abraham

    2016-01-01

    As a result of our limited data on reionization, the total optical depth for electron scattering, τ, limits precision measurements of cosmological parameters from the Cosmic Microwave Background (CMB). It was recently shown that the predicted 21 cm signal of neutral hydrogen contains enough information to reconstruct τ with sub-percent accuracy, assuming that the neutral gas was much hotter than the CMB throughout the entire epoch of reionization (EoR). Here we relax this assumption and use the global 21 cm signal alone to extract τ for realistic X-ray heating scenarios. We test our model-independent approach using mock data for a wide range of ionization and heating histories and show that an accurate measurement of the reionization optical depth at a sub-percent level is possible in most of the considered scenarios even when heating is not saturated during the EoR, assuming that the foregrounds are mitigated. However, we find that in cases where heating sources had hard X-ray spectra and their luminosity was close to or lower than what is predicted based on low-redshift observations, the global 21 cm signal alone is not a good tracer of the reionization history

  10. Experimental demonstration of all-optical 781.25-Mb/s binary phase-coded UWB Signal Generation and Transmission

    DEFF Research Database (Denmark)

    Yu, Xianbin; Gibbon, Timothy Braidwood; Tafur Monroy, Idelfonso

    2009-01-01

    In this letter, an all-optical incoherent scheme for generation of binary phase-coded ultra-wideband (UWB) impulse radio signals is proposed. The generated UWB pulses utilize relaxation oscillations of an optically injected distributed feedback laser that are binary phase encoded (0 and ) and meet...

  11. Digital rotational microphotometer of the module conception with optical separation of control signals for measurement of granularity of the colour photographic films

    Czech Academy of Sciences Publication Activity Database

    Hrdý, J.; Pospíšil, Jaroslav

    2003-01-01

    Roč. 114, č. 6 (2003), s. 279-288 ISSN 0030-4026 Institutional research plan: CEZ:AV0Z1010921 Keywords : colour photographic granularity * digital rotational microphotometrical granulometer * low- speed scaning * modul conception of microphotometer * optical separation of control signals Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.534, year: 2003

  12. Calculating the reduced scattering coefficient of turbid media from a single optical reflectance signal

    Science.gov (United States)

    Johns, Maureen; Liu, Hanli

    2003-07-01

    When light interacts with tissue, it can be absorbed, scattered or reflected. Such quantitative information can be used to characterize the optical properties of tissue, differentiate tissue types in vivo, and identify normal versus diseased tissue. The purpose of this research is to develop an algorithm that determines the reduced scattering coefficient (μs") of tissues from a single optical reflectance spectrum with a small source-detector separation. The basic relationship between μs" and optical reflectance was developed using Monte Carlo simulations. This produced an analytical equation containing μs" as a function of reflectance. To experimentally validate this relationship, a 1.3-mm diameter fiber optic probe containing two 400-micron diameter fibers was used to deliver light to and collect light from Intralipid solutions of various concentrations. Simultaneous measurements from optical reflectance and an ISS oximeter were performed to validate the calculated μs" values determined by the reflectance measurement against the 'gold standard" ISS readings. The calculated μs" values deviate from the expected values by approximately -/+ 5% with Intralipid concentrations between 0.5 - 2.5%. The scattering properties within this concentration range are similar to those of in vivo tissues. Additional calculations are performed to determine the scattering properties of rat brain tissues and to discuss accuracy of the algorithm for measured samples with a broad range of the absorption coefficient (μa).

  13. MIMO signal progressing with RLSCMA algorithm for multi-mode multi-core optical transmission system

    Science.gov (United States)

    Bi, Yuan; Liu, Bo; Zhang, Li-jia; Xin, Xiang-jun; Zhang, Qi; Wang, Yong-jun; Tian, Qing-hua; Tian, Feng; Mao, Ya-ya

    2018-01-01

    In the process of transmitting signals of multi-mode multi-core fiber, there will be mode coupling between modes. The mode dispersion will also occur because each mode has different transmission speed in the link. Mode coupling and mode dispersion will cause damage to the useful signal in the transmission link, so the receiver needs to deal received signal with digital signal processing, and compensate the damage in the link. We first analyzes the influence of mode coupling and mode dispersion in the process of transmitting signals of multi-mode multi-core fiber, then presents the relationship between the coupling coefficient and dispersion coefficient. Then we carry out adaptive signal processing with MIMO equalizers based on recursive least squares constant modulus algorithm (RLSCMA). The MIMO equalization algorithm offers adaptive equalization taps according to the degree of crosstalk in cores or modes, which eliminates the interference among different modes and cores in space division multiplexing(SDM) transmission system. The simulation results show that the distorted signals are restored efficiently with fast convergence speed.

  14. Capacity-Approaching Modulation Formats for Optical Transmission Systems: Signal shaping and advanced de/muxing for efficient resource exploitation

    DEFF Research Database (Denmark)

    Estaran Tolosa, Jose Manuel

    Aiming for efficient fiber-optic data transport, this thesis addresses three scenario-specific modulation and/or multiplexing techniques which, leveraging digital signal processing, can further exploit the available resources.The considered environments are: (i) (ultra) long-haul networks, where we...... focus on improving the receiver sensitivity; (ii) metropolitan area networks, where the target is providing spectral and rate adaptability with fine granularity and easy reconfigurability; and (iii) short-haul networks, where facilitating more affordable throughput scaling is pursued. Functioning...

  15. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Ninth Edition Optics: Ninth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommen

  16. Photonic synthesis of continuous‐wave millimeter‐wave signals using a passively mode‐locked laser diode and selective optical filtering

    DEFF Research Database (Denmark)

    Acedo, P.; Carpintero, G.; Criado, A.R.

    2012-01-01

    We report a photonic synthesis scheme for continuous wave millimeter‐wave signal generation using a single passively mode‐locked laser diode (PMLLD), optical filtering and photomixing in a fast photodiode.The phase noise of the photonically synthesized signals is evaluated and inherits...

  17. Experimental investigation of saturation effect on pump-to-signal intensity modulation transfer in single-pump phase-insensitive fiber optic parametric amplifiers

    DEFF Research Database (Denmark)

    Cristofori, Valentina; Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke

    2013-01-01

    We present an experimental characterization of how signal gain saturation affects the transfer of intensity modulation from the pump to the signal in single-pump, phase-insensitive fiber optic parametric amplifiers (FOPAs). In this work, we demonstrate experimentally for the first time, to our...

  18. Solid and liquid 129Xe NMR signals enhanced by spin-exchange optical pumping under flow

    International Nuclear Information System (INIS)

    Zhou Xin; Luo Jun; Sun Xianping; Zeng Xizhi; Liu Maili; Liu Wuyang

    2002-01-01

    Laser-polarized 129 Xe gas was produced by spin-exchange with Cs atom optically pumped with diode laser array in a low field under flow. The nuclear spin polarizations of the solid and liquid 129 Xe frozen from the laser-polarized 129 Xe gas were 2.16% and 1.45% respectively in the SY-80M NMR spectrometer, which corresponded to the enhancements of 6000 and 5000 compared to those without optical pumping under the same conditions. It could provide the base and possibility for quantum computers using laser-enhanced solid and liquid 129 Xe. Polarization loss of transport and state change was also discussed

  19. Experimental Demonstration of Mixed Formats and Bit Rates Signal Allocation for Spectrum-flexible Optical Networking

    DEFF Research Database (Denmark)

    Borkowski, Robert; Karinou, Fotini; Angelou, Marianna

    2012-01-01

    We report on an extensive experimental study for adaptive allocation of 16-QAM and QPSK signals inside spectrum flexible heterogeneous superchannel. Physical-layer performance parameters are extracted for use in resource allocation mechanisms of future flexible networks....

  20. Pump-to-Signal Intensity Modulation Transfer in Saturated- Gain Fiber Optical Parametric Amplifiers

    DEFF Research Database (Denmark)

    Lali-Dastjerdi, Zohreh; Lund-Hansen, Toke; Rottwitt, Karsten

    2011-01-01

    The pump-to-signal intensity modulation transfer in saturated degenerate FOPAs is numerically investigated over the whole gain bandwidth. The intensity modulation transfer decreases and the OSNR improves when the amplifier operates in the saturation regime....

  1. A comparison of nonlinear media for parametric all-optical signal processing

    DEFF Research Database (Denmark)

    Martinez Diaz, Jordi; Bohigas Nadal, Jaume; Vukovic, Dragana

    2013-01-01

    We systematically compare nonlinear media for parametric signal processing by determining the minimum pump power that is required for a given conversion efficiency in a degenerate four-wave mixing process, including the effect of nonlinear loss.......We systematically compare nonlinear media for parametric signal processing by determining the minimum pump power that is required for a given conversion efficiency in a degenerate four-wave mixing process, including the effect of nonlinear loss....

  2. Frequency dependence of the pump-to-signal RIN transfer in fiber optical parametric amplifiers

    DEFF Research Database (Denmark)

    Pakarzadeh Dezfuli Nezhad, Hassan; Rottwitt, Karsten; Zakery, A.

    2009-01-01

    Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams.......Using a numerical model, the frequency dependence of the pump-to-signal RIN transfer in FOPAs has been investigated. The model includes fiber loss, pump depletion as well as difference in group velocity among interacting beams....

  3. Detection and recognition of mechanical, digging and vehicle signals in the optical fiber pre-warning system

    Science.gov (United States)

    Tian, Qing; Yang, Dan; Zhang, Yuan; Qu, Hongquan

    2018-04-01

    This paper presents detection and recognition method to locate and identify harmful intrusions in the optical fiber pre-warning system (OFPS). Inspired by visual attention architecture (VAA), the process flow is divided into two parts, i.e., data-driven process and task-driven process. At first, data-driven process takes all the measurements collected by the system as input signals, which is handled by detection method to locate the harmful intrusion in both spatial domain and time domain. Then, these detected intrusion signals are taken over by task-driven process. Specifically, we get pitch period (PP) and duty cycle (DC) of the intrusion signals to identify the mechanical and manual digging (MD) intrusions respectively. For the passing vehicle (PV) intrusions, their strong low frequency component can be used as good feature. In generally, since the harmful intrusion signals only account for a small part of whole measurements, the data-driven process reduces the amount of input data for subsequent task-driven process considerably. Furthermore, the task-driven process determines the harmful intrusions orderly according to their severity, which makes a priority mechanism for the system as well as targeted processing for different harmful intrusion. At last, real experiments are performed to validate the effectiveness of this method.

  4. Ultra-high speed all-optical signal processing using silicon waveguides and a carbon nanotubes based mode-locked laser

    DEFF Research Database (Denmark)

    Ji, Hua

    for demultiplexing of 1.28 Tbit/s optical time division multiplexing data signal is investigated. A sampling system for ultra-high speed signal waveforms based on nano-engineered silicon waveguide is explored. To set up a sampling source, using carbon nanotubes for generating ultra-short pulses is pursued. A silicon......This thesis concerns the use of nano-engineered silicon waveguides for ultra-high speed optical serial data signal processing. The fundamental nonlinear properties of nano-engineered silicon waveguides are characterized. Utilizing the nonlinear effect in nano-engineered silicon waveguides...

  5. 110 km transmission of 160 Gbit/s RZ-DQPSK signals by midspan polarization-insensitive optical phase conjugation in a Ti:PPLN waveguide

    DEFF Research Database (Denmark)

    Hu, Hao; Nouroozi, R.; Ludwig, R.

    2010-01-01

    We demonstrate 160Gbit/s return-to-zero (RZ) differential quarternary phase-shift keying (DQPSK) signal transmission over a 110km single-mode fiber by taking advantage of mid-span optical phase conjugation (OPC). The technique is based on nonlinear wavelength conversion by cascaded second harmonic...... and difference frequency generation in a Ti:PPLN waveguide. Error-free operation with a negligible optical signal-to-noise ratio penalty for the signal after the OPC transmission without and with polarization scrambling was achieved. The results also show the polarization insensitivity of the OPC system using...

  6. Packaged semiconductor laser optical phase locked loop for photonic generation, processing and transmission of microwave signals

    DEFF Research Database (Denmark)

    Langley, L.N.; Elkin, M.D.; Edege, C.

    1999-01-01

    In this paper, we present the first fully packaged semiconductor laser optical phase-locked loop (OPLL) microwave photonic transmitter. The transmitter is based on semiconductor lasers that are directly phase locked without the use of any other phase noise-reduction mechanisms. In this transmitte...

  7. Fine tuning of optical signals in nanoporous anodic alumina photonic crystals by apodized sinusoidal pulse anodisation.

    Science.gov (United States)

    Santos, Abel; Law, Cheryl Suwen; Chin Lei, Dominique Wong; Pereira, Taj; Losic, Dusan

    2016-11-03

    In this study, we present an advanced nanofabrication approach to produce gradient-index photonic crystal structures based on nanoporous anodic alumina. An apodization strategy is for the first time applied to a sinusoidal pulse anodisation process in order to engineer the photonic stop band of nanoporous anodic alumina (NAA) in depth. Four apodization functions are explored, including linear positive, linear negative, logarithmic positive and logarithmic negative, with the aim of finely tuning the characteristic photonic stop band of these photonic crystal structures. We systematically analyse the effect of the amplitude difference (from 0.105 to 0.840 mA cm -2 ), the pore widening time (from 0 to 6 min), the anodisation period (from 650 to 950 s) and the anodisation time (from 15 to 30 h) on the quality and the position of the characteristic photonic stop band and the interferometric colour of these photonic crystal structures using the aforementioned apodization functions. Our results reveal that a logarithmic negative apodisation function is the most optimal approach to obtain unprecedented well-resolved and narrow photonic stop bands across the UV-visible-NIR spectrum of NAA-based gradient-index photonic crystals. Our study establishes a fully comprehensive rationale towards the development of unique NAA-based photonic crystal structures with finely engineered optical properties for advanced photonic devices such as ultra-sensitive optical sensors, selective optical filters and all-optical platforms for quantum computing.

  8. Which colors would extraterrestrial civilizations use to transmit signals?: The ;magic wavelengths; for optical SETI

    Science.gov (United States)

    Narusawa, Shin-ya; Aota, Tatusya; Kishimoto, Ryo

    2018-04-01

    In the case of radio SETI, there are predicted frequencies which extraterrestrial beings select to send messages to other civilizations. Those are called ;magic frequencies. Considering the optical region, terrestrial technologies can not transmit arbitrary wavelengths of high-power optical lasers, easily. In this article, we discuss communications among civilizations with the same level of technology as us to enhance the persuasive power. It might be possible to make a reasonable assumption about the laser wavelengths transmitted by extraterrestrial intelligences to benefit optical SETI (OSETI) methods. Therefore, we propose some ;magic wavelengths; for spectroscopic OSETI observations in this article. From the senders point of view, we argue that the most favorable wavelength used for interstellar communication would be the one of YAG lasers, at 1.064 μm or its Second Harmonic Generation (532.1 nm). On the contrary, there are basic absorption lines in the optical spectra, which are frequently observed by astrophysicists on Earth. It is possible that the extraterrestrials used lasers, which wavelengths are tuned to such absorption lines for sending messages. In that case, there is a possibility that SHG and/or Sum Frequency Generation of YAG and YLF lasers are used. We propose three lines at, 393.8 nm (near the Ca K line), 656.5 nm (near the Hα line) and 589.1 nm (Na D2 line) as the magic wavelengths.

  9. MEG event-related desynchronization and synchronization deficits during basic somatosensory processing in individuals with ADHD

    Directory of Open Access Journals (Sweden)

    Wang Frank

    2008-02-01

    Full Text Available Abstract Background Attention-Deficit/Hyperactivity Disorder (ADHD is a prevalent, complex disorder which is characterized by symptoms of inattention, hyperactivity, and impulsivity. Convergent evidence from neurobiological studies of ADHD identifies dysfunction in fronto-striatal-cerebellar circuitry as the source of behavioural deficits. Recent studies have shown that regions governing basic sensory processing, such as the somatosensory cortex, show abnormalities in those with ADHD suggesting that these processes may also be compromised. Methods We used event-related magnetoencephalography (MEG to examine patterns of cortical rhythms in the primary (SI and secondary (SII somatosensory cortices in response to median nerve stimulation, in 9 adults with ADHD and 10 healthy controls. Stimuli were brief (0.2 ms non-painful electrical pulses presented to the median nerve in two counterbalanced conditions: unpredictable and predictable stimulus presentation. We measured changes in strength, synchronicity, and frequency of cortical rhythms. Results Healthy comparison group showed strong event-related desynchrony and synchrony in SI and SII. By contrast, those with ADHD showed significantly weaker event-related desynchrony and event-related synchrony in the alpha (8–12 Hz and beta (15–30 Hz bands, respectively. This was most striking during random presentation of median nerve stimulation. Adults with ADHD showed significantly shorter duration of beta rebound in both SI and SII except for when the onset of the stimulus event could be predicted. In this case, the rhythmicity of SI (but not SII in the ADHD group did not differ from that of controls. Conclusion Our findings suggest that somatosensory processing is altered in individuals with ADHD. MEG constitutes a promising approach to profiling patterns of neural activity during the processing of sensory input (e.g., detection of a tactile stimulus, stimulus predictability and facilitating our

  10. Cortical Neural Synchronization Underlies Primary Visual Consciousness of Qualia: Evidence from Event-Related Potentials

    OpenAIRE

    Babiloni, Claudio; Marzano, Nicola; Soricelli, Andrea; Cordone, Susanna; Mill?n-Calenti, Jos? Carlos; Del Percio, Claudio; Buj?n, Ana

    2016-01-01

    This article reviews three experiments on event-related potentials (ERPs) testing the hypothesis that primary visual consciousness (stimulus self-report) is related to enhanced cortical neural synchronization as a function of stimulus features. ERP peak latency and sources were compared between “seen” trials and “not seen” trials, respectively related and unrelated to the primary visual consciousness. Three salient features of visual stimuli were considered (visuospatial, emotional face expre...

  11. An Event-related Brain Potential Study of English Morphosyntactic Processing in Japanese Learners of English

    OpenAIRE

    Tatsuta, Natsuko

    2014-01-01

    This dissertation investigated the neural mechanisms underlying English morphosyntactic processing in Case, subject-verb agreement, and past tense inflection in Japanese learners of English (JLEs) using event-related brain potentials (ERPs) in terms of the effects of the age of second language (L2) acquisition (the age of learning English), L2 proficiency level (the English proficiency level), and native/first language (L1) transfer. Researchers have debated for a number of years the question...

  12. The origin and nature of categorical perception of colour: Evidence from event-related brain potentials.

    OpenAIRE

    Clifford, Alexandra.

    2009-01-01

    Categorical perception (CP) of colour is demonstrated by faster or more accurate discrimination of colours that cross a category boundary, compared to equivalently spaced colours from the same colour category. Despite a plethora of behavioural research exploring the origin and nature of colour CP, the processes involved in the effect are still unresolved. This thesis investigates the time course and underlying mechanisms of colour CP by using the Event-Related Potential (ERP) technique. This ...

  13. Change detection in children with autism: an auditory event-related fMRI study

    OpenAIRE

    Gomot, M; Bernard, FA; Davis, MH; Belmonte, MK; Ashwin, C; Bullmore, ET; Baron-Cohen, S

    2006-01-01

    Autism involves impairments in communication and social interaction, as well as high levels of repetitive, stereotypic and ritualistic behaviours, and extreme resistance to change. This latter dimension, whilst required for a diagnosis, has received less research attention. We hypothesise that this extreme resistance to change in autism is rooted in atypical processing of unexpected stimuli. We tested this using auditory event-related fMRI to determine regional brain activity associated with ...

  14. [Olfactory functional magnetic resonance imaging with modified OEP-98C olfactometer and event-related design].

    Science.gov (United States)

    You, Hui; Wang, Jian; Liu, Jian-Feng; Feng, Feng; Ni, Dao-Feng; Jin, Zheng-Yu

    2009-04-01

    To explore the feasibility of functional magnetic resonance imaging (fMRI) in analysis of olfaction function with modified OEP-98C olfactometer and event-related design. Six young right-handed men underwent olfactory fMRI with event-related design. OEP-98C olfactometer was modified to accommodate MR environment. There were 2 types of tasks in the experiment. In one task, only isoamyl acetate was used as odorant. In the other task, to avoid possible decreased olfactory attention, vanillin was given before each presentation of isoamyl acetate. In both tasks, uniform activation in piriform cortex and secondary olfactory cortexes was determined. The activation of piriform cortex was not significantly different between the two tasks (P > 0.01). With isoamyl acetate as odorant, modified OEP-98C olfactometer, and event-related design, olfaction fMRI can depict cortex activation at primary and secondary olfactory cortex. Applying other odorant with similar quality to avoid olfactory attention decrease can not promote depiction of activation in primary olfactory cortex.

  15. Neural markers for immediate performance accuracy in a Stroop color-word matching task: an event-related potentials analysis.

    Science.gov (United States)

    Shou, Guofa; Ding, Lei

    2014-01-01

    The present study examined the neural markers measured in event-related potentials (ERPs) for immediate performance accuracy during a cognitive task with less conflict, i.e., a Stroop color-word matching task, in which participants were required to judge the congruency of two feature dimensions of a stimulus. In an effort to make ERP components more specific to distinct underlying neural substrates, recorded EEG signals were firstly dissolved into multiple independent components (ICs) using independent component analysis (ICA). Thereafter, individual ICs with prominent sensory- or cognitive-related ERP components were selected to separately reconstruct scalp EEG signals at representative channels, from which ERP waveforms were built, respectively. Statistical comparisons on amplitudes of stimulus-locked ERP components, i.e., prefrontal P2 and N2, parietal P3, bilateral occipital P1 and N1, revealed significant reduced P3 amplitude in error trials than in correct trials. In addition, significant evident ERN was also observed in error trials but not in correct trials. Considering the temporal locus of semantic conflict in the present task, we concluded that reduced P3 amplitude in error trials reflect impaired resolving process of semantic conflict, which further lead to a performance error in the Stroop color-word matching task.

  16. Optics

    CERN Document Server

    Fincham, W H A

    2013-01-01

    Optics: Eighth Edition covers the work necessary for the specialization in such subjects as ophthalmic optics, optical instruments and lens design. The text includes topics such as the propagation and behavior of light; reflection and refraction - their laws and how different media affect them; lenses - thick and thin, cylindrical and subcylindrical; photometry; dispersion and color; interference; and polarization. Also included are topics such as diffraction and holography; the limitation of beams in optical systems and its effects; and lens systems. The book is recommended for engineering st

  17. MR and optical imaging of early micrometastases in lymph nodes: triple labeling with nano-sized agents yielding distinct signals.

    Science.gov (United States)

    Kosaka, Nobuyuki; Bernardo, Marcelino; Mitsunaga, Makoto; Choyke, Peter L; Kobayashi, Hisataka

    2012-01-01

    Few imaging methods are available for depicting in vivo cancer cell migration within the lymphatic system. Detection of such early micrometastases requires extremely high target to background. In this study, we dual-labeled human breast cancer cells (MDA-MB468) with a small particle of iron oxide (SPIO) and a quantum dot (QD), and tracked these cells in the lymphatic system in mice using in vivo MRI and optical imaging. A generation-6 gadolinium-dendrimer-based MRI contrast agent (Gd-G6) was employed for visualizing regional lymphatic channels and nodes. Since Gd-G6 shortened T(1) leading to high signal, whereas SPIO-labeled cancer cells greatly lowered signal, a small number of cells were simultaneously visualized within the draining lymphatic basins. One million dual-labeled cancer cells were subcutaneously injected into the paws of mice 24 h prior to imaging. Then whole body images were acquired pre- and post-intracutaneous injection of Gd-G6 with 3D-T(1) w-FFE and balanced-FFE sequences for cancer cell tracking and MR lymphangiography. In vivo MRI clearly visualized labeled cancer cells migrating from the paw to the axillary lymph nodes using draining lymphatics. In vivo optical imaging using a fluorescence surgical microscope demonstrated tiny cancer cell clusters in the axillary lymph node with high spatial resolution. Thus, using a combination of MRI and optical imaging, it is possible to depict macro- and early micrometastases within the lymphatic system. This platform offers a versatile research tool for investigating and treating lymphatic metastases in animal models. Copyright © 2011 John Wiley & Sons, Ltd.

  18. Flat-top pulse generation by the optical Fourier transform technique for ultrahigh speed signal processing

    DEFF Research Database (Denmark)

    Palushani, Evarist; Oxenløwe, Leif Katsuo; Galili, Michael

    2009-01-01

    This paper reports on the generation of 1.6-ps fullwidth at half-maximum flat-top pulses by the optical Fourier transform technique, and the utilization of these pulses in a 320-Gb/s demultiplexing experiment. It is demonstrated how a narrow pulse having a 15-nm wide third-order super-Gaussian sp......This paper reports on the generation of 1.6-ps fullwidth at half-maximum flat-top pulses by the optical Fourier transform technique, and the utilization of these pulses in a 320-Gb/s demultiplexing experiment. It is demonstrated how a narrow pulse having a 15-nm wide third-order super...

  19. All-Optical Signal processing using Highly Nonlinear Photonic Crystal Fiber

    DEFF Research Database (Denmark)

    Andersen, Peter Andreas

    2006-01-01

    in an optical system showed the importance of the fiber design. Different HNL-PCFs were tested for supercontinuum generation with the widest spectrum seen to be 210 nm (20 dB bandwidth). A comparison between two supercontinua generated by two different HNL PCFs with different dispersion profiles, but similar...... and having a 20 dB bandwidth of -70 nm was discussed. A comparison between different pulse sources also showed the importance of low timing and amplitude jitter in the pulse source. The strict requirements on the pulse source and the fiber design in order to get a broad supercontinuum limits the choice...... but efficient all-optical wavelength converter was realized. The dispersion profile of a fiber remains one of the most important parameters to control for the fiber designer. The manufacturing of a HNLPCF with negative dispersion slope and zero dispersion wavelength in the C-band made it possible to build...

  20. Independent component analysis based digital signal processing in coherent optical fiber communication systems

    Science.gov (United States)

    Li, Xiang; Luo, Ming; Qiu, Ying; Alphones, Arokiaswami; Zhong, Wen-De; Yu, Changyuan; Yang, Qi

    2018-02-01

    In this paper, channel equalization techniques for coherent optical fiber transmission systems based on independent component analysis (ICA) are reviewed. The principle of ICA for blind source separation is introduced. The ICA based channel equalization after both single-mode fiber and few-mode fiber transmission for single-carrier and orthogonal frequency division multiplexing (OFDM) modulation formats are investigated, respectively. The performance comparisons with conventional channel equalization techniques are discussed.

  1. Comparison of optical models and signals from XPS and VASE characterized titanium after PBS immersion

    Czech Academy of Sciences Publication Activity Database

    Penttinen, N.; Hasoň, Stanislav; Silvennoinen, M.; Joska, L.; Silvennoinen, R.

    2012-01-01

    Roč. 285, č. 6 (2012), s. 965-968 ISSN 0030-4018 Grant - others:GA ČR(CZ) GAP108/10/1782 Program:GA Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : permittivity * XPS titanium * diffractive optical element-based sensor Subject RIV: BO - Biophysics Impact factor: 1.438, year: 2012

  2. Optical data exchange of m-QAM signals using a silicon-organic hybrid slot waveguide: proposal and simulation.

    Science.gov (United States)

    Gui, Chengcheng; Wang, Jian

    2014-10-06

    We present modulation-format-transparent data exchange for m-ary quadrature amplitude modulation (m-QAM) signals using a single silicon-organic hybrid slot waveguide which offers tight light confinement and enhanced nonlinearity. By exploiting the parametric depletion effect of non-degenerate four-wave mixing (ND-FWM) process in the slot waveguide, we simulate low-power (exchange of 640 Gbaud (2.56 Tbit/s) optical time-division multiplexed (OTDM) 16-QAM and 640 Gbaud (3.84 Tbit/s) OTDM 64-QAM signals and characterize the operation performance in terms of error vector magnitude (EVM) and bit-error rate (BER). The calculated signal-to-noise ratio (SNR) penalties of data exchange are negligible for 2.56 Tbit/s 16-QAM signals and less than 2 dB for 3.84 Tbit/s 64-QAM signals at a BER of 2e-3. For a given pump power of 9 mW, the operation performance dependence on the waveguide length is studied, showing an optimized waveguide length of ~17 mm. For a given waveguide length of 17 mm, the SNR penalty of data exchange, at a BER of 2e-3, is kept below 4 dB when varying input pump power from 8.4 to 9.8 mW for 2.56 Tbit/s 16-QAM and from 8.9 to 9.2 mW for 3.84 Tbit/s 64-QAM. In addition, data exchange running at low speed (e.g. 20 Gbaud) and data exchange taking into account waveguide propagation loss are also analyzed with favorable operation performance.

  3. The Design and Use of an Optical Mapping System for the Study of Intracardiac Electrical Signaling

    Directory of Open Access Journals (Sweden)

    Maneesh Shrivastav, PhD

    2012-07-01

    Full Text Available Fluorescent optical mapping of electrically active cardiac tissues provides a unique method to examine the excitation wave dynamics of underlying action potentials. Such mapping can be viewed as a bridge between cellular level and organ systems physiology, e.g., by facilitating the development of advanced theoretical concepts of arrhythmia. We present the design and use of a high-speed, high-resolution optical mapping system composed entirely of “off the shelf” components. The electrical design integrates a 256 element photodiode array with a 16 bit data acquisition system. Proper grounding and shielding at various stages of the design reduce electromagnetic interference. Our mechanical design provides flexibility in terms of mounting positions and applications (use for whole heart or tissue preparations, while maintaining precise alignment between all optical components. The system software incorporates a user friendly graphical user interface, e.g., spatially recorded action potentials can be represented as intensity graphs or in strip chart format. Thus, this system is capable of displaying cardiac action potentials with high spatiotemporal resolution. Results from cardiac action potential mapping with intact mouse hearts are provided. It should be noted that this system could be readily configured to study isolated myocardial biopsies (e.g., isolated ventricular trabeculae. We describe the details of a versatile, user-friendly system that could be employed for a magnitude of study protocols.

  4. Fabrication and Analysis Signal Optical Fiber Sensor Based On Bend Loss for Weight in Motion Applications

    Science.gov (United States)

    Aftah Syukron, Ahmad; Marzuki, Ahmad; Setyawan, Ary

    2017-11-01

    Road network plays very important role in economic development. Overweight is one of the main factors contributing to road damage. To minimize this factor, road authority has to make sure that all vehicles operate in according to maximum vehicle regulation set by the government. The one solution can use from this problem is Weight in motion (WIM) technology. WIM technology allows measuring vehicle weight quickly. The sensor is one of the important components in the WIM system. This paper presents a model of WIM fiber sensor work based on bend loss. Fiber sensor has made by coiling optical fiber. Coiling optical fiber has managed in the elliptical shape rubber coil. Rubber coil then is planted in the pad of sensor. The principle of this sensor is a detecting of the shift light intensity output of optical fiber when the vehicles a passing through on fiber sensor. Loading was carried out using loaded truck model. Data was carried out with variations of load and load positions in the truck. The results can be concluded that the shift light intensity is greater with the more shift loads. The loader of the truck has also resulted in the greater loss. Loads in the truck distributed on the axles due to the position of loads.

  5. Accumulation of weak optical signals and spectral memory in InSe single crystals

    International Nuclear Information System (INIS)

    Abdinov, A.Shj.; Babaeva, R.F.

    1995-01-01

    Dysprosium alloying effect on the electron and physico-chemical properties of InSe monocrystals is studied. Accumulation of low light signals and spectral or color memory is shown to be observed under certain conditions (temperature, content of admitted impurity, wave length and light intensity)

  6. A transfer function approach to the small-signal response of saturated semiconductor optical amplifiers

    DEFF Research Database (Denmark)

    Nielsen, Mads Lønstrup; Blumenthal, D. J.; Mørk, Jesper

    2000-01-01

    response. The limitations to the magnitude of the spectral overshoot are also accounted for. Operating with the data and CW signals in a co-propagating configuration, we End that the resonance only exists for a finite waveguide loss. In a counter-propagating scheme, a resonance can exist regardless...

  7. Classification of reflected signals from cavitated tooth surfaces using an artificial intelligence technique incorporating a fiber optic displacement sensor

    Science.gov (United States)

    Rahman, Husna Abdul; Harun, Sulaiman Wadi; Arof, Hamzah; Irawati, Ninik; Musirin, Ismail; Ibrahim, Fatimah; Ahmad, Harith

    2014-05-01

    An enhanced dental cavity diameter measurement mechanism using an intensity-modulated fiber optic displacement sensor (FODS) scanning and imaging system, fuzzy logic as well as a single-layer perceptron (SLP) neural network, is presented. The SLP network was employed for the classification of the reflected signals, which were obtained from the surfaces of teeth samples and captured using FODS. Two features were used for the classification of the reflected signals with one of them being the output of a fuzzy logic. The test results showed that the combined fuzzy logic and SLP network methodology contributed to a 100% classification accuracy of the network. The high-classification accuracy significantly demonstrates the suitability of the proposed features and classification using SLP networks for classifying the reflected signals from teeth surfaces, enabling the sensor to accurately measure small diameters of tooth cavity of up to 0.6 mm. The method remains simple enough to allow its easy integration in existing dental restoration support systems.

  8. Synthesis of Photoswitchable Δ9-Tetrahydrocannabinol Derivatives Enables Optical Control of Cannabinoid Receptor 1 Signaling.

    Science.gov (United States)

    Westphal, Matthias V; Schafroth, Michael A; Sarott, Roman C; Imhof, Michael A; Bold, Christian P; Leippe, Philipp; Dhopeshwarkar, Amey; Grandner, Jessica M; Katritch, Vsevolod; Mackie, Ken; Trauner, Dirk; Carreira, Erick M; Frank, James A

    2017-12-20

    The cannabinoid receptor 1 (CB1) is an inhibitory G protein-coupled receptor abundantly expressed in the central nervous system. It has rich pharmacology and largely accounts for the recreational use of cannabis. We describe efficient asymmetric syntheses of four photoswitchable Δ 9 -tetrahydrocannabinol derivatives (azo-THCs) from a central building block 3-Br-THC. Using electrophysiology and a FRET-based cAMP assay, two compounds are identified as potent CB1 agonists that change their effect upon illumination. As such, azo-THCs enable CB1-mediated optical control of inwardly rectifying potassium channels, as well as adenylyl cyclase.

  9. Fresh Prime Codes Evaluation for Synchronous PPM and OPPM Signaling for Optical CDMA Networks

    Science.gov (United States)

    Karbassian, M. Massoud; Ghafouri-Shiraz, H.

    2007-06-01

    In this paper, we have proposed a novel prime spreading sequence family hereby referred to as “Double-Padded Modified Prime Code (DPMPC)” for direct-detection synchronous optical code-division multiple-access (OCDMA) networks. The new code is applied to both pulse-position and overlapping pulse-position modulation CDMA networks, and their performances were evaluated and compared with existing prime codes family. In addition, we have analyzed the system throughput and also introduced a new interference cancellation technique which significantly improves the bit error probability of OCDMA networks.

  10. Signal model of noise in open-loop fiber-optic gyros.

    Science.gov (United States)

    He, K; Ye, W; He, Z

    1997-12-01

    The characteristics of noise in fiber-optic gyros are analyzed quantitatively. Based on its physical characteristics and on autocorrelation function evidence, the noise is modeled as the addition of fractal Brownian motion (FBM) and Gaussian white noise (GWN). The value of self-similarlity parameter H in FBM and the intensity of GWN, sigma(w), in the model are robustly determined with an algorithm based on an orthonormal wavelet transform, which demonstrates well the coexistence of the long- and short-term correlation components of the gyro noise. Moreover, it is revealed that FBM dominates the gyro noise, whereas the GWN is minor.

  11. Fabrication and Characterisation of Silicon Waveguides for High-Speed Optical Signal Processing

    DEFF Research Database (Denmark)

    Jensen, Asger Sellerup

    This Ph.D. thesis treats various aspects of silicon photonics. From the limitations of silicon as a linear and nonlinear waveguide medium to its synergy with other waveguide materials. Various methods for reducing sidewall roughness and line edge roughness of silicon waveguides are attempted...... was too high for any practical applications. It is speculated that the attempt at creating a material with low density of dangling bonds was unsuccessful. Nevertheless, linear losses of 2.4dB/cm at 1550nm wavelength in the silicon waveguides remained sufficiently low that high speed nonlinear optical...

  12. Optical spectral reshaping for directly modulated 4-pulse amplitude modulation signals

    DEFF Research Database (Denmark)

    Ozolins, Oskars; Da Ros, Francesco; Cristofori, Valentina

    2017-01-01

    The tremendous traffic growth in intra/inter-datacenters requires low-cost high-speed integrated solutions [1]. To enable a significantly reduced footprint directly modulated lasers (DMLs) have been proposed instead of large external modulators. However, it is challenging to use DMLs due to their......The tremendous traffic growth in intra/inter-datacenters requires low-cost high-speed integrated solutions [1]. To enable a significantly reduced footprint directly modulated lasers (DMLs) have been proposed instead of large external modulators. However, it is challenging to use DMLs due...... (PAM) [3] signals. However, moving to 4-PAM,many of the impressive demonstrations reported so far rely heavily on off-line digital signal processing (DSP), which increases latency, power consumption and cost. In this talk, we report on (i) a detailed numerical analysis on the complex transfer function...

  13. Comparative analysis of optical coherence tomography signal and microhardness for demineralization evaluation of human tooth enamel

    Science.gov (United States)

    de Cara, Ana Claudia Ballet; Zezell, Denise Maria; Ana, Patricia A.; Deana, Alessandro Melo; Amaral, Marcello Magri; Dias Vieira, Nilson, Jr.; de Freitas, Anderson Zanardi

    2012-06-01

    The diagnosis of dental caries at an early stage enables the implementation of conservative treatments based on dental preservation. Several diagnostic methods have been developed, like visual-tactile and radiographic are the most commons but are limited for this application. The Optical Coherence Tomography is a technique that provides information of optical properties of enamel, which may change due to the decay process. The objective of this study was to evaluate the ability of OCT to detect different stages of demineralization of tooth enamel during the development of artificial caries lesions, taking as a reference standard for comparison sectional microhardness testing. Different stages of caries lesions were simulated using the pH cycling model suggested Feathestone and modified by Argenta. The samples were exposed to 0 (control group), 5, 10, 15, 20 and 25 days at a daily regimen of three hours demineralization followed by remineralization during 20 hours. It was used an OCT system with at 930nm. Sectional images were generated in all lesion region. The results obtained from the OCT technique presented similar behavior to microhardness, except for the group 25 days, due to inability to perform indentations reading in areas of more intense demineralization. A linear relationship was observed between the OCT and microhardness techniques for detection of demineralization in enamel. This relationship will allow the use of OCT technique in quantitative assessment of mineral loss and for the evaluation of incipient caries lesions.

  14. Low Cost Plastic Optical Fiber Pressure Sensor Embedded in Mattress for Vital Signal Monitoring.

    Science.gov (United States)

    Sartiano, Demetrio; Sales, Salvador

    2017-12-13

    The aim of this paper is to report the design of a low-cost plastic optical fiber (POF) pressure sensor, embedded in a mattress. We report the design of a multipoint sensor, a cheap alternative to the most common fiber sensors. The sensor is implemented using Arduino board, standard LEDs for optical communication in POF (λ = 645 nm) and a silicon light sensor. The Super ESKA ® plastic fibers were used to implement the fiber intensity sensor, arranged in a 4 × 4 matrix. During the breathing cycles, the force transmitted from the lungs to the thorax is in the order of tens of Newtons, and the respiration rate is of one breath every 2-5 s (0.2-0.5 Hz). The sensor has a resolution of force applied on a single point of 2.2-4.5%/N on the normalized voltage output, and a bandwidth of 10 Hz, it is then suitable to monitor the respiration movements. Another issue to be addressed is the presence of hysteresis over load cycles. The sensor was loaded cyclically to estimate the drift of the system, and the hysteresis was found to be negligible.

  15. Superior digit memory of abacus experts: an event-related functional MRI study.

    Science.gov (United States)

    Tanaka, Satoshi; Michimata, Chikashi; Kaminaga, Tatsuro; Honda, Manabu; Sadato, Norihiro

    2002-12-03

    Abacus experts exhibit superior short-term memory for digits, but the underlying neurophysiological mechanism remains unknown. Using event-related fMRI, we examined the brain activity of abacus experts and non-experts during the memory retention period of a delayed match-to-sample task using digits as stimuli. In controls, activity was greater in cortical areas related to verbal working memory, including Broca's area. In contrast, in experts, activity was greater in cortical areas related to visuo-spatial working memory, including the bilateral superior frontal sulcus and superior parietal lobule. This provides neurophysiological evidence that abacus experts utilize a visuo-spatial representation for digit memory.

  16. Event-related potentials reveal increased distraction by salient global objects in older adults

    DEFF Research Database (Denmark)

    Wiegand, Iris; Finke, Kathrin; Töllner, Thomas

    Age-related changes in visual functions influence how older individuals perceive and react upon objects in their environment. In particular, older individuals might be more distracted by highly salient, irrelevant information. Kanizsa figures induce a ‘global precedence’ effect, which reflects...... a processing advantage for salient whole-object representations relative to configurations of local elements not inducing a global form. We investigated event-related potential (ERP) correlates of age-related decline in visual abilities, and specifically, distractibility by salient global objects in visual...

  17. Cognitive event-related potentials in comatose and post-comatose states.

    Science.gov (United States)

    Vanhaudenhuyse, Audrey; Laureys, Steven; Perrin, Fabien

    2008-01-01

    We review the interest of cognitive event-related potentials (ERPs) in comatose, vegetative, or minimally conscious patients. Auditory cognitive ERPs are useful to investigate residual cognitive functions, such as echoic memory (MMN), acoustical and semantic discrimination (P300), and incongruent language detection (N400). While early ERPs (such as the absence of cortical responses on somatosensory-evoked potentials) predict bad outcome, cognitive ERPs (MMN and P300) are indicative of recovery of consciousness. In coma-survivors, cognitive potentials are more frequently obtained when using stimuli that are more ecologic or have an emotional content (such as the patient's own name) than when using classical sine tones.

  18. Cortical localization of cognitive function by regression of performance on event-related potentials.

    Science.gov (United States)

    Montgomery, R W; Montgomery, L D; Guisado, R

    1992-10-01

    This paper demonstrates a new method of mapping cortical localization of cognitive function, using electroencephalographic (EEG) data. Cross-subject regression analyses are used to identify cortical sites and post-stimulus latencies where there is a high correlation between subjects' performance and their cognitive event-related potential (ERP) amplitude. The procedure was tested using a mental arithmetic task and was found to identify essentially the same cortical regions that have been associated with such tasks on the basis of research with patients suffering localized cortical lesions. Thus, it appears to offer an inexpensive, noninvasive tool for exploring the dynamics of localization in neurologically normal subjects.

  19. Cortical localization of cognitive function by regression of performance on event-related potentials

    Science.gov (United States)

    Montgomery, R. W.; Montgomery, L. D.; Guisado, R.

    1992-01-01

    This paper demonstrates a new method of mapping cortical localization of cognitive function, using electroencephalographic data. Cross-subject regression analyses are used to identify cortical sites and post-stimulus latencies where there is a high correlation between subjects' performance and their cognitive event-related potential amplitude. The procedure was tested using a mental arithmetic task and was found to identify essentially the same cortical regions that have been associated with such tasks on the basis of research with patients suffering localized cortical lesions. Thus, it appears to offer an inexpensive, noninvasive tool for exploring the dynamics of localization in neurologically normal subjects.

  20. Stereotype activation is unintentional: Behavioural and event-related potenials evidence.

    Science.gov (United States)

    Wang, Pei; Yang, Ya-Ping; Tan, Chen-Hao; Zhao, Xiang-Xia; Liu, Yong-He; Lin, Chong-De

    2016-04-01

    In this study, a priming Stroop paradigm was used to determine whether stereotype activation is unintentional. Priming conditions (priming/no-priming) and the relationship between priming and target (consistent/inconsistent/no-relation) were the independent variables; accuracy, reaction time and N400 amplitude were used as dependent variables. The reaction time revealed that stereotype activation is, to some extent, unintentional. Furthermore, the event-related potenial (ERP) results showed that N400 amplitude was larger for inconsistent conditions than for consistent conditions. This result supported the notion that stereotype activation is an unintentional and automatic process. © 2015 International Union of Psychological Science.

  1. Signal-to-Noise Ratio Enhancement Based on Empirical Mode Decomposition in Phase-Sensitive Optical Time Domain Reflectometry Systems.

    Science.gov (United States)

    Qin, Zengguang; Chen, Hui; Chang, Jun

    2017-08-14

    We propose a novel denoising method based on empirical mode decomposition (EMD) to improve the signal-to-noise ratio (SNR) for vibration sensing in phase-sensitive optical time domain reflectometry (φ-OTDR) systems. Raw Rayleigh backscattering traces are decomposed into a series of intrinsic mode functions (IMFs) and a residual component using an EMD algorithm. High frequency noise is eliminated by removing several IMFs at the position without vibration selected by the Pearson correlation coefficient (PCC). When the pulse width is 50 ns, the SNR of location information for the vibration events of 100 Hz and 1.2 kHz is increased to as high as 42.52 dB and 39.58 dB, respectively, with a 2 km sensing fiber, which demonstrates the excellent performance of this new method.

  2. Single photon detection and signal analysis for high sensitivity dosimetry based on optically stimulated luminescence with beryllium oxide

    Science.gov (United States)

    Radtke, J.; Sponner, J.; Jakobi, C.; Schneider, J.; Sommer, M.; Teichmann, T.; Ullrich, W.; Henniger, J.; Kormoll, T.

    2018-01-01

    Single photon detection applied to optically stimulated luminescence (OSL) dosimetry is a promising approach due to the low level of luminescence light and the known statistical behavior of single photon events. Time resolved detection allows to apply a variety of different and independent data analysis methods. Furthermore, using amplitude modulated stimulation impresses time- and frequency information into the OSL light and therefore allows for additional means of analysis. Considering the impressed frequency information, data analysis by using Fourier transform algorithms or other digital filters can be used for separating the OSL signal from unwanted light or events generated by other phenomena. This potentially lowers the detection limits of low dose measurements and might improve the reproducibility and stability of obtained data. In this work, an OSL system based on a single photon detector, a fast and accurate stimulation unit and an FPGA is presented. Different analysis algorithms which are applied to the single photon data are discussed.

  3. Digital passband processing of wideband-modulated optical signals for enhanced underwater imaging.

    Science.gov (United States)

    Mullen, Linda; Lee, Robert; Nash, Justin

    2016-11-01

    Radar modulation, demodulation, and signal processing techniques have been merged with laser imaging to enhance visibility in murky underwater environments. The modulation provides a way to reject multiple scattered light that would otherwise reduce image contrast and resolution. Recent work has focused on the use of wideband modulation schemes and digital passband processing to resolve range details of an underwater scene. Use of the CLEAN algorithm has also been investigated to extract object features that are obscured by scattered light. Results from controlled laboratory experiments show an improvement in the range resolution and accuracy of underwater imagery relative to data collected with a conventional short pulse system.

  4. Probability density function formalism for optical coherence tomography signal analysis: a controlled phantom study.

    Science.gov (United States)

    Weatherbee, Andrew; Sugita, Mitsuro; Bizheva, Kostadinka; Popov, Ivan; Vitkin, Alex

    2016-06-15

    The distribution of backscattered intensities as described by the probability density function (PDF) of tissue-scattered light contains information that may be useful for tissue assessment and diagnosis, including characterization of its pathology. In this Letter, we examine the PDF description of the light scattering statistics in a well characterized tissue-like particulate medium using optical coherence tomography (OCT). It is shown that for low scatterer density, the governing statistics depart considerably from a Gaussian description and follow the K distribution for both OCT amplitude and intensity. The PDF formalism is shown to be independent of the scatterer flow conditions; this is expected from theory, and suggests robustness and motion independence of the OCT amplitude (and OCT intensity) PDF metrics in the context of potential biomedical applications.

  5. Optical phase-modulated radio-over-fiber links with k-means algorithm for digital demodulation of 8PSK subcarrier multiplexed signals

    DEFF Research Database (Denmark)

    Guerrero Gonzalez, Neil; Zibar, Darko; Yu, Xianbin

    2010-01-01

    A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission......A k-means algorithm for phase recovery of three, 50 Mbaud, 8PSK subcarrier multiplexed signals at 5 GHz for optical phase-modulated radio-over-fiber is proposed and experimentally demonstrated after 40 km of single mode fiber transmission...

  6. Comparison of all-optical co- and counter-propagating high-speed signal processing in SOA-based Mach-Zehnder interferometers

    DEFF Research Database (Denmark)

    Bischoff, Svend; Buxens, Alvaro; Fischer, S.

    2001-01-01

    The all-optical signal processing performance of a Mach-Zehnder interferometer (MZI) is investigated. Calculated switching windows are used to investigate and understand the physical mechanisms limiting the high speed performance. Especially, the co- and counter-propagating operation of the MZI...... is discussed and important differences in the performance for the two schemes are addressed. The non-regenerative all-optical clear and drop functionality is investigated for a 2, 4 and 8 x 40 Gbit/s signal, showing good performance in the co-propagating case. Regenerative simultaneous clear and drop...

  7. ERPWAVELAB a toolbox for multi-channel analysis of time-frequency transformed event related potentials.

    Science.gov (United States)

    Mørup, Morten; Hansen, Lars Kai; Arnfred, Sidse M

    2007-04-15

    The open source toolbox 'ERPWAVELAB' is developed for multi-channel time-frequency analysis of event related activity of EEG and MEG data. The toolbox provides tools for data analysis and visualization of the most commonly used measures of time-frequency transformed event related data as well as data decomposition through non-negative matrix and multi-way (tensor) factorization. The decompositions provided can accommodate additional dimensions like subjects, conditions or repeats and as such they are perfected for group analysis. Furthermore, the toolbox enables tracking of phase locked activity from one channel-time-frequency instance to another as well as tools for artifact rejection in the time-frequency domain. Several other features are highlighted. ERPWAVELAB can freely be downloaded from www.erpwavelab.org, requires EEGLAB [Delorme A, Makeig S. EEGLAB: an open source toolbox for analysis of single-trial EEG dynamics including independent component analysis. J Neurosci Meth 2004;134:9-21] and runs under MATLAB (The Mathworks, Inc.).

  8. Effects of Stimulus Duration on Event-Related Potentials Recorded From Cochlear-Implant Users.

    Science.gov (United States)

    Presacco, Alessandro; Innes-Brown, Hamish; Goupell, Matthew J; Anderson, Samira

    Several studies have investigated the feasibility of using electrophysiology as an objective tool to efficiently map cochlear implants. A pervasive problem when measuring event-related potentials is the need to remove the direct-current (DC) artifact produced by the cochlear implant. Here, we describe how DC artifact removal can corrupt the response waveform and how the appropriate choice of stimulus duration may minimize this corruption. Event-related potentials were recorded to a synthesized vowel /a/ with a 170- or 400-ms duration. The P2 response, which occurs between 150 and 250 ms, was corrupted by the DC artifact removal algorithm for a 170-ms stimulus duration but was relatively uncorrupted for a 400-ms stimulus duration. To avoid response waveform corruption from DC artifact removal, one should choose a stimulus duration such that the offset of the stimulus does not temporally coincide with the specific peak of interest. While our data have been analyzed with only one specific algorithm, we argue that the length of the stimulus may be a critical factor for any DC artifact removal algorithm.

  9. Event-related delta, theta, alpha and gamma correlates to auditory oddball processing during Vipassana meditation

    Science.gov (United States)

    Delorme, Arnaud; Polich, John

    2013-01-01

    Long-term Vipassana meditators sat in meditation vs. a control (instructed mind wandering) states for 25 min, electroencephalography (EEG) was recorded and condition order counterbalanced. For the last 4 min, a three-stimulus auditory oddball series was presented during both meditation and control periods through headphones and no task imposed. Time-frequency analysis demonstrated that meditation relative to the control condition evinced decreased evoked delta (2–4 Hz) power to distracter stimuli concomitantly with a greater event-related reduction of late (500–900 ms) alpha-1 (8–10 Hz) activity, which indexed altered dynamics of attentional engagement to distracters. Additionally, standard stimuli were associated with increased early event-related alpha phase synchrony (inter-trial coherence) and evoked theta (4–8 Hz) phase synchrony, suggesting enhanced processing of the habituated standard background stimuli. Finally, during meditation, there was a greater differential early-evoked gamma power to the different stimulus classes. Correlation analysis indicated that this effect stemmed from a meditation state-related increase in early distracter-evoked gamma power and phase synchrony specific to longer-term expert practitioners. The findings suggest that Vipassana meditation evokes a brain state of enhanced perceptual clarity and decreased automated reactivity. PMID:22648958

  10. Effect of Anodal-tDCS on Event-Related Potentials: A Controlled Study

    Directory of Open Access Journals (Sweden)

    Ahmed Izzidien

    2016-01-01

    Full Text Available We aim to measure the postintervention effects of A-tDCS (anodal-tDCS on brain potentials commonly used in BCI applications, namely, Event-Related Desynchronization (ERD, Event-Related Synchronization (ERS, and P300. Ten subjects were given sham and 1.5 mA A-tDCS for 15 minutes on two separate experiments in a double-blind, randomized order. Postintervention EEG was recorded while subjects were asked to perform a spelling task based on the “oddball paradigm” while P300 power was measured. Additionally, ERD and ERS were measured while subjects performed mental motor imagery tasks. ANOVA results showed that the absolute P300 power exhibited a statistically significant difference between sham and A-tDCS when measured over channel Pz (p=0.0002. However, the difference in ERD and ERS power was found to be statistically insignificant, in controversion of the the mainstay of the litrature on the subject. The outcomes confirm the possible postintervention effect of tDCS on the P300 response. Heightening P300 response using A-tDCS may help improve the accuracy of P300 spellers for neurologically impaired subjects. Additionally, it may help the development of neurorehabilitation methods targeting the parietal lobe.

  11. Effect of Anodal-tDCS on Event-Related Potentials: A Controlled Study.

    Science.gov (United States)

    Izzidien, Ahmed; Ramaraju, Sriharasha; Roula, Mohammed Ali; McCarthy, Peter W

    2016-01-01

    We aim to measure the postintervention effects of A-tDCS (anodal-tDCS) on brain potentials commonly used in BCI applications, namely, Event-Related Desynchronization (ERD), Event-Related Synchronization (ERS), and P300. Ten subjects were given sham and 1.5 mA A-tDCS for 15 minutes on two separate experiments in a double-blind, randomized order. Postintervention EEG was recorded while subjects were asked to perform a spelling task based on the "oddball paradigm" while P300 power was measured. Additionally, ERD and ERS were measured while subjects performed mental motor imagery tasks. ANOVA results showed that the absolute P300 power exhibited a statistically significant difference between sham and A-tDCS when measured over channel Pz ( p = 0.0002). However, the difference in ERD and ERS power was found to be statistically insignificant, in controversion of the the mainstay of the litrature on the subject. The outcomes confirm the possible postintervention effect of tDCS on the P300 response. Heightening P300 response using A-tDCS may help improve the accuracy of P300 spellers for neurologically impaired subjects. Additionally, it may help the development of neurorehabilitation methods targeting the parietal lobe.

  12. Social exclusion modulates event-related frontal theta and tracks ostracism distress in children.

    Science.gov (United States)

    van Noordt, Stefon J R; White, Lars O; Wu, Jia; Mayes, Linda C; Crowley, Michael J

    2015-09-01

    Social exclusion is a potent elicitor of distress. Previous studies have shown that medial frontal theta oscillations are modulated by the experience of social exclusion. Using the Cyberball paradigm, we examined event-related dynamics of theta power in the EEG at medial frontal sites while children aged 8-12 years were exposed to conditions of fair play and social exclusion. Using an event-related design, we found that medial frontal theta oscillations (4-8Hz) increase during both early (i.e., 200-400ms) and late (i.e., 400-800ms) processing of rejection events during social exclusion relative to perceptually identical "not my turn" events during inclusion. Importantly, we show that only for the later time window (400-800ms) slow-wave theta power tracks self-reported ostracism distress. Specifically, greater theta power at medial frontal sites to "rejection" events predicted higher levels of ostracism distress. Alpha and beta oscillations for rejection events were unrelated to ostracism distress at either 200-400ms or 400-800ms time windows. Our findings extend previous studies by showing that medial frontal theta oscillations for rejection events are a neural signature of social exclusion, linked to experienced distress in middle childhood. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Event-related frontal alpha asymmetries: electrophysiological correlates of approach motivation.

    Science.gov (United States)

    Schöne, Benjamin; Schomberg, Jessica; Gruber, Thomas; Quirin, Markus

    2016-02-01

    Over the last decades, frontal alpha asymmetries observed during resting state periods of several minutes have been used as a marker of affective-motivational states. To date, there is no evidence that alpha asymmetries can be observed in response to brief affective-motivational stimuli, as typically presented in event-related designs. As we argue, frontal alpha asymmetry might indeed be elicited by brief events if they are salient enough. In an event-related design, we used erotic pictures, i.e., highly salient incentives to elicit approach motivation, and contrasted them with pictures of dressed attractive women. As expected, we found significant alpha asymmetries for erotic pictures as compared to control pictures. Our findings suggest that the highly reactive reward system can lead to immediate, phasic changes in frontal alpha asymmetries. We discuss the findings with respect to the notion that high salience of erotic pictures derives from their potential of satisfying an individuals' need by mere visual inspection, which is not the case for pictures showing other types of motivational stimuli such as food.

  14. Effects of white noise on event-related potentials in somatosensory Go/No-go paradigms.

    Science.gov (United States)

    Ohbayashi, Wakana; Kakigi, Ryusuke; Nakata, Hiroki

    2017-09-06

    Exposure to auditory white noise has been shown to facilitate human cognitive function. This phenomenon is termed stochastic resonance, and a moderate amount of auditory noise has been suggested to benefit individuals in hypodopaminergic states. The present study investigated the effects of white noise on the N140 and P300 components of event-related potentials in somatosensory Go/No-go paradigms. A Go or No-go stimulus was presented to the second or fifth digit of the left hand, respectively, at the same probability. Participants performed somatosensory Go/No-go paradigms while hearing three different white noise levels (45, 55, and 65 dB conditions). The peak amplitudes of Go-P300 and No-go-P300 in ERP waveforms were significantly larger under 55 dB than 45 and 65 dB conditions. White noise did not affect the peak latency of N140 or P300, or the peak amplitude of N140. Behavioral data for the reaction time, SD of reaction time, and error rates showed the absence of an effect by white noise. This is the first event-related potential study to show that exposure to auditory white noise at 55 dB enhanced the amplitude of P300 during Go/No-go paradigms, reflecting changes in the neural activation of response execution and inhibition processing.

  15. The impacts of racial group membership on people's distributive justice: an event-related potential study.

    Science.gov (United States)

    Wang, Yan; Tang, Yi-Yuan; Deng, Yuqin

    2014-04-16

    How individuals and societies distribute benefits has long been studied by psychologists and sociologists. Previous work has highlighted the importance of social identity on people's justice concerns. However, it is not entirely clear how racial in-group/out-group relationship affects the brain activity in distributive justice. In this study, event-related potentials were recorded while participants made their decisions about donation allocation. Behavioral results showed that racial in-group factor affected participants' decisions on justice consideration. Participants were more likely to make relatively equity decisions when racial in-group factor was congruent with equity compared with the corresponding incongruent condition. Moreover, this incongruent condition took longer response times than congruent condition. Meanwhile, less equity decisions were made when efficiency was larger in the opposite side to equity than it was equal between the two options. Scalp event-related potential analyses revealed that greater P300 and late positive potential amplitudes were elicited by the incongruent condition compared with the congruent condition. These findings suggest that the decision-making of distributive justice could be modulated by racial group membership, and greater attentional resources or cognitive efforts are required when racial in-group factor and equity conflict with each other.

  16. Harmonic decomposition of magneto-optical signal from suspensions of superparamagnetic nanoparticles

    Science.gov (United States)

    Patterson, Cody; Syed, Maarij; Takemura, Yasushi

    2018-04-01

    Magnetic nanoparticles (MNPs) are widely used in biomedical applications. Characterizing dilute suspensions of superparamagnetic iron oxide nanoparticles (SPIONs) in bio-relevant media is particularly valuable for magnetic particle imaging, hyperthermia, drug delivery, etc. Here, we study dilute aqueous suspensions of single-domain magnetite nanoparticles using an AC Faraday rotation (FR) setup. The setup uses an oscillating magnetic field (800 Hz) which generates a multi-harmonic response. Each harmonic is collected and analyzed using the Fourier components of the theoretical signal determined by a Langevin-like magnetization. With this procedure, we determine the average magnetic moment per particle μ , particle number density n, and Verdet constant of the sample. The fitted values of μ and n are shown to be consistent across each harmonic. Additionally, we present the results of these parameters as n is varied. The large values of μ reveal the possibility of clustering as reported in other literature. This suggests that μ is representative of the average magnetic moment per cluster of nanoparticles. Multiple factors, including the external magnetic field, surfactant degradation, and laser absorption, can contribute to dynamic and long-term aggregation leading to FR signals that represent space- and time-averaged sample parameters. Using this powerful analysis procedure, future studies are aimed at determining the clustering mechanisms in this AC system and characterizing SPION suspensions at different frequencies and viscosities.

  17. Flexible and re-configurable optical three-input XOR logic gate of phase-modulated signals with multicast functionality for potential application in optical physical-layer network coding.

    Science.gov (United States)

    Lu, Guo-Wei; Qin, Jun; Wang, Hongxiang; Ji, XuYuefeng; Sharif, Gazi Mohammad; Yamaguchi, Shigeru

    2016-02-08

    Optical logic gate, especially exclusive-or (XOR) gate, plays important role in accomplishing photonic computing and various network functionalities in future optical networks. On the other hand, optical multicast is another indispensable functionality to efficiently deliver information in optical networks. In this paper, for the first time, we propose and experimentally demonstrate a flexible optical three-input XOR gate scheme for multiple input phase-modulated signals with a 1-to-2 multicast functionality for each XOR operation using four-wave mixing (FWM) effect in single piece of highly-nonlinear fiber (HNLF). Through FWM in HNLF, all of the possible XOR operations among input signals could be simultaneously realized by sharing a single piece of HNLF. By selecting the obtained XOR components using a followed wavelength selective component, the number of XOR gates and the participant light in XOR operations could be flexibly configured. The re-configurability of the proposed XOR gate and the function integration of the optical logic gate and multicast in single device offer the flexibility in network design and improve the network efficiency. We experimentally demonstrate flexible 3-input XOR gate for four 10-Gbaud binary phase-shift keying signals with a multicast scale of 2. Error-free operations for the obtained XOR results are achieved. Potential application of the integrated XOR and multicast function in network coding is also discussed.

  18. Generalization of Context-Specific Training in Individuals with Mild Cognitive Impairment: An Event-Related Potential Study.

    Science.gov (United States)

    Chan, Sam C C; Lam, Tommy L H; Fong, Kenneth N K; Pang, Marco Y C; Chan, Chetwyn C H

    2016-01-01

    This study examined the neural processes associated with the generalization of the effect of context-specific (CS) training to noncontextual situations among individuals with mild cognitive impairment (MCI). Fourteen and 16 participants with MCI were randomly allocated to a Chinese calligraphy writing (CW) training or a control group, respectively. The CW participants learned how to write Chinese strokes in a semicursive style to construct characters, tapping on working memory functions. The control group, on the other hand, learned how to use a tablet computer without emphasis on working memory functions. They then performed two 2-back tasks with CS semicursive strokes and non-context-specific (NCS) digits. Event-related electroencephalogram signals were concurrently recorded. The CW participants had a significantly shorter reaction time in the CS than in the NCS task ( p 11 = 4.70, p = 0.05) and shorter latency in the evaluation of visual representation (P300; t 12 = 4.67; p = 0.05) than the control group when performing the 2-back CS task. Shorter P300 latency was also revealed in the 2-back NCS task ( t 12 = 5.15, p = 0.041), suggesting a possible generalization of the training effect among the CW participants. The results suggest that CS working memory is likely to be generalized to NCS domains among individuals with MCI. Future research should extend the scope of the generalization and apply it beyond experimental conditions.

  19. Average BER analysis of SCM-based free-space optical systems by considering the effect of IM3 with OSSB signals under turbulence channels.

    Science.gov (United States)

    Lim, Wansu; Cho, Tae-Sik; Yun, Changho; Kim, Kiseon

    2009-11-09

    In this paper, we derive the average bit error rate (BER) of subcarrier multiplexing (SCM)-based free space optics (FSO) systems using a dual-drive Mach-Zehnder modulator (DD-MZM) for optical single-sideband (OSSB) signals under atmospheric turbulence channels. In particular, we consider the third-order intermodulation (IM3), a significant performance degradation factor, in the case of high input signal power systems. The derived average BER, as a function of the input signal power and the scintillation index, is employed to determine the optimum number of SCM users upon the designing FSO systems. For instance, when the user number doubles, the input signal power decreases by almost 2 dBm under the log-normal and exponential turbulence channels at a given average BER.

  20. Optical and digital GaAs technologies for signal-processing applications; Proceedings of the Meeting, Orlando, FL, Apr. 16-18, 1990

    Science.gov (United States)

    Bendett, Mark P.; Butler, Daniel H., Jr.; Prabhakar, Arati; Yang, Andrew

    1990-10-01

    Practical problems that need to be solved for the introduction of optical modules into processing systems are reviewed. Some papers deal with the state of the art in such key devices as Bragg cells, spatial light modulators, and fast CCDs. Issues unique to optical packaging are also highlightened. New architectures to enable real-time operations are demonstrated, and optical interconnects for parallel processors are discussed. Particular attention is given to the status and operational advantages of government-sponsored efforts to upgrade existing military systems with digital GaAs signal processors and the state of the art in computer-aided design and advanced system architectures.

  1. Integration of Si-CMOS embedded photo detector array and mixed signal processing system with embedded optical waveguide input

    Science.gov (United States)

    Kim, Daeik D.; Thomas, Mikkel A.; Brooke, Martin A.; Jokerst, Nan M.

    2004-06-01

    Arrays of embedded bipolar junction transistor (BJT) photo detectors (PD) and a parallel mixed-signal processing system were fabricated as a silicon complementary metal oxide semiconductor (Si-CMOS) circuit for the integration optical sensors on the surface of the chip. The circuit was fabricated with AMI 1.5um n-well CMOS process and the embedded PNP BJT PD has a pixel size of 8um by 8um. BJT PD was chosen to take advantage of its higher gain amplification of photo current than that of PiN type detectors since the target application is a low-speed and high-sensitivity sensor. The photo current generated by BJT PD is manipulated by mixed-signal processing system, which consists of parallel first order low-pass delta-sigma oversampling analog-to-digital converters (ADC). There are 8 parallel ADCs on the chip and a group of 8 BJT PDs are selected with CMOS switches. An array of PD is composed of three or six groups of PDs depending on the number of rows.

  2. Evidence of ventricular contamination of the optical signal in preterm neonates with post hemorrhagic ventricle dilation

    Science.gov (United States)

    Kishimoto, J.; Diop, M.; McLachlan, P.; de Ribaupierre, S.; Lee, D. S. C.; St. Lawrence, K.

    2015-03-01

    Dilation of the cerebral ventricles is a common condition in preterm neonates with intraventricular hemorrhage (IVH). This post hemorrhagic ventricle dilation (PHVD) can lead to lifelong neurological impairment through ischemic injury due to increased intracranial pressure (ICP). Interventions, such as ventricular tapping to remove cerebrospinal fluid (CSF), are used to prevent injury, but determining the optimal time for treatment is difficult as clinical signs of increased ICP lack sensitivity. There is a growing interest in using near-infrared spectroscopy (NIRS) because of its ability to monitor cerebral oxygen saturation (StO2) at the bedside. However, the accuracy of NIRS may be affected by signal contamination from enlarged ventricles, especially if there are blood breakdown products (bbp) in CSF following IVH. To investigate this, serial NIR spectra from the head and from CSF samples were acquired over a month from seven IVH patients undergoing treatment for PHVD. Over time, the visual appearance of the CSF samples progressed from dark brown ("tea color") to clear yellow, reflecting the reduction in bbp concentration as confirmed by the stronger absorption around 760 nm at the earlier time points. All CSF samples contained strong absorption at 960 nm due to water. More importantly the same trend in these absorption features was observed in the in vivo spectra, and Monte Carlo simulations confirmed the potential for signal contamination from enlarged ventricles. These findings highlight the challenges of accurately measuring StO2 in this patient population and the necessity of using a hyperspectral NIRS system to resolve the additional chromophores.

  3. Electrophysiological correlates of refreshing: Event-related potentials associated with directing reflective attention to face, scene, or word representations

    Science.gov (United States)

    Johnson, Matthew R.; McCarthy, Gregory; Muller, Kathleen A.; Brudner, Samuel N.; Johnson, Marcia K.

    2016-01-01

    Refreshing is the component cognitive process of directing reflective attention to one of several active mental representations. Previous studies using functional magnetic resonance imaging (fMRI) suggested that refresh tasks involve a component process of initiating refreshing as well as the top-down modulation of representational regions central to refreshing. However, those studies were limited by fMRI’s low temporal resolution. In the present study, we used electroencephalography (EEG) to examine the timecourse of refreshing on the scale of milliseconds rather than seconds. Event-related potential (ERP) analyses showed that a typical refresh task does have a distinct electrophysiological response as compared to a control condition, and includes at least two main temporal components: an earlier (~400ms) positive peak reminiscent of a P3 response, and a later (~800ms–1400ms) sustained positivity over several sites reminiscent of the late directing attention positivity (LDAP). Overall, the evoked potentials for refreshing representations from three different visual categories (faces, scenes, words) were similar, but multivariate pattern analysis (MVPA) showed that some category information was nonetheless present in the EEG signal. When related to previous fMRI studies, these results are consistent with a two-phase model, with the first phase dominated by frontal control signals involved in initiating refreshing and the second by the top-down modulation of posterior perceptual cortical areas that constitutes refreshing a representation. This study also lays the foundation for future studies of the neural correlates of reflective attention at a finer temporal resolution than is possible using fMRI. PMID:25961640

  4. Event-related potentials to visual, auditory, and bimodal (combined auditory-visual) stimuli.

    Science.gov (United States)

    Isoğlu-Alkaç, Ummühan; Kedzior, Karina; Keskindemirci, Gonca; Ermutlu, Numan; Karamursel, Sacit

    2007-02-01

    The purpose of this study was to investigate the response properties of event related potentials to unimodal and bimodal stimulations. The amplitudes of N1 and P2 were larger during bimodal evoked potentials (BEPs) than auditory evoked potentials (AEPs) in the anterior sites and the amplitudes of P1 were larger during BEPs than VEPs especially at the parieto-occipital locations. Responses to bimodal stimulation had longer latencies than responses to unimodal stimulation. The N1 and P2 components were larger in amplitude and longer in latency during the bimodal paradigm and predominantly occurred at the anterior sites. Therefore, the current bimodal paradigm can be used to investigate the involvement and location of specific neural generators that contribute to higher processing of sensory information. Moreover, this paradigm may be a useful tool to investigate the level of sensory dysfunctions in clinical samples.

  5. Protective role of educational level on episodic memory aging: an event-related potential study.

    Science.gov (United States)

    Angel, Lucie; Fay, Séverine; Bouazzaoui, Badiâa; Baudouin, Alexia; Isingrini, Michel

    2010-12-01

    The aim of the present experiment was to investigate whether educational level could modulate the effect of aging on episodic memory and on the electrophysiological correlates of retrieval success. Participants were divided into four groups based on age (young vs. older) and educational level (high vs. low), with 14 participants in each group. Event-related potentials (ERP) were recorded while participants performed a word-stem cued-recall task. Age-related memory deficits were greater for the less educated individuals. Age differences in the ERP old/new effects were also modulated by the level of education. This study demonstrated that the effects of age on episodic memory and ERP correlates of retrieval success are smaller in participants with high educational levels than those with lower levels. These findings provide support for the reserve hypothesis and highlight the need to consider individual differences when studying cognitive and cerebral changes in aging. Copyright © 2010 Elsevier Inc. All rights reserved.

  6. The neural processing of fearful faces without attention and consciousness: an event-related potential study.

    Science.gov (United States)

    Wang, Lili; Fu, Shimin; Feng, Chunliang; Luo, Wenbo; Zhu, Xiangru; Luo, Yue-jia

    2012-01-11

    To investigate whether the non-conscious processing of fearful faces exist in unattended condition, event-related potentials (ERPs) were recorded in a facial expression detection task. Participants were asked to discriminate the facial expressions (fearful or neutral) at the attended location. Unattended faces were associated with a response that was either congruent or in conflict with the response to the attended face. ERP results showed that the trials with response conflict between attended and unattended faces enhanced the amplitude of the P3 component when the neutral face was presented at attended location and the fearful face was presented at the unattended location. Our findings imply that the non-conscious fearful faces can be processed in the unattended condition. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  7. Modulations of 'late' event-related brain potentials in humans by dynamic audiovisual speech stimuli.

    Science.gov (United States)

    Lebib, Riadh; Papo, David; Douiri, Abdel; de Bode, Stella; Gillon Dowens, Margaret; Baudonnière, Pierre-Marie

    2004-11-30

    Lipreading reliably improve speech perception during face-to-face conversation. Within the range of good dubbing, however, adults tolerate some audiovisual (AV) discrepancies and lipreading, then, can give rise to confusion. We used event-related brain potentials (ERPs) to study the perceptual strategies governing the intermodal processing of dynamic and bimodal speech stimuli, either congruently dubbed or not. Electrophysiological analyses revealed that non-coherent audiovisual dubbings modulated in amplitude an endogenous ERP component, the N300, we compared to a 'N400-like effect' reflecting the difficulty to integrate these conflicting pieces of information. This result adds further support for the existence of a cerebral system underlying 'integrative processes' lato sensu. Further studies should take advantage of this 'N400-like effect' with AV speech stimuli to open new perspectives in the domain of psycholinguistics.

  8. Spatial and Semantic Processing between Audition and Vision: An Event-Related Potential Study

    Directory of Open Access Journals (Sweden)

    Xiaoxi Chen

    2011-10-01

    Full Text Available Using a crossmodal priming paradigm, this study investigated how the brain bound the spatial and semantic features in multisensory processing. The visual stimuli (pictures of animals were presented after the auditory stimuli (sounds of animals, and the stimuli from different modalities may match spatially (or semantically or not. Participants were required to detect the head orientation of the visual target (an oddball paradigm. The event-related potentials (ERPs to the visual stimuli was enhanced by spatial attention (150–170 ms irrespectively of semantic information. The early crossmodal attention effect for the visual stimuli was more negative in the spatial-congruent condition than in the spatial-incongruent condition. By contrast, the later effects of spatial ERPs were significant only for the semantic- congruent condition (250–300 ms. These findings indicated that spatial attention modulated early visual processing, and semantic and spatial features were simultaneously used to orient attention and modulate later processing stages.

  9. Event-related Desynchronization of Mu Rhythms During Concentric and Eccentric Contractions.

    Science.gov (United States)

    Park, Joo-Hee; Cynn, Heon-Seock; Cha, Kwang Su; Kim, Kyung Hwan; Jeon, Hye-Seon

    2017-09-19

    The purpose of this study was to compare the electroencephalographic (EEG) patterns and reaction times (RTs) of muscle activation between concentric and eccentric biceps brachii contractions under the RT paradigm and to evaluate how the EEG patterns and RTs changed with practice. Sixteen subjects performed 3 sets of 30 repetitions of submaximal voluntary concentric and eccentric biceps contractions. RT, event-related desynchronization (ERD) patterns of mu rhythm onset, and ERD amplitudes were selectively analyzed. Mental demand decreased as familiarity with the motor action increased due to practice regardless of contraction type. However, the 2 types of muscle contractions still have differences in brain activity regardless of decreased mental demand: eccentric contractions require earlier preparation than concentric contractions.

  10. A comparative study of event-related coupling patterns during an auditory oddball task in schizophrenia

    Science.gov (United States)

    Bachiller, Alejandro; Poza, Jesús; Gómez, Carlos; Molina, Vicente; Suazo, Vanessa; Hornero, Roberto

    2015-02-01

    Objective. The aim of this research is to explore the coupling patterns of brain dynamics during an auditory oddball task in schizophrenia (SCH). Approach. Event-related electroencephalographic (ERP) activity was recorded from 20 SCH patients and 20 healthy controls. The coupling changes between auditory response and pre-stimulus baseline were calculated in conventional EEG frequency bands (theta, alpha, beta-1, beta-2 and gamma), using three coupling measures: coherence, phase-locking value and Euclidean distance. Main results. Our results showed a statistically significant increase from baseline to response in theta coupling and a statistically significant decrease in beta-2 coupling in controls. No statistically significant changes were observed in SCH patients. Significance. Our findings support the aberrant salience hypothesis, since SCH patients failed to change their coupling dynamics between stimulus response and baseline when performing an auditory cognitive task. This result may reflect an impaired communication among neural areas, which may be related to abnormal cognitive functions.

  11. Neuroprotection against vascular dementia after acupuncture combined with donepezil hydrochloride: P300 event related potential

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2016-01-01

    Full Text Available Acupuncture can be used to treat various nervous system diseases. Here, 168 vascular dementia patients were orally administered donepezil hydrochloride alone (5 mg/day, once a day for 56 days, or combined with acupuncture at Shenting (DU24, Tianzhu (BL10, Sishencong (Extra, Yintang (Extra, Renzhong (DU26, Neiguan (PC6, Shenmen (HT7, Fengchi (GB20, Wangu (GB12 and Baihui (DU20 (once a day for 56 days. Compared with donepezil hydrochloride alone, P300 event related potential latency was shorter with an increased amplitude in patients treated with donepezil hydrochloride and acupuncture. Mini-Mental State Examination score was also higher. Moreover, these differences in P300 latency were identified within different infarcted regions in patients treated with donepezil hydrochloride and acupuncture. These findings indicate that acupuncture combined with donepezil hydrochloride noticeably improves cognitive function in patients with vascular dementia, and exerts neuroprotective effects against vascular dementia.

  12. The delay effect on outcome evaluation: results from an Event-related Potential study

    Directory of Open Access Journals (Sweden)

    Chen eQu

    2013-11-01

    Full Text Available Behavioral studies demonstrate that the timing of receiving gains or losses affects decision-making, a phenomenon known as temporal discounting, as participants are inclined to prefer immediate rewards over delayed ones and vice versa for losses. The present study used the event-related potential (ERP technique with a simple gambling task to investigate how delayed rewards and losses affected the brain activity in outcome evaluations made by 20 young adults. Statistical analysis revealed a larger feedback related negativity (FRN effect between loss and gain following immediate outcomes than following future outcomes. In addition, delay impacted FRN only in gain conditions, with delayed winning eliciting a more negative FRN than immediatewinning. These results suggest that temporal discounting and sign effect could be encoded in the FRN in the early stage of outcome evaluation.

  13. Self-relevant beauty evaluation: Evidence from an event-related potentials study.

    Science.gov (United States)

    Kong, Fanchang; Zhang, Yan; Tian, Yuan; Fan, Cuiying; Zhou, Zongkui

    2015-03-01

    This study examines the electrophysiological correlates of beauty evaluation when participants performed the self-reference task. About 13 (7 men, 6 women) undergraduates participated in the experiment using event-related potentials. Results showed that the response to self-relevant information was faster compared to other-relevant information and no significant differences for self-relevant relative to mother-relevant information were observed. Both physical and interior beauty words for self-relevant information showed an enhanced late positive component as compared to other-relevant information. Physical beauty for self-relevant information yielded a larger late positive component in contrast to mother-relevant information but not for interior beauty. This study indicates that beauty is specific to the person who judges it though an individual and one's mother may hold similar views of interior beauty.

  14. Aesthetic appreciation: event-related field and time-frequency analyses.

    Science.gov (United States)

    Munar, Enric; Nadal, Marcos; Castellanos, Nazareth P; Flexas, Albert; Maestú, Fernando; Mirasso, Claudio; Cela-Conde, Camilo J

    2011-01-01

    Improvements in neuroimaging methods have afforded significant advances in our knowledge of the cognitive and neural foundations of aesthetic appreciation. We used magnetoencephalography (MEG) to register brain activity while participants decided about the beauty of visual stimuli. The data were analyzed with event-related field (ERF) and Time-Frequency (TF) procedures. ERFs revealed no significant differences between brain activity related with stimuli rated as "beautiful" and "not beautiful." TF analysis showed clear differences between both conditions 400 ms after stimulus onset. Oscillatory power was greater for stimuli rated as "beautiful" than those regarded as "not beautiful" in the four frequency bands (theta, alpha, beta, and gamma). These results are interpreted in the frame of synchronization studies.

  15. An event-related potential study of supramodal attentional control and crossmodal attention effects.

    Science.gov (United States)

    Green, Jessica J; McDonald, John J

    2006-03-01

    We conducted two audiovisual experiments to determine whether event-related potential (ERP) components elicited by attention-directing cues reflect supramodal attentional control. Symbolic visual cues were used to direct attention prior to auditory targets in Experiment 1, and symbolic auditory cues were used to direct attention prior to visual targets in Experiment 2. Different patterns of cue ERPs were found in the two experiments. A frontal negativity called the ADAN was absent in Experiment 2, which indicates that this component does not reflect supramodal attentional control. A posterior positivity called the LDAP was observed in both experiments but was focused more posteriorly over the occipital scalp in Experiment 2. This component appears to reflect multiple processes, including visual processes involved in location marking and target preparation as well as supramodal processes involved in attentional control.

  16. Cognitive function and event-related potentials in children with type 1 diabetes mellitus.

    Science.gov (United States)

    Shehata, Ghaydaa; Eltayeb, Azza

    2010-04-01

    Type 1 diabetes mellitus is associated with cognitive changes, but the extent of cognition decline depends on age at onset, duration of diabetes, and occurrence of attacks of hypoglycemia or ketoacidosis. This study was designed to assess cognitive function in a group of children with type 1 diabetes mellitus. A total of 40 diabetic children were recruited from the pediatric department of Assiut University Hospital, Egypt. Forty healthy children matched for age, sex, and socioeconomic status were chosen as controls for comparison. Cognition was assessed using Stanford-Binet and event-related potentials tests. Compared to the control group, patients reported a significant reduction in intelligent quotient, comprehension, abstract visual reasoning, quantitative reasoning, bead memory, and total short memory testing for cognitive functions. Prolonged N1, P200, N2, and P300 latencies and reduced P300-N2 amplitude were reported. Significant negative correlations were identified in most studied cognitive functions and ketoacidosis or family history of diabetes mellitus.

  17. P300 component of event-related potentials in persons with asperger disorder.

    Science.gov (United States)

    Iwanami, Akira; Okajima, Yuka; Ota, Haruhisa; Tani, Masayuki; Yamada, Takashi; Yamagata, Bun; Hashimoto, Ryuichiro; Kanai, Chieko; Takashio, Osamu; Inamoto, Atsuko; Ono, Taisei; Takayama, Yukiko; Kato, Nobumasa

    2014-10-01

    In the present study, we investigated auditory event-related potentials in adults with Asperger disorder and normal controls using an auditory oddball task and a novelty oddball task. Task performance and the latencies of P300 evoked by both target and novel stimuli in the two tasks did not differ between the two groups. Analysis of variance revealed that there was a significant interaction effect between group and electrode site on the mean amplitude of the P300 evoked by novel stimuli, which indicated that there was an altered distribution of the P300 in persons with Asperger disorder. In contrast, there was no significant interaction effect on the mean P300 amplitude elicited by target stimuli. Considering that P300 comprises two main subcomponents, frontal-central-dominant P3a and parietal-dominant P3b, our results suggested that persons with Asperger disorder have enhanced amplitude of P3a, which indicated activated prefrontal function in this task.

  18. Effects of context on implicit and explicit lexical knowledge: an event-related potential study.

    Science.gov (United States)

    Choi, Sungmook; Kim, Jingu; Ryu, Kwangmin

    2014-10-01

    Although much is known about how contextualized and decontextualized learning affects explicit lexical knowledge, how these learning conditions contribute to implicit lexical knowledge remains unclear. To address this problem, Korean high school students were instructed to learn 30 English words by reading meaningful passages (i.e., in context) and another 30 English words using a wordlist (i.e., out of context). Five weeks later, implicit lexical knowledge was gauged by reaction time and the N400 event-related brain potential component, and explicit lexical knowledge was assessed with an explicit behavioral measure. Results showed that neither learning type was superior to the other in terms of implicit lexical knowledge acquisition, whereas learning words out of context was more effective than learning words in context for establishing explicit lexical knowledge. These results suggest that the presence or absence of context may lead to dissociation in the development of implicit and explicit lexical knowledge. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Crossmodal effects of Guqin and piano music on selective attention: an event-related potential study.

    Science.gov (United States)

    Zhu, Weina; Zhang, Junjun; Ding, Xiaojun; Zhou, Changle; Ma, Yuanye; Xu, Dan

    2009-11-27

    To compare the effects of music from different cultural environments (Guqin: Chinese music; piano: Western music) on crossmodal selective attention, behavioral and event-related potential (ERP) data in a standard two-stimulus visual oddball task were recorded from Chinese subjects in three conditions: silence, Guqin music or piano music background. Visual task data were then compared with auditory task data collected previously. In contrast with the results of the auditory task, the early (N1) and late (P300) stages exhibited no differences between Guqin and piano backgrounds during the visual task. Taking our previous study and this study together, we can conclude that: although the cultural-familiar music influenced selective attention both in the early and late stages, these effects appeared only within a sensory modality (auditory) but not in cross-sensory modalities (visual). Thus, the musical cultural factor is more obvious in intramodal than in crossmodal selective attention.

  20. Conveying the concept of movement in music: An event-related brain potential study.

    Science.gov (United States)

    Zhou, Linshu; Jiang, Cunmei; Wu, Yingying; Yang, Yufang

    2015-10-01

    This study on event-related brain potential investigated whether music can convey the concept of movement. Using a semantic priming paradigm, natural musical excerpts were presented to non-musicians, followed by semantically congruent or incongruent pictures that depicted objects either in motion or at rest. The priming effects were tested in object decision and implicit recognition tasks to distinguish the effects of automatic conceptual activation from response competition. Results showed that in both tasks, pictures that were incongruent to preceding musical excerpts elicited larger N400 than congruent pictures, suggesting that music can prime the representations of movement concepts. Results of the multiple regression analysis showed that movement expression could be well predicted by specific acoustic and musical features, indicating the associations between music per se and the processing of iconic musical meaning. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Attentional Selection Accompanied by Eye Vergence as Revealed by Event-Related Brain Potentials.

    Directory of Open Access Journals (Sweden)

    Maria Sole Puig

    Full Text Available Neural mechanisms of attention allow selective sensory information processing. Top-down deployment of visual-spatial attention is conveyed by cortical feedback connections from frontal regions to lower sensory areas modulating late stimulus responses. A recent study reported the occurrence of small eye vergence during orienting top-down attention. Here we assessed a possible link between vergence and attention by comparing visual event related potentials (vERPs to a cue stimulus that induced attention to shift towards the target location to the vERPs to a no-cue stimulus that did not trigger orienting attention. The results replicate the findings of eye vergence responses during orienting attention and show that the strength and time of eye vergence coincide with the onset and strength of the vERPs when subjects oriented attention. Our findings therefore support the idea that eye vergence relates to and possibly has a role in attentional selection.

  2. Event-related potential study of frontal activity during imagination of rhythm.

    Science.gov (United States)

    Jomori, Izumi; Uemura, Jun-ichi; Nakagawa, Yoshiro; Hoshiyama, Minoru

    2011-12-01

    In 11 healthy volunteers, we used event-related potentials (ERP) to investigate the frontal activity associated with imagining a beat. In imagery sessions, subjects were asked to imagine a rhythm during a silent recording period following a series of guide sounds played at 1 Hz. In control sessions, subjects were asked to imagine a vowel sound ("a") continuously during the silent recording period. In eight subjects, relative negative potentials were recorded during imagery sessions (compared with potentials in control sessions), with timing that was similar to that of the guide sounds. Activity in the left frontal region was more significant than that in other areas during beat imagination. These data indicate that a semantic strategy for simple rhythm imagery might involve temporary phasic activation in the left frontal area, although rhythm production and perception might be generated in the right side, as reported in previous studies. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Correlation between event-related potentials and MR measurements in chronic alcoholic patients

    International Nuclear Information System (INIS)

    Kaseda, Yumiko; Miyazato, Yoshikazu; Ogura, Chikara; Nakamoto, Haruo; Uema, Takeshi; Yamamoto, Kazuyoshi; Ohta, Ikuya

    1994-01-01

    Event-related potentials were recorded in 25 abstinent alcoholics, and 25 gender- and age-matched controls during a two-tone discrimination (odd ball) task. All the subjects were free from medication and dextral. MR images were examined in the alcoholics. The amplitudes of N100, N200 and P300 in the alcoholics were reduced compared with those of the controls. In order to identify morphological changes responsible for ERP abnormalities, linear regression analyses were performed between ERP measures and MRI parameters. The amplitude of N100 was inversely correlated with ventricular size. The amplitudes of P300 were inversely correlated with both ventricular size and width of cortical sulci. It was suggested that the N100 abnormality was related to subcortical structure, and P300 alteration was related to both subcortical and cortical structures in the alcoholics. (author)

  4. The correlation between motor impairments and event-related desynchronization during motor imagery in ALS patients

    Directory of Open Access Journals (Sweden)

    Kasahara Takashi

    2012-06-01

    Full Text Available Abstract Background The event-related desynchronization (ERD in EEG is known to appear during motor imagery, and is thought to reflect cortical processing for motor preparation. The aim of this study is to examine the modulation of ERD with motor impairment in ALS patients. ERD during hand motor imagery was obtained from 8 ALS patients with a variety of motor impairments. ERD was also obtained from age-matched 11 healthy control subjects with the same motor task. The magnitude and frequency of ERD were compared between groups for characterization of ALS specific changes. Results The ERD of ALS patients were significantly smaller than those of control subjects. Bulbar function and ERD were negatively correlated in ALS patients. Motor function of the upper extremities did was uncorrelated with ERD. Conclusions ALS patients with worsened bulbar scales may show smaller ERD. Motor function of the upper extremities did was uncorrelated with ERD.

  5. Human event-related brain potentials to auditory periodic noise stimuli.

    Science.gov (United States)

    Kaernbach, C; Schröger, E; Gunter, T C

    1998-02-06

    Periodic noise is perceived as different from ordinary non-repeating noise due to the involvement of echoic memory. Since this stimulus does not contain simple physical cues (such as onsets or spectral shape) that might obscure sensory memory interpretations, it is a valuable tool to study sensory memory functions. We demonstrated for the first time that the processing of periodic noise can be tapped by event-related brain potentials (ERPs). Human subjects received repeating segments of noise embedded in non-repeating noise. They were instructed to detect the periodicity inherent to the stimulation. We observed a central negativity time-locked on the periodic segment that correlated to the subjects behavioral performance in periodicity detection. It is argued that the ERP result indicates an enhancement of sensory-specific processing.

  6. Event-related brain potentials reflect traces of echoic memory in humans.

    Science.gov (United States)

    Winkler, I; Reinikainen, K; Näätänen, R

    1993-04-01

    In sequences of identical auditory stimuli, infrequent deviant stimuli elicit an event-related brain potential component called mismatch negativity (MMN). MMN is presumed to reflect the existence of a memory trace of the frequent stimulus at the moment of presentation of the infrequent stimulus. This hypothesis was tested by applying the recognition-masking paradigm of cognitive psychology. In this paradigm, a masking sound presented shortly before or after a test stimulus diminishes the recognition memory of this stimulus, the more so the shorter the interval between the test and masking stimuli. This interval was varied in the present study. It was found that the MMN amplitude strongly correlated with the subject's ability to discriminate between frequent and infrequent stimuli. This result strongly suggests that MMN provides a measure for a trace of sensory memory, and further, that with MMN, this memory can be studied without performance-related distortions.

  7. Bilingualism and increased attention to speech: Evidence from event-related potentials.

    Science.gov (United States)

    Kuipers, Jan Rouke; Thierry, Guillaume

    2015-10-01

    A number of studies have shown that from an early age, bilinguals outperform their monolingual peers on executive control tasks. We previously found that bilingual children and adults also display greater attention to unexpected language switches within speech. Here, we investigated the effect of a bilingual upbringing on speech perception in one language. We recorded monolingual and bilingual toddlers' event-related potentials (ERPs) to spoken words preceded by pictures. Words matching the picture prime elicited an early frontal positivity in bilingual participants only, whereas later ERP amplitudes associated with semantic processing did not differ between groups. These results add to the growing body of evidence that bilingualism increases overall attention during speech perception whilst semantic integration is unaffected. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  8. Multiple sources of positive- and negative-priming effects: an event-related potential study.

    Science.gov (United States)

    Gibbons, Henning; Rammsayer, Thomas H; Stahl, Jutta

    2006-01-01

    Event-related potential correlates of positive priming (PP) and negative priming (NP) were investigated in order to further elucidate the cognitive mechanisms involved. Thirty-six participants performed both an identity- and a location-based priming task. Repeating the target stimulus/location from the immediately preceding display produced behavioral PP. With localization, but not with identification, behavioral NP was observed when the target stimulus/location matched the preceding distractor stimulus/location. Smaller P300 amplitude accompanied identity-based PP, suggesting persisting target-specific activation. The lateralized readiness potential, an index of correct/incorrect response activation, indicated persisting central motor activation as another source of PP. Both location-based PP and NP were accompanied by reduced P1/N1 and P300 amplitudes, pointing to the involvement of inhibition of return in location-based priming. The results support the view that multiple brain processes underlie behavioral priming.

  9. Additive effects of repetition and predictability during comprehension: evidence from event-related potentials.

    Directory of Open Access Journals (Sweden)

    Wing-Yee Chow

    Full Text Available Previous research has shown that neural responses to words during sentence comprehension are sensitive to both lexical repetition and a word's predictability in context. While previous research has often contrasted the effects of these variables (e.g. by looking at cases in which word repetition violates sentence-level constraints, little is known about how they work in tandem. In the current study we examine how recent exposure to a word and its predictability in context combine to impact lexical semantic processing. We devise a novel paradigm that combines reading comprehension with a recognition memory task, allowing for an orthogonal manipulation of a word's predictability and its repetition status. Using event-related brain potentials (ERPs, we show that word repetition and predictability have qualitatively similar and additive effects on the N400 amplitude. We propose that prior exposure to a word and predictability impact lexical semantic processing in an additive and independent fashion.

  10. Attentional Selection Accompanied by Eye Vergence as Revealed by Event-Related Brain Potentials.

    Science.gov (United States)

    Sole Puig, Maria; Pallarés, Josep Marco; Perez Zapata, Laura; Puigcerver, Laura; Cañete, Josep; Supèr, Hans

    2016-01-01

    Neural mechanisms of attention allow selective sensory information processing. Top-down deployment of visual-spatial attention is conveyed by cortical feedback connections from frontal regions to lower sensory areas modulating late stimulus responses. A recent study reported the occurrence of small eye vergence during orienting top-down attention. Here we assessed a possible link between vergence and attention by comparing visual event related potentials (vERPs) to a cue stimulus that induced attention to shift towards the target location to the vERPs to a no-cue stimulus that did not trigger orienting attention. The results replicate the findings of eye vergence responses during orienting attention and show that the strength and time of eye vergence coincide with the onset and strength of the vERPs when subjects oriented attention. Our findings therefore support the idea that eye vergence relates to and possibly has a role in attentional selection.

  11. Processing of emotional faces in congenital amusia: An emotional music priming event-related potential study.

    Science.gov (United States)

    Zhishuai, Jin; Hong, Liu; Daxing, Wu; Pin, Zhang; Xuejing, Lu

    2017-01-01

    Congenital amusia is characterized by lifelong impairments in music perception and processing. It is unclear whether pitch detection deficits impact amusic individuals' perception of musical emotion. In the current work, 19 amusics and 21 healthy controls were subjected to electroencephalography (EEG) while being exposed to music excerpts and emotional faces. We assessed each individual's ability to discriminate positive- and negative-valenced emotional faces and analyzed electrophysiological indices, in the form of event-related potentials (ERPs) recorded at 32 sites, following exposure to emotionally positive or negative music excerpts. We observed smaller N2 amplitudes in response to facial expressions in the amusia group than in the control group, suggesting that amusics were less affected by the musical stimuli. The late-positive component (LPC) in amusics was similar to that in controls. Our results suggest that the neurocognitive deficit characteristic of congenital amusia is fundamentally an impairment in musical information processing rather than an impairment in emotional processing.

  12. Processing of emotional faces in congenital amusia: An emotional music priming event-related potential study

    Directory of Open Access Journals (Sweden)

    Jin Zhishuai

    2017-01-01

    Full Text Available Congenital amusia is characterized by lifelong impairments in music perception and processing. It is unclear whether pitch detection deficits impact amusic individuals' perception of musical emotion. In the current work, 19 amusics and 21 healthy controls were subjected to electroencephalography (EEG while being exposed to music excerpts and emotional faces. We assessed each individual's ability to discriminate positive- and negative-valenced emotional faces and analyzed electrophysiological indices, in the form of event-related potentials (ERPs recorded at 32 sites, following exposure to emotionally positive or negative music excerpts. We observed smaller N2 amplitudes in response to facial expressions in the amusia group than in the control group, suggesting that amusics were less affected by the musical stimuli. The late-positive component (LPC in amusics was similar to that in controls. Our results suggest that the neurocognitive deficit characteristic of congenital amusia is fundamentally an impairment in musical information processing rather than an impairment in emotional processing.

  13. Information structure influences depth of syntactic processing: event-related potential evidence for the Chomsky illusion.

    Science.gov (United States)

    Wang, Lin; Bastiaansen, Marcel; Yang, Yufang; Hagoort, Peter

    2012-01-01

    Information structure facilitates communication between interlocutors by highlighting relevant information. It has previously been shown that information structure modulates the depth of semantic processing. Here we used event-related potentials to investigate whether information structure can modulate the depth of syntactic processing. In question-answer pairs, subtle (number agreement) or salient (phrase structure) syntactic violations were placed either in focus or out of focus through information structure marking. P600 effects to these violations reflect the depth of syntactic processing. For subtle violations, a P600 effect was observed in the focus condition, but not in the non-focus condition. For salient violations, comparable P600 effects were found in both conditions. These results indicate that information structure can modulate the depth of syntactic processing, but that this effect depends on the salience of the information. When subtle violations are not in focus, they are processed less elaborately. We label this phenomenon the Chomsky illusion.

  14. Auditory event-related responses to diphthongs in different attention conditions

    DEFF Research Database (Denmark)

    Morris, David Jackson; Steinmetzger, Kurt; Tøndering, John

    2016-01-01

    (i) attended to the auditory stimuli, (ii) ignored the auditory stimuli and watched a film, and (iii) diverted their attention to a visual discrimination task. Responses elicited by diphthongs where F2 values rose and fell were found to be different and this precluded their combined analysis......The modulation of auditory event-related potentials (ERP) by attention generally results in larger amplitudes when stimuli are attended. We measured the P1-N1-P2 acoustic change complex elicited with synthetic overt (second formant, F2 = 1000 Hz) and subtle (F2 = 100 Hz) diphthongs, while subjects...... quality transitions, even when the attention of a subject is diverted to an unrelated visual task....

  15. A new method for detecting interactions between the senses in event-related potentials

    DEFF Research Database (Denmark)

    Gondan, Matthias; Röder, B.

    2006-01-01

    Event-related potentials (ERPs) can be used in multisensory research to determine the point in time when different senses start to interact, for example, the auditory and the visual system. For this purpose, the ERP to bimodal stimuli (AV) is often compared to the sum of the ERPs to auditory (A......) and visual (V) stimuli: AV - (A + V). If the result is non-zero, this is interpreted as an indicator for multisensory interactions. Using this method, several studies have demonstrated auditory-visual interactions as early as 50 ms after stimulus onset. The subtraction requires that A, V, and AV do...... not contain common activity: This activity would be subtracted twice from one ERP and would, therefore, contaminate the result. In the present study, ERPs to unimodal, bimodal, and trimodal auditory, visual, and tactile stimuli (T) were recorded. We demonstrate that (T + TAV) - (TA + TV) is equivalent to AV...

  16. Event-related brain potential evidence for animacy processing asymmetries during sentence comprehension.

    Science.gov (United States)

    Nieuwland, Mante S; Martin, Andrea E; Carreiras, Manuel

    2013-08-01

    The animacy distinction is deeply rooted in the language faculty. A key example is differential object marking, the phenomenon where animate sentential objects receive specific marking. We used event-related potentials to examine the neural processing consequences of case-marking violations on animate and inanimate direct objects in Spanish. Inanimate objects with incorrect prepositional case marker 'a' ('al suelo') elicited a P600 effect compared to unmarked objects, consistent with previous literature. However, animate objects without the required prepositional case marker ('el obispo') only elicited an N400 effect compared to marked objects. This novel finding, an exclusive N400 modulation by a straightforward grammatical rule violation, does not follow from extant neurocognitive models of sentence processing, and mirrors unexpected "semantic P600" effects for thematically problematic sentences. These results may reflect animacy asymmetry in competition for argument prominence: following the article, thematic interpretation difficulties are elicited only by unexpectedly animate objects. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. Pharmacodynamic Modelling of Placebo and Buprenorphine Effects on Event-Related Potentials in Experimental Pain

    DEFF Research Database (Denmark)

    Juul, Rasmus V; Foster, David J R; Upton, Richard N

    2014-01-01

    The purpose of the study was to investigate placebo and buprenorphine effects on event-related potentials (ERPs) in experimental pain and the potential benefit of population pharmacodynamic modelling in data analysis. Nineteen healthy volunteers received transdermal placebo and buprenorphine...... in a cross-over study. Drug plasma concentrations and ERPs after electrical stimulation at the median nerve with intensity adjusted to pain detection threshold were recorded until 144 hrs after administration. Placebo and concentration-effect models were fitted to data using non-linear mixed-effects...... modelling implemented in NONMEM (V7.2.0.). Pharmacodynamic models were developed to adequately describe both placebo and buprenorphine ERP data. Models predicted significant placebo effects, but did not predict significant effects related to buprenorphine concentration. Models revealed that ERPs varied both...

  18. Effects of rearranged vision on event-related lateralizations of the EEG during pointing.

    Science.gov (United States)

    Berndt, Isabelle; Franz, Volker H; Bülthoff, Heinrich H; Gotz, Karl G; Wascher, Edmund

    2005-01-01

    We used event-related lateralizations of the EEG (ERLs) and reversed vision to study visuomotor processing with conflicting proprioceptive and visual information during pointing. Reversed vision decreased arm-related lateralization, probably reflecting the simultaneous activity of left and right arm specific neurons: neurons in the hemisphere contralateral to the observed action were probably activated by visual feedback, neurons in the hemisphere contralateral to the response side by the somatomotor feedback. Lateralization related to the target in parietal cortex increased, indicating that visual to motor transformation in parietal cortex required additional time and resources with reversed vision. A short period of adaptation to an additional lateral displacement of the visual field increased arm-contralateral activity in parietal cortex during the movement. This is in agreement with the, which showed that adaptation to a lateral displacement of the visual field is reflected in increased parietal involvement during pointing.

  19. The impact of transcranial magnetic stimulation on cognitive processing: an event-related potential study.

    Science.gov (United States)

    Evers, S; Böckermann, I; Nyhuis, P W

    2001-09-17

    Several neuropsychological studies have shown that repetitive transcranial magnetic stimulation (rTMS) can improve cognitive processing. We performed a study on the impact of rTMS on cognitive processing as measured by a neurophysiological method. In 14 healthy subjects, visually evoked event-related potentials (ERP) and mean choice reaction time were measured before and after 20 Hz rTMS of the left and of the right prefrontal cortex. The data were compared to sham stimulation and to 1 Hz single TMS. P3 latencies and reaction time were significantly decreased by rTMS of the left but not of the right prefrontal cortex, single TMS did not have any significant impact on the ERP components. We conclude that the facilitating effects of rTMS on cognitive processing can be proven even by objective neurophysiological measures.

  20. Adverse Health Events Related to Self-Medication Practices Among Elderly: A Systematic Review.

    Science.gov (United States)

    Locquet, Médéa; Honvo, Germain; Rabenda, Véronique; Van Hees, Thierry; Petermans, Jean; Reginster, Jean-Yves; Bruyère, Olivier

    2017-05-01

    Older adults often resort to self-medication to relieve symptoms of their current illnesses; however, the risks of this practice are multiplied in old age. In particular, this age group is more vulnerable to adverse drug events because of the physiological changes that occur due to senescence. The aim of the study was to obtain an overview of the adverse health events related to self-medication among subjects aged 60 years and over through a systematic review of the literature. A study of relevant articles was conducted among databases (MEDLINE, PsycINFO, and EBM Reviews-Cochrane Database of Systematic Reviews). Eligibility criteria were established and applied by two investigators to include suitable studies. The results and outcomes of interest were detailed in a descriptive report. The electronic search identified 4096 references, and the full texts of 74 were reviewed, of which four were retained in the analysis: three had a cross-sectional design and one prospectively followed elderly subjects. The first study showed a 26.7% prevalence of adverse drug reactions (ADRs) among elders, the second study found a 75% prevalence of side effects, and, finally, a prospective study showed an ADR incidence of 4.5% among self-medicated elders. These studies showed that adverse health events related to self-medication are relatively frequently reported. They also highlighted that analgesics and anti-inflammatory drugs are the most self-medicated products, while vitamins and dietary supplements also appear to be frequently self-administered, but by older individuals. Studies on self-medication in the elderly and its adverse health effects are clearly lacking. There is a need to perform prospective studies on this topic to gain a clear understanding of the extent of this problem and to enhance the awareness of health professionals to better inform seniors.

  1. Self-Referential Processing in Adolescents: Stability of Behavioral and Event-Related Potential Markers

    Science.gov (United States)

    Auerbach, Randy P.; Bondy, Erin; Stanton, Colin H.; Webb, Christian A.; Shankman, Stewart A.; Pizzagalli, Diego A.

    2016-01-01

    The self-referential encoding task (SRET)—an implicit measure of self-schema—has been used widely to probe cognitive biases associated with depression, including among adolescents. However, research testing the stability of behavioral and electrocortical effects is sparse. Therefore, the current study sought to evaluate the stability of behavioral markers and event-related potentials (ERP) elicited from the SRET over time in healthy, female adolescents (n = 31). At baseline, participants were administered a diagnostic interview and a self-report measure of depression severity. In addition, they completed the SRET while 128-channel event-related potential (ERP) data were recorded to examine early (P1) and late (late positive potential [LPP]) ERPs. Three months later, participants were re-administered the depression self-report measure and the SRET in conjunction with ERPs. Results revealed that healthy adolescents endorsed, recalled, and recognized more positive and fewer negative words at each assessment, and these effects were stable over time (rs = 0.44–0.83). Similarly, they reported a faster reaction time when endorsing self-relevant positive words, as opposed to negative words, at both the initial and follow-up assessment (r = 0.82). Second, ERP responses, specifically potentiated P1 and late LPP positivity to positive versus negative words, were consistent over time (rs = 0.56–0.83), and the internal reliability of ERPs were robust at each time point (rs = 0.52–0.80). As a whole, these medium-to-large effects suggest that the SRET is a reliable behavioral and neural probe of self-referential processing. PMID:27302282

  2. [Differential effects of attention deficit/hyperactivity disorder subtypes in event-related potentials].

    Science.gov (United States)

    Tamayo-Orrego, Lukas; Osorio Forero, Alejandro; Quintero Giraldo, Lina Paola; Parra Sánchez, José Hernán; Varela, Vilma; Restrepo, Francia

    2015-01-01

    To better understand the neurophysiological substrates in attention deficit/hyperactivity disorder (ADHD), a study was performed on of event-related potentials (ERPs) in Colombian patients with inattentive and combined ADHD. A case-control, cross-sectional study was designed. The sample was composed of 180 subjects between 5 and 15 years of age (mean, 9.25±2.6), from local schools in Manizales. The sample was divided equally in ADHD or control groups and the subjects were paired by age and gender. The diagnosis was made using the DSM-IV-TR criteria, the Conners and WISC-III test, a psychiatric interview (MINIKID), and a medical evaluation. ERPs were recorded in a visual and auditory passive oddball paradigm. Latency and amplitude of N100, N200 and P300 components for common and rare stimuli were used for statistical comparisons. ADHD subjects show differences in the N200 amplitude and P300 latency in the auditory task. The N200 amplitude was reduced in response to visual stimuli. ADHD subjects with combined symptoms show a delayed P300 in response to auditory stimuli, whereas inattentive subjects exhibited differences in the amplitude of N100 and N200. Combined ADHD patients showed longer N100 latency and smaller N200-P300 amplitude compared to inattentive ADHD subjects. The results show differences in the event-related potentials between combined and inattentive ADHD subjects. Copyright © 2014 Asociación Colombiana de Psiquiatría. Publicado por Elsevier España. All rights reserved.

  3. Best Practices for Event-Related Potential Research in Clinical Populations.

    Science.gov (United States)

    Kappenman, Emily S; Luck, Steven J

    2016-03-01

    The event-related potential (ERP) technique has been used for decades to answer important questions about sensory, cognitive, motor, and emotion-related processes in clinical disorders. However, ERP research with clinical populations often involves unique challenges above and beyond the general issues involved in conducting ERP studies in typical research participants. The goal of this paper is to provide an overview of the common challenges that arise in ERP research with clinical populations, including issues in experimental design, recording, analysis, and interpretation of ERPs. In addition, we provide strategies that have proven effective in each of these areas for maximizing the potential of the ERP technique to provide important insights about clinical disorders. The event-related potential (ERP) technique has been used for decades to assess sensory, cognitive, motor, and emotion-related processes in individuals with clinical disorders, and it has great promise for yielding new insights in the future. However, many complex methodological challenges arise in applying this technique to clinical populations, and these challenges must be overcome for the ERP technique to live up to its potential. The goal of this paper is to describe some of the most salient challenges and provide effective strategies for dealing with them. Our own experience has been mainly in schizophrenia, but much of the information presented here applies to any clinical population. We focus our discussion on traditional approaches to ERPs, for which methods been refined over many decades. Information about newer approaches, such as time-frequency analysis, can be found elsewhere (1; 2). We begin with a brief overview of the ERP technique, followed by a discussion of the challenges in designing experiments, practical considerations in recording and analysis, and issues in interpreting ERP effects. The present article is necessarily brief and focused, but broader reviews are available

  4. Auditory event-related brain potentials for an early discrimination between normal and pathological brain aging.

    Science.gov (United States)

    Dushanova, Juliana; Christov, Mario

    2013-05-25

    The brain as a system with gradually decreasing resources maximizes its chances by reorganizing neural networks to ensure efficient performance. Auditory event-related potentials were recorded in 28 healthy volunteers comprising 14 young and 14 elderly subjects in auditory discrimination motor task (low frequency tone - right hand movement and high frequency tone - left hand movement). The amplitudes of the sensory event-related potential components (N1, P2) were more pronounced with increasing age for either tone and this effect for P2 amplitude was more pronounced in the frontal region. The latency relationship of N1 between the groups was tone-dependent, while that of P2 was tone-independent with a prominent delay in the elderly group over all brain regions. The amplitudes of the cognitive components (N2, P3) diminished with increasing age and the hemispheric asymmetry of N2 (but not for P3) reduced with increasing age. Prolonged N2 latency with increasing age was widespread for either tone while between-group difference in P3 latency was tone-dependent. High frequency tone stimulation and movement requirements lead to P3 delay in the elderly group. The amplitude difference of the sensory components between the age groups could be due to a general greater alertness, less expressed habituation, or decline in the ability to retreat attentional resources from the stimuli in the elderly group. With aging, a neural circuit reorganization of the brain activity affects the cognitive processes. The approach used in this study is useful for an early discrimination between normal and pathological brain aging for early treatment of cognitive alterations and dementia.

  5. A cognitive stressor for event-related potential studies: the Portland arithmetic stress task.

    Science.gov (United States)

    Atchley, Rachel; Ellingson, Roger; Klee, Daniel; Memmott, Tabatha; Oken, Barry

    2017-05-01

    In this experiment, we developed and evaluated the Portland Arithmetic Stress Task (PAST) as a cognitive stressor to evaluate acute and sustained stress reactivity for event-related potential (ERP) studies. The PAST is a titrated arithmetic task adapted from the Montreal Imaging Stress Task (MIST), with added experimental control over presentation parameters, improved and synchronized acoustic feedback and generation of timing markers needed for physiological analyzes of real-time brain activity. Thirty-one older adults (M = 60 years) completed the PAST. EEG was recorded to assess feedback-related negativity (FRN) and the magnitude of the stress response through autonomic nervous system activity and salivary cortisol. Physiological measures other than EEG included heart rate, respiration rate, heart rate variability, blood pressure and salivary cortisol. These measures were collected at several time points throughout the task. Feedback-related negativity evoked-potential responses were elicited and they significantly differed depending on whether positive or negative feedback was received. The PAST also increased systolic blood pressure, heart rate variability and respiration rates compared to a control condition attentional task. These preliminary results suggest that the PAST is an effective cognitive stressor. Successful measurement of the feedback-related negativity suggests that the PAST is conducive to EEG and time-sensitive ERP experiments. Moreover, the physiological findings support the PAST as a potent method for inducing stress in older adult participants. Further research is needed to confirm these results, but the PAST shows promise as a tool for cognitive stress induction for time-locked event-related potential experiments.

  6. Resilience to traumatic events related to urban violence and increased IL10 serum levels.

    Science.gov (United States)

    Teche, Stefania P; Rovaris, Diego L; Aguiar, Bianca W; Hauck, Simone; Vitola, Eduardo S; Bau, Claiton H D; Freitas, Lucia H; Grevet, Eugenio H

    2017-04-01

    The exposition to traumatic events related to urban violence is epidemic in Brazil, with rate of 80% in the general population, and is becoming a major cause of post-traumatic stress disorder (PTSD). The objective of the study was to compare serum levels of pro-inflammatory interleukin-6 (IL-6) and anti-inflammatory interleukin-10 (IL-10) in PTSD and resilient individuals. We hypothesized that resilient individuals present an attenuated pro-inflammatory and enhanced anti-inflammatory state. We conducted a case-control study comparing 30 resilient individuals and 30 PTSD patients exposed to traumatic events related to urban violence. The groups were evaluated using Self-Report Questionnaire (SRQ-20), Mini-International Neuropsychiatric Interview (MINI) and the Davidson Trauma Scale. For all individuals, blood samples were collected to determine IL-6, IL-10 and cortisol serum levels. All samples were frozen at -80°C until the assay and were analyzed with the same immunoassay kit and in duplicates. The resilient group presented higher IL-10 levels than PTSD patients [mean (CI95%); 1.03 (0.52-2.08) pg/mL vs. 0.29 (0.20-0.43) pg/mL; P=0.002]. There were no differences in terms of IL-6 or cortisol levels. The results provided evidence for increased levels of IL-10 in resilient individuals when compared to PTSD patients, probably conferring them a better anti-inflammatory response after exposition. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  7. On the possibility of developing incoherent fibre-optic data transmission systems based on signal spectral coding with matched acousto-optical filters

    International Nuclear Information System (INIS)

    Proklov, Valerii V; Byshevski-Konopko, O A; Grigorievski, V I

    2013-01-01

    The scheme is suggested for developing the optical communication line based on the principle of code division of multiple access with matched acousto-optical filters and a 16-bit long Walsh sequence. Results of modelling show that such a line can operate if adjacent spectral lines are separated by at least double the Rayleigh criterion. (optical information transmission)

  8. Optical coherence tomography signal analysis: LIDAR like equation and inverse methods; Analise de sinais de tomografia por coerencia optica: equacao LIDAR e metodos de inversao

    Energy Technology Data Exchange (ETDEWEB)

    Amaral, Marcello Magri

    2012-07-01

    Optical Coherence Tomography (OCT) is based on the media backscattering properties in order to obtain tomographic images. In a similar way, LIDAR (Light Detection and Range) technique uses these properties to determine atmospheric characteristics, specially the signal extinction coefficient. Exploring this similarity allowed the application of signal inversion methods to the OCT images, allowing to construct images based in the extinction coefficient, original result until now. The goal of this work was to study, propose, develop and implement algorithms based on OCT signal inversion methodologies with the aim of determine the extinction coefficient as a function of depth. Three inversion methods were used and implemented in LABView{sup R}: slope, boundary point and optical depth. Associated errors were studied and real samples (homogeneous and stratified) were used for two and three dimension analysis. The extinction coefficient images obtained from the optical depth method were capable to differentiate air from the sample. The images were studied applying PCA and cluster analysis that established the methodology strength in determining the sample's extinction coefficient value. Moreover, the optical depth methodology was applied to study the hypothesis that there is some correlation between signal extinction coefficient and the enamel teeth demineralization during a cariogenic process. By applying this methodology, it was possible to observe the variation of the extinction coefficient as depth function and its correlation with microhardness variation, showing that in deeper layers its values tends to a healthy tooth values, behaving as the same way that the microhardness. (author)

  9. Substrate-mediated sub-diffraction guiding of optical signals through a linear chain of metal nanoparticles : Polarization dependence and the role of the dispersion relation

    NARCIS (Netherlands)

    Compaijen, P.J.; Malyshev, V.A.; Knoester, J.

    We theoretically investigate the efficiency of transmitting optical signals through a linear chain consisting of identical and equidistantly spaced silver nanoparticles in the presence of a reflecting substrate. The energy exchange between surface plasmon polaritons of the chain and the substrate

  10. The application of the signal flow graph method to charged-particle optics - the formula derivation of a three-sector isotope separator

    International Nuclear Information System (INIS)

    Lu Hongyou; Zhao Zhiyong; Sun Quinren

    1987-01-01

    A brief introduction of the Signal Flow Graph (SFG) method is given. The application of it to charged-particle optics (CPO) is described. The method has the advantages of simplicity, visualisation and computerisation. An example of the application of SFG is given for the design of a three-sector electromagnetic isotope separator. (orig.)

  11. The application of the signal flow graph method to charged-particle optics: The formula derivation of a three-sector isotope separator

    International Nuclear Information System (INIS)

    Lu, H.; Zhao, Z.; Sun, Q.

    1987-01-01

    A brief introduction of the Signal Flow Graph (SFG) Method is given. The application of it to charged-particle optics (CPO) is described. The method has the advantages of simplicity, visualisation and computerisation. An example of the application of SFG is given for the design of a three-sector electromagnetic isotope separator

  12. Wide range operation of regenerative optical parametric wavelength converter using ASE-degraded 43-Gb/s RZ-DPSK signals.

    Science.gov (United States)

    Gao, Mingyi; Kurumida, Junya; Namiki, Shu

    2011-11-07

    For sustainable growth of the Internet, wavelength-tunable optical regeneration is the key to scaling up high energy-efficiency dynamic optical path networks while keeping the flexibility of the network. Wavelength-tunable optical parametric regenerator (T-OPR) based on the gain saturation effect of parametric amplification in a highly nonlinear fiber is promising for noise reduction in phase-shift keying signals. In this paper, we experimentally evaluated the T-OPR performance for ASE-degraded 43-Gb/s RZ-DPSK signals over a 20-nm input wavelength range between 1527 nm and 1547 nm. As a result, we achieved improved power penalty performance for the regenerated idler with a proper pump power range.

  13. Division Multiplexing of 10 Gbit/s Ethernet Signals Synchronized by All-Optical Signal Processing Based on a Time-Lens

    DEFF Research Database (Denmark)

    Areal, Janaina Laguardia

    This Thesis presents 3 years work of an optical circuit that performs both pulse compression and frame synchronization and retiming. Our design aims at directly multiplexing several 10G Ethernet data packets (frames) to a high-speed OTDM link. This scheme is optically trans-parent and does...... pulse compression, as well. The over-all design is: (1) Pulses are converted from NRZ to RZ; (2) pulses are synchronized, retimed and further compressed at the specially de-signed time-lens; and (3) with adequate optical delays, frames from different input interfaces are added, with a simple optical...

  14. The cooperation of the functional activation areas in human brain: an application of event-related fMRI study of the voluntary motor function

    International Nuclear Information System (INIS)

    Li Enzhong; Tian Jie; Dai Ruwei

    2002-01-01

    Objective: To detect the cooperation of the functional activation areas in human brain using event-related fMRI technique developed in recent years. Methods: Forty-four subjects were selected in this experiment and scanned by GE Signa Horizon 1.5 Tesla superconductive MR system. A CUE-GO paradigm was used in this experiment. The data were analyzed in SUN and SGI workstation. Results: The activation areas were found in contralateral primary motor area (Ml), bilateral supplementary motor areas (SMA), pre-motor areas (PMA), basal ganglia, and cerebellar cortices. The time-signal curve of Ml was a typical single-peak curve, but the curves in PMA, basal ganglia, and cerebellar cortices were double-peak curves. SMA had 2 parts, one was Pre-SMA, and another was SMA Proper. The curve was double-peak type in Pre-SMA and single-peak type in SMA Proper. There was difference between the time-signal intensity curves in above-mentioned areas. Conclusion: (1) Ml is mainly associated with motor execution, while others with both motor preparation and execution. There are differences in the function at the variant areas in the brain. (2) The fact that bilateral SMA, PMA, basal ganglia, and cerebellar cortices were activated, is different from what the classical theories told. (3) Event-related fMRI technique has higher temporary and spatial resolutions. (4) There is cooperation among different cortical areas, basal ganglia, and cerebellum

  15. Signal transmission in a human body medium-based body sensor network using a Mach-Zehnder electro-optical sensor.

    Science.gov (United States)

    Song, Yong; Hao, Qun; Zhang, Kai; Wang, Jingwen; Jin, Xuefeng; Sun, He

    2012-11-30

    The signal transmission technology based on the human body medium offers significant advantages in Body Sensor Networks (BSNs) used for healthcare and the other related fields. In previous works we have proposed a novel signal transmission method based on the human body medium using a Mach-Zehnder electro-optical (EO) sensor. In this paper, we present a signal transmission system based on the proposed method, which consists of a transmitter, a Mach-Zehnder EO sensor and a corresponding receiving circuit. Meanwhile, in order to verify the frequency response properties and determine the suitable parameters of the developed system, in-vivo measurements have been implemented under conditions of different carrier frequencies, baseband frequencies and signal transmission paths. Results indicate that the proposed system will help to achieve reliable and high speed signal transmission of BSN based on the human body medium.

  16. Exogenous Modulation of Retinoic Acid Signaling Affects Adult RGC Survival in the Frog Visual System after Optic Nerve Injury.

    Directory of Open Access Journals (Sweden)

    Mildred V Duprey-Díaz

    Full Text Available After lesions to the mammalian optic nerve, the great majority of retinal ganglion cells (RGCs die before their axons have even had a chance to regenerate. Frog RGCs, on the other hand, suffer only an approximately 50% cell loss, and we have previously investigated the mechanisms by which the application of growth factors can increase their survival rate. Retinoic acid (RA is a vitamin A-derived lipophilic molecule that plays major roles during development of the nervous system. The RA signaling pathway is also present in parts of the adult nervous system, and components of it are upregulated after injury in peripheral nerves but not in the CNS. Here we investigate whether RA signaling affects long-term RGC survival at 6 weeks after axotomy. Intraocular injection of all-trans retinoic acid (ATRA, the retinoic acid receptor (RAR type-α agonist AM80, the RARβ agonist CD2314, or the RARγ agonist CD1530, returned axotomized RGC numbers to almost normal levels. On the other hand, inhibition of RA synthesis with disulfiram, or of RAR receptors with the pan-RAR antagonist Ro-41-5253, or the RARβ antagonist LE135E, greatly reduced the survival of the axotomized neurons. Axotomy elicited a strong activation of the MAPK, STAT3 and AKT pathways; this activation was prevented by disulfiram or by RAR antagonists. Finally, addition of exogenous ATRA stimulated the activation of the first two of these pathways. Future experiments will investigate whether these strong survival-promoting effects of RA are mediated via the upregulation of neurotrophins.

  17. Connectivity Reveals Sources of Predictive Coding Signals in Early Visual Cortex During Processing of Visual Optic Flow.

    Science.gov (United States)

    Schindler, Andreas; Bartels, Andreas

    2017-05-01

    Superimposed on the visual feed-forward pathway, feedback connections convey higher level information to cortical areas lower in the hierarchy. A prominent framework for these connections is the theory of predictive coding where high-level areas send stimulus interpretations to lower level areas that compare them with sensory input. Along these lines, a growing body of neuroimaging studies shows that predictable stimuli lead to reduced blood oxygen level-dependent (BOLD) responses compared with matched nonpredictable counterparts, especially in early visual cortex (EVC) including areas V1-V3. The sources of these modulatory feedback signals are largely unknown. Here, we re-examined the robust finding of relative BOLD suppression in EVC evident during processing of coherent compared with random motion. Using functional connectivity analysis, we show an optic flow-dependent increase of functional connectivity between BOLD suppressed EVC and a network of visual motion areas including MST, V3A, V6, the cingulate sulcus visual area (CSv), and precuneus (Pc). Connectivity decreased between EVC and 2 areas known to encode heading direction: entorhinal cortex (EC) and retrosplenial cortex (RSC). Our results provide first evidence that BOLD suppression in EVC for predictable stimuli is indeed mediated by specific high-level areas, in accord with the theory of predictive coding. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  18. Chiral recognition of tyrosine enantiomers based on decreased resonance scattering signals with silver nanoparticles as optical sensor.

    Science.gov (United States)

    Tan, Xuanping; Li, Qin; Shen, Yizhong; Wu, Huan; Zhao, Yanmei; Yang, Jidong

    2015-03-01

    A novel chiral sensing platform, employing silver nanoparticles capped with N-acetyl-L-cysteine (NALC-Ag NPs), was utilized for the discrimination of L-tyrosine and D-tyrosine. This nanosensor, which could be used as an optical sensing unit and chiral probe, was characterized by transmission electron microscopy (TEM) and resonance Rayleigh scattering (RRS) spectroscopy. After the proposed sensing platform interacted with L-tyrosine and D-tyrosine, a decreased resonance scattering signal was only obtained from L-tyrosine. This phenomenon offered a useful assay for the selectivity and determination of L-tyrosine with the RRS method. The linear range and detection limit of L-tyrosine were 0.2838-20.0 µg⋅mL(-1) and 0.0860 µg⋅mL(-1) , respectively. In addition, experimental factors such as acidity, interaction time, and the concentration of enantiomers were investigated with regard to the effect on enantioselective interaction. © 2014 Wiley Periodicals, Inc.

  19. Sensitive optical detection of an early metastatic tumor using a new cell line with enhanced luminescent and fluorescent signals

    Directory of Open Access Journals (Sweden)

    Yeon Joo Kim

    2011-10-01

    Full Text Available Animal models using cell lines that are dual-labeled with luciferase and green fluorescent protein (GFP are powerful tools for performing simultaneous quantitative and qualitative analysis of metastatic tumors. However, the applications of such dual-labeled tumor models have been limited due to the technical challenges associated with low bioluminescent signaling from tumor cells. Here, we used lentiviral vector (LV encoding firefly luciferase and GFP and engineered a more sensitive and highly metastatic prostate cancer cell line (MLL-Luc/GFP cells, which allows simultaneous fluorescence and luminescence imaging. The light emission of MLL-Luc/GFP cells was 33.5 fold higher than that of PC-3-luc2-GFP prostate cancer cells which showed 750 p/s light emission per cell. Furthermore, the MLL-Luc/GFP cells showed 3.9 fold higher luciferase activities than did 4T1-luc2, which was previously recognized as exhibiting the highest luciferase activity. An in vivo evaluation with optical imaging showed pinpoint localization of GFP-positive cells in a metastatic lung as well as easy detection of early metastatic spreading. The newly engineered MLL-Luc/GFP cells provide an appropriate metastatic animal model system for future studies of metastasis and the testing of anti-metastatic therapies specifically aimed at prostatic cancer.

  20. The neural and psychological basis of herding in purchasing books online: an event-related potential study.

    Science.gov (United States)

    Chen, Mingliang; Ma, Qingguo; Li, Minle; Dai, Shenyi; Wang, Xiaoyi; Shu, Liangchao

    2010-06-01

    In this study, event-related brain potentials (ERPs) were used to investigate the neural and psychological bases of consumer herding decision in purchasing books online. Sixteen participants were asked to decide as quickly as possible whether to buy a book on the basis of its title keywords and the numbers of positive and negative reviews in stimulus. The given title keywords were very similar, and participants did not have special preference for any particular one. Hence, they were forced to adopt the strategy of herding decision: choosing to buy the book when there were consistent positive reviews, choosing not to buy when there were consistent negative reviews, randomly choosing to buy or not to buy when there were no consistent reviews. The herding decision triggers a categorical processing of the consistency level of customer reviews. Remarkable late positive potential (LPP), a component of ERP sensitive to categorization processes, was elicited. The LPP amplitudes varied as a function of review consistency. The LPP amplitudes for three categories of review consistency were significantly different, and their order is such that absolute consistent review was greater than relative consistent review, which was greater than inconsistent review. In addition, behavioral data revealed that the higher the consistency of the customer reviews, the higher the herd rate. It is possible that customer reviews with higher consistency let participants make herding decisions more resolutely. The present results suggest that the LPP may be regarded as an endogenous neural signal of the herding mechanism in a sense and that the LPP amplitude is potentially a measure of consumers' herd tendency in purchase decisions.