Beyond nonlinear saturation of backward Raman amplifiers
Barth, Ido; Toroker, Zeev; Balakin, Alexey A.; Fisch, Nathaniel J.
2016-06-01
Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. Pump detuning is employed to mitigate the relativistic phase mismatch and to overcome the associated saturation. The amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. This detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small.
NONLINEAR EXPECTATIONS AND NONLINEAR MARKOV CHAINS
Institute of Scientific and Technical Information of China (English)
PENG SHIGE
2005-01-01
This paper deals with nonlinear expectations. The author obtains a nonlinear generalization of the well-known Kolmogorov's consistent theorem and then use it to construct filtration-consistent nonlinear expectations via nonlinear Markov chains. Compared to the author's previous results, i.e., the theory of g-expectations introduced via BSDE on a probability space, the present framework is not based on a given probability measure. Many fully nonlinear and singular situations are covered. The induced topology is a natural generalization of Lp-norms and L∞-norm in linear situations.The author also obtains the existence and uniqueness result of BSDE under this new framework and develops a nonlinear type of von Neumann-Morgenstern representation theorem to utilities and present dynamic risk measures.
Linear and nonlinear analysis of high-power rf amplifiers
International Nuclear Information System (INIS)
After a survey of the state variable analysis method the final amplifier for the CBA is analyzed taking into account the real beam waveshape. An empirical method for checking the stability of a non-linear system is also considered
Thermally induced nonlinear mode coupling in high power fiber amplifiers
DEFF Research Database (Denmark)
Johansen, Mette Marie; Hansen, Kristian Rymann; Alkeskjold, Thomas T.;
2013-01-01
Thermally induced nonlinear mode coupling leads to transverse mode instability (TMI) in high power fiber amplifiers. A numerical model including altering mode profiles from thermal effects and waveguide perturbations predicts a TMI threshold of ~200W.......Thermally induced nonlinear mode coupling leads to transverse mode instability (TMI) in high power fiber amplifiers. A numerical model including altering mode profiles from thermal effects and waveguide perturbations predicts a TMI threshold of ~200W....
On the unlimited gain of a nonlinear parametric amplifier
DEFF Research Database (Denmark)
Sorokin, Vladislav
2014-01-01
The present paper is concerned with analysis of the response of a nonlinear parametric amplifier in abroad range of system parameters, particularly beyond resonance. Such analysis is of particular interestfor micro- and nanosystems, since many small-scale parametric amplifiers exhibit a distinctly...... nonlinearbehavior when amplitude of their response is sufficiently large. The modified method of direct separa-tion of motions is employed to study the considered system. As the result it is obtained that steady-stateamplitude of the nonlinear parametric amplifier response can reach large values in the case...... of arbitrarilysmall amplitude of external excitation, so that the amplifier gain tends to infinity. Very large amplifiergain can be achieved in a broad range of system parameters, in particular when the amplitude of para-metric excitation is comparatively small. The obtained results clearly demonstrate that very...
Delocalized periodic vibrations in nonlinear electrical chains
Chechin, G. M.; Shcherbinin, S. A.
2013-01-01
We consider an electrical chain of N nonlinear capacitors coupled by linear inductors assuming that voltage dependence of capacitors represents an even function. We prove that only 5 symmetry determined nonlinear normal modes (NNM) can exist in the considered system. The stability of all these dynamical regimes for different N is studied with the aid of the group-theoretical method [Physical Review E 73 (2006) 36216] which allows to simplify radically the variational systems appearing in the ...
On the power amplifier nonlinearity in MIMO transmit beamforming systems
Qi, Jian
2012-03-01
In this paper, single-carrier multiple-input multiple-output (MIMO) transmit beamforming (TB) systems in the presence of high-power amplifier (HPA) nonlinearity are investigated. Specifically, due to the suboptimality of the conventional maximal ratio transmission/maximal ratio combining (MRT/MRC) under HPA nonlinearity, we propose the optimal TB scheme with the optimal beamforming weight vector and combining vector, for MIMO systems with nonlinear HPAs. Moreover, an alternative suboptimal but much simpler TB scheme, namely, quantized equal gain transmission (QEGT), is proposed. The latter profits from the property that the elements of the beamforming weight vector have the same constant modulus. The performance of the proposed optimal TB scheme and QEGT/MRC technique in the presence of the HPA nonlinearity is evaluated in terms of the average symbol error probability and mutual information with the Gaussian input, considering the transmission over uncorrelated quasi-static frequency-flat Rayleigh fading channels. Numerical results are provided and show the effects on the performance of several system parameters, namely, the HPA parameters, numbers of antennas, quadrature amplitude modulation modulation order, number of pilot symbols, and cardinality of the beamforming weight vector codebook for QEGT. © 2012 IEEE.
NONLINEAR CHARACTERIZATION OF CONCURRENT DUAL-BAND RF POWER AMPLIFIERS
Institute of Scientific and Technical Information of China (English)
Hui Ming; Liu Taijun; Ye Yan; Zhang Haili; Shen Dongya; Li Liang
2012-01-01
In this paper,the synchronous concurrent dual-band RF signal is used to drive the RF Power Amplifier (PA).The nonlinear characterization of a concurrent dual-band RF PA is discussed while two band signals in the dual-band are modulated by CDMA2000 and WCDMA signals.When the two band signals in the dual-band of the PA are modulated with the same signals,it is found that the nonlinearity of the PA can be expressed by any of the two corresponding baseband data.On the other hand,when the two band signals in the dual-band of the PA are modulated with two different signals,the PA nonlinearity cannot be characterized by any of the two corresponding baseband data.In this case,its nonlinearity has to be denoted by a composite signals consisting of the two baseband signals.Consequently,the requirements for the speed of the A/D converter can be largely reduced.The experimental results with CDMA2000 and WCDMA signals demonstrate the speed of the A/D converter required is only 30 M Sample Per Second (SaPS),but it will be at least 70 M SaPS for the conventional method.
Nonlinear gain dynamics of quantum dot optical amplifiers
International Nuclear Information System (INIS)
In this work, the ultrafast gain dynamics of a quantum dot (QD)-based semiconductor optical amplifier (SOA) is modeled on the basis of semiconductor Bloch equations that include microscopically calculated nonlinear scattering rates between QD carriers and the surrounding carrier reservoir. This enables us to separately study the dynamics of electrons and holes inside the device as well as the coherent effects related to the fast polarization dynamics. We show that the optical pulse power and the dephasing time of the polarization mainly affect the gain depletion inside the active region, while the electric injection current density and thus the internal carrier dynamics influence the gain recovery. We observe that carrier–carrier scattering is the source of desynchronized behavior of electrons and holes in the recovery dynamics of QD-based SOAs. The amplification of pulse trains in the SOA predicted by our model agrees well with experimental data
Compact surface plasmon amplifier in nonlinear hybrid waveguide
Shu-shu, Wang; Dan-qing, Wang; Xiao-peng, Hu; Tao, Li; Shi-ning, Zhu
2016-07-01
Surface plasmon polariton (SPP), a sub-wavelength surface wave promising for photonic integration, always suffers from the large metallic loss that seriously restricts its practical application. Here, we propose a compact SPP amplifier based on a nonlinear hybrid waveguide (a combination of silver, LiNbO3, and SiO2), where a couple of Bragg gratings are introduced in the waveguide to construct a cavity. This special waveguide is demonstrated to support a highly localized SPP-like hybrid mode and a low loss waveguide-like hybrid mode. To provide a large nonlinear gain, a pumping wave input from the LiNbO3 waveguide is designed to resonate inside the cavity and satisfy the cavity phase matching to fulfill the optical parametric amplification (OPA) of the SPP signal. Proper periods of gratings and the cavity length are chosen to satisfy the impedance matching condition to ensure the high input efficiency of the pump wave from the outside into the cavity. In theoretical calculations, this device demonstrates a high performance in a very compact scheme (∼ 3.32 μm) and a much lower pumping power for OPA compared with single-pass pumping. To obtain a comprehensive insight into this cavity OPA, the influences of the pumping power, cavity length, and the initial phase are discussed in detail. Project supported by the National Basic Research Program of China (Grant No. 2012CB921501), the National Natural Science Foundation of China (Grant Nos. 11322439, 11274165, 11321063, and 91321312), the Dengfeng Project B of Nanjing University, China, and the PAPD of Jiangsu Higher Education Institutions, China.
Augmented Twin-Nonlinear Two-Box Behavioral Models for Multicarrier LTE Power Amplifiers
Oualid Hammi
2014-01-01
A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory ef...
Augmented twin-nonlinear two-box behavioral models for multicarrier LTE power amplifiers.
Hammi, Oualid
2014-01-01
A novel class of behavioral models is proposed for LTE-driven Doherty power amplifiers with strong memory effects. The proposed models, labeled augmented twin-nonlinear two-box models, are built by cascading a highly nonlinear memoryless function with a mildly nonlinear memory polynomial with cross terms. Experimental validation on gallium nitride based Doherty power amplifiers illustrates the accuracy enhancement and complexity reduction achieved by the proposed models. When strong memory effects are observed, the augmented twin-nonlinear two-box models can improve the normalized mean square error by up to 3 dB for the same number of coefficients when compared to state-of-the-art twin-nonlinear two-box models. Furthermore, the augmented twin-nonlinear two-box models lead to the same performance as previously reported twin-nonlinear two-box models while requiring up to 80% less coefficients.
Institute of Scientific and Technical Information of China (English)
Wenhua Cao; Songhao Liu
2005-01-01
Stable picosecond soliton transmission is demonstrated numerically by use of concatenated gain-distributed nonlinear amplifying fiber loop mirrors (NALMs). We show that, as compared with previous soliton transmission schemes that use conventional NALMs or nonlinear optical loop mirror (NOLM) and amplifier combinations, the present scheme permits significant increase of loop-mirror (amplifier) spacing. The broad switching window of the present device and the high quality pulses switched from it provide a reasonable stability range for soliton transmission. Soliton-soliton interactions can be reduced efficiently by using lowly dispersive fibers.
The Simulation Analysis of Nonlinear for a Power Amplifier with Memory Effects
Directory of Open Access Journals (Sweden)
Lv. Jinqiu
2014-09-01
Full Text Available For the nonlinear distortion problem of current power amplifiers (PAs with memory effects, we use goal programming to present a memoryless predistorter matrix model based on limiting baseband predistortion technique, and the normalized mean squared error (NMSE is limited in a satisfactory range while the output power is maximum. Then we propose a nonlinear power amplifier with memory effects based on back propagation neural network (BPNN with three tapped delay nodes and six single hidden layer nodes, which is single input - dual output. Simulation results show that the method proposed in this paper makes the experimental precision higher. Further, the linearization effect of power amplifiers becomes better.
Nonlinear elastic waves in a monatomic chain with nonlinear interaction
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
Nonlinear wave equation for a one-dimensional anharmonic crystal lattice in terms of its microscopic parameters is obtained by means of a continuum approximation. Using a small time scale transformation, the nonlinear wave equation is reduced to a combined KdV equation and its single soliton solution yields the supersonic kink form of nonlinear elastic waves for the system.
Nguyen, Ba Phi; Kim, Kihong
2014-06-01
We study theoretically the influence of nonlinear gain effects on the transmission and the Anderson localization of waves in both uniform and random one-dimensional amplifying media by using the discrete nonlinear Schrödinger equation. In uniform amplifying media with nonlinear gain, we find that the strong oscillatory behavior of the transmittance and the reflectance for odd and even values of the sample length disappears for large nonlinearities. The exponential decay rate of the transmittance in the asymptotic limit is found to be independent of nonlinear gain. In random amplifying media, we find that the maximum values of the disorder-averaged logarithmic transmittance and reflectance depend nonmonotonically on the strength of nonlinear gain. We also find that the localization length is independent of nonlinear gain. In other words, the Anderson localization is neither enhanced nor weakened due to nonlinear gain. In both the uniform and the random cases, the crossover length, which is the critical length for the amplification to be efficient, is strongly reduced by the nonlinear nature of the gain.
Nonlinear carrier dynamics in a quantum dash optical amplifier
DEFF Research Database (Denmark)
Hansen, Per Lunnemann; Ek, Sara; Yvind, Kresten;
2012-01-01
Results of experimental pump-probe spectroscopy of a quantum dash optical amplifier biased at transparency are presented. Using strong pump pulses we observe a competition between free carrier absorption and two-photon induced stimulated emission that can have drastic effects on the transmission...
Short Pulse Dynamics in Strongly Nonlinear Dissipative Granular Chains
Rosas, Alexandre; Romero, Aldo H.; Nesterenko, Vitali F.; Lindenberg, Katja
2008-01-01
We study the energy decay properties of a pulse propagating in a strongly nonlinear granular chain with damping proportional to the relative velocity of the grains. We observe a wave disturbance that at low viscosities consists of two parts exhibiting two entirely different time scales of dissipation. One part is an attenuating solitary wave, is dominated by discreteness and nonlinearity effects as in a dissipationless chain, and has the shorter lifetime. The other is a purely dissipative sho...
Kennedy, Brendan F.
2005-01-01
In order to fully exploit the capacity of optical networks it is necessary to develop alloptical signal processing techniques. One device which can be used for this purpose is the Semiconductor Optical Amplifier (SOA). A lot of research has been devoted to this device. This work concentrates mainly on the nonlinearities in the device to perform alloptical processes such as switching and wavelength conversion. The main nonlinearities that have been considered are cross-phase modulation, cross-...
Nonlinear dynamics of zigzag molecular chains (in Russian)
DEFF Research Database (Denmark)
Savin, A. V.; Manevitsch, L. I.; Christiansen, Peter Leth;
1999-01-01
models (two-dimensional alpha-spiral, polyethylene transzigzag backbone, and the zigzag chain of hydrogen bonds) shows that the zigzag structure essentially limits the soliton dynamics to finite, relatively narrow, supersonic soliton velocity intervals and may also result in that several acoustic soliton......Nonlinear, collective, soliton type excitations in zigzag molecular chains are analyzed. It is shown that the nonlinear dynamics of a chain dramatically changes in passing from the one-dimensional linear chain to the more realistic planar zigzag model-due, in particular, to the geometry......-dependent anharmonism that comes into the picture. The existence or otherwise of solitons is determined in this case by the interplay between the geometrical anharmonism and the physical anharmonism of the interstitial interaction, of opposite signs. The nonlinear dynamic analysis of the three most typical zigzag...
Cascaded Optical Buffer Based on Nonlinear Polarization Rotation in Semiconductor Optical Amplifiers
Institute of Scientific and Technical Information of China (English)
CHENG Mu; WU Chong-Qing; LIU Hua
2008-01-01
A cascaded buffer based on nonlinear polarization rotation in semiconductor optical amplifiers is proposed, which is suitable for fast reconfiguration of buffering time at picoseconds. With the proposed buffer, sixty different buffer times are demonstrated at 2.5 Gb/s.
34-fs, all-fiber all-polarization-maintaining single-mode pulse nonlinear amplifier.
Yu, Jia; Feng, Ye; Cai, Yajun; Li, Xiaohui; Hu, Xiaohong; Zhang, Wei; Duan, Lina; Yang, Zhi; Wang, Yishan; Liu, Yuanshan; Zhao, Wei
2016-07-25
We present an all-fiber all-polarization-maintaining (PM) single mode (SM) fiber pulse nonlinear amplification system. The seed laser with a repetition rate of 200 MHz is amplified by two-section erbium-doped PM gain fibers with different peak-absorption rate. The amplified pulse duration can be compressed into 34-fs with 320-mW output power, which corresponds to 1.6-nJ pulse energy and approximate 23.5-kW peak power. In addition, the amplified and compressed pulse is further coupled into the high nonlinear fiber and an octave-spanning supercontinuum generation can be obtained. To the best of our knowledge, it is the highest peak power and the shortest pulse duration obtained in the field of all-fiber all-PM SM pulse-amplification systems. PMID:27464117
Linearisation of asymmetrical Doherty amplifier by the even-order non-linear signals
Maleš-Ilić, Nataša; Atanasković, Aleksandar; Blau, Kurt; Hein, Matthias
2016-08-01
This paper considers the linearisation of an asymmetrical two-way Doherty amplifier by the method that uses the second harmonics and fourth-order non-linear signals for linearisation. These even-order signals for linearisation are extracted at the output of the peaking amplifier, adjusted in amplitude and phase and injected at the input and output of the carrier amplifier transistor in the Doherty configuration. The effect of linearisation has been experimentally confirmed on a fabricated asymmetrical Doherty amplifier with the additional circuit for linearisation. The suppression of the third-order intermodulation products has been carried out for two-tone test, 64QAM and WCDMA digitally modulated signals in a range of signal power.
Rectification of nonlinearity in pre-amplifier and A/D converter of biomedical instruments
Yang, Jun; Yim, Seong-Bin; Kopriva, Ivica; Szu, Harold H.
2003-04-01
Nonlinear distortions are always introduced to biomedical signals during the acquisition stage, which consequently fail the traditional linear independent component analysis (ICA) methods for further signal processing. This paper investigates the non-linearity system function in the pre-amplifier and A/D converter of the biomedical instruments. A polynomial general model structure with adjustable parameters to approximate the nonlinear relation is proposed for medical instruments. Model parameters are validated using a typical electrocardiograph (ECG) acquisition system with sinusoids of varying frequency and amplitude. Thus the inverse nonlinear transform is applied to acquired data to cancel the nonlinear distortions. The ICA method is then applied to the originally linear mixed data, non-rectified data and also rectified data and the results are favorably compared in the designed experiment using both clinical ECGs and the simulated data from cardiac simulators.
Strongly nonlinear waves in a chain of Teflon beads
Daraio, C.; Nesterenko, V. F.; Herbold, E.; Jin, S.
2005-01-01
One-dimensional “sonic vacuum” type phononic crystals were assembled from a chain of polytetrafluoroethylene (PTFE,Teflon) spheres with different diameters in a Teflon holder. It was demonstrated that this polymer-based sonic vacuum, with exceptionally low elastic modulus of particles, supports propagation of strongly nonlinear solitary waves with a very low speed. These solitary waves can be described using the classical nonlinear Hertz law despite the viscoelastic nature of the polymer and ...
Short-pulse dynamics in strongly nonlinear dissipative granular chains.
Rosas, Alexandre; Romero, Aldo H; Nesterenko, Vitali F; Lindenberg, Katja
2008-11-01
We study the energy decay properties of a pulse propagating in a strongly nonlinear granular chain with damping proportional to the relative velocity of the grains. We observe a wave disturbance that at low viscosities consists of two parts exhibiting two entirely different time scales of dissipation. One part is an attenuating solitary wave, dominated by discreteness and nonlinearity effects as in a dissipationless chain, and has the shorter lifetime. The other is a purely dissipative shocklike structure with a much longer lifetime and exists only in the presence of dissipation. The range of viscosities and initial configurations that lead to this complex wave disturbance are explored.
Casas, F J; Pascual, J P; de la Fuente, M L; Artal, E; Portilla, J
2010-07-01
This paper describes a comparative nonlinear analysis of low-noise amplifiers (LNAs) under different stimuli for use in astronomical applications. Wide-band Gaussian-noise input signals, together with the high values of gain required, make that figures of merit, such as the 1 dB compression (1 dBc) point of amplifiers, become crucial in the design process of radiometric receivers in order to guarantee the linearity in their nominal operation. The typical method to obtain the 1 dBc point is by using single-tone excitation signals to get the nonlinear amplitude to amplitude (AM-AM) characteristic but, as will be shown in the paper, in radiometers, the nature of the wide-band Gaussian-noise excitation signals makes the amplifiers present higher nonlinearity than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNA's nominal operation, the 1 dBc point has to be obtained, but using realistic excitation signals. In this work, an analytical study of compression effects in amplifiers due to excitation signals composed of several tones is reported. Moreover, LNA nonlinear characteristics, as AM-AM, total distortion, and power to distortion ratio, have been obtained by simulation and measurement with wide-band Gaussian-noise excitation signals. This kind of signal can be considered as a limit case of a multitone signal, when the number of tones is very high. The work is illustrated by means of the extraction of realistic nonlinear characteristics, through simulation and measurement, of a 31 GHz back-end module LNA used in the radiometer of the QUIJOTE (Q U I JOint TEnerife) CMB experiment. PMID:20687750
Casas, F J; Pascual, J P; de la Fuente, M L; Artal, E; Portilla, J
2010-07-01
This paper describes a comparative nonlinear analysis of low-noise amplifiers (LNAs) under different stimuli for use in astronomical applications. Wide-band Gaussian-noise input signals, together with the high values of gain required, make that figures of merit, such as the 1 dB compression (1 dBc) point of amplifiers, become crucial in the design process of radiometric receivers in order to guarantee the linearity in their nominal operation. The typical method to obtain the 1 dBc point is by using single-tone excitation signals to get the nonlinear amplitude to amplitude (AM-AM) characteristic but, as will be shown in the paper, in radiometers, the nature of the wide-band Gaussian-noise excitation signals makes the amplifiers present higher nonlinearity than when using single tone excitation signals. Therefore, in order to analyze the suitability of the LNA's nominal operation, the 1 dBc point has to be obtained, but using realistic excitation signals. In this work, an analytical study of compression effects in amplifiers due to excitation signals composed of several tones is reported. Moreover, LNA nonlinear characteristics, as AM-AM, total distortion, and power to distortion ratio, have been obtained by simulation and measurement with wide-band Gaussian-noise excitation signals. This kind of signal can be considered as a limit case of a multitone signal, when the number of tones is very high. The work is illustrated by means of the extraction of realistic nonlinear characteristics, through simulation and measurement, of a 31 GHz back-end module LNA used in the radiometer of the QUIJOTE (Q U I JOint TEnerife) CMB experiment.
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
To assess the penalty due to nonlinear effect in C+L band long-haul optical amplified transmission link,a new parameter of modified nonlinear phase shift (φD) is proposed,which is the accumulated nonlinear phase shift weighted by a normalized group velocity dispersion (GVD).Based on the numerical simulation result of broadband long-haul hybrid Raman/erbium-doped fiber amplified transmission line,it is validated that φD is more reasonable and suitable than the previous proposed nonlinear phase shift (φNL) for broadband applications.
Institute of Scientific and Technical Information of China (English)
P.; K.; A.; Wai
2003-01-01
A nonlinear amplifying loop mirror constructed from erbium-doped fiber is proposed for simultaneous amplification and compression of ultrashort fundamental solitons. Numerical simulations show that, the proposed device performs efficient high-quality amplification and compression of solitons.
Thermal conductivity of nonlinear waves in disordered chains
Indian Academy of Sciences (India)
Sergej Flach; Mikhail Ivanchenko; Nianbei Li
2011-11-01
We present computational data on the thermal conductivity of nonlinear waves in disordered chains. Disorder induces Anderson localization for linear waves and results in a vanishing conductivity. Cubic nonlinearity restores normal conductivity, but with a strongly temperature-dependent conductivity (). We ﬁnd indications for an asymptotic low-temperature ∼ 4 and intermediate temperature ∼ 2 laws. These ﬁndings are in accord with theoretical studies of wave packet spreading, where a regime of strong chaos is found to be intermediate, followed by an asymptotic regime of weak chaos (Laptyeva et al, Europhys. Lett. 91, 30001 (2010)).
Numerical analysis of the performance of an atomic iodine laser amplifier chain
International Nuclear Information System (INIS)
The performance of an atomic iodine laser amplifier chain with output pulse powers close to 2 TW is analyzed by a numerical solution of the Maxwell-Bloch equations. Two subjects are discussed in detail. The first one refers to the pulse compression occurring in the chain as a result of saturation and some related aspects such as damage to components, self-focussing, correlation between the input and output pulse shapes, and the means of pulse shape control. The second deals with various schemes suited for achieving extraction efficiencies of about or larger than 55%. These include the single-pass and double-pass schemes, pulses with two carrier frequencies and a variation of the pulse carrier frequency. In addition, the response of the chain to a variation of those parameters which are most easily subject to change in a routine operation is investigated. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Fox, John D.; Mastorides, Themis; Rivetta, Claudio Hector; Van Winkle, Daniel; /SLAC
2007-07-06
Several high-current accelerators use feedback techniques in the accelerating RF systems to control the impedances seen by the circulating beam. These Direct and Comb Loop architectures put the high power klystron and LLRF signal processing components inside feedback loops, and the ultimate behavior of the systems depends on the individual sub-component properties. Imperfections and non-idealities in the signal processing leads to reduced effectiveness in the impedance control loops. In the PEP-II LLRF systems non-linear effects have been shown to reduce the achievable beam currents, increase low-mode longitudinal growth rates and reduce the margins and stability of the LLRF control loops. We present measurements of the driver amplifiers used in the PEP-II systems, and present measurement techniques needed to quantify the small-signal gain, linearity, transient response and image frequency generation of these amplifiers.
A Unified Distortion Analysis of Nonlinear Power Amplifiers with Memory Effects for OFDM Signals
Zhang, Yitao; Araki, Kiyomichi
Nonlinear distortions in power amplifiers (PAs) generate spectral regrowth at the output, which causes interference to adjacent channels and errors in digitally modulated signals. This paper presents a novel method to evaluate adjacent channel leakage power ratio (ACPR) and error vector magnitude (EVM) from the amplitude-to-amplitude (AM/AM) and amplitude-to-phase (AM/PM) characteristics. The transmitted signal is considered to be complex Gaussian distributed in orthogonal frequency-division multiplexing (OFDM) systems. We use the Mehler formula to derive closed-form expressions of the PAs output power spectral density (PSD), ACPR and EVM for memoryless PA and memory PA respectively. We inspect the derived relationships using an OFDM signal in the IEEE 802.11a WLAN standard. Simulation results show that the proposed method is appropriate to predict the ACPR and EVM values of the nonlinear PA output in OFDM systems, when the AM/AM and AM/PM characteristics are known.
Directory of Open Access Journals (Sweden)
Santamaría Ignacio
2003-01-01
Full Text Available A comparative study among several nonlinear high-power amplifier (HPA models using real measurements is carried out. The analysis is focused on specific models for wideband OFDM signals, which are known to be very sensitive to nonlinear distortion. Moreover, unlike conventional techniques, which typically use a single-tone test signal and power measurements, in this study the models are fitted using subsampled time-domain data. The in-band and out-of-band (spectral regrowth performances of the following models are evaluated and compared: Saleh's model, envelope polynomial model (EPM, Volterra model, the multilayer perceptron (MLP model, and the smoothed piecewise-linear (SPWL model. The study shows that the SPWL model provides the best in-band characterization of the HPA. On the other hand, the Volterra model provides a good trade-off between model complexity (number of parameters and performance.
Institute of Scientific and Technical Information of China (English)
ZHAO Shuang; WU Chong-Qing; WANG Yong-Jun
2009-01-01
Linewidth enhancement factors (LEFs) of the transverse electric mode and the transverse magnetic mode in bulk semiconductor optical amplifiers are measured using the nonlinear optical loop mirror method and the principal state of polarization vector method.The polarization dependence of LEFs plays an important role in the nonlinear polarization rotation.The relationship between the polarization-dependence of LEFs and nonlinear polarization rotation in the Stokes space is demonstrated.
Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers
Isaienko, Oleksandr; Robel, István
2016-03-01
Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OPO/OPA), and to efficient polariton-phonon scattering. In this work, we investigate the behavior of infrared OPAs employing KTP or KTA crystals when pumped with ~800-nm ultrashort pulses of duration comparable to the oscillation period of the optical phonons. We demonstrate that under conditions of coherent impulsive Raman excitation of the phonons, when the effective χ(2) nonlinearity cannot be considered instantaneous, the parametrically amplified waves (most notably, signal) undergo significant spectral modulations leading to an overall redshift of the OPA output. The pump intensity dependence of the redshifted OPA output, the temporal evolution of the parametric gain, as well as the pump spectral modulations suggest the presence of coupling between the nonlinear optical polarizations PNL of the impulsively excited phonons and those of parametrically amplified waves.
Amplifying genes using the polymerase chain reaction: A promising diagnostic tool
International Nuclear Information System (INIS)
The power to amplify genetic material several millionfold using the polymerase chain reaction (PCR) has greatly enhanced the ability of molecular biologists to examine and manipulate genes. We have used the PCR reaction to detect bluetongue virus (BTV) in infected animals and are currently able to serogroup, serotype and determine the geographic origin of a BTV isolate. Similarly, using a combination of hybridization analyses and direct sequencing of the PCR products we can rapidly detect avian influenza virus, Newcastle disease virus and Mycoplasma and predict if we have nucleic acid sequences that are characteristic of a virulent or avirulent isolate. The ability to manipulate genetic information has made it possible to generate proteins containing deletions or create chimeric proteins which contain additions to their sequences. Such studies are important for the understanding of immune responses to various protein epitopes. Besides its sensitivity, PCR has the advantage of speed over some other detection systems. A comprehensive detection and diagnosis can be done in a few hours compared with several weeks previously required for virus isolations. However, there are disadvantages to using PCR. Because of its ability to amplify a sequence several millionfold, contaminants other than the target species may be amplified and since the DNA polymerase used in PCR has no editing or proofreading functions, errors may be quickly incorporated into the final PCR product. 13 refs, 8 figs
Nonlinear resonances in a multi-stage free-electron laser amplifier
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, S. [Graduate Univ. for Advanced Studies, Ibaraki-ken (Japan); Takayama, K. [National Lab. for High Energy Physics, Ibaraki-ken (Japan)
1995-12-31
A two-beam accelerator (TBA) is a possible candidate of future linear colliders, in which the demanded rf power is provided by a multi-stage free-electron laser (MFEL). After if amplification in each stage, a driving beam is re-accelerated by an induction unit and propagates into the next stage. Recently it has been recognized that the multi-stage character of the MFEL causes resonances between its periodicity and the synchrotron motion in an rf bucket. Since the synchrotron oscillation is strongly modulated by the resonance and at the worst a large fraction of particles is trapped in the resonance islands, the nonlinear resonances in the FEL longitudinal beam dynamics can lead to notable degradation of the MFEL performance, such as output fluctuation and phase modulation which have been big concerns in the accelerator society. The overall efficiency of the MFEL and the quality of the amplified microwave power are key issues for realizing the TBA/FEL Particularly the rf phase and amplitude errors must be maintained within tolerance. One of significant obstacles is an amplification of undesired modes. If a small-size waveguide is employed, the FEL resonance energies for undesired higher order modes shift very far from that for a fundamental mode; so it is possible to prevent higher order modes from evolving. Such a small-size waveguide, however, gives a high power density in the FEL. Simulation results have demonstrated that the nonlinear resonances occur in die FEL longitudinal motion when the power density exceeds some threshold. An analytical method for studying the nonlinear resonance in the TBA/FEL is developed based on the macroparticle model which can describe analytically the drastic behaviors in the evolutions of the phase and amplitude. In the theory the basic 1D-FEL equations are reduced to a nonlinear pendulum equation with respect to the ponderomotive phase.
Multiphysics Modeling in Watershed Systems: How Weak Nonlinearities Amplify Extreme Events
Duffy, C.; Kumar, M.
2009-04-01
This research is developing a modeling system for the synthesis of multi-state, multi-scale distributed hydrologic processes based on the semi-discrete representation of the underlying physical process equations and state variables (Qu and Duffy, WRR 2007). Our interest is in devising a concise representation of watershed or river basin hydrodynamics, which allows interactions among major physical processes operating simultaneously, but with the flexibility to add or eliminate states/processes/constitutive relations depending on the objective of the numerical experiment or purpose of the scientific or operational application. In this paper we demonstrate how nonlinear coupling effects (e.g. unsaturated-saturated flow, gaining-losing streams) in the presence of weak periodic climate forcing can amplify or heavily damp streamflow during large rainfall events. Several examples are given where weak climate variations may have large effects on terrestrial response to large random precipitation events. The research demonstrates how climate and weather, interacting with weakly nonlinear and coupled processes in the watershed, can have a large impact on flooding from extreme precipitation events.
Nonlinear optical frequency conversion of an amplified Fourier Domain Mode Locked (FDML) laser.
Leonhardt, Rainer; Biedermann, Benjamin R; Wieser, Wolfgang; Huber, Robert
2009-09-14
We report on the highly efficient non-linear optical frequency conversion of the wavelength swept output from a Fourier Domain Mode Locked (FDML) laser. Different concepts for power scaling of FDML lasers by post-amplification with active fibers are presented. A two-stage post-amplification of an FDML laser with an amplification factor of 300 up to a peak power of 1.5 W is used to supply sufficient power levels for non-linear conversion. Using a single-mode dispersion shifted fiber (DSF), we convert this amplified output that covers the region between 1541 nm and 1545 nm to a wavelength range from 1572 nm to 1663 nm via modulation instability (MI). For this four wave mixing process we observe an efficiency of approximately 40%. The anti-Stokes signal between 1435 nm and 1516 nm was observed with lower conversion efficiency. In addition to shifting the wavelength, the effect of MI also enables a substantial increase in the wavelength sweep rate of the FDML laser by a factor of approximately 50 to 0.55 nm/ns. PMID:19770897
The quasi-equilibrium phase of nonlinear chains
Indian Academy of Sciences (India)
T R Krishna Mohan; Surajit Sen
2005-03-01
We show that time evolution initiated via kinetic energy perturbations in conservative, discrete, spring-mass chains with purely nonlinear, non-integrable, algebraic potentials of the form ( − +1 ∼ $(_{} − _{+1})^{2}$, ≥ 2 and an integer, occurs via discrete solitary waves (DSWs) and discrete antisolitary waves (DASWs). Presence of reflecting and periodic boundaries in the system leads to collisions between the DSWs and DASWs. Such collisions lead to the breakage and subsequent reformation of (different) DSWs and DASWs. Our calculations show that the system eventually reaches a stable `quasi-equilibrium' phase that appears to be independent of initial conditions, possesses Gaussian velocity distribution, and has a higher mean kinetic energy and larger range of kinetic energy fluctuations as compared to the pure harmonic system with = 1; the latter indicates possible violation of equipartition.
Nonlinear properties of quantum dot semiconductor optical amplifiers at 1.3 μm Invited Paper
Institute of Scientific and Technical Information of China (English)
D. Bimberg; C. Meuer; M. L(a)mmlin; S. Liebich; J. Kim; A. Kovsh; I. Krestnikov; G. Eisenstein
2008-01-01
@@ The dynamics of nonlinear processes in quantum dot (QD) semiconductor optical amplifiers (SOAs) are investigated. Using small-signal measurements, the suitabilities of cross-gain and cross-phase modulation as well as four wave mixing (FWM) for wavelength conversion are examined. The cross-gain modulation is found to be suitable for wavelength conversion up to a frequency of 40 GHz.
Slow and fast light using nonlinear processes in semiconductor optical amplifiers
Pesala, Bala Subrahmanyam
Ability to control the velocity of light is usually referred to as slow or fast light depending on whether the group velocity of light is reduced or increased. The slowing of light as it passes through the glass to 2/3rd its original value is a well known phenomenon. This slowing down happens due to the interaction of light with the electrons in the medium. As a general principle, stronger the interaction, larger is the reduction in velocity. Recently, a fascinating field has emerged with the objective of not only slowing down the velocity of light but also speeding it up as it goes through the medium by enhancing light-matter interaction. This unprecedented control opens up several exciting applications in various scientific disciplines ranging from nonlinear science, RF photonics to all-optical networks. Initial experiments succeeded in reducing the velocity of light more than a million times to a very impressive 17 m/s. This speed reduction is extremely useful to enhance various nonlinear processes. For RF photonic applications including phased array antennas and tunable filters, control of phase velocity of light is required while control of group velocity serves various functionalities including packet synchronization and contention resolution in an optical buffer. Within the last 10 years, several material systems have been proposed and investigated for this purpose. Schemes based on semiconductor systems for achieving slow and fast light has the advantage of extremely high speed and electrical control. In addition, they are compact, operate at room temperature and can be easily integrated with other optical subsystems. In this work, we propose to use nonlinear processes in semiconductor optical amplifiers (SOAs) for the purpose of controlling the velocity of light. The versatility of the physical processes present in SOAs enables the control of optical signals ranging from 1GHz to larger than 1000 GHz (1 THz). First, we experimentally demonstrate both
Tunable parametric amplifier for mid-IR application based on highly nonlinear chalcogenide material
Energy Technology Data Exchange (ETDEWEB)
Maji, Partha Sona; Roy Chaudhuri, Partha [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India)
2015-06-28
A novel dispersion controlling technique towards attaining tunable parametric amplification based on highly nonlinear photonic crystal fibers has been investigated. Selective infiltration of the liquid into the air-holes leads to alter the zero dispersion wavelength towards a broader parametric gain in the mid-IR spectrum by only changing the temperature of the system externally. The dispersion profile specially the zero dispersion wavelengths can be well tuned around the pumping wavelength, thereby generating several hundred nanometer parametric bandwidth in near-IR to mid-IR region. The tunability of the photonic crystal fibers (PCFs) can also be useful for generating new frequencies in both the red- and blue-shifted regions far from the pumping wavelength. Our numerical calculations reveal that we could achieve very wide band fiber optic parametric amplifier both in the communication wavelength and in the IR region. Also two different types of PCFs can be used to achieve same broadband wavelength spectra however with a tradeoff between the fiber lengths and pump power.
Spiegler, VLM; Naim, MM; Potter, AT; Towill, DR
2015-01-01
Purpose of this paper: Previous control theory research on supply chain dynamics has predominantly taken a linear perspective of the real world, whereas nonlinearities have usually been studied via a simulation approach. Nonlinearities can naturally occur in supply chains through the existence of physical and economic constraints, for example, capacity limitations. Since the ability to flex capacity is an important aspect of supply chain resilience, there is a need to rigorously study such no...
Stankiewicz, N.
1982-01-01
The multiple channel input signal to a soft limiter amplifier as a traveling wave tube is represented as a finite, linear sum of Gaussian functions in the frequency domain. Linear regression is used to fit the channel shapes to a least squares residual error. Distortions in output signal, namely intermodulation products, are produced by the nonlinear gain characteristic of the amplifier and constitute the principal noise analyzed in this study. The signal to noise ratios are calculated for various input powers from saturation to 10 dB below saturation for two specific distributions of channels. A criterion for the truncation of the series expansion of the nonlinear transfer characteristic is given. It is found that he signal to noise ratios are very sensitive to the coefficients used in this expansion. Improper or incorrect truncation of the series leads to ambiguous results in the signal to noise ratios.
Institute of Scientific and Technical Information of China (English)
Song Rui; Hou Jing; Wang Ze-Feng; Xiao Rui; Lu Qi-Sheng
2013-01-01
Theoretical and experimental research on the effect of initial chirp on near-infrared supercontinuum generation by a nanosecond pulse in a nonlinear fiber amplifier is carried out.The complex Ginzburg-Landau equation is used to simulate the propagation of the pulse in the fiber amplifier and the results show that pulses with negative initial chirp produce the widest supercontinuum and pulses with positive initial chirp produce the narrowest supercontinuum when the central wavelength of the pump lies in the normal dispersion region of the gain fiber.A self-made line width narrowing system is utilized to control the initial chirp of the nanosecond pump pulse and a four-stage master oscillator power amplifier configuration is adopted to produce a high power near-infrared suppercontinuum.The experimental results are in good agreement with simulations which can provide some guidance on further optimization of the system in future work.
Subpicosecond fiber optical parametric chirped pulse amplifier based on highly-nonlinear fiber
Chui, PC; Wong, KKY; Zhou, Y.; Q. Li; Cheung, KKY; Yang, S.
2010-01-01
We experimentally demonstrate a fiber optical parametric chirped pulse amplifier. A 750-fs signal is stretched to 40 ps, amplified with a gain of 30 dB through parametric process and then compressed to 808 fs. 2010 Optical Society of America. © 2010 IEEE.
Institute of Scientific and Technical Information of China (English)
Luo Bo-Wen; Dong Jian-Ji; Yu Yuan; Yang Ting; Zhang Xin-Liang
2013-01-01
We propose and demonstrate a scheme to implement photonic multi-shape ultra-wideband (UWB) signal generation using a semiconductor optical amplifier (SOA) based nonlinear optical loop mirror (NOLM).By employing the cross phase modulation (XPM) effect,cross gain modulation (XGM),or both,multi-shape UWB waveforms are generated including monocycle,doublet,triplet,and quadruplet pulses.Both the shapes and polarities of the generated pulses are flexible to adjust,which may be very useful in UWB pulse shape modulation and pulse polarity modulation.
Institute of Scientific and Technical Information of China (English)
LI De-Jun; MI Xian-Wu; DENG Ke; TANG Yi
2006-01-01
In the classical lattice theory, solitons and locaLized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solitons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j = j0.
Impact of nonlinear power amplifier on link adaptation algorithm of OFDM systems
Das, S. S.; Tariq, F.; Rahman, M. I.; Frederiksen, F. B.; E.D. Carvalho; Prasad, R.
2007-01-01
The impact of non linear distortion due to High Power Amplifier (HPA) on the performance of Link Adaptation (LA) - Orthogonal Frequency Division Multiplexing (OFDM) based wireless system is analyzed. The performance of both Forward Error Control Coding (FEC) en-coded and uncoded system is evaluated. LA maximizes the throughput while maintaining a required Block Error Rate (BLER). It is found that when OFDM signal, which has high PAPR, suffers non linear distortion due to non ideal HPA, the...
Credit Chains and Sectoral Comovement : Does the Use of Trade Credit Amplify Sectoral Shocks?
Raddatz, Claudio
2010-01-01
This paper provides evidence of the presence and relevance of the credit chain propagation and amplification mechanism described by Kiyotaki and Moore (1997) by looking at its implications for the correlation of industries. In particular, it tests the hypothesis that an increase in the use of trade credit, along the input-output chain linking two industries, results in an increase in their output correlation using detailed data on the correlations and input-output relations of 378 manufacturi...
Low-frequency band gaps in chains with attached non-linear oscillators
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Jensen, Jakob Søndergaard
2007-01-01
in structures with periodic or random inclusions are located mainly in the high frequency range, as the wavelength has to be comparable with the distance between the alternating parts. Band gaps may also exist in structures with locally attached oscillators. In the linear case the gap is located around......The aim of this article is to investigate the wave propagation in one-dimensional chains with attached non-linear local oscillators by using analytical and numerical models. The focus is on the influence of non-linearities on the filtering properties of the chain in the low frequency range...
Parametrically Driven Solitons in a Chain of Nonlinear Coupled Pendula with an Impurity
Institute of Scientific and Technical Information of China (English)
XU Hai-Qing; TANG Yi
2006-01-01
The system consisting of a chain of parametrically driven and damped nonlinear coupled pendula with a mass impurity is studied by means of a discrete version of the envelope function approach. An analogue of theparametrically driven damped nonlinear Sch(o)dinger equation with an impurity term is derived from the original lattice equation.Analytical solutions of impurity pinned high-frequency breathers and kinks are obtained.The resuIts show that the mass impurity has striking influence on the high-frequency modes.In addition,we perform numerical sjmulations,showing that the light mass impurity has a stabilizing effect on the chain.The breathers seeding chaos in the homogeneous chain are pinned on a suitable light impurity to pull the chain from the chaotic state.
Third-order nonlinear optical characterization of side-chain copolymers
Norwood, Robert A.; Sounik, James R.; Popolo, J.; Holcomb, Douglas P.
1991-12-01
Third order nonlinear optical properties of side-chain methacrylate copolymers incorporating 4-amino-4'-nitrostilbene, 4-oxy-4'nitrostilbene, and functionalized silicon phthalocyanine chromophores are measured by picosecond degenerate four wave mixing at 598 nm. The nonresonant stilbene system exhibits a pulse limited ultrafast response, while the resonant phthalocyanine system has a large excited state nonlinearity. Comparison of silicon phthalocyanine copolymers with solubilized guest/host systems dispersed in polymethylmethacrylate illustrate the importance of aggregation and phthalocyanine ring interaction in determining the linear optical properties and the magnitude and speed of the nonlinear optical response.
Intrinsic localized modes and nonlinear impurity modes in curved Fermi-Pasta-Ulam chain
Indian Academy of Sciences (India)
Ranja Sarkar; Bishwajyoti Dey
2008-06-01
We explore the nature of intrinsic localized modes (ILMs) in a curved FermiPasta-Ulam (FPU) chain and the effects of geometry and second-neighbor interaction on the localization and movability properties of such modes. We determine analytically the structure of the localized modes induced by an isotopic light-mass impurity in this chain. We further demonstrate that a nonlinear impurity mode may be treated as a bound state of an ILM with the impurity.
Directory of Open Access Journals (Sweden)
Abd El-Naser A. Mohammed
2010-09-01
Full Text Available In the present paper, the problem amplification techniques of ultra dense wavelength division multiplexing (UDWDM in nonlinear optical networks are investigated through five transmission techniques. The impact of tailoring of chirped pulses of different temporal waveforms is investigated in a normal dispersion fiber. The set of multiplexed signals are tailored in a different a subset to assure approximately the same output level of power to hold the signal-to-noise ratio at the same level. Moreover, three different transmission techniques, namely, soliton propagation, maximum time division multiplexing (MTDM and ìShannonî capacity, are employed where successive section of alternating dispersion are used as a technique to manage the dispersion. Distributed ìRamanî amplifiers as well as Erbium doped fiber amplifier are engaged to maximize the repeater spacing. We have succeeded to multiplex 2400 (UDWDM channels in the optical range 1.45 1.65 µm with channel spacing ranging from 0.3 up to 0.6 nm where each channel has its own characteristic parameters of loss, dispersion, and amplification. The channels are divided into sub-groups ( each of 4, 5, 6, 7,Ö.,24 where the technique of space division multiplexing (SDM is applied. The multispan effects of ìKerrî nonlinearity and amplifier noise on ìShannonî channel capacity of dispersion-free nonlinear fiber is considered as a ceiling value for the sake of comparison. The case of soliton with modified Raman amplification via parametric gain also is investigated. Each link has special chemical structure, optical signals power, and optical Raman pumping. The cable contains {4, 5, 6, 7,Ö. , 24} links in SDM. It has been shown that the modified Raman gain yields higher effects on the variable under consideration if compared with the conventional Raman gain. The number of links is in positive correlations with the set of effects {Repeater spacing, Soliton product, MTDM product}. In general
Impact of Nonlinear Power Amplifier on Link Adaptation Algorithm of OFDM Systems
DEFF Research Database (Denmark)
Das, Suvra S.; Tariq, Faisal; Rahman, Muhammad Imadur;
2007-01-01
The impact of non linear distortion due to High Power Amplifier (HPA) on the performance of Link Adaptation (LA) - Orthogonal Frequency Division Multiplexing (OFDM) based wireless system is analyzed. The performance of both Forward Error Control Coding (FEC) en-coded and uncoded system is evaluated....... LA maximizes the throughput while maintaining a required Block Error Rate (BLER). It is found that when OFDM signal, which has high PAPR, suffers non linear distortion due to non ideal HPA, the LA fails to meet the target BLER. Detailed analysis of the distortion and effects on LA are presented...
Complex statistics and diffusion in nonlinear disordered particle chains
Energy Technology Data Exchange (ETDEWEB)
Antonopoulos, Ch. G., E-mail: chris.antonopoulos@abdn.ac.uk [Institute for Complex Systems and Mathematical Biology (ICSMB), Department of Physics, University of Aberdeen, AB24 3UE Aberdeen (United Kingdom); Bountis, T., E-mail: bountis@math.upatras.gr [Center for Research and Applications of Nonlinear Systems (CRANS), Department of Mathematics, University of Patras, 26500 Patras (Greece); Skokos, Ch., E-mail: haris.skokos@uct.ac.za [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, Cape Town 7701 (South Africa); Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Drossos, L., E-mail: ldrossos@teimes.gr [High Performance Computing Systems Lab (HPCS lab), Department of Computer and Informatics Engineering, Technological Educational Institute of Western Greece, 30300 Antirion (Greece)
2014-06-15
We investigate dynamically and statistically diffusive motion in a Klein-Gordon particle chain in the presence of disorder. In particular, we examine a low energy (subdiffusive) and a higher energy (self-trapping) case and verify that subdiffusive spreading is always observed. We then carry out a statistical analysis of the motion, in both cases, in the sense of the Central Limit Theorem and present evidence of different chaos behaviors, for various groups of particles. Integrating the equations of motion for times as long as 10{sup 9}, our probability distribution functions always tend to Gaussians and show that the dynamics does not relax onto a quasi-periodic Kolmogorov-Arnold-Moser torus and that diffusion continues to spread chaotically for arbitrarily long times.
A nonlinear analysis of the terahertz serpentine waveguide traveling-wave amplifier
International Nuclear Information System (INIS)
A nonlinear model for the numerical simulation of terahertz serpentine waveguide traveling-wave tube (SW-TWT) is described. In this model, the electromagnetic wave transmission in the SW is represented as an infinite set of space harmonics to interact with an electron beam. Analytical expressions for axial electric fields in axisymmetric interaction gaps of SW-TWTs are derived and compared with the results from CST simulation. The continuous beam is treated as discrete macro-particles with different initial phases. The beam-tunnel field equations, space-charge field equations, and motion equations are combined to solve the beam-wave interaction. The influence of backward wave and relativistic effect is also considered in the series of equations. The nonlinear model is used to design a 340 GHz SW-TWT. Several favorable comparisons of model predictions with results from a 3-D Particle-in-cell simulation code CHIPIC are presented, in which the output power versus beam voltage and interaction periods are illustrated. The relative error of the predicted output power is less than 15% in the 3 dB bandwidth and the relative error of the saturated length is less than 8%.The results show that the 1-D nonlinear analysis model is appropriate to solve the terahertz SW-TWT operation characteristics
Directory of Open Access Journals (Sweden)
Iñiguez Alena M
2003-01-01
Full Text Available The aim of this work was to determine approaches that would improve the quality of ancient DNA (aDNA present in coprolites to enhance the possibility of success in retrieving specific sequence targets. We worked with coprolites from South American archaeological sites in Brazil and Chile dating up to 7,000 years ago. Using established protocols for aDNA extraction we obtained samples showing high degradation as usually happens with this kind of material. The reconstructive polymerization pretreatment was essential to overcome the DNA degradation and the serial dilutions helped with to prevent polymerase chain reaction (PCR inhibitors. Moreover, the random amplified polymorphic DNA-PCR has been shown to be a reliable technique for further experiments to recover specific aDNA sequences.
Ming, Yi; Li, Hui-Min; Ding, Ze-Jun
2016-03-01
Thermal rectification and negative differential thermal conductance were realized in harmonic chains in this work. We used the generalized Caldeira-Leggett model to study the heat flow. In contrast to most previous studies considering only the linear system-bath coupling, we considered the nonlinear system-bath coupling based on recent experiment [Eichler et al., Nat. Nanotech. 6, 339 (2011)]. When the linear coupling constant is weak, the multiphonon processes induced by the nonlinear coupling allow more phonons transport across the system-bath interface and hence the heat current is enhanced. Consequently, thermal rectification and negative differential thermal conductance are achieved when the nonlinear couplings are asymmetric. However, when the linear coupling constant is strong, the umklapp processes dominate the multiphonon processes. Nonlinear coupling suppresses the heat current. Thermal rectification is also achieved. But the direction of rectification is reversed compared to the results of weak linear coupling constant.
Ming, Yi; Li, Hui-Min; Ding, Ze-Jun
2016-03-01
Thermal rectification and negative differential thermal conductance were realized in harmonic chains in this work. We used the generalized Caldeira-Leggett model to study the heat flow. In contrast to most previous studies considering only the linear system-bath coupling, we considered the nonlinear system-bath coupling based on recent experiment [Eichler et al., Nat. Nanotech. 6, 339 (2011), 10.1038/nnano.2011.71]. When the linear coupling constant is weak, the multiphonon processes induced by the nonlinear coupling allow more phonons transport across the system-bath interface and hence the heat current is enhanced. Consequently, thermal rectification and negative differential thermal conductance are achieved when the nonlinear couplings are asymmetric. However, when the linear coupling constant is strong, the umklapp processes dominate the multiphonon processes. Nonlinear coupling suppresses the heat current. Thermal rectification is also achieved. But the direction of rectification is reversed compared to the results of weak linear coupling constant.
Thermal entanglement in 1D optical lattice chains with nonlinear coupling
Institute of Scientific and Technical Information of China (English)
Zhou Ling; Yi Xue-Xi; Song He-Shan; Guo Yan-Qing
2005-01-01
he thermal entanglement of spin-1 atoms with nonlinear coupling in an optical lattice chain is investigated for two-particle and multi-particle systems. It is found that the relation between linear coupling and nonlinear coupling is the key to determine thermal entanglement, which shows in what kinds of atoms thermal entanglement exists. This result is true both for two-particle and multi-particle systems. For multi-particle systems, the thermal entanglement does not decrease greatly, and the critical temperature decreases only slightly.
Quantum correlations and entanglement in a model comprised of a short chain of nonlinear oscillators
Kalaga, J. K.; Kowalewska-Kudłaszyk, A.; Leoński, W.; Barasiński, A.
2016-09-01
We discuss a model comprised of a chain of three Kerr-like nonlinear oscillators pumped by two modes of external coherent field. We show that the system can be treated as nonlinear quantum scissors and behave as a three-qubit model. For such situation, different types of tripartite entangled states can be generated, even when damping effects are present in the system. Some amount of such entanglement can survive even in a long-time limit. The flow of bipartite entanglement between subsystems of the model and relations among first-order correlations, second-order correlations, and the entanglement are discussed.
Energy Technology Data Exchange (ETDEWEB)
Runge, Patrick
2010-10-19
The presented work discusses physical properties of ultralong semiconductor optical amplifiers (UL-SOAs) and some of their possible applications in optical communication systems. At the beginning of this thesis the analytical framework for the optical properties of UL-SOAs is presented. Based on this theoretical description, a numerical simulation model is derived used for the investigation of this thesis. To obtain from the simulation model realistic results the important properties of UL-SOAs have to be included, e.g., being the saturation of the main part of the device. In this saturated part of the device, fast intraband effects dominate over the slow interband effects. The intention of UL-SOAs is to make use of these pronounced fast intraband effects in applications. Due to the short relaxation times of the fast intraband effects, they can be used for high-speed signal processing (>20 GBaud). With the help of an additional continuous wave (CW) signal propagating with the data signal in the UL-SOA, the capability for all-optical signal processing with 100 Gbit/s on-off keying RZ-50% pseudo random bit sequence signals has been demonstrated in this thesis. With an optimised device under proper driving conditions, bit pattern effects are negligible compared to the degradation due to amplified spontaneous emission. The suppression of the bit pattern effects can be ascribed to the additional CW signal operating as a holding beam. Investigations of the UL-SOA's driving condition showed that the data signal's extinction ratio (ER) can be regenerated if the two input signals are co-polarised and the data signal has a shorter wavelength than the CW signal. These two and other driving conditions have indicated, that parametric amplification due to four-wave mixing (FWM) (Bogatov-like effect) is the reason for the ER improvement. Moreover, due to the additional CW signal, all-optical wavelength conversion (AOWC) is possible which can be combined with the ER
Wang, Sijia; Liu, Bowen; Song, Youjian; Hu, Minglie
2016-04-01
We report on a simple passive scheme to reduce the intensity noise of high-power nonlinear fiber amplifiers by use of the spectral-breathing parabolic evolution of the pulse amplification with an optimized negative initial chirp. In this way, the influences of amplified spontaneous emission (ASE) on the amplifier intensity noise can be efficiently suppressed, owing to the lower overall pulse chirp, shorter spectral broadening distance, as well as the asymptotic attractive nature of self-similar pulse amplification. Systematic characterizations of the relative intensity noise (RIN) of a free-running nonlinear Yb-doped fiber amplifier are performed over a series of initial pulse parameters. Experiments show that the measured amplifier RIN increases respect to the decreased input pulse energy, due to the increased amount of ASE noise. For pulse amplification with a proper negative initial chirp, the increase of RIN is found to be smaller than with a positive initial chirp, confirming the ASE noise tolerance of the proposed spectral-breathing parabolic amplification scheme. At the maximum output average power of 27W (25-dB amplification gain), the incorporation of an optimum negative initial chirp (-0.84 chirp parameter) leads to a considerable amplifier root-mean-square (rms) RIN reduction of ~20.5% (integrated from 10 Hz to 10 MHz Fourier frequency). The minimum amplifier rms RIN of 0.025% (integrated from 1 kHz to 5 MHz Fourier frequency) is obtained along with the transform-limited compressed pulse duration of 55fs. To our knowledge, the demonstrated intensity noise performance is the lowest RIN level measured from highpower free-running femtosecond fiber amplifiers.
THE DEMAND DISRUPTION MANAGEMENT PROBLEM FOR A SUPPLY CHAIN SYSTEM WITH NONLINEAR DEMAND FUNCTIONS
Institute of Scientific and Technical Information of China (English)
Minghui XU; Xiangtong QI; Gang YU; Hanqin ZHANG; Chengxiu GAO
2003-01-01
This paper addresses the problem of handling the uncertainty of demand in aone-supplier-one-retailer supply chain system. Demand variation often makes the real productiondifferent from what is originally planned, causing a deviation cost from the production plan. Assumethe market demand is sensitive to the retail price in a nonlinear form, we show how to effectivelyhandle the demand uncertainty in a supply chain, both for the case of centralized-decision-makingsystem and the case of decentralized-decision-making system with perfect coordination.
International Nuclear Information System (INIS)
We have carried out numerical investigations of transmittance fluctuations in disordered chains in the presence of external electric fields. We have obtained an almost constant fluctuation in a length scale smaller than the localization length. However, the value of the fluctuation in the plateau region is dependent on the external electric field and strength of disorder. We have also studied the transmittance autocorrelation as a function of external electric field to probe non-linearity in transmittance. (author). 26 refs, 4 figs
Phase-shift-controlled logic gates in Y-shaped nonlinearly coupled chains.
Assunção, T F; Nascimento, E M; Sombra, A S B; Lyra, M L
2016-02-01
We introduce a model system composed of two input discrete chains nonlinearly coupled to a single output chain which mimics the geometry of Y-shaped carbon nanotubes, photonic crystal wave guides, and DNA junctions. We explore the capability of the proposed system to perform logic gate operations based on the transmission of phase-shifted harmonic incoming waves. Within a tight-binding approach, we determine the exact transmission spectrum which exhibits a nonlinear induced bistability. Using a digitalization scheme of the output signal based on amplitude modulation, we show that AND, OR, and XOR logic operations can be achieved. Nonlinearity strongly favors the realization of logic operations in the regime of large wavelengths, while phase shifting is required for the OR logic gate to be realizable. A detailed analysis of the contrast ratio shows that optimal operation of the AND and OR logic gates takes place when the nonlinear response is the predominant physical property distinguishing the coupling and regular sites. These results point towards the possibility of Y-branched junctions to perform logic operations based on the transmission of traveling waves.
Institute of Scientific and Technical Information of China (English)
Feng Chuan-Fen; Wu Jian; Zhang Jun-Yi; Xu Kun; Lin Jin-Tong
2008-01-01
Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation (NPR) in a single semiconductor optical amplifier (SOA) and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams.To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio (ER) on some key parameters used in simulation is illustrated. Furthermore,simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.
Indian Academy of Sciences (India)
Jong-Man Yoon; Gye-Woong Kim
2001-12-01
Genetic similarity and diversity of cultured catfish Silurus asotus populations collected from two areas in western Korea were examined using randomly amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). Out of 20 random primers tested, 5 produced 1344 RAPD bands ranging from 8.2 to 13.6 polymorphic bands per primer. The polymorphic bands in these populations ranged from 56.4% to 59.6%. Polymorphic bands per lane within populations ranged from 4.9% to 5.3%. The similarity within the Kunsan population varied from 0.39 to 0.82 with a mean (± SD) of 0.56 ± 0.08. The level of bandsharing values was 0.59 ± 0.07 within the catfish population from Yesan. The genetic similarity in cultured catfish populations may have been caused because individuals from two populations were reared in the same environmental conditions or by inbreeding during several generations. However, in view of bandsharing values, polymorphic bands and also the specific major bands that were inter-population-specific, significant genetic differentiation between these populations were present even if bandsharing (BS) values were somewhat numerically different. Therefore, the number of RAPD polymorphisms identified in this study may be sufficient to permit estimating genetic similarity and diversity. However, in future, additional populations, sampling sites and individuals will be necessary to make up for these weak points.
International Nuclear Information System (INIS)
Compact and stable ultrafast laser sources for electron diffraction experiments are the first step in accomplishing the dream experiment of producing a molecular movie. This thesis work focuses on developing new robust laser sources to enable arbitrary scaling in laser repetition rate, pulse energy, duration and stability as needed to provide sufficient integrated detected electrons for high quality diffraction patterns that can be inverted to real space movies. In chapter 2, the construction of a novel stable and high power stretched pulse fiber oscillator outputting 300 mW at 31 MHz and compressible pulses to below 90 fs will be described. Chapter 3 describes the construction of a solid-state regenerative amplifier that was developed to achieve pulse energies above 1mJ with 0.40 mJ already achieved at 1 kHz. Novel simulation techniques were explored that aided the construction of the amplifier. Chapter 4 derives a new, fast and powerful numerical theory that is implemented for generalized non-linear Schrodinger equations in all spatial dimensions and time. This new method can model complicated terms in these equations that outperforms other numerical methods with respect to minimizing numerical error and increased speed. These advantages are due to this method's Fourier nature. A simulation tool was created, employing this numerical technique to simulate white-light generation in bulk media. The simulation matches extremely well with published experimental data, and is superior to the original simulation method used to match the experiment. The use of this tool enables accurate calculations of continuum or white light generation as needed for different experimental protocols and serves as the primary input to generate wide bandwidth coherent light.This work has solved the problem of predictably designing continuum generation within targeted wavelength ranges. This information is needed as part of an overall scheme in laser source development to coherently
Energy Technology Data Exchange (ETDEWEB)
Zia, Haider
2015-12-15
Compact and stable ultrafast laser sources for electron diffraction experiments are the first step in accomplishing the dream experiment of producing a molecular movie. This thesis work focuses on developing new robust laser sources to enable arbitrary scaling in laser repetition rate, pulse energy, duration and stability as needed to provide sufficient integrated detected electrons for high quality diffraction patterns that can be inverted to real space movies. In chapter 2, the construction of a novel stable and high power stretched pulse fiber oscillator outputting 300 mW at 31 MHz and compressible pulses to below 90 fs will be described. Chapter 3 describes the construction of a solid-state regenerative amplifier that was developed to achieve pulse energies above 1mJ with 0.40 mJ already achieved at 1 kHz. Novel simulation techniques were explored that aided the construction of the amplifier. Chapter 4 derives a new, fast and powerful numerical theory that is implemented for generalized non-linear Schrodinger equations in all spatial dimensions and time. This new method can model complicated terms in these equations that outperforms other numerical methods with respect to minimizing numerical error and increased speed. These advantages are due to this method's Fourier nature. A simulation tool was created, employing this numerical technique to simulate white-light generation in bulk media. The simulation matches extremely well with published experimental data, and is superior to the original simulation method used to match the experiment. The use of this tool enables accurate calculations of continuum or white light generation as needed for different experimental protocols and serves as the primary input to generate wide bandwidth coherent light.This work has solved the problem of predictably designing continuum generation within targeted wavelength ranges. This information is needed as part of an overall scheme in laser source development to coherently
Chong, C; Kim, E; Charalampidis, E G; Kim, H; Li, F; Kevrekidis, P G; Lydon, J; Daraio, C; Yang, J
2016-05-01
This article explores the excitation of different vibrational states in a spatially extended dynamical system through theory and experiment. As a prototypical example, we consider a one-dimensional packing of spherical particles (a so-called granular chain) that is subject to harmonic boundary excitation. The combination of the multimodal nature of the system and the strong coupling between the particles due to the nonlinear Hertzian contact force leads to broad regions in frequency where different vibrational states are possible. In certain parametric regions, we demonstrate that the nonlinear Schrödinger equation predicts the corresponding modes fairly well. The electromechanical model we apply predicts accurately the conversion from the obtained mechanical energy to the electrical energy observed in experiments. PMID:27300876
Scarcella, S; Miranda-Miranda, E; Solana, M V; Solana, H
2015-04-01
The aim of the present study was to genetically characterize Fasciola hepatica strains from diverse ecogeographical regions (America and Europe), susceptible and resistant to Triclabendazole, using the random amplified polymorphic DNA fragments (RAPDs-PCR) technique to elucidate genetic variability between the different isolates. Ten different oligonucleotide primers of 10 bases with GC content varying from 50-70% were used. A polymerase chain reaction (PCR) was carried out in 25 μl of total volume. Duplicate PCR reactions on each individual template DNA were performed to test the reproducibility of the individual DNA bands. The size of the RAPD-PCR fragments was determined by the reciprocal plot between the delay factors (Rf) versus the logarithm of molecular weight ladder. The phenogram obtained showed three main clusters, the major of which contained European Strains (Cullompton and Sligo) showing a genetic distance of 27.2 between them. The American strains (Cedive and Cajamarca) on the other hand formed each their distinctive group but clearly maintaining a closer genetic relationship among them than that to their European counterparts, with which showed a distance of 33.8 and 37.8, respectively. This polymorphism would give this species enhanced adaptability against the host, as well as the environment. The existence of genetically different populations of F. hepatica could allow, against any selection pressure, natural or artificial (for use fasciolicides products and/or control measures), one or more populations of F. hepatica to be able to survive and create resistance or adaptability to such selective pressure.
BAND GAP EFFECTS IN PERIODIC CHAIN WITH LOCAL LINEAR OR NON-LINEAR OSCILLATORS
DEFF Research Database (Denmark)
Lazarov, Boyan Stefanov; Jensen, Jakob Søndergaard
2007-01-01
attached linear oscillators. The stop band is located around the resonant frequency of the local oscillators, and thus a stop band can be created in the lower frequency range. In this paper, wave propagation in one-dimensional infinite periodic chains with attached linear and non-linear local oscillators...... within bands of frequencies called stop bands. Stop bands in structures with periodic or random inclusions are located mainly in the high frequency range, as the wave length has to be comparable with the distance between the alternating parts. Wave attenuation is also possible in structures with locally...
Gillis, Julie M.; Corcovilos, Theodore A.; Edstrom, Dean R., Jr.; Ruan, Jinhao; Santucci, James K.
The RF photoinjector of the 50 MeV superconducting electron linear accelerator at the Fermilab Accelerator Science and Technology (FAST) Facility is driven by a phase-locked laser system. The neodymium-doped yttrium-lithium fluoride (Nd:YLF) seed laser provides short (3 ps) infrared (1053 nm) pulses to an amplifier chain before conversion to ultraviolet (263 nm) through two frequency-doubling BBO crystals. The amplification section consists of seven diode-pumped solid state (DPSS) amplifiers, which increase the pulse energy of the seed laser using optically end-pumped Nd:YLF crystals. To maximize the total gain of the amplifier chain, each stage must be properly tuned with optimized optics, alignment, and laser beam characterization. In this paper we report on one of the single-pass amplifier improvements to achieve a consistent gain of 4.83 with stabilized output pulse trains for up to 1500 seed pulses. The final ultraviolet pulses imaged onto the Cs2Te photocathode of the RF electron gun have been doubled in energy to 10.2 μJ per pulse as a result of these alterations. Operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the United States Department of Energy.
Merkelbach, S.; Gehlen, J.; Handt, S.; Füzesi, L
1997-01-01
Four different DNA extraction methods were compared to determine their ability to provide DNA for amplification of viral sequences from paraffin-embedded human tissue samples by polymerase chain reaction (PCR). The suitability of extraction methods was assessed using parameters like DNA yield, length of recovered DNA fragments, and duration. Furthermore, the efficiency of amplifying a human single-copy gene, the beta-globin gene, from DNA samples was tested. The best preservation of DNA molec...
Energy Technology Data Exchange (ETDEWEB)
Kakad, Amar [Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011 (Japan); Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410-218 (India); Omura, Yoshiharu [Research Institute for Sustainable Humanosphere, Kyoto University, Uji, Kyoto 611-0011 (Japan); Kakad, Bharati [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410-218 (India)
2013-06-15
We perform one-dimensional fluid simulation of ion acoustic (IA) solitons propagating parallel to the magnetic field in electron-ion plasmas by assuming a large system length. To model the initial density perturbations (IDP), we employ a KdV soliton type solution. Our simulation demonstrates that the generation mechanism of IA solitons depends on the wavelength of the IDP. The short wavelength IDP evolve into two oppositely propagating identical IA solitons, whereas the long wavelength IDP develop into two indistinguishable chains of multiple IA solitons through a wave breaking process. The wave breaking occurs close to the time when electrostatic energy exceeds half of the kinetic energy of the electron fluid. The wave breaking amplitude and time of its initiation are found to be dependent on characteristics of the IDP. The strength of the IDP controls the number of IA solitons in the solitary chains. The speed, width, and amplitude of IA solitons estimated during their stable propagation in the simulation are in good agreement with the nonlinear fluid theory. This fluid simulation is the first to confirm the validity of the general nonlinear fluid theory, which is widely used in the study of solitary waves in laboratory and space plasmas.
Directory of Open Access Journals (Sweden)
Zhe Zhang
2014-06-01
Full Text Available Purpose: The aim of this paper is to deal with the supply chain management (SCM with quantity discount policy under the complex fuzzy environment, which is characterized as the bi-fuzzy variables. By taking into account the strategy and the process of decision making, a bi-fuzzy nonlinear multiple objective decision making (MODM model is presented to solve the proposed problem.Design/methodology/approach: The bi-fuzzy variables in the MODM model are transformed into the trapezoidal fuzzy variables by the DMs's degree of optimism ?1 and ?2, which are de-fuzzified by the expected value index subsequently. For solving the complex nonlinear model, a multi-objective adaptive particle swarm optimization algorithm (MO-APSO is designed as the solution method.Findings: The proposed model and algorithm are applied to a typical example of SCM problem to illustrate the effectiveness. Based on the sensitivity analysis of the results, the bi-fuzzy nonlinear MODM SCM model is proved to be sensitive to the possibility level ?1.Practical implications: The study focuses on the SCM under complex fuzzy environment in SCM, which has a great practical significance. Therefore, the bi-fuzzy MODM model and MO-APSO can be further applied in SCM problem with quantity discount policy.Originality/value: The bi-fuzzy variable is employed in the nonlinear MODM model of SCM to characterize the hybrid uncertain environment, and this work is original. In addition, the hybrid crisp approach is proposed to transferred to model to an equivalent crisp one by the DMs's degree of optimism and the expected value index. Since the MODM model consider the bi-fuzzy environment and quantity discount policy, so this paper has a great practical significance.
Institute of Scientific and Technical Information of China (English)
Shinobu; Tamaoki; Tetsufumi; Tsuzaki; Motoki; Kakui; Masayuki; Shigematsu
2003-01-01
We have investigated the transient characteristics of discrete Raman Amplifiers and found that the response time caused by gain saturation is dependent upon the wavelength, which corresponds to the effective length of the pump light.
Institute of Scientific and Technical Information of China (English)
Liu Yang; Tang Yi
2008-01-01
By means of the Glauber's coherent state method combined with multiple-scale method,this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion of annihilation operator is reduced to the nonlinear Schr(o)dinger equation.Interestingly,the model can support both bright and dark small amplitude travelling and non-travelling nonlinear localized modes in different parameter spaces.
Institute of Scientific and Technical Information of China (English)
ZHOU En-Bo; ZHANG Xin-Liang; YU Yu; HUANG De-Xiu
2009-01-01
Nonlinear patterning (NLP) effect in wavelength conversion based on transient cross-phase modulation (XPM) in semiconductor optical amplifier (SOA) assisted with a detuning filter is theoretically investigated.A nonadiabatic model is used to estimate the ultrafast dynamics o[ gain,phase and electron temperature in the SOA.Simulation results show that the NLP can be greatly suppressed by introducing an assist light,especially for the probe wavelength distant from gain peak.Furthermore,the results also indicate that the improvement is more evident for long wavelength probe light and assist light in counter-propagating configuration.
International Nuclear Information System (INIS)
A 1.97 μm multiwavelength Tm-doped fiber laser based on a nonlinear amplifier loop mirror (NALM) has been experimentally demonstrated. The NALM with 500 m standard single mode fiber introduces intensity-dependent gain to alleviate mode competition caused by homogeneous gain broadening in Tm-doped fibers. At room temperature, up to 42 wavelengths with a wavelength spacing of 0.33 nm oscillate within a 10-dB bandwidth simultaneously. Repeat measurement of the laser spectrum shows the wavelength drift of a multiwavelength Tm-doped fiber laser is less than 0.05 nm in 40 min. (letter)
International Nuclear Information System (INIS)
Nonlinear patterning (NLP) effect in wavelength conversion based on transient cross-phase modulation (XPM) in semiconductor optical amplifier (SOA) assisted with a detuning filter is theoretically investigated. A non-adiabatic model is used to estimate the ultrafast dynamics of gain, phase and electron temperature in the SOA. Simulation results show that the NLP can be greatly suppressed by introducing an assist light, especially for the probe wavelength distant from gain peak. Furthermore, the results also indicate that the improvement is more evident for long wavelength probe light and assist light in counter-propagating configuration. (fundamental areas of phenomenology (including applications))
Traveling wave solutions in a chain of periodically forced coupled nonlinear oscillators
Duanmu, M.; Whitaker, N.; Kevrekidis, P. G.; Vainchtein, A.; Rubin, J. E.
2016-06-01
Motivated by earlier studies of artificial perceptions of light called phosphenes, we analyze traveling wave solutions in a chain of periodically forced coupled nonlinear oscillators modeling this phenomenon. We examine the discrete model problem in its co-traveling frame and systematically obtain the corresponding traveling waves in one spatial dimension. Direct numerical simulations as well as linear stability analysis are employed to reveal the parameter regions where the traveling waves are stable, and these waves are, in turn, connected to the standing waves analyzed in earlier work. We also consider a two-dimensional extension of the model and demonstrate the robust evolution and stability of planar fronts. Our simulations also suggest the radial fronts tend to either annihilate or expand and flatten out, depending on the phase value inside and the parameter regime. Finally, we observe that solutions that initially feature two symmetric fronts with bulged centers evolve in qualitative agreement with experimental observations of phosphenes.
Yao, Haomin; Wright, Malcolm W; Marciante, John R
2014-09-20
Lasers for use in deep-space applications such as interplanetary optical communications employ multiwatt resonantly pumped dual-clad erbium-doped fiber amplifiers and the pulse-position modulation scheme. Nonlinear optical effects and dynamic gain effects often impair their performance and limit their operational range. These effects are analyzed theoretically and numerically with a time-dependent two-level propagation model, respectively. Self-phase modulation and stimulated Raman scattering are found to limit the usable data format space. In operational regimes free from nonlinear effects, dynamic gain effects such as the variation in the output pulse energy and square-pulse distortion are quantified. Both are found to primarily depend on the symbol duration and can be as large as 28% and 21%, respectively.
International Nuclear Information System (INIS)
The integrability of one dimensional classical continuum inhomogeneous biquadratic Heisenberg spin chain and the effect of nonlinear inhomogeneity on the soliton of an underlying completely integrable spin model are studied. The dynamics of the spin system is expressed in terms of a higher order generalized nonlinear Schroedinger equation through a differential geometric approach which becomes integrable for a particular choice of the biquadratic exchange interaction and for linear inhomogeneity. The effect of nonlinear inhomogeneity on the spin soliton is studied by carrying out a multiple scale perturbation analysis. (author)
DEFF Research Database (Denmark)
Chi, Mingjun; Huignard, J.-P.; Petersen, Paul Michael
2008-01-01
equations of two-wave mixing are derived based on the Maxwell’s wave equation and rate equation of the carrier density. The analytical solutions of the coupled-wave equations are obtained in the condition of small signal when the total intensity is far below the saturation intensity of the amplifier......The two-wave mixing in a broad-area semiconductor amplifier with moving gratings is investigated theoretically, where a pump beam and a signal beam with different frequencies are considered, thus both a moving phase grating and a moving gain grating are induced in the amplifier. The coupled-wave...... or decrease due to the two-wave mixing. © 2008 Optical Society of America...
Choi, Ho-Lim
2014-12-01
In this paper, we provide an output feedback solution over one given by Choi and Lim [Systems & Control Letters, 59(6), 374-379 (2010)] under more generalised system set-up. More specifically, we consider a stabilisation problem of a chain of integrators that has nonlinearity and an uncertain delay in the input by output feedback. The nonlinearity is classified into four types. Then, we propose a memoryless output feedback controller which contains a gain-scaling factor to adjust controller gains depending on the given nonlinearity type. Our stability analysis shows that the controlled system has unique stabilisation result associated with each type of nonlinearity. Our result provides a new aspect to the stabilisation problem of nonlinear time-delay systems and broadens the existing control results of time-delay systems. Two examples are given for illustration.
Directory of Open Access Journals (Sweden)
Mohammed Forhad UDDIN
2012-01-01
Full Text Available In this paper, a supply chain with a coordination mechanism consisting of a single vendor and buyeris considered. Further, instead of a price sensitive linear or deterministic demand function, a price-sensitivenon-linear demand function is introduced. To find the inventory cost, penalty cost and transportation cost, it isassumed that the production and shipping functions of the vendor are continuously harmonized and occur at thesame rate. In this integrated supply chain, the Buyer’s Linear Program (LP, vendor’s Integer Program (IP andcoordinated Mixed Integer Program (MIP models are formulated. In this research, numerical example ispresented which includes the sensitivity of the key parameters to illustrate the models. The solution proceduresdemonstrate that the individual profit as well as joint profit could be increased by a coordination mechanismeven though the demand function is non-linear. In addition, the results illustrate that Buyer’s selling price, alongwith the consumers purchasing price, could be decreased, which may increase the demand of the end market.Finally, a conclusion
Rotstein, Horacio G
2015-04-01
We investigate the biophysical and dynamic mechanisms of generation of subthreshold amplitude and phase resonance in response to sinusoidal input currents in two-dimensional models of quadratic type. These models feature a parabolic voltage nullcline and a linear nullcline for the recovery gating variable, capturing the interplay of the so-called resonant currents (e.g., hyperpolarization-activated mixed-cation inward and slow potassium) and amplifying currents (e.g., persistent sodium) in biophysically realistic parameter regimes. These currents underlie the generation of resonance in medial entorhinal cortex layer II stellate cells and CA1 pyramidal cells. We show that quadratic models exhibit nonlinear amplifications of the voltage response to sinusoidal inputs in the resonant frequency band. These are expressed as an increase in the impedance profile as the input amplitude increases. They are stronger for values positive than negative to resting potential and are accompanied by a shift in the phase profile, a decrease in the resonant and phase-resonant frequencies, and an increase in the sharpness of the voltage response. These effects are more prominent for smaller values of ∊ (larger levels of the time scale separation between the voltage and the resonant gating variable) and for values of the resting potential closer to threshold for spike generation. All other parameter fixed, as ∊ increases the voltage response becomes "more linear"; i.e., the nonlinearities are present, but "ignored". In addition, the nonlinear effects are strongly modulated by the curvature of the parabolic voltage nullcline (partially reflecting the effects of the amplifying current) and the slope of the resonant current activation curve. Following the effects of changes in the biophysical conductances of realistic conductance-based models through the parameters of the quadratic model, we characterize the qualitatively different effects that resonant and amplifying currents have on
宽带功率放大器的非线性研究%A Study on Nonlinear Distortion of Broadband Power Amplifier
Institute of Scientific and Technical Information of China (English)
程雨生
2016-01-01
功率放大器更多时候是工作在饱和区，此时其非线性特性成为需要考虑的重要因素之一。在宽带功率放大器中，低频段信号的二次谐波也在其工作频带之内。当前级功放模块产生的二次谐波与基频信号同时进入末级功放时，产生的二阶交调信号频率与基频相同，对输出造成影响。文中从理论上分析了放大器的非线性表现形式以及产生的机理，介绍了X参数的优势，利用NVNA网络分析仪提取X参数，并且使用ADS软件进行谐波平衡仿真，研究了宽带功率放大器中二次谐波的相位对基频功率的影响。%Power amplifier works more often in the saturated zone, at this point the nonlinear characteristics become one of the im-portant factors to consider.In the broadband power amplifier, the second harmonic wave of the low frequency signal is also in the working band.The second-order intermodulation signals produced by the second harmonic and the fundamental frequency will cause an effect to the output.The nonlinear characteristics of broadband power amplifier and the explanations of nonlinear distortion are discussed in this paper.Then the advantages of X-parameter extracted with NVNA network analyzer is introduced in detail.The influence of the phase of the second harmonic in broadband power amplifier is studied with the help of simulation software ADS.
Oscillators and operational amplifiers
DEFF Research Database (Denmark)
Lindberg, Erik
2005-01-01
A generalized approach to the design of oscillators using operational amplifiers as active elements is presented. A piecewise-linear model of the amplifier is used so that it make sense to investigate the eigenvalues of the Jacobian of the differential equations. The characteristic equation...... of the general circuit is derived. The dynamic nonlinear transfer characteristic of the amplifier is investigated. Examples of negative resistance oscillators are discussed....
Mixed mono- and multilayers of poly(isocyanide)s with non-linear optically active side chains
Teerenstra, M.N.; Hagting, J.G.; Oostergetel, G.T.; Schouten, A.J.; Devillers, M.A.C.; Nolte, R.J.M.
1994-01-01
The properties and structure of Langmuir-Blodgett mono- and multilayers of several poly(isocyanide)s with non-linear optically active side-chains were studied. These polymers formed very rigid layers or layers which appeared to be unstable. To circumvent this problem they were mixed with other poly(
Institute of Scientific and Technical Information of China (English)
Song Wei
2009-01-01
We have investigated the intrinsic decoherence on the entanglement of a two-qutrit one-dimensional (1D) optical lattice chain with nonlinear coupling.As a measure of the entanglement,the negativity of the system is calculated.It is shown that the influence of intrinsic decoherence on the entanglement varies in different initial systems.
Srivastava, Nilabh; Haque, Imtiaz
2009-03-01
Over the past two decades, extensive research has been conducted on developing vehicle transmissions that meet the goals of reduced exhaust emissions and increased vehicle efficiency. A continuously variable transmission is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. A chain CVT is a friction-limited drive whose dynamic performance and torque capacity rely significantly on the friction characteristic of the contact patch between the chain and the pulley. Although a CVT helps to maximize the vehicle fuel economy, its complete potential has not been accomplished in a mass-production vehicle. The present research focuses on developing models to analyze friction-induced nonlinear dynamics of a chain CVT drive and identify possible mechanisms that cause degradation of the overall dynamic performance by inducing chaos and self-sustained vibrations in the system. Two different mathematical models of friction, which characterize different operating or loading conditions, are embedded into a detailed planar multibody model of chain CVT in order to capture the various friction-induced effects in the system. Tools such as stick-slip oscillator dynamics, Lyapunov exponents, phase-space reconstruction, and recurrence plotting are incorporated to characterize the nonlinear dynamics of such a friction-limited system. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of friction characteristics on the nonlinear dynamics and torque transmitting capacity of a chain CVT drive.
Haleem, Kamran
2015-01-01
Objective of modern small satellite communication is to provide the end users with higher data rate downlink capability, in addition to, reliability and system efficiency. A significant device, with respect to power consumption and influence on system linearity, use in the transmission chain of small satellites, is power amplifier. The power amplifier tends to add distortion and non-linearity in the transmitted signal, when operating close to saturation point. For avoiding the non-linearity a...
Shukla, Deepak; Adiga, Shashishekar P; Ahearn, Wendy G; Dinnocenzo, Joseph P; Farid, Samir
2013-03-01
Photoinduced electron transfer to N-alkoxypyridiniums, which leads to N–O bond cleavage and alkoxyl radical formation, is highly chain amplified in the presence of a pyridine base such as lutidine. Density functional theory calculations support a mechanism in which the alkoxyl radicals react with lutidine via proton-coupled electron transfer (PCET) to produce lutidinyl radicals (BH•). A strong electron donor, BH• is proposed to reduce another alkoxypyridinium cation, leading to chain amplification, with quantum yields approaching 200. Kinetic data and calculations support the formation of a second, stronger reducing agent: a hydrogen-bonded complex between BH• and another base molecule (BH•···B). Global fitting of the quantum yield data for the reactions of four pyridinium salts (4-phenyl and 4-cyano with N-methoxy and N-ethoxy substituents) led to a consistent set of kinetic parameters. The chain nature of the reaction allowed rate constants to be determined from steady-state kinetics and independently determined chain-termination rate constants. The rate constant of the reaction of CH3O• with lutidine to form BH•, k1, is ~6 × 10(6) M(–1) s(–1); that of CH3CH2O• is ~9 times larger. Reaction of CD3O• showed a deuterium isotope effect of ~6.5. Replacing lutidine by 3-chloropyridine, a weaker base, decreases k1 by a factor of ~400.
International Nuclear Information System (INIS)
We propose a simple approach to generate a high quality 10 GHz 1.9 ps optical pulse train using a semiconductor optical amplifier and silica-based highly nonlinear fiber. An optical pulse generator based on our proposed scheme is easy to set up with commercially available optical components. A 10 GHz, 1.9 ps optical pulse train is obtained with timing jitter as low as 60 fs over the frequency range 10 Hz–1 MHz. With a wavelength tunable CW laser, a wide wavelength tunable span can be achieved over the entire C band. The proposed optical pulse generator also can operate at different repetition rates from 3 to 10 GHz
International Nuclear Information System (INIS)
In this paper we investigate an ultra-long cavity passively mode-locked fiber laser based on a semiconductor optical amplifier (SOA). Experimental results are presented which indicate that stable mode-locked pulses can be obtained by combining nonlinear polarization rotation (NPR) in the SOA with a polarization controller. By adding a 4 km single mode fiber into the ring cavity, a stable fundamental-order mode-locked pulse train with a repetition rate of 50.72 kHz is generated through the NPR effect in the SOA. The central wavelength, 3 dB bandwidth and single pulse energy of the output pulse are 1543.95 nm, 1.506 nm and 33.12 nJ, respectively. Harmonic mode-locked pulses are also observed in experiments when the parameters are chosen properly. (paper)
Directory of Open Access Journals (Sweden)
Comfort O. AFOLAYAN
2015-09-01
Full Text Available The genetic differentiation of Archachatina marginata populations from three different zones of Nigeria was studied with a view to delimiting them into sub-species. One hundred and nineteen (119 snail specimens were collected, comprising of forty (40 specimens from Yenagoa (Mangrove forest and from Kabba (Guinea Savanna and thirty nine (39 specimens were from Ile-Ife (Rainforest. Eight parameters of the shell specimens of A. marginata which included height of shell, width of shell, aperture height, aperture width, spire length, spire width, penultimate whorl length and first whorl length were subjected to Principal Component Analysis (PCA and Canonical Variates Analysis (CVA to delimit the populations into sub-species. DNA of the various populations was extracted from the foot muscle using CTAB (Cetyl Trimethyl Ammonium Bromide method, which was subjected to RAPD analysis. The RAPD studies employed five (5 oligonucleotide primers (OPB – 17, OPH – 12, OPH – 17, OPI – 06 and OPU – 14 to amplify DNA from 27 samples of A. marginata selected. All five primers produced different band patterns, and the number of fragments amplified per primer varied. Among them, OPB- 17 gave DNA profiles with more numerous bands than the others primers. Both PCA and CVA produced overlapped clusters of A. marginata specimens from the three vegetation zones. The height of shell was observed to be the most variable feature and preferably the most suitable parameter for population grouping. Analysis of the proportions of polymorphic loci and band sharing based on similarity indices for A. marginata samples indicated a relatively high level of genetic variation in the populations from the three areas.
DNA Amplified Technique Out body Polymerase chain Reaction (PCR)%DNA体外扩增技术——聚合酶链式反应(PCR)
Institute of Scientific and Technical Information of China (English)
李莹
2000-01-01
PCR is DNA amplified technique outbody. It possess high - speed, simple and specific merit. It has wide out look of applificalion in Molecular Biology. This paper introduced PCR's basic principle, factors of effect and applification.%PcR(Polymerase Chain Reaction)译为聚合酶链式反应，是近年来发展起来的一种DNA体外扩增技术．具有快速，简便和特异性强的优点，在分子生物学研究方面的应用具有广阔的前景．本文简要介绍了PCR技术的原理，影响因素及其应用．
López-González, Dany; Molina, Mario I.
2016-03-01
We examine the transport of extended and localized excitations in one-dimensional linear chains populated by linear and nonlinear symmetric identical n -mers (with n =3 , 4, 5, and 6), randomly distributed. First, we examine the transmission of plane waves across a single linear n -mer, paying attention to its resonances, and looking for parameters that allow resonances to merge. Within this parameter regime we examine the transmission of plane waves through a disordered and nonlinear segment composed by n -mers randomly placed inside a linear chain. It is observed that nonlinearity tends to inhibit the transmission, which decays as a power law at long segment lengths. This behavior still holds when the n -mer parameters do not obey the resonance condition. On the other hand, the mean square displacement exponent of an initially localized excitation does not depend on nonlinearity at long propagation distances z , and shows a superdiffusive behavior ˜z1.8 for all n -mers, when parameters obey the resonance merging condition; otherwise the exponent reverts back to the random dimer model value ˜z1.5 .
Karni, Ouri; Eisenstein, Gad; Reithmaier, Johann Peter
2014-01-01
We study the interplay between coherent light-matter interactions and non-resonant pulse propagation effects when ultra-short pulses propagate in room-temperature quantum-dot (QD) semiconductor optical amplifiers (SOAs). The signatures observed on a pulse envelope after propagating in a transparent SOA, when coherent Rabi-oscillations are absent, highlight the contribution of two-photon absorption (TPA), and its accompanying Kerr-like effect, as well as of linear dispersion, to the modification of the pulse complex electric field profile. These effects are incorporated into our previously developed finite-difference time-domain comprehensive model that describes the interaction between the pulses and the QD SOA. The present, generalized, model is used to investigate the combined effect of coherent and non-resonant phenomena in the gain and absorption regimes of the QD SOA. It confirms that in the QD SOA we examined, linear dispersion in the presence of the Kerr-like effect causes pulse compression, which coun...
Saldaña-Díaz, J. E.; Jarabo, S.; Salgado-Remacha, F. J.
2016-09-01
We report a simple method for supercontinuum generation. The set-up consists of an Er-doped mode-locked fibre laser, used as seed, and a highly nonlinear fibre with zero dispersion at 1550 nm. Thus, all the components are easily attainable. With this novel system the requirements in terms of control of dispersion are reduced. In addition, the spectral width is optimized using fibres with positive and negative dispersion. The supercontinuum emission is characterized by means of an optical spectrum analyser and a PbS photodetector, showing an octave-spanning spectral width, with a flat profile from 1100 nm up to 2100 nm. Compared to other supercontinuum sources, this new proposal results in a very competitive and attainable system, particularly in the 1500-2100 nm region.
DEFF Research Database (Denmark)
Xu, Zhenbo; Rottwitt, Karsten; Jeppesen, Palle
2005-01-01
Five-channel 160-Gb/s wavelength-division-multiplexing (WDM) systems using ABA dispersion map and Raman amplification are investigated numerically. Transmission distance and system margin are evaluated for return-to-zero differential phase-shift keying (RZ-DPSK) and carrier-suppressed return......-to-zero (CSRZ)-DPSK formats. The results show that RZ-DPSK can offer 2300-km system reach at large WDM channel spacing, while CSRZ-DPSK is more robust against nonlinear effects in the fibers and offers a reach of 1900 km at a spectral efficiency of 0.53 b/s/Hz. CSRZ-DPSK can also provide twice the dispersion...
Saldaña-Díaz, J. E.; Jarabo, S.; Salgado-Remacha, F. J.
2016-09-01
We report a simple method for supercontinuum generation. The set-up consists of an Er-doped mode-locked fibre laser, used as seed, and a highly nonlinear fibre with zero dispersion at 1550 nm. Thus, all the components are easily attainable. With this novel system the requirements in terms of control of dispersion are reduced. In addition, the spectral width is optimized using fibres with positive and negative dispersion. The supercontinuum emission is characterized by means of an optical spectrum analyser and a PbS photodetector, showing an octave-spanning spectral width, with a flat profile from 1100 nm up to 2100 nm. Compared to other supercontinuum sources, this new proposal results in a very competitive and attainable system, particularly in the 1500–2100 nm region.
Complex spatiotemporal behavior in a chain of one-way nonlinearly coupled elements
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Berkemer, Rainer; Gorria, C.;
2011-01-01
The dynamics of asymmetrically coupled nonlinear elements is considered. It is shown that there are two distinctive regimes of oscillatory behavior of one-way nonlinearly coupled elements depending on the relaxation time and the strength of the coupling. In the subcritical regime when...
Institute of Scientific and Technical Information of China (English)
李红玉; 代丽美
2012-01-01
本文研究了测度链上具有变号非线性项微分方程的问题.利用拓扑方法,获得了此微分方程的正解存在性结果,推广和改进了一些文献中相应的结果.%In this paper,we study nonlinear differential equations on a measure chain.By topological methods,the existence of positive solutions of nonlinear differential equations with sign changing nonlinearity on a measure chain is discussed.The results generalize and improve the known results.
Zoiros, K. E.; Demertzis, C.
2011-10-01
The feasibility of increasing by a factor of two the data speed of the semiconductor optical amplifier (SOA)-based ultrafast nonlinear interferometer in dual rail switching mode by means of a cascaded optical delay interferometer (ODI) is explored and shown through numerical simulation. From the theoretical analysis it has been found that such extension cannot be done without employing this passive element for any selection of the critical parameters but the SOA carrier lifetime, for which the requirements are yet very demanding. If, however, the time delay introduced by the ODI is adjusted to almost 1/3rd of the bit period, then the result of Boolean XOR operation can be improved for a specified range of parameter values, which can be further selected to be more relaxed than is possible when the ODI is not being used. The use of the ODI allows both error-free and pattern-free performance at the output of the interferometric structure configured as ultrafast XOR gate. In this manner the scheme can offer a practical alternative solution for extending the operating rate of this logical module and enabling its exploitation as a basic building unit in more sophisticated all-optical circuits and subsystems.
Siarkos, Thanassis; Zoiros, Kyriakos E.
2009-08-01
The performance of a single semiconductor optical amplifier (SOA)-based ultrafast nonlinear interferometer that is simultaneously driven by two ultrafast data streams with respect to the timing deviation between these signals and the standard clock input is theoretically studied and investigated. For this purpose, a numerical model is applied to simulate the operation of the specific module in pattern-operated dual rail-switching mode and under the presence of such imperfect synchronization. The thorough analysis and interpretation of the obtained results allows one to evaluate the impact of this temporal offset on the achievement of both bitwise logical correctness and high quality at the output. In this manner, the conditions that it must necessarily fulfill are derived and the dependence of its permissible margin and accordingly the way the latter can be extended is revealed, while its optimal amount for maximizing the defined metric is quantified by the difference between the orthogonal polarization clock components' relative walk-off and the control pulse width. These findings can help compensate for the existence of this effect as well as strengthen the tolerance against it so that it can be properly handled in the context of the considered type of SOA-based interferometric switch.
Siarkos, T.; Zoiros, K. E.; Nastou, D.
2009-07-01
The possibility of implementing an ultrafast all-optical XOR gate using a single semiconductor optical amplifier (SOA)-based ultrafast nonlinear interferometer (UNI) is theoretically investigated and demonstrated. For this purpose a comprehensive model that characterizes the performance of a SOA when it is successively driven by two strong pseudorandom binary sequences is applied to simulate the specific module under dual rail switching mode of operation. In this manner an extensive set of curves is obtained allowing to analyze and evaluate the impact of the input data, SOA and interferometer critical parameters on the fully loaded Q-factor. Their thorough study and interpretation reveals that the satisfaction of their requirements in order to render acceptable this metric is feasible from a technological perspective and thus if their selection is made according to the extracted guidelines then pattern-free and error-free modulo-2 arithmetic can be straightforwardly realized at 20 Gb/s. This prediction can be of practical interest in simplifying and assisting the design of more sophisticated interconnections of enhanced combinatorial and sequential functionality in which the XOR gate is the core logical unit.
International Nuclear Information System (INIS)
A stable multi-wavelength polarization-maintaining erbium-doped fiber (PM-EDF) ring cavity laser employing a twin-core fiber (TCF) comb filter and a nonlinear amplifying loop mirror (NALM) is proposed and demonstrated. By appropriately adjusting the polarization controllers, the NALM as an amplitude equalizer can effectively reduce the mode competition caused by the homogeneous broadening gain medium in the PM-EDF. Under 150 mW pump power, up to 26 wavelength outputs within a 3 dB bandwidth are achieved and their signal-to-noise ratio (SNR) is 39.5 dB. Besides, the TCF comb filter is experimentally fabricated using a length of 0.78 m TCF spliced between two segments of the single-mode fiber. The transmission spectra of the filter in experimental measurements are in accord with the results of theoretical analysis, and its wavelength spacing is 0.29 nm. Meanwhile, the power fluctuation and wavelength shift are within 0.1 dB and 0.02 nm, respectively. The experimental results indicate that the proposed multi-wavelength fiber laser performs with high stability at room temperature. In addition, the multi-wavelength laser with the TCF comb filter can offer more wavelengths in a 3 dB spectral range and higher SNR than one using a Sagnac loop filter, and the length of the filter is also reduced by more than six times. (paper)
S波段T/R组件用GaN功率放大器链的设计%GaN High Power Amplifier Chain for S-band T/R Modules
Institute of Scientific and Technical Information of China (English)
姚小江; 谢武涛; 施鹤年; 刘珊; 胡永芳; 赵亮
2011-01-01
High power amplifier (HPA) chain based on Si-substrated AlGaN/GaN HEMT is the key component in next generation T/R modules for future S band phased array antenna.Designed S-band amplifier chain is composed of a driver and a power amplifier,both of which are HMICs based on Si-substrated AlGaN/GaN HEMT.In HMIC-Based amplifier chain design,excellent peak power level and associated power added efficiency (PAE) are realized.This amplifier is covering a bandwidth of 800MHz frequency rang with output power level higher than 20 W and PAE more than 50％.%基于Si村底AlGaN/GaN HEMT器件的功率放大器链是下一代S波段相控阵雷达T/R组件的核心部分.研制的S波段放大器链主要由驱动放大器和功率放大器组成,驱动放大器与功率放大器都是基于Si衬底AlGaN/GaN HEMT器件的混合集成电路.基于混合集成电路的放大器链获得了高的输出峰值功率和附加功率(PAE),整个放大器链输出功率在800 MHz频率范围内大于20W,附加效率(PAE)大于50％.
Van Camp, Koen
2015-01-01
Value still resides at the heart of the marketing place. Companies creating superior value will achieve higher satisfaction among their customers leading to higher loyalty and profits. The different relationships in the customer value-satisfaction-loyalty chain are therefore of utmost importance. Most companies, assume that the relationships between customer value, customer satisfaction and customer loyalty are simple symmetric, linear ones. The question remains, if this assumption is always ...
Yin, Sisi; Nishi, Tatsushi
2014-11-01
Quantity discount policy is decision-making for trade-off prices between suppliers and manufacturers while production is changeable due to demand fluctuations in a real market. In this paper, quantity discount models which consider selection of contract suppliers, production quantity and inventory simultaneously are addressed. The supply chain planning problem with quantity discounts under demand uncertainty is formulated as a mixed-integer nonlinear programming problem (MINLP) with integral terms. We apply an outer-approximation method to solve MINLP problems. In order to improve the efficiency of the proposed method, the problem is reformulated as a stochastic model replacing the integral terms by using a normalisation technique. We present numerical examples to demonstrate the efficiency of the proposed method.
Energy Technology Data Exchange (ETDEWEB)
Zhang, Jianxin; Zhang, Zhenjun [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Tong, Peiqing, E-mail: pqtong@njnu.edu.cn [Department of Physics and Institute of Theoretical Physics, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Key Laboratory for Numerical Simulation of Large Scale Complex Systems, Nanjing Normal University, Nanjing 210023 (China)
2013-07-15
We investigate the spreading of an initially localized wave packet in one-dimensional generalized Fibonacci (GF) lattices by solving numerically the discrete nonlinear Schrödinger equation (DNLSE) with a delayed cubic nonlinear term. It is found that for short delay time, the wave packet is self-trapping in first class of GF lattices, that is, the second moment grows with time, but the corresponding participation number does not grow. However, both the second moment and the participation number grow with time for large delay time. This illuminates that the wave packet is delocalized. For the second class of GF lattices, the dynamic behaviors of wave packet depend on the strength of on-site potential. For a weak on-site potential, the results are similar to the case of the first class. For a strong on-site potential, both the second moment and the participation number does not grow with time in the regime of short delay time. In the regime of large delay time, both the second moment and the participation number exhibit stair-like growth.
Dostal, Jiri
1993-01-01
This book provides the reader with the practical knowledge necessary to select and use operational amplifier devices. It presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits.Provides the reader with practical knowledge necessary to select and use operational amplifier devices. Presents an extensive treatment of applications and a practically oriented, unified theory of operational circuits
Numerical experiments on the modulation theory for the nonlinear atomic chain
Dreyer, W.; Herrmann, M.
2008-02-01
Modulation theory with periodic travelling waves is a powerful, but not rigorous tool to derive a thermodynamic description for atomic chains with nearest neighbour interactions (FPU chains). This theory is sufficiently complex to deal with strong oscillations on the microscopic scale, and therefore it is capable to describe the creation of temperature and the transport of heat on a macroscopic scale. In this paper we investigate the validity of modulation theory by means of several numerical experiments. We start with a survey on the foundations of modulation theory. In particular, we discuss the hyperbolic scaling, the notion of cold data, microscopic oscillations and Young measures, periodic and modulated travelling waves, and, finally, the resulting macroscopic conservation laws. Afterwards we discuss how the validity of a macroscopic theory may be tested within numerical simulations of the microscopic dynamics. To this end we describe an approach to thermodynamic data exploration which is motivated by the theory of Young measures, and relies on mesoscopic windows in space and time. The last part is devoted to several numerical experiments including examples with periodic boundary conditions and smooth initial data, and macroscopic Riemann problems. We interpret the outcome of these experiments in the framework of thermodynamics, and end up with two conclusions. (1) There are many examples for which modulation theory provides in fact the right thermodynamic description because it can predict both the structure of the microscopic oscillations and their macroscopic evolution correctly. (2) Modulation theory will fail if the oscillations exhibit a more complicate structure.
Effect of Soliton Propagation in Fiber Amplifiers
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The propagation of optical solitons in fiber amplifiers is discussed by considering a model that includes linear high order dispersion, two-photon absorption, nonlinear high-order dispersion, self-induced Ramam and five-order nonlinear effects. Based on travelling wave method, the solutions of the nonlinear Schrdinger equations, and the influence on soliton propagation as well as high-order effect in the fiber amplifier are discussed in detail. It is found that because of existing five-order nonlinear effect, the solution is not of secant hyperbola type, but shows high gain state of the fiber amplifier which is very favourable to the propagation of solitons.
Directory of Open Access Journals (Sweden)
SR Naddaf Dezfouli
2002-09-01
Full Text Available Anopheles fluviatilis complex is known to be a vector of malaria in Iran. Since mosquitoes of this species cover a wide geographical range in Iran, they might have evolved into different separated populations. Random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR assay was used to differentiate geographic populations of this species. DNA was extracted from individual mosquitoes from 8 localities in 4 south and southeast provinces and amplified in PCR reactions using 18 single primers of arbitrary nucleotide sequence. Results of RAPD-PCR showed that Kazeroun populations could simply be differentiated from other populations using a diagnostic fragment amplified with primer UBC-306. But other populations could not be differentiated either visually or by means of statistical analysis. Moreover ITS2 fragments of some selected specimens were amplified using a pair of universal primer and sequenced as a key standard for detection of putative sibling species. Sequence analysis of the ITS2 fragments revealed a very high (100% homology among the populations. These findings are crucial in epidemiological studies concerning relatedness of geographic populations and vector movement in the region. Results of RAPD-PCR and ITS2 analysis suggest that this taxon in Iran comprises of only one species with a low genetic variation among geographic populations.
Directory of Open Access Journals (Sweden)
Manuel eBedia
2012-10-01
Full Text Available Dual system approaches of decision making examine the interaction between affective/intuitive and deliberative processes underlying value judgment. Decisions are arise from a combination of relatively explicit capabilities for abstract reasoning and relatively implicit evolved domain-general as well as learned domain-specific affective responses. One such approach, the somatic markers hypothesis (SMH, expresses these processes as a system of evolved primary emotions supplemented by associations between affect and experience that accrue over lifetime, or somatic markers (SMs. In this view, SMs are useful only if their local capability to predict the value of an action is above a baseline equal to the predictive capability of the combined rational and primary emotional subsystems. We argue that decision making has often been conceived of as a linear process: the effect of decision sequences is additive, local utility is cumulative, and there is no strong environmental feedback. This widespread assumption has consequences for answering questions regarding the relative weight between the systems and their interaction within a cognitive architecture. We introduce a mathematical formalization of the SMH and study it in situations of dynamic, nonlinear decision chains using a discrete-time stochastic model. We find, contrary to expectations, that decision making events can interact non-additively with the environment in apparently paradoxical ways. We find that primary emotions are represented globally over and above their local weight, showing a tendency for overcaution in situated decision chains. We also show that because they tend to counteract this trend, poorly attuned somatic markers that by themselves do not locally enhance decision making, can still produce an overall positive effect. This result has developmental and evolutionary implications since, by promoting exploratory behavior, SMs are beneficial even at early stages when experiential
Matching Analysis of Front-End Amplifier Chain & Digital A/D Module Interface%接收机前端放大链与数字模块接口匹配分析
Institute of Scientific and Technical Information of China (English)
张财生; 丁家会; 何友
2009-01-01
The problem of matching between a receiving front-end amplifier chain and a digital A/D converter module is explored in details. Then the limit performances of a receiving system sensitivity and dynamic range are analyzed when the front-end amplifier chain and the digital A/D converter module are interconnected. An experimental test results is presented to demonstrate and compare with our deduction values in theory. Several compromising suggestions on choosing the right gain of an amplifier chain and a proper AD converter are given. Some aspects and referential curves on receiving system design are summarized which is used to obtain the required sensitivity and dynamic range within the available performances of the front-end and the digital A/D converter modules.%探讨了雷达数字化接收系统前端放大链与数字A/D模块级联后,接收系统的噪声系数、灵敏度和瞬时动态范围等参数的变化;研究了在工程上接收系统为获得最佳性能,前端放大链与数字A/D模块性能指标的折衷问题,推导了相应的设计公式并给出了实验验证.最后总结了在接收系统前端和A/D性能允许范围内,获得设计师希望得到的接收系统灵敏度和动态范围的方法及设计参考曲线.
Biernasiuk, Anna; Korona-Głowniak, Izabela; Grzegorczyk, Agnieszka; Malm, Anna
2014-01-01
Cancer patients are predisposed to fungal infections caused by Candida albicans, especially to oral or respiratory tract candidiasis. The aim of this study was to estimate genetic diversity by RAPD-PCR (random amplified polymorphic DNA-polymerase chain reaction) of C. albicans isolated from upper respiratory tract of 100 patients with non-small cell lung cancer. Among 52 strains, 34 genotypes were defined. 10 clusters comprising 28 (53.85%) isolates with similarity coefficient ≥ 80% were formed. The remaining 24 (46.15%) isolates represented individual genotypes. The RAPD-PCR technique revealed genomic variability within C. albicans isolated from upper respiratory tract of the cancer patients. PMID:25371918
Bedia, Manuel G; Di Paolo, Ezequiel
2012-01-01
Dual-process approaches of decision-making examine the interaction between affective/intuitive and deliberative processes underlying value judgment. From this perspective, decisions are supported by a combination of relatively explicit capabilities for abstract reasoning and relatively implicit evolved domain-general as well as learned domain-specific affective responses. One such approach, the somatic markers hypothesis (SMH), expresses these implicit processes as a system of evolved primary emotions supplemented by associations between affect and experience that accrue over lifetime, or somatic markers. In this view, somatic markers are useful only if their local capability to predict the value of an action is above a baseline equal to the predictive capability of the combined rational and primary emotional subsystems. We argue that decision-making has often been conceived of as a linear process: the effect of decision sequences is additive, local utility is cumulative, and there is no strong environmental feedback. This widespread assumption can have consequences for answering questions regarding the relative weight between the systems and their interaction within a cognitive architecture. We introduce a mathematical formalization of the SMH and study it in situations of dynamic, non-linear decision chains using a discrete-time stochastic model. We find, contrary to expectations, that decision-making events can interact non-additively with the environment in apparently paradoxical ways. We find that in non-lethal situations, primary emotions are represented globally over and above their local weight, showing a tendency for overcautiousness in situated decision chains. We also show that because they tend to counteract this trend, poorly attuned somatic markers that by themselves do not locally enhance decision-making, can still produce an overall positive effect. This result has developmental and evolutionary implications since, by promoting exploratory behavior
International Nuclear Information System (INIS)
A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here
Energy Technology Data Exchange (ETDEWEB)
Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)
2003-05-07
A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.
Bachelard, R; Mercère, P; Idir, M; Couprie, M-E; Labat, M; Chubar, O; Lambert, G; Zeitoun, Ph; Kimura, H; Ohashi, H; Higashiya, A; Yabashi, M; Nagasono, M; Hara, T; Ishikawa, T
2011-06-10
The single-shot spatial characteristics of the vacuum ultraviolet self-amplified spontaneous emission of a free electron laser (FEL) is measured at different stages of amplification up to saturation with a Hartmann wavefront sensor. We show that the fundamental radiation at 61.5 nm tends towards a single-mode behavior as getting closer to saturation. The measurements are found in good agreement with simulations and theory. A near diffraction limited wavefront was measured. The analysis of Fresnel diffraction through the Hartmann wavefront sensor hole array also provides some further insight for the evaluation of the FEL transverse coherence, of high importance for various applications.
Energy Technology Data Exchange (ETDEWEB)
Bachelard, R.; Chubar, O.; Mercere, P.; Idir, M.; Couprie, M.E.; Lambert, G.; Zeitoun, Ph.; Kimura, H.; Ohashi, H.; Higashiya, A.; Yabashi, M.; Nagasono, M.; Hara, T. and Ishikawa, T.
2011-06-08
The single-shot spatial characteristics of the vacuum ultraviolet self-amplified spontaneous emission of a free electron laser (FEL) is measured at different stages of amplification up to saturation with a Hartmann wavefront sensor. We show that the fundamental radiation at 61.5 nm tends towards a single-mode behavior as getting closer to saturation. The measurements are found in good agreement with simulations and theory. A near diffraction limited wavefront was measured. The analysis of Fresnel diffraction through the Hartmann wavefront sensor hole array also provides some further insight for the evaluation of the FEL transverse coherence, of high importance for various applications.
Parametric Amplifiers for Microwave Kinectic Inductance Detector (MKID) Readout Project
National Aeronautics and Space Administration — Find numerical solutions to the non-linear partial differential equations describing our amplifier transmission lines. Optimize periodic choke structure to block...
International Nuclear Information System (INIS)
Quadratic nonlinear-optical characteristics of thin films based on methacrylic copolymers with of chromophore-containing monomers incorporated at various concentrations are measured by Second Harmonic Generation technique. Optimal chromophores content is obtained to be about 17 mol%, rather high values of nonlinear-optical coefficient, d33, up to 60 pm/V, are determined
Nagata, Yuuya; Nishikawa, Tsuyoshi; Suginome, Michinori
2014-11-12
Poly(quinoxaline-2,3-diyl) containing (S)-3-octyloxymethyl side chains was synthesized to investigate the induction of a single-handed helical sense to the main chain in various alkane solvents. The polymer showed an efficient solvent dependent helix inversion between n-octane (M-helix) and cyclooctane (P-helix). After a screening of alkane solvents, it was found that linear alkanes having large molecular aspect ratios induced M-helical structure, and branched or cyclic alkanes having small molecular aspect ratios induced P-helical structure. A polymer ligand containing (S)-3-octyloxymethyl side chains and diphenylphosphino pendants also exhibited solvent-dependent helical inversion between n-octane and cyclooctane, leading to the highly enantioselective production of the both enantiomeric product in a palladium-catalyzed asymmetric hydrosilylation reaction of styrene (R-product 94% ee in n-octane and S-product 90% ee in cyclooctane). PMID:25343492
Liu, Jianguo; Cheng, Tee Hiang; Yeo, Yong kee; Wang, Yixin; Xue, Lifang; Wang, Dawei; Yu, Xiaojun
2008-11-01
The idler is separated from the co-propagating pump in a degenerate four-wave mixing (DFWM) with a symmetrical parametric loop mirror (PALM), which is composed of two identical SOAs and a 70 m highly-nonlinear photonic crystal fiber (HN-PCF). The signal and pump are coupled into the symmetrical PALM from different ports, respectively. After the DFWM based wavelength conversion (WC) in the clockwise and anticlockwise, the idler exits from the signal port, while the pump outputs from its input port. Therefore, the pump is effectively suppressed in the idler channel without a high-speed tunable filter. Contrast to a traditional PALM, the DFWM based conversion efficiency is increased greatly, and the functions of the amplification and the WC are integrated in the smart SOA and HN-PCF PALM.
Miyazawa, Toshifumi; Iguchi, Wakana
2013-10-01
The enantioselectivity of the transesterification of the 2,2,2-trifluoroethyl esters of 2-(substituted phenoxy)propanoic acids, as catalyzed by the lipase from Carica papaya, was greatly improved by using long-chain ethers, such as di-n-hexyl ether, as solvents instead of the conventional diisopropyl ether. Thus, for example, the E value was enhanced from 21 [in diisopropyl ether (0.8 ml)] to 57 [in di-n-hexyl ether (0.8 ml)] in the reaction of 2,2,2-trifluoroethyl(RS)-2-phenoxypropanoate (0.1 mmol) with methanol (0.4 mmol) in the presence of the plant lipase preparation (10 mg); it was also improved from 13 (in diisopropyl ether) to 44 (in di-n-hexyl ether) in the reaction of 2,2,2-trifluoroethyl(RS)-2-(2-chlorophenoxy)propanoate with methanol under the same reaction conditions.
Predistortion of a Bidirectional Cuk Audio Amplifier
DEFF Research Database (Denmark)
Birch, Thomas Hagen; Nielsen, Dennis; Knott, Arnold;
2014-01-01
Some non-linear amplifier topologies are capable of providing a larger voltage gain than one from a DC source, which could make them suitable for various applications. However, the non-linearities introduce a significant amount of harmonic distortion (THD). Some of this distortion could be reduced...... using predistortion. This paper suggests linearizing a nonlinear bidirectional Cuk audio amplifier using an analog predistortion approach. A prototype power stage was built and results show that a voltage gain of up to 9 dB and reduction in THD from 6% down to 3% was obtainable using this approach....
Nieuwoudt, Martin; Lameris, Roeland; Corcoran, Craig; Rossouw, Theresa M; Slavik, Tomas; Du Plessis, Johannie; Omoshoro-Jones, Jones A O; Stivaktas, Paraskevi; Potgieter, Fritz; Van der Merwe, Schalk W
2014-09-01
Abdominal lymphadenopathy in human immunodeficiency virus (HIV) infection remains a diagnostic challenge. We performed a prospective cohort study by recruiting 31 symptomatic HIV + patients with abdominal lymphadenopathy and assessing the diagnostic yield of endoscopic ultrasound fine-needle aspiration (EUS-FNA). Mean age was 38 years; 52% were female; and mean CD4 count and viral load were 124 cells/μL and 4 log, respectively. EUS confirmed additional mediastinal nodes in 26%. The porta hepatis was the most common abdominal site. Aspirates obtained by EUS-FNA were subjected to cytology, culture and polymerase chain reaction (PCR) analysis. Mycobacterial infections were confirmed in 67.7%, and 31% had reactive lymphadenopathy. Cytology and culture had low sensitivity, whereas PCR identified 90% of mycobacterial infections. By combining the appearance of aspirates obtained by EUS-FNA and cytologic specimens, we developed a diagnostic algorithm to indicate when analysis with PCR would be useful. PCR performed on material obtained by EUS-FNA was highly accurate in confirming mycobacterial disease and determining genotypic drug resistance.
Institute of Scientific and Technical Information of China (English)
LI, Zhen; QIN, Jin-Gui; LI, Shao-Jun; YE, Cheng
2003-01-01
A new strategy, a post coupling method to develop the polyphosphazene (P2) functionalized with carbazolyl groups and nonlinear optical (NLO) chromophores, has been explored. P2 exhibits good solubility in common organic solvents.The poled film of P2 exhibits a resonant d33 value of 42 pm/Vby second harmonic generation (SHG) measurements.
Gaussian amplifier for nuclear spectrometry
International Nuclear Information System (INIS)
One of the major goals of nuclear spectrometry is the determination of the energy spectrum of a radioactive source. To measure this spectrum with electronic instrumentation one need to use a nuclear spectrometry chain of which the amplifier is part of, and whose filter shaping considerably influences the final energy resolution achieved. The amplifier released accomplishes a 7th order Gaussian filter shape with Taylor series approximation synthesized by the Shifted Companion Form and mounted using only electronic components availablein Brazil. The final version has been tested and the results showed a very good performance and the energy resolution achieved was equivalent to the imported models. (Author)
International Nuclear Information System (INIS)
A gain ranging amplifier system is provided for use in the acquisition of data. Voltage offset compensation is utilized to correct errors in the gain ranging amplifier system caused by thermal drift and temperature dependent voltage offsets, both of which are associated with amplifiers in the gain ranging amplifier system
Portable musical instrument amplifier
Energy Technology Data Exchange (ETDEWEB)
Christian, David E. (Danbury, CT)
1990-07-24
The present invention relates to a musical instrument amplifier which is particularly useful for electric guitars. The amplifier has a rigid body for housing both the electronic system for amplifying and processing signals from the guitar and the system's power supply. An input plug connected to and projecting from the body is electrically coupled to the signal amplifying and processing system. When the plug is inserted into an output jack for an electric guitar, the body is rigidly carried by the guitar, and the guitar is operatively connected to the electrical amplifying and signal processing system without use of a loose interconnection cable. The amplifier is provided with an output jack, into which headphones are plugged to receive amplified signals from the guitar. By eliminating the conventional interconnection cable, the amplifier of the present invention can be used by musicians with increased flexibility and greater freedom of movement.
Ultrafast optical signal processing using semiconductor quantum dot amplifiers
DEFF Research Database (Denmark)
Berg, Tommy Winther; Mørk, Jesper
2002-01-01
The linear and nonlinear properties of quantum dot amplifiers are discussed on the basis of an extensive theoretical model. These devices show great potential for linear amplification as well as ultrafast signal processing.......The linear and nonlinear properties of quantum dot amplifiers are discussed on the basis of an extensive theoretical model. These devices show great potential for linear amplification as well as ultrafast signal processing....
Thermodynamic indistinguishability and field state fingerprint of quantum optical amplifiers
Perl, Yossi; Band, Yehuda B.; Boukobza, Erez
2016-01-01
Dissipation tends to wash out dynamical features observed at early evolution times. In this paper we analyze a resonant single--atom two--photon quantum optical amplifier both dynamically and thermodynamically. A detailed thermodynamic balance shows that the non--linear amplifier is thermodynamically equivalent to the linear amplifier discussed in (Phys. Rev. A, 74 (2006), 063822). However, by calculating the Wigner quasi--probability distribution for various initial field states, we show tha...
A high performance switching audio amplifier using sliding mode control
Pillonnet, Gael; Cellier, Rémy; Abouchi, Nacer; Chiollaz, Monique
2008-01-01
International audience The switching audio amplifiers are widely used in various portable and consumer electronics due to their high efficiency, but suffers from low audio performances due to inherent nonlinearity. This paper presents an integrated class D audio amplifier with low consumption and high audio performances. It includes a power stage and an efficient control based on sliding mode technique. This monolithic class D amplifier is capable of delivering up to 1W into 8Ω load at les...
Optimisation of High-Power Amplifiers using non linear models
Hek, A.P. de; Bogaart, F.L.M. van den
1999-01-01
This paper identifies the areas where the use of non-linear simulations for the design of high-power amplifiers is useful. The identified areas are: operating class selection, determination source and load impedance for matching network design, overall amplifier simulations and stability analysis un
High voltage distributed amplifier
Willems, D.; Bahl, I.; Wirsing, K.
1991-12-01
A high-voltage distributed amplifier implemented in GaAs MMIC technology has demonstrated good circuit performance over at least two octave bandwidth. This technique allows for very broadband amplifier operation with good efficiency in satellite, active-aperture radar, and battery-powered systems. Also, by increasing the number of FETs, the amplifier can be designed to match different voltage rails. The circuit does require a small amount of additional chip size over conventional distributed amplifiers but does not require power dividers or additional matching networks. This circuit configuration should find great use in broadband power amplifier design.
K-band FET amplifier for satellite downlink
Goel, J.; Cheung, R. P.
1984-01-01
State-of-the-art performance is demonstrated with solid-state amplifiers in K-band. The amplifier provides 8.2 watts of power with 39 dB gain over a frequency band of 1.4 GHz. Nonlinearity analyses of solid-state amplifiers suggest that system performance can be improved significantly by using an FET amplifier. Preliminary investigations reveal that the solid-state amplifiers can be space-qualified and can be expected to replace the TWTA in many communication links in the near future. It is pointed out that with improvements in device technology, the power, bandwidth and efficiency of solid-state amplifiers using FETs can be further improved. With FETs operating at a junction temperature of less than 125 C, solid-state amplifiers are inherently reliable, indicating a ten-year mean time to failure.
Barrett, John W.; Süli, Endre
2016-07-01
We prove the existence of global-in-time weak solutions to a general class of models that arise from the kinetic theory of dilute solutions of nonhomogeneous polymeric liquids, where the polymer molecules are idealized as bead-spring chains with finitely extensible nonlinear elastic (FENE) type spring potentials. The class of models under consideration involves the unsteady, compressible, isentropic, isothermal Navier-Stokes system in a bounded domain Ω in Rd, d = 2, for the density ρ, the velocity u ˜ and the pressure p of the fluid, with an equation of state of the form p (ρ) =cpργ, where cp is a positive constant and γ > 1. The right-hand side of the Navier-Stokes momentum equation includes an elastic extra-stress tensor, which is the classical Kramers expression. The elastic extra-stress tensor stems from the random movement of the polymer chains and is defined through the associated probability density function that satisfies a Fokker-Planck-type parabolic equation, a crucial feature of which is the presence of a centre-of-mass diffusion term. This extends the result in our paper J.W. Barrett and E. Süli (2016) [9], which established the existence of global-in-time weak solutions to the system for d ∈ { 2 , 3 } and γ >3/2, but the elastic extra-stress tensor required there the addition of a quadratic interaction term to the classical Kramers expression to complete the compactness argument on which the proof was based. We show here that in the case of d = 2 and γ > 1 the existence of global-in-time weak solutions can be proved in the absence of the quadratic interaction term. Our results require no structural assumptions on the drag term in the Fokker-Planck equation; in particular, the drag term need not be corotational. With a nonnegative initial density ρ0 ∈L∞ (Ω) for the continuity equation; a square-integrable initial velocity datum u˜0 for the Navier-Stokes momentum equation; and a nonnegative initial probability density function ψ0
Dual Band High Efficiency Power Amplifier Based on CRLH Lines
Directory of Open Access Journals (Sweden)
D. Segovia-Vargas
2009-12-01
Full Text Available In this paper we propose the use of Composite Right/Left Hand (CRLH and Extended Composite Right/Left Hand (ECRLH transmission lines for the design of dual band high efficiency power amplifiers working in CE class. The harmonic termination can be synthesized using the meta-lines is particularly suitable for CE class amplifiers, which have a termination not as sensitive to the third harmonic as F class amplifier. This paper presents the design procedure and the design equations. The nonlinear phase response of a CRLH and ECRLH transmission line has been utilized to design arbitrary dual-band amplifiers.
DEFF Research Database (Denmark)
Liu, Xiang; Hu, Hao; Chandrasekhar, S.;
2014-01-01
We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all...
Wideband pulse amplifiers for the NECTAr chip
Energy Technology Data Exchange (ETDEWEB)
Sanuy, A., E-mail: asanuy@ecm.ub.es [Dept. AM i Dept. ECM, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona. Marti i Franques 1, E08028, Barcelona (Spain); Delagnes, E. [IRFU/DSM/CEA, CE-Saclay, Bat. 141 SEN Saclay, F-91191, Gif-sur-Yvette (France); Gascon, D. [Dept. AM i Dept. ECM, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona. Marti i Franques 1, E08028, Barcelona (Spain); Sieiro, X. [Departament d' Electronica, Universitat de Barcelona. Marti i Franques 1, E08028, Barcelona (Spain); Bolmont, J.; Corona, P. [LPNHE, Universite Paris VI and Universite Paris VII and IN2P3/CNRS, Barre 12-22, 1er etage, 4 place Jussieu, 75252 Paris (France); Feinstein, F. [LUPM, Universite Montpellier II and IN2P3/CNRS, CC072, bat. 13, place Eugene Bataillon, 34095 Montpellier (France); Glicenstein, J-F. [IRFU/DSM/CEA, CE-Saclay, Bat. 141 SEN Saclay, F-91191, Gif-sur-Yvette (France); Naumann, C.L.; Nayman, P. [LPNHE, Universite Paris VI and Universite Paris VII and IN2P3/CNRS, Barre 12-22, 1er etage, 4 place Jussieu, 75252 Paris (France); Ribo, M. [Dept. AM i Dept. ECM, Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona. Marti i Franques 1, E08028, Barcelona (Spain); and others
2012-12-11
The NECTAr collaboration's FE option for the camera of the CTA is a 16 bits and 1-3 GS/s sampling chip based on analog memories including most of the readout functions. This works describes the input amplifiers of the NECTAr ASIC. A fully differential wideband amplifier, with voltage gain up to 20 V/V and a BW of 400 MHz. As it is impossible to design a fully differential OpAmp with an 8 GHz GBW product in a 0.35 CMOS technology, an alternative implementation based on HF linearized transconductors is explored. The output buffer is a class AB miller operational amplifier, with special non-linear current boost.
Nonlinear Hysteretic Torsional Waves.
Cabaret, J; Béquin, P; Theocharis, G; Andreev, V; Gusev, V E; Tournat, V
2015-07-31
We theoretically study and experimentally report the propagation of nonlinear hysteretic torsional pulses in a vertical granular chain made of cm-scale, self-hanged magnetic beads. As predicted by contact mechanics, the torsional coupling between two beads is found to be nonlinear hysteretic. This results in a nonlinear pulse distortion essentially different from the distortion predicted by classical nonlinearities and in a complex dynamic response depending on the history of the wave particle angular velocity. Both are consistent with the predictions of purely hysteretic nonlinear elasticity and the Preisach-Mayergoyz hysteresis model, providing the opportunity to study the phenomenon of nonlinear dynamic hysteresis in the absence of other types of material nonlinearities. The proposed configuration reveals a plethora of interesting phenomena including giant amplitude-dependent attenuation, short-term memory, as well as dispersive properties. Thus, it could find interesting applications in nonlinear wave control devices such as strong amplitude-dependent filters. PMID:26274421
Compensation of pulse-distortion in saturated laser amplifiers.
Schimpf, Damian N; Ruchert, Clemens; Nodop, Dirk; Limpert, Jens; Tünnermann, Andreas; Salin, Francois
2008-10-27
We derive an expression describing pre-compensation of pulse-distortion due to saturation effects in short pulse laser-amplifiers. The analytical solution determines the optimum input pulse-shape required to obtain any arbitrary target pulse-shape at the output of the saturated laser-amplifier. The relation is experimentally verified using an all-fiber amplifier chain that is seeded by a directly modulated laser-diode. The method will prove useful in applications of high power, high energy laser-amplifier systems that need particular pulse-shapes to be efficient, e.g. micromachining and scientific laser-matter-interactions. PMID:18958044
Time-reversal duality of high-efficiency RF power amplifiers
Energy Technology Data Exchange (ETDEWEB)
Reveyrand, T; Ramos, I; Popovic, Z
2012-12-06
The similarity between RF power amplifiers and rectifiers is discussed. It is shown that the same high-efficiency harmonically-terminated power amplifier can be operated in a dual rectifier mode. Nonlinear simulations with a GaN HEMT transistor model show the time-reversal intrinsic voltage and current waveform relationship between a class-F amplifier and rectifier. Measurements on a class-F-1 amplifier and rectifier at 2.14 GHz demonstrate over 80% efficiency in both cases.
Institute of Scientific and Technical Information of China (English)
庄品; 赵林度
2008-01-01
The challenge for supply chain management is to create appropriate supply chain contracts so as to optimize the system performance. To examine the role of asymmetric information in a two-echelon supply chain system and derive supply chain contracts to deal with existing asymmetric information, a two level supply chain model including one supplier and one retailer under the demand of price elasticity is developed. By using the principal-agent principle and the optimal control theory, three types of supply chain contract, i.e., a wholesale pricing contract, a two-parameter linear and a two-parameter nonlinear contracts are obtained. In these contracts, the supplier has asymmetric information about the retailer cost structure. Simulation results show that the two-parameter contracts are more effective strategies to achieve supply chain coordination.%为研究两级供应链系统中不对称信息的作用,并设计供应链契约有效地解决信息不对称问题,文中建立了市场需求为价格弹性需求,包含一个供应商和一个零售商的两级供应链模型.当零售商成本结构为非对称信息时,利用委托-代理理论和最优控制原理设计了3种不对称信息和非线性需求下供应链契约:批发价契约、双参数线性契约和双参数非线性契约,并对上述3种契约模型进行数值仿真分析.研究显示双参数契约模型能够更有效地达到供应链协调.
Electrospun Amplified Fiber Optics
Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario
2015-01-01
A lot of research is focused on all-optical signal processing, aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for an efficient signal transmission. However, the complex fabrication methods, involving high-temperature processes performed in highly pure environment, slow down the fabrication and make amplified components expensive with respect to an ideal, ...
Directory of Open Access Journals (Sweden)
M. Lokay
1993-04-01
Full Text Available The special program is presented for the demonstration of RF power transistor amplifiers for the purposes of the high-school education in courses of radio transmitters. The program is written in Turbo Pascal 6. 0 and enables to study the waveforms in selected points of the amplifier and to draw the trajectories of the working point in a plot of output transistor characteristics.
DEFF Research Database (Denmark)
Jeppesen, Palle
1997-01-01
Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived.......Noise in optical amplifiers is discussed on the basis of photons and electromagntic fields. Formulas for quantum noise from spontaneous emission, signal-spontaneous beat noise and spontaneous-spontaneous beat noise are derived....
Directory of Open Access Journals (Sweden)
Trunev A. P.
2015-09-01
Full Text Available The article presents a project of the Yang-Mills amplifier. Amplifier model is a multilayer spherical shell with increasing density towards the center. In the center of the amplifier is the core of high-density material. It is shown that in such a system, the amplitude of the Yang-Mills waves rises from the periphery to the center of several orders of magnitude. The role of the Yang-Mills field in the processes occurring in the nuclei of galaxies, stars and planets is discussed. The data modeling to strengthen the Yang-Mills field in the bowels of the planet, with an atomic explosion, and in some special devices such as the voltaic pile. To describe the mechanism of amplification chromodynamics field used as accurate results in Yang-Mills theory and numerical models developed based on an average and the exact equations as well. Among the exact solutions of the special role played by the centralsymmetric metric describing the contribution of the Yang-Mills field in the speed of recession of galaxies. Among the approximate numerical models can be noted the eight-scalar model we have developed for the simulation of non-linear color oscillations and chaos in the Yang-Mills theory. Earlier models were investigated spatio-temporal oscillations of the YangMills theory in the case of three and eight colors. The results of numerical simulation show that the nonlinear interaction does not lead to a spatial mixing of colors as it might be in the case of turbulent diffusion. Depending on the system parameters there is a suppression of the amplitude of the oscillations the first three by five colors or vice versa. The kinetic energy fluctuations or shared equally between the color components, or dominated by the kinetic energy of repressed groups of colors. In the present study, we found that amplification chromodynamic field leads to a sharp increase in the amplitude of the suppressed color, which can lead to an increase in entropy, excitation of nuclear
Ferrite bead effect on Class-D amplifier audio quality
Haddad, Kevin El; Mrad, Roberto; Morel, Florent; Pillonnet, Gael; Vollaire, Christian; Nagari, Angelo
2014-01-01
International audience This paper studies the effect of ferrite beads on the audio quality of Class-D audio amplifiers. This latter is a switch-ing circuit which creates high frequency harmonics. Generally, a filter is used at the amplifier output for the sake of electro-magnetic compatibility (EMC). So often, in integrated solutions, this filter contains ferrite beads which are magnetic components and present nonlinear behavior. Time domain measurements and their equivalence in frequency ...
Directory of Open Access Journals (Sweden)
Mrityunjoy Roy
2013-04-01
Full Text Available In this paper, a technique has been developed to determine the optimum mix of logistic service providers of a make-to-order (MTO supply chain. A serial MTO supply chain with different stages/ processes has been considered. For each stage different logistic service providers with different mean processing lead times, but same lead time variances are available. A realistic assumption that for each stage, the logistic service provider who charges more for his service consumes less processing lead time and vice-versa has been made in our study. Thus for each stage, for each service provider, a combination of cost and mean processing lead time is available. Using these combinations, for each stage, a polynomial curve, expressing cost of that stage as a function of mean processing lead time is fit. Cumulating all such expressions of cost for the different stages along with incorporation of suitable constraints arising out of timely delivery, results in the formulation of a constrained nonlinear cost optimization problem. On solving the problem using mathematica, optimum processing lead time for each stage is obtained. Using these optimum processing lead times and by employing a simple technique the optimum logistic service provider mix of the supply chain along with the corresponding total cost of processing is determined. Finally to examine the effect of changes in different parameters on the optimum total processing cost of the supply chain, sensitivity analysis has been carried out graphically.
Electrospun amplified fiber optics.
Morello, Giovanni; Camposeo, Andrea; Moffa, Maria; Pisignano, Dario
2015-03-11
All-optical signal processing is the focus of much research aiming to obtain effective alternatives to existing data transmission platforms. Amplification of light in fiber optics, such as in Erbium-doped fiber amplifiers, is especially important for efficient signal transmission. However, the complex fabrication methods involving high-temperature processes performed in a highly pure environment slow the fabrication process and make amplified components expensive with respect to an ideal, high-throughput, room temperature production. Here, we report on near-infrared polymer fiber amplifiers working over a band of ∼20 nm. The fibers are cheap, spun with a process entirely carried out at room temperature, and shown to have amplified spontaneous emission with good gain coefficients and low levels of optical losses (a few cm(-1)). The amplification process is favored by high fiber quality and low self-absorption. The found performance metrics appear to be suitable for short-distance operations, and the large variety of commercially available doping dyes might allow for effective multiwavelength operations by electrospun amplified fiber optics.
Institute of Scientific and Technical Information of China (English)
张学龙; 王云峰
2014-01-01
平稳运行是精敏供应链管理的重要基础，针对具有区间灰色非线性特征的精敏供应链系统波动性的难题，以非线性时滞精敏供应链系统为研究基础，建立了灰色非线性精敏供应链系统，采用线性矩阵不等式算法分析其稳定性问题，并获取了一种灰色非线性精敏供应链系统的稳定性判定方法。为验证该方法的有效性和可行性，以医药行业YL集团核心产品的供应链系统为案例分析对象，通过观测两个时点的运行数据，使用Matlab7.0计算工具，得出[0，20]和[20，40]2个时间段供应链系统的稳定性状态变化图。并假设当客户订货分离点（ CODP）下移时，运用同样的观测数据，模拟系统稳定性状态的变化。对比案例分析的结果得出结论：随着CODP从精敏供应链的上游端在下移至下游端时，不仅仅体现的是供应链系统类型的改变，而且更重要的是揭示了精益供应链和敏捷供应链稳定性的影响因素不同，前者受订单量大小程度的影响，而后者由市场需求预测的准确性程度决定。%In leagile supply chain management , it is important to operate a supply chain smoothly .Howev-er, with grey and non-linearity, it is very challenging to model and control such a supply chain .On the basis of non-linear and time delay leagile supply chain systems , a grey and non-linear model is developed for a leagile supply chain .Then, a linear matrix inequality method is used to analyze its stability and an effective stability criterion is obtained .In order to verify the feasibility and effectiveness of the proposed method, a core product supply chain systems of YL Group in the medicine industry is used as a case stud -y.By using Matlab 7.0, the stability of the system state diagram is drawn before and after customer order decoupling point ( CODP) .Results show that when CODP moves down , not only the supply chain type is changed but
A micropower electrocardiogram amplifier.
Fay, L; Misra, V; Sarpeshkar, R
2009-10-01
We introduce an electrocardiogram (EKG) preamplifier with a power consumption of 2.8 muW, 8.1 muVrms input-referred noise, and a common-mode rejection ratio of 90 dB. Compared to previously reported work, this amplifier represents a significant reduction in power with little compromise in signal quality. The improvement in performance may be attributed to many optimizations throughout the design including the use of subthreshold transistor operation to improve noise efficiency, gain-setting capacitors versus resistors, half-rail operation wherever possible, optimal power allocations among amplifier blocks, and the sizing of devices to improve matching and reduce noise. We envision that the micropower amplifier can be used as part of a wireless EKG monitoring system powered by rectified radio-frequency energy or other forms of energy harvesting like body vibration and body heat. PMID:23853270
International Nuclear Information System (INIS)
A cavity vircator has demonstrated that formation of a virtual cathode in a cavity can improve microwave production efficiency and narrow the radiation bandwidth. When the virtual cathode radiates the microwave fields grow from noise. For each cavity, there is only one or a limited number of allowable modes for a given frequency. In this paper, a novel device - a vircator amplifier is described. The device consists of a relativistic magnetron and a cavity vircator with both devices powered by a 1 MeV, 3 Ω, 65 ns FWHM pulser. The idea is to inject a signal from the magnetron before and during virtual cathode formation in a cavity. The injected signal should lock the frequency and enhance electron bunching and therefore improve efficiency further. Experiments underway to evaluate the amplifier operating characteristics are discussed. The applicability of vircator amplifiers to the next generation of high-power microwave devices are addressed
Adaptation of a Digitally Predistorted RF Amplifier Using Selective Sampling
Institute of Scientific and Technical Information of China (English)
R. Neil Braithwaite
2011-01-01
In this paper, a reduced-cost method of measuring residual nonlinearities in an adaptive digitally predistorted amplifier is proposed. Measurements obtained by selective sampling of the amplifier output are integrated over the input envelope range to adapt a fourth-order polynomial predistorter with memory correction. Results for a WCDMA input with a 101 carrier configuration show that a transmitter using the proposed method can meet the adjacent channel leakage ratio （ACLR） specification. Inverse modeling of the nonlinearity is proposed as a future extension that will reduce the cost of the system further.
Bogatov, A. P.; Drakin, A. E.; D'yachkov, N. V.; Gushchik, T. I.
2016-08-01
Expressions for the amplitudes of amplified spontaneous emission waves in a diode amplifier near the frequency ω0 of a 'strong' input monochromatic wave have been derived in terms of a random function of a stationary Gaussian process. We have found expressions for the spectral density of the amplitudes and shown that, on the red side of the spectrum with respect to frequency ω0, spontaneous emission waves obtain additional nonlinear gain, induced by the strong wave, whereas on the blue side of the spectrum an additional loss is induced. Such behaviour of the amplitudes of amplified waves agrees with previous results.
Lee, Chao-Kuei; Zhang, Jing-Yuan; Huang, J; Pan, Ci-Ling
2003-07-14
We report the generation of tunable femtosecond pulses from 380nm to 465nm near the degenerate point of a 405-nm pumped type-I BBO noncollinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a fixed seeding angle, the generated SFG and SHG covers from 385 nm to 465-nm. With a pumping energy of 75 J at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%.
Liu, Xiang; Hu, Hao; Chandrasekhar, S; Jopson, R M; Gnauck, A H; Dinu, M; Xie, C; Winzer, P J
2014-03-24
We experimentally demonstrate the generation of 1.024-Tb/s Nyquist-WDM phase-conjugated vector twin waves (PCTWs), consisting of eight 128-Gb/s polarization-division-multiplexed QPSK signals and their idlers, by a broadband polarization-insensitive fiber optic parametric amplifier. This novel all-optical signal processing approach to generate WDM-PCTWs enables a 2-fold reduction in the needed optical transmitters as compared to the conventional approach where each idler is generated by a dedicated transmitter. Digital coherent superposition of the twin waves at the receiver enables more than doubled reach in a dispersion-managed transmission link. We further study the impact of polarization-mode dispersion on the performance gain brought by the phase-conjugated twin waves, showing a gain of ~3.8 dB in signal quality factors.
Lee, Chao-Kuei; Zhang, Jing-Yuan; Huang, J; Pan, Ci-Ling
2003-07-14
We report the generation of tunable femtosecond pulses from 380nm to 465nm near the degenerate point of a 405-nm pumped type-I BBO noncollinearly phase-matched optical parametric amplifier (NOPA). The tunable UV/blue radiation is obtained from sum frequency generation (SFG) between the OPA output and the residual fundamental beam at 810-nm and cascaded second harmonic generation (SHG) of OPA. With a fixed seeding angle, the generated SFG and SHG covers from 385 nm to 465-nm. With a pumping energy of 75 J at 405 nm, the optical conversion efficiency from the pump to the tunable SFG is more than 5% and the efficiency of SHG of the OPA is about 2%. PMID:19466049
Hackel, L.A.; Hermann, M.R.; Dane, C.B.; Tiszauer, D.H.
1995-12-12
A solid state laser is frequency tripled to 0.3 {micro}m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only about 1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power. 1 fig.
Nonlinear Optics and Applications
Abdeldayem, Hossin A. (Editor); Frazier, Donald O. (Editor)
2007-01-01
Nonlinear optics is the result of laser beam interaction with materials and started with the advent of lasers in the early 1960s. The field is growing daily and plays a major role in emerging photonic technology. Nonlinear optics play a major role in many of the optical applications such as optical signal processing, optical computers, ultrafast switches, ultra-short pulsed lasers, sensors, laser amplifiers, and many others. This special review volume on Nonlinear Optics and Applications is intended for those who want to be aware of the most recent technology. This book presents a survey of the recent advances of nonlinear optical applications. Emphasis will be on novel devices and materials, switching technology, optical computing, and important experimental results. Recent developments in topics which are of historical interest to researchers, and in the same time of potential use in the fields of all-optical communication and computing technologies, are also included. Additionally, a few new related topics which might provoke discussion are presented. The book includes chapters on nonlinear optics and applications; the nonlinear Schrodinger and associated equations that model spatio-temporal propagation; the supercontinuum light source; wideband ultrashort pulse fiber laser sources; lattice fabrication as well as their linear and nonlinear light guiding properties; the second-order EO effect (Pockels), the third-order (Kerr) and thermo-optical effects in optical waveguides and their applications in optical communication; and, the effect of magnetic field and its role in nonlinear optics, among other chapters.
International Nuclear Information System (INIS)
We present a sensitive scheme, for the first time to our knowledge, to observe photo-refraction (PR) effects in some nonlinear optical crystals, e.g. β-BBO, LBO and BIBO, pumped by an intense ultrashort laser pulse chain. These quite weak effects are 'amplified' by sensitive cw intracavity loss modulation. Our results show that they are repeatable and are dependent on pumping power and wavelength, and their response time ranges from tens of seconds to several minutes. The recorded dynamical transitions between the self-focusing to the self-defocusing (or vice versa) induced by the PR effect may be critically important for us to give more insight into the stability of some cascade nonlinear frequency conversions, e.g. multi-stage optical parametric amplifiers. (fundamental areas of phenomenology (including applications))
Institute of Scientific and Technical Information of China (English)
XU Shi-Xiang; GAO Yan-Xia; CAI Hua; LI Jing-Zhen
2009-01-01
We present a sensitive scheme, for the first time to our knowledge, to observe photo-refraction (PR) effects in some nonlinear optical crystals, e.g.β-BBO, LBO and BIBO, pumped by an intense ultrashort laser pulse chain. These quite weak effects are "amplified" by sensitive cw intracavity loss modulation. Our results show that they are repeatable and are dependent on pumping power and wavelength, and their response time ranges from tens of seconds to several minutes. The recorded dynamical transitions between the self-focusing to the self-defocusing (or vice versa) induced by the PR effect may be critically important for us to give more insight into the stability of some cascade nonlinear frequency conversions, e.g. multi-stage optical parametric amplifiers.
Fundamentals of fiber lasers and fiber amplifiers
Ter-Mikirtychev, Valerii (Vartan)
2014-01-01
This book covers the fundamental aspects of fiber lasers and fiber amplifiers, and includes a wide range of material from laser physics fundamentals to state-of-the-art topics in this rapidly growing field of quantum electronics. Emphasis is placed on the nonlinear processes taking place in fiber lasers and amplifiers, their similarities, differences to, and their advantages over other solid-state lasers. The reader will learn basic principles of solid-state physics and optical spectroscopy of laser active centers in fibers, main operational laser regimes, and practical recommendations and suggestions on fiber laser research, laser applications, and laser product development. The book will be useful for students, researchers, and professionals who work with lasers, in the optical communications, chemical and biological industries, etc.
Nonlinear Waves in Complex Systems
DEFF Research Database (Denmark)
2007-01-01
The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations, it is the ......The study of nonlinear waves has exploded due to the combination of analysis and computations, since the discovery of the famous recurrence phenomenon on a chain of nonlinearly coupled oscillators by Fermi-Pasta-Ulam fifty years ago. More than the discovery of new integrable equations...
Koplow, Jeffrey P.; Kliner, Dahy; Goldberg, Lew
2002-12-17
A multi-mode gain fiber is provided which affords substantial improvements in the maximum pulse energy, peak power handling capabilities, average output power, and/or pumping efficiency of fiber amplifier and laser sources while maintaining good beam quality (comparable to that of a conventional single-mode fiber source). These benefits are realized by coiling the multimode gain fiber to induce significant bend loss for all but the lowest-order mode(s).
Can El Nino Amplify the Solar Forcing of Climate?
Ruzmaikin, A.
1999-01-01
ENSO (El Nino and the Southern Oscillation) is considered as a stochastic driver that excites the atmospheric anomaly states, such as Pacific North American pattern. This can make the 11 year solar activity forcing feasible to climate through stochastic resonance -- a phenomenon that amplifies a weak input to a nonlinear bistable system by the assistance of noise.
Optimized Pump Power Ratio on 2nd Order Pumping Discrete Raman Amplifier
Institute of Scientific and Technical Information of China (English)
Renxiang Huang; Youichi Akasaka; David L. Harris; James Pan
2003-01-01
By optimizing pump power ratio between 1st order backward pump and 2nd order forward pump on discrete Raman amplifier, we demonstrated over 2dB noise figure improvement without excessive non-linearity degradation.
Josephson traveling-wave parametric amplifier for superconducting qubit readout
Macklin, Chris; Slichter, D. H.; Yaakobi, O.; Friedland, L.; Bolkhovsky, V.; Braje, D. A.; Fitch, G.; Oliver, W. D.; Siddiqi, I.
2014-03-01
Superconducting parametric amplifiers (paramps) have successfully demonstrated near quantum limited sensitivity, enabling single-shot qubit readout, feedback, and state tracking. However, these amplifiers are commonly limited to narrow bandwidth and modest dynamic range, and most require microwave circulators to separate input and output modes. These limitations stem from the use of a resonant non-linearity to achieve mixing between a signal and pump mode. Our traveling-wave parametric amplifier (TWPA) is based on a superconducting nonlinear Josephson junction transmission line, thereby inherently sidestepping the limitations associated with a cavity structure. We present theoretical predictions and experimental results, including improved gain and noise performance. We discuss transmon qubit readout in the circuit QED architecture using a TWPA. We also comment on promising architectures for chip-level integration and multiplexing. Work supported by IARPA.
Gain Characteristics of Fiber Optical Parametric Amplifier
Institute of Scientific and Technical Information of China (English)
高明义; 姜淳; 胡卫生
2004-01-01
The theory model of fiber optical parametric amplifier (FOPA) was introduced, which is based on optical nonlinear effect. And then numerical simulation was done to analyze and discuss the gain spectral characteristics of one-pump and two-pump FOPA. The results show that for one-pump FOPA, when pump wavelength is near to fiber zero-dispersion wavelength(ZDW), the gain flatness is better, and with the increase of the pump power, fiber length and its nonlinear coefficient, the gain value will increase while the gain bandwidth will become narrow. For two-pump FOPA, when the pump central wavelength is near to fiber ZDW, the gain flatness is better. Moreover, by decreasing the space of two pumps wavelength, the gain flatness can be improved. Finally, some problems existing in FOPA were addressed.
Institute of Scientific and Technical Information of China (English)
纪静文; 蔡超时; 胡峰; 梁云英
2011-01-01
过高的峰均比（PAPR,peak-to-average power ratio）是正交频分复用技术（OFDM,Orthogonal Frequency-Di-vision Multiplexing）的一个主要缺陷。PAPR抑制技术的应用可以最大限度地减小的非线性失真,提高功率放大器（HPA,High Power Amplifier）的效率。在OFDM系统中,随着载波数的增加,PAPR性能会变差。本文使用了一种削波滤波（CF,Clipping＆Filtering）与星座图扩展（ACE,Active Constellation Extension）相结合的方法,可以在无数据率损失的情况下减小PAPR。在本方案中,计算出一个标准OFDM信号的PAPR数据作为参考。先对信号进行CF操作,把信号的PAPR值限制到很低的幅度,再用星座图扩展的方法恢复MER指标,就可以让信号进入非线性功放之前降低PAPR,并保证带外噪声符合发射机的要求。最后,把经过处理的OFDM信号和原始OFDM信号同时送入不同功率回退（IBO）参数的HPA进行了对比。实验结果表明,把信号送入功率回退为7dB的HPA,经过PAPR抑制算法处理的信号带肩比可以改善2dB以上,MER改善1dB以上。%High peak-to-average power ratio（PAPR） is one of the major drawbacks of Orthogonal Frequency-Division Multiplexing（OFDM）.PAPR reduction can be utilized to decrease the nonlinear distortion and to improve the power efficiency of the nonlinear HPA（high power amplifier）.In an OFDM system,as the frame size increases,the PAPR probability performance will get worse.In this paper,a novel approach,clipping-and-filtering（CF） scheme with the proposed active constellation extension（ACE） algorithm is presented to reduce the PAPR without any date rate loss.In our proposal,the target PAPR is firstly set and the level clipping is fundamentally used.ACE algorithm is then applied to improve be MER performance characteristics for the OFDM system.Finally,we analyze the PAPR reduction effects on HPA and show the performance variation in the HPA nonlinear characteristic
Extinction Ratio and Gain Optimization of Dual- Pump Degenerate-Idler Phase Sensitive Amplifiers
DEFF Research Database (Denmark)
Kang, Ning; Lund-Hansen, Toke; Seoane, Jorge;
2011-01-01
Numerical optimization of dual-pump degenerateidler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed.......Numerical optimization of dual-pump degenerateidler phase sensitive amplifiers is performed for Al-doped and standard highly nonlinear fibers. Design considerations for operating the PSAs at an optimum combination of gain and extinction ratio are discussed....
Numerical model of frequency converter based on four-wave mixing in semiconductor amplifiers
DEFF Research Database (Denmark)
Cassioli, D.; Scotti, S.; Mecozzi, A.;
1999-01-01
We describe a numerical model of the dynamics of a semiconductor optical amplifier that includes the description of the nonlinear optical processes within the waveguide and the longitudinal inhomogeneity caused by the saturating field.......We describe a numerical model of the dynamics of a semiconductor optical amplifier that includes the description of the nonlinear optical processes within the waveguide and the longitudinal inhomogeneity caused by the saturating field....
International Nuclear Information System (INIS)
For describing the dynamics of alpha helical proteins with internal molecular excitations, nonlinear couplings between lattice vibrations and molecular excitations, and spin excitations in one-dimensional isotropic biquadratic Heisenberg ferromagnetic spin with the octupole–dipole interactions, we consider an inhomogeneous generalized fourth-order nonlinear Schrödinger equation. Based on the Ablowitz–Kaup–Newell–Segur system, infinitely many conservation laws for the equation are derived. Through the auxiliary function, bilinear forms and N-soliton solutions for the equation are obtained. Interactions of solitons are discussed by means of the asymptotic analysis. Effects of linear inhomogeneity on the interactions of solitons are also investigated graphically and analytically. Since the inhomogeneous coefficient of the equation h=α x+β, the soliton takes on the parabolic profile during the evolution. Soliton velocity is related to the parameter α, distance scale coefficient and biquadratic exchange coefficient, but has no relation with the parameter β. Soliton amplitude and width are only related to α. Soliton position is related to β
Electronic amplifiers for automatic compensators
Polonnikov, D Ye
1965-01-01
Electronic Amplifiers for Automatic Compensators presents the design and operation of electronic amplifiers for use in automatic control and measuring systems. This book is composed of eight chapters that consider the problems of constructing input and output circuits of amplifiers, suppression of interference and ensuring high sensitivity.This work begins with a survey of the operating principles of electronic amplifiers in automatic compensator systems. The succeeding chapters deal with circuit selection and the calculation and determination of the principal characteristics of amplifiers, as
Simplified design of IC amplifiers
Lenk, John
1996-01-01
Simplified Design of IC Amplifiers has something for everyone involved in electronics. No matter what skill level, this book shows how to design and experiment with IC amplifiers. For experimenters, students, and serious hobbyists, this book provides sufficient information to design and build IC amplifier circuits from 'scratch'. For working engineers who design amplifier circuits or select IC amplifiers, the book provides a variety of circuit configurations to make designing easier.Provides basics for all phases of practical design.Covers the most popular forms for amplif
Hollister, Allen L
2007-01-01
In this book, the theory needed to understand wideband amplifier design using the simplest models possible will be developed. This theory will be used to develop algebraic equations that describe particular circuits used in high frequency design so that the reader develops a ""gut level"" understanding of the process and circuit. SPICE and Genesys simulations will be performed to show the accuracy of the algebraic models. By looking at differences between the algebraic equations and the simulations, new algebraic models will be developed that include parameters originally left out of the model
Jones, Morgan
2013-01-01
Building Valve Amplifiers is a unique hands-on guide for anyone working with tube audio equipment--as an electronics hobbyist, audiophile or audio engineer. This 2nd Edition builds on the success of the first with technology and technique revisions throughout and, significantly, a major new self-build project, worked through step-by-step, which puts into practice the principles and techniques introduced throughout the book. Particular attention has been paid to answering questions commonly asked by newcomers to the world of the valve, whether audio enthusiasts tackling their first build or
Gaurav Solanki
2015-01-01
The polymerase chain reaction (PCR) is a technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. There are three major steps involved in the PCR technique: denaturation, annealing and extension. PCR is useful in the investigation...
Design criteria for ultrafast optical parametric amplifiers
Manzoni, C.; Cerullo, G.
2016-10-01
Optical parametric amplifiers (OPAs) exploit second-order nonlinearity to transfer energy from a fixed frequency pump pulse to a variable frequency signal pulse, and represent an easy way of tuning over a broad range the frequency of an otherwise fixed femtosecond laser system. OPAs can also act as broadband amplifiers, transferring energy from a narrowband pump to a broadband signal and thus considerably shortening the duration of the pump pulse. Due to these unique properties, OPAs are nowadays ubiquitous in ultrafast laser laboratories, and are employed by many users, such as solid state physicists, atomic/molecular physicists, chemists and biologists, who are not experts in ultrafast optics. This tutorial paper aims at providing the non-specialist reader with a self-consistent guide to the physical foundations of OPAs, deriving the main equations describing their performance and discussing how they can be used to understand their most important working parameters (frequency tunability, bandwidth, pulse energy/repetition rate scalability, control over the carrier-envelope phase of the generated pulses). Based on this analysis, we derive practical design criteria for OPAs, showing how their performance depends on the type of the nonlinear interaction (crystal type, phase-matching configuration, crystal length), on the characteristics of the pump pulse (frequency, duration, energy, repetition rate) and on the OPA architecture.
Universal Signal Conditioning Amplifier
Kinney, Frank
1997-01-01
The Technological Research and Development Authority (TRDA) and NASA-KSC entered into a cooperative agreement in March of 1994 to achieve the utilization and commercialization of a technology development for benefiting both the Space Program and U.S. industry on a "dual-use basis". The technology involved in this transfer is a new, unique Universal Conditioning Amplifier (USCA) used in connection with various types of transducers. The project was initiated in partnership with I-Net Corporation, Lockheed Martin Telemetry & Instrumentation (formerly Loral Test and Information Systems) and Brevard Community College. The project consists of designing, miniaturizing, manufacturing, and testing an existing prototype of USCA that was developed for NASA-KSC by the I-Net Corporation. The USCA is a rugged and field-installable self (or remotely)- programmable amplifier that works in combination with a tag random access memory (RAM) attached to various types of transducers. This summary report comprises performance evaluations, TRDA partnership tasks, a project summary, project milestones and results.
DIAMOND AMPLIFIED PHOTOCATHODES.
Energy Technology Data Exchange (ETDEWEB)
SMEDLEY,J.; BEN-ZVI, I.; BOHON, J.; CHANG, X.; GROVER, R.; ISAKOVIC, A.; RAO, T.; WU, Q.
2007-11-26
High-average-current linear electron accelerators require photoinjectors capable of delivering tens to hundreds of mA average current, with peak currents of hundreds of amps. Standard photocathodes face significant challenges in meeting these requirements, and often have short operational lifetimes in an accelerator environment. We report on recent progress toward development of secondary emission amplifiers for photocathodes, which are intended to increase the achievable average current while protecting the cathode from the accelerator. The amplifier is a thin diamond wafer which converts energetic (few keV) primary electrons into hundreds of electron-hole pairs via secondary electron emission. The electrons drift through the diamond under an external bias and are emitted into vacuum via a hydrogen-terminated surface with negative electron affinity (NEA). Secondary emission gain of over 200 has been achieved. Two methods of patterning diamond, laser ablation and reactive-ion etching (RIE), are being developed to produce the required geometry. A variety of diagnostic techniques, including FTIR, SEM and AFM, have been used to characterize the diamonds.
Nonlinear distortion in wireless systems modeling and simulation with Matlab
Gharaibeh, Khaled M
2011-01-01
This book covers the principles of modeling and simulation of nonlinear distortion in wireless communication systems with MATLAB simulations and techniques In this book, the author describes the principles of modeling and simulation of nonlinear distortion in single and multichannel wireless communication systems using both deterministic and stochastic signals. Models and simulation methods of nonlinear amplifiers explain in detail how to analyze and evaluate the performance of data communication links under nonlinear amplification. The book addresses the analysis of nonlinear systems
Experimental examinations of semiconductor laser amplifiers for optical communication technology
Ludwig, Reinhold
1993-01-01
Properties of SLA (Semiconductor Laser Amplifier), which are particularly interesting for application to linear repeaters in coherent multichannel systems, are studied and design rules for future optimized amplifier structure are deduced. Laser diode antireflection was examined and reflection factor was measured. Low signal properties were discussed considering injection current, wavelengths, temperature and polarization. The coupling between amplifiers and glass fibers was examined. The utilization of cascade amplifiers as linear repeaters in multichannel heterodyne systems and television distribution systems was investigatied. The following results are obtained: measurement and calculation of the paradiaphony between two signals radiated in a SLA; multichannel data transfer through a SLA; polarization independent amplification with SLA configurations; measurement of the frequency dependence of four wave mixing sidelines in a SLA; measurement of the system degradation through echoes in a bidirectional SLA chain; data transmission with frequency conversion and calculation of multichannel transmission systems with cascade SLA, taking into account saturation, signal to noise ratio, bandwidth reduction and echo.
Nanoscale electromechanical parametric amplifier
Energy Technology Data Exchange (ETDEWEB)
Aleman, Benjamin Jose; Zettl, Alexander
2016-09-20
This disclosure provides systems, methods, and apparatus related to a parametric amplifier. In one aspect, a device includes an electron source electrode, a counter electrode, and a pumping electrode. The electron source electrode may include a conductive base and a flexible conductor. The flexible conductor may have a first end and a second end, with the second end of the flexible conductor being coupled to the conductive base. A cross-sectional dimension of the flexible conductor may be less than about 100 nanometers. The counter electrode may be disposed proximate the first end of the flexible conductor and spaced a first distance from the first end of the flexible conductor. The pumping electrode may be disposed proximate a length of the flexible conductor and spaced a second distance from the flexible conductor.
Nonlinear Dynamic Force Spectroscopy
Björnham, Oscar
2016-01-01
Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information of the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear regime. For example, bacterial adhesion pili and polymers with worm-like chain properties are examples of structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory we modeled a bio-complex expressed on a stiff, an elastic and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found th...
The development of DUV chemically amplified resists
Energy Technology Data Exchange (ETDEWEB)
Thackeray, J.W.; Fedynyshyn, T.H.; Small, R.D. [Shipley Co. Inc., Marlboro, MA (United States)
1993-12-31
The development of deep ultraviolet (DUV) resists has necessitated the introduction of new concepts in resist materials and chemistry. Successful DUV resist systems now employ the concept of chemical amplification. This catalytic reaction leads to a substantial enhancement in the imaging dose. Another benefit of chemical amplified resists is that they allow the design of materials which can be transparent to DUV exposure wavelengths, yet they can still have high sensitivity. Commercial and prototype positive- and negative-tone resists are now readily available and these resists have been used in pilot production to make the most advanced integrated circuits with {le}0.35 {mu}m design rules. At Shipley, we have undertaken to develop both negative- and positive-tone chemically amplified resists for DUV lithography. These resists are capable of high resolution (0.3 {mu}m), fast photospeed ({le}30 mJ/sq. cm), and excellent etch resistance. This presentation will discuss the chemical and lithographic properties of the Shipley negative- and positive-tone DUV chemically amplified resists. General discussion of the importance of activation energy for the catalytic process, catalytic chain length, and environmental stability will be given.
Modeling of semiconductor optical amplifiers
DEFF Research Database (Denmark)
Mørk, Jesper; Bischoff, Svend; Berg, Tommy Winther;
We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed.......We discuss the modelling of semiconductor optical amplifiers with emphasis on their high-speed properties. Applications in linear amplification as well as ultrafast optical signal processing are reviewed. Finally, the possible role of quantum-dot based optical amplifiers is discussed....
Multislice behavioral modeling based on envelope domain for power amplifiers
Institute of Scientific and Technical Information of China (English)
Wang Huadong; Bao Jingfu; Wu Zhengde
2009-01-01
An envelope domain multislice behavioral modeling is introduced. The tradition AM-AM and AM-PM characteristics of power amplifiers are extended to envelope domain and base-band filter is applied to distortion complex envelope signal for description of the envelope memory effect. Using traditional one and two-tone tests, the coefficients of nonlinear model and the FIR filter can be extracted. At last the model has been applied to a 10 W WCDMA power amplifier to predict its output signal. And simulation results show that the model output conforms very well to the traditional transistor level simulation results.
Amplification of supercontinuum by semiconductor and Er-doped fiber optical amplifiers
International Nuclear Information System (INIS)
We demonstrated selective amplification of supercontinuum ultrashort optical pulses around 1300-nm and 1550-nm bands by injecting a supercontinuum source into a semiconductor optical amplifier (SOA) and an erbium-doped fiber amplifier (EDFA), respectively. The broadband supercontinuum source was obtained by coupling femtosecond Ti:Sapphire laser pulses into a dual zero-dispersion wavelengths nonlinear photonic crystal fiber. The amplified supercontinuum has fully utilized the gain bandwidth of SOA and EDFA. However, the CW background amplified spontaneous emission increases as a result of the reflection at fiber ends to cause noisy pulse train
Nonlinear excitation of lo calized plasmon in one-dimensional atomic chain%一维原子链局域等离激元的非线性激发∗
Institute of Scientific and Technical Information of China (English)
尹海峰; 毛力
2016-01-01
本文基于含时密度泛函理论，研究了不同频率光脉冲场作用下一维钠原子链中电子的输运与等离激元共振之间的耦合规律.在等离激元共振点附近约0.8 eV频率范围内的光脉冲场，都可以激发体系的等离激元共振.这些不同频率外场激发的等离激元共振强度大小在一个数量级.外场频率越接近等离激元共振频率，外场激起的等离激元振动的振幅越大.对于线性原子链等离激元的非线性激发现象，本文用经典谐振子模型给出了定性解释.%At different frequencies of light pulse field, the coupling between plasmon resonance and electron transport of one-dimensional sodium atomic chain is investigated by using time-dependent density functional theory. Light pulse field, whose frequency is in about 0.8 eV range around the plasmon resonance point, can stimulate plasmon resonance of the system. Plasmon resonance intensity magnitude which is stimulated by these different frequency light pulse fields are in the same order of magnitude. The more closely the external field frequency approaches to plasmon resonance frequency, the larger plasmon resonance amplitude stimulated by the external field fields will be. With regard to the nonlinear excitation phenomenon of linear atomic chain plasmon, using a classical harmonic oscillator model, we gives a qualitative explanation.
Cascade Structure of Digital Predistorter for Power Amplifier Linearization
Directory of Open Access Journals (Sweden)
E. B. Solovyeva
2015-12-01
Full Text Available In this paper, a cascade structure of nonlinear digital predistorter (DPD synthesized by the direct learning adaptive algorithm is represented. DPD is used for linearization of power amplifier (PA characteristic, namely for compensation of PA nonlinear distortion. Blocks of the cascade DPD are described by different models: the functional link artificial neural network (FLANN, the polynomial perceptron network (PPN and the radially pruned Volterra model (RPVM. At synthesis of the cascade DPD there is possibility to overcome the ill conditionality problem due to reducing the dimension of DPD nonlinear operator approximation. Results of compensating nonlinear distortion in Wiener–Hammerstein model of PA at the GSM–signal with four carriers are shown. The highest accuracy of PA linearization is produced by the cascade DPD containing PPN and RPVM.
FPGA-Based Digital Current Switching Power Amplifiers Used in Magnetic Bearing Systems
Wang, Yin; Zhang, Kai; Dong, Jinping
For a traditional two-level current switching power amplifier (PA) used in a magnetic bearing system, its current ripple is obvious. To increase its current ripple performance, three-level amplifiers are designed and their current control is generally based on analog and logical circuits. So the required hardware is complex and a performance increase from the hardware adjustment is difficult. To solve this problem, a FPGA-based digital current switching power amplifier (DCSPA) was designed. Its current ripple was obviously smaller than a two-level amplifier and its control circuit was much simpler than a tri-level amplifier with an analog control circuit. Because of the field-programmable capability of a FPGA chip used, different control algorithms including complex nonlinear algorithms could be easily implemented in the amplifier and their effects could be compared with the same hardware.
Modal instabilities in very large mode area rod fiber amplifiers
DEFF Research Database (Denmark)
Jørgensen, Mette Marie; Hansen, Kristian Rymann; Laurila, Marko;
Optical fiber amplifiers have gained increased scientific and commercial interest due to high output powers with easy operation and maintenance. The main advantages of fiber amplifiers are good thermal properties, due to a large surface/volume ratio, excellent beam quality and stability [1]. Very...... large core fiber areas are highly desirable to mitigate various nonlinear processes, such as Kerr, four-wave mixing, Raman, and Brillouin effects. It is difficult to scale up the core area without going into a multi-moded regime. Microstructured fiber technology has allowed core diameters of 60...... with the finite element method to allow complex micro structured fibers to be considered. Thereby the modal instability threshold is estimated for very large mode area fiber amplifiers of various photonic crystal fiber designs. Experimentally the modal instability threshold for very large mode area fiber...
Modeling Distortion Effects in Class-D Amplifier Filter Inductors
DEFF Research Database (Denmark)
Knott, Arnold; Stegenborg-Andersen, Tore; Thomsen, Ole Cornelius;
2010-01-01
Distortion is generally accepted as a quantifier to judge the quality of audio power amplifiers. In switchmode power amplifiers various mechanisms influence this performance measure. After giving an overview of those, this paper focuses on the particular effect of the nonlinearity of the output...... filter components on the audio performance. While the physical reasons for both, the capacitor and the inductor induced distortion are given, the practical in depth demonstration is done for the inductor only. This includes measuring the inductors performance, modeling through fitting and resulting...... into simulation models. The fitted models achieve distortion values between 0.03 % and 0.2 % as a basis to enable the design of a 200 W amplifier....
Intraband effects on ultrafast pulse propagation in semiconductor optical amplifier
Indian Academy of Sciences (India)
K Hussain; S K Varshney; P K Datta
2010-11-01
High bit-rate (>10 Gb/s) signals are composed of very short pulses and propagation of such pulses through a semiconductor optical amplifier (SOA) requires consideration of intraband phenomena. Due to the intraband effects, the propagating pulse sees a fast recovering nonlinear gain which introduces less distortion in the pulse shape and spectrum of the output pulse but introduces a positive chirping at the trailing edge of the pulse.
Noise Shaping Filter Compensating PWM Distortion for Fully Digital Amplifier
Yoneya, Akihiko
The full-digital audio amplifiers have several merits such as a high power enabling a small size of the amplifier and digital implementation of the signal processing which allows desired precision of the processing except for the final stage switching amplifiers. Unfortunately, the pulse width modulation (PWM) causes signal distortions because of the non-linearity of the modulation from the viewpoint of the transient response. This paper proposes a compensation method of the PWM distortion with feedback approach. In the noise-shaping filter of the delta-sigma modulator to calculate the pulse codes for the PWM, the distortion caused by the PWM is evaluated and fed it back to compensate the distortion. Eventually the filter is implemented as a state-variable filter with non-linear feedback from the quantizer. The calculation of the filter elements is also described. By using proposed filters, PWM signals with small distortions and small floor noise can be obtained to realize high-fidelity audio amplifiers.
International Standardization Activities for Optical Amplifiers
Institute of Scientific and Technical Information of China (English)
Haruo Okamura
2003-01-01
International standardization activities for Optical Amplifiers at IECTC86 and ITU-T SG15 are reviewed. Current discussions include Optical Amplifier safety guideline, Reliability standard, Rest methods of Noise and PMD, Definitions of Raman amplifier parameters and OA classification.
New Packaging for Amplifier Slabs
Energy Technology Data Exchange (ETDEWEB)
Riley, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Thorsness, C. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Suratwala, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Steele, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rogowski, G. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2015-03-18
The following memo provides a discussion and detailed procedure for a new finished amplifier slab shipping and storage container. The new package is designed to maintain an environment of <5% RH to minimize weathering.
TARC: Carlo Rubbia's Energy Amplifier
Laurent Guiraud
1997-01-01
Transmutation by Adiabatic Resonance Crossing (TARC) is Carlo Rubbia's energy amplifier. This CERN experiment demonstrated that long-lived fission fragments, such as 99-TC, can be efficiently destroyed.
A Transformer Class E Amplifier
Directory of Open Access Journals (Sweden)
Mikolajewski Miroslaw
2014-12-01
Full Text Available In a high-efficiency Class E ZVS resonant amplifier a matching and isolation transformer can replace some or even all inductive components of the amplifier thus simplifying the circuit and reducing its cost. In the paper a theoretical analysis, a design example and its experimental verification for a transformer Class E amplifier are presented. In the experimental amplifier with a transformer as the only inductive component in the circuit high efficiency ηMAX = 0.95 was achieved for supply voltage VI = 36 V, maximum output power POMAX = 100 W and the switching frequency f = 300 kHz. Measured parameters and waveforms showed a good agreement with theoretical predictions. Moreover, the relative bandwidth of the switching frequency was only 19% to obtain output power control from 4.8 W to POMAX with efficiency not less than 0.9 in the regulation range.
Institute of Scientific and Technical Information of China (English)
YIN XUN-HE; FENG RU-PENG; REN YONG
2000-01-01
Chaotic characteristics in the iteration of logistic map (one-dimensional discrete dynamic system) are simulatedand analyzed. The circuit implementation of a kind of chaotic amplifier model is based on the chaotic characteristicsthat chaos is sensitively dependent on its initial conditions, and the circuit simulation result is given using simulationprogram with integrated circuit emphasis for personal computer (PSPICE), and is compared with linear amplifier.Advantages and disadvantages of such a model are indicated.
Ways to suppress click and pop for class D amplifiers
Haishi, Wang; Bo, Zhang; Jiang, Sun
2012-08-01
Undesirable audio click and pop may be generated in a speaker or headphone. Compared to linear (class A/B/AB) amplifiers, class D amplifiers that comprise of an input stage and a modulation stage are more prone to producing click and pop. This article analyzes sources that generate click and pop in class D amplifiers, and corresponding ways to suppress them. For a class D amplifier with a single-ended input, click and pop is likely to be due to two factors. One is from a voltage difference (VDIF) between the voltage of an input capacitance (VCIN) and a reference voltage (VREF) of the input stage, and the other one is from the non-linear switching during the setting up of the bias and feedback voltages/currents (BFVC) of the modulation stage. In this article, a fast charging loop is introduced into the input stage to charge VCIN to roughly near VREF. Then a correction loop further charges or discharges VCIN, substantially equalizing it with VREF. Dummy switches are introduced into the modulation stage to provide switching signals for setting up BFVC, and the power switches are disabled until the BFVC are set up successfully. A two channel single-ended class D amplifier with the above features is fabricated with 0.5 μm Bi-CMOS process. Road test and fast Fourier transform analysis indicate that there is no noticeable click and pop.
Measurements of non-linear noise re-distribution in an SOA
DEFF Research Database (Denmark)
Öhman, Filip; Tromborg, Bjarne; Mørk, Jesper;
2004-01-01
Measurements of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate non-linear noise re-distribution with a strong power and bandwidth dependence.......Measurements of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate non-linear noise re-distribution with a strong power and bandwidth dependence....
An integrated class D audio amplifier based on sliding mode control
Pillonnet, Gael; Cellier, Rémy; Abouchi, Nacer; Chiollaz, Monique
2008-01-01
International audience Class D amplifiers are becoming the most feasible solution for embedded audio application. However, distortions due to the non-linear nature of switching stage are the main drawback for this amplifier topology. This paper discusses the design and implementation of high fidelity audio class D using sliding mode control scheme. This design method proves to be a cost effective solution for industrial circuit. Experimental IC results, using commercial 0.13 µm CMOS techno...
Thermal effects in high average power optical parametric amplifiers.
Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas
2013-03-01
Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given. PMID:23455291
Thermal effects in high average power optical parametric amplifiers.
Rothhardt, Jan; Demmler, Stefan; Hädrich, Steffen; Peschel, Thomas; Limpert, Jens; Tünnermann, Andreas
2013-03-01
Optical parametric amplifiers (OPAs) have the reputation of being average power scalable due to the instantaneous nature of the parametric process (zero quantum defect). This Letter reveals serious challenges originating from thermal load in the nonlinear crystal caused by absorption. We investigate these thermal effects in high average power OPAs based on beta barium borate. Absorption of both pump and idler waves is identified to contribute significantly to heating of the nonlinear crystal. A temperature increase of up to 148 K with respect to the environment is observed and mechanical tensile stress up to 40 MPa is found, indicating a high risk of crystal fracture under such conditions. By restricting the idler to a wavelength range far from absorption bands and removing the crystal coating we reduce the peak temperature and the resulting temperature gradient significantly. Guidelines for further power scaling of OPAs and other nonlinear devices are given.
EMI-resilient amplifier circuits
van der Horst, Marcel J; Linnenbank, André C
2014-01-01
This book enables circuit designers to reduce the errors introduced by the fundamental limitations and electromagnetic interference (EMI) in negative-feedback amplifiers. The authors describe a systematic design approach for application specific negative-feedback amplifiers, with specified signal-to-error ratio (SER). This approach enables designers to calculate noise, bandwidth, EMI, and the required bias parameters of the transistors used in application specific amplifiers in order to meet the SER requirements. · Describes design methods that incorporate electromagnetic interference (EMI) in the design of application specific negative-feedback amplifiers; · Provides designers with a structured methodology to avoid the use of trial and error in meeting signal-to-error ratio (SER) requirements; · Equips designers to increase EMI immunity of the amplifier itself, thus avoiding filtering at the input, reducing the number of components and avoiding detr...
Kleinberg, L.
1982-01-01
Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.
DEFF Research Database (Denmark)
Durhuus, Terji; Mikkelsen, Benny; Stubkjær, Kristian
1992-01-01
An advanced dynamic model for multisection semiconductor optical amplifiers is presented. It accounts for the carrier and field distributions in the longitudinal direction as well as for the facet reflectivities. The model can handle arbitrary time-varying input signals and current modulations....... The model is used to assess intermodulation distortion and crosstalk. Cascaded amplifiers are considered, and the crosstalk and intermodulation distortion due to cascaded amplifiers are found to accumulate by adding together in amplitude; this may limit the number or cascaded amplifiers in multichannel...... systems. Carrier-induced nonlinearities depend strongly on facet reflectivities; for 25 dB of single-pass gain, a reflectivity of 5×10-4 will result in 3 dB excess distortion. Reduction of intermodulation distortion by use of multisection amplifiers is found to be possible only for small channel...
Institute of Scientific and Technical Information of China (English)
Zhao Jia-Sheng; Li Pan; Chen Xiao-Dong; Feng Su-Juan; Mao Qing-He
2012-01-01
The evolutions of the pulses propagating in decreasing and increasing gain distributed fiber amplifiers with finite gain bandwidths are investigated by simulations with the nonlinear Schrodinger equation.The results show that the parabolic pulse propagations in both the decreasing and the increasing gain amplifiers are restricted by the finite gain bandwidth.For a given input pulse,by choosing a small initial gain coefficient and gain variation rate,the whole gain for the pulse amplification limited by the gain bandwidth may be higher,which is helpful for the enhancement of the output linearly chirped pulse energy.Compared to the decreasing gain distributed fiber amplifier,the increasing gain distributed amplifier may be more conducive to suppress the pulse spectral broadening and increase the critical amplifier length for achieving a larger output linearly chirped pulse energy.
A Two-Step Identification Approach for Twin-Box Models of RF Power Amplifier
Directory of Open Access Journals (Sweden)
You-Jiang Liu
2011-01-01
Full Text Available We propose a two-step identification approach for twin-box model (Wiener or Hammerstein of RF power amplifier. The linear filter block and the static nonlinearity block are extracted, respectively, based on least-squares method, by iterative calculation. Simulations show that the method can get quite accurate parameters to model different nonlinear models with memory such as Wiener, Hammerstein, Wiener-Hammerstein (W-H, and memory polynomial models, hence, demonstrating its robustness. Furthermore, experimental results show excellent agreement between measured output and modeled output, where one carrier WCDMA signal is used as the excitation for a wideband RF amplifier.
DEFF Research Database (Denmark)
Borri, Paola; Scaffetti, Stefano; Mørk, Jesper;
1999-01-01
The nonlinear gain response of InGaAsP bulk optical amplifiers under ultrafast optical excitation at 1.53 ìm investigated. In particular, the dependence of the gain saturation energy on the pulse duration is measured in the range of pulse durations from 150 fs to 11 ps, for different bias currents...... and lengths of the amplifier. By comparison with a theoretical model, a critical pulsewidth is inferred below which nonlinear carrier dynamics like carrier heating and spectral hole burning dominate the gain saturation....
Nanda, Sudarsan
2013-01-01
"Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.
Wong, Chun Wa; Yasui, Kosuke
2006-06-01
The one-dimensional fall of a folded chain with one end suspended from a rigid support and a chain falling from a resting heap on a table is studied. Because their Lagrangians contain no explicit time dependence, the falling chains are conservative systems. Their equations of motion are shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is incorrect because it neglects the energy gained when a link leaves a subchain. The maximum chain tension measured by Calkin and March for the falling folded chain is given a simple if rough interpretation. Other aspects of the falling folded chain are briefly discussed.
Dielectric waveguide amplifiers and lasers
Pollnau, M.
2014-01-01
The performance of semiconductor amplifiers and lasers has made them the preferred choice for optical gain on a micro-chip. In the past few years, we have demonstrated that also rare-earth-ion-doped dielectric waveguides show remarkable performance, ranging from a small-signal gain per unit length o
Thermal recovery of NIF amplifiers
Energy Technology Data Exchange (ETDEWEB)
Sutton, S.; Marshall, C.; Petty, C.; Smith, L.; van Wonterghem, B.; Mills, S.
1997-02-01
The issue of thermal recovery of the NIF amplifiers has taken on increased emphasis as program goals move toward increasing the shot rate to once every four hours. This paper addresses the technical issues associated with achieving thermal recovery in the NIF amplifiers. We identify two temperature related thermal recovery quantities: (1) the difference between the average slab temperature and the temperature of other surfaces in the amplifier cavity, and (2) the temperature difference in the slab over the aperture. The first quantity relates to optical disturbances in the gas column in the system, while the second quantity is associated with optical aberrations in the laser media itself. Calculations and experiments are used to quantify recovery criteria, and develop cooling approaches. The cooling approaches discussed are (1) active cooling of the flashlamps with ambient gas and chilled gas, and (2) active cooling of the slab edge cladding. Calculations indicate that the NIF baseline cooling approach of 20 cfm per lamp ambient temperature gas flow in both the central and side flashlamp cassettes is capable of meeting thermal recovery requirements for an 8 hour shot period, while to achieve a 4 hour shot period requires use of chilled gas and edge cladding cooling. In addition, the effect of changing the amplifier cavity and beamtube fill gas from nitrogen to helium is addressed, showing that a factor of 8 reduction in the sensitivity to thermal disturbances is possible. 6 refs., 9 figs., 1 tab.
Grey Self-similar Solitary Waves in Inhomogeneous Nonlinear Media
Institute of Scientific and Technical Information of China (English)
LI Hua-Mei
2009-01-01
This paper analyzes spatial grey self-similar solitary waves propagation and collision in graded-index nonlinear waveguide amplifiers with self-focusing and self-defocusing Kerr nonlinearities.New exact self-similar solutions are found using a novel transformation and their main features are investigated by using direct computer simulations.
Parametrically Driven Nonlinear Oscillators with an Impurity
Institute of Scientific and Technical Information of China (English)
张卓; 唐翌
2002-01-01
By virtue of the method of multiple scales, we study a chain of parametrically driven nonlinear oscillators with a mass impurity. An equation is presented to describe the nonlinear wave of small amplitude in the chain.In our derivation, the equation is applicable to any eigenmode of coupled pendulum. Our result shows that a nonpropagation soliton emerges as the lowest or highest eigenmode of coupled pendulum is excited, and the impurity tends to pin the nonpropagation soliton excitation.
Optimizing bandwidth and dynamic range of lumped Josephson parametric amplifiers
Eddins, A.; Vijay, R.; Macklin, C.; Minev, Z.; Siddiqi, I.
2013-03-01
Superconducting parametric amplifiers have revolutionized the field of quantum measurement by providing high gain, ultra-low noise amplification. They have been used successfully for high-fidelity qubit state measurements, probing nano-mechanical resonators, quantum feedback, and for microwave quantum optics experiments. Though several designs exist, a simple and robust architecture is the Lumped Josephson Parametric Amplifier (LJPA). This device consists of a capacitively shunted SQUID directly coupled to a transmission line to form a low quality factor (Q) nonlinear resonator. We discuss amplifiers which can be tuned over the full 4-8 GHz band with 20-25 dB of gain and 10 - 50 MHz of signal bandwidth. However, similar to other parametric amplifiers employing a resonant circuit, the LJPA suffers from low dynamic range and has a -1 dB gain compression point of order -130 dBm. We explore new designs comprised of an array of SQUIDs to improve the dynamic range. We will present the results of numerical simulations and preliminary experiments. We will also briefly discuss improvements obtained from different biasing methods and packaging. This research was supported by the Army Research Office under a QCT grant.
A wideband dc-coupled amplifier
International Nuclear Information System (INIS)
A method is described whereby an ac-coupled high-frequency amplifier and a dc-coupled low-frequency amplifier are connected in parallel in order to obtain a dc-coupled wideband amplifier. By using an operational amplifier which compares the output voltage with the input voltage, the low-frequency amplifier contributes to the overall gain only when the gain of the ac-coupled amplifier droops at low frequencies. Thus, no frequency splitting networks are necessary and the excellent low-frequency features of an operational amplifier are added to those of the ac-coupled wideband amplifier. As an example, a low noise amplifier is described which exhibits a hundredfold gain, a bandwidth from dc to 550 MHz, an input bias current of less than 1 nA, and an output voltage range of ±1 V
On accumulated signal degradation in a cascade of semiconductor optical amplifiers
International Nuclear Information System (INIS)
We study a design and limitations of a wavelength division multiplexing packet- switched network based on semiconductor optical amplifiers (SOAs) under different modulations formats (QPSK, 8-QAM and 16-QAM). A simple convergence rule for accumulated SOA nonlinearities based on the so-called nonlinear threshold is proposed. We calculate the signal reach depending on various SOA and network parameters by means of numerical simulation. We provide a design tool enabling optimization of a SOA-based optical network architecture
Nonlinear Femtosecond Pulse Reshaping in Waveguide Arrays
Darren D. Hudson; Shish, Kimberlee; Schibli, Thomas R.; Kutz, J. Nathan; Christodoulides, Demetrios N.; Morandotti, Roberto; Cundiff, Steven T.
2008-01-01
We observe nonlinear pulse reshaping of femtosecond pulses in a waveguide array due to coupling between waveguides. Amplified pulses from a mode-locked fiber laser are coupled to an AlGaAs core waveguide array structure. The observed power-dependent pulse reshaping agrees with theory, including shortening of the pulse in the central waveguide.
Dark Solitons in FPU Lattice Chain
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Based on multiple scales method, we study the nonlinear properties of a new Fermi-Pasta-Ulam lattice model analytically. It is found that the lattice chain exhibits a novel nonlinear elementary excitation, i.e. a dark soliton.Moreover, the modulation depth of dark soliton is increasing as the anharmonic parameter increases.
Cambou, A D; Hamm, E; Hanna, J A; Menon, N; Santangelo, C D; Walsh, L
2012-01-01
A loop of chain can move along its own tangents, maintaining a steady shape. An open-ended chain undergoing a nontrivial motion must change its shape. One consequence is that chains pulled around objects will fail to follow the contours of the objects, unwrapping themselves instead. This short note accompanies a fluid dynamics video submission (83068) to the APS DFD Gallery of Fluid Motion 2012.
Dispersive properties of quasi-phase-matched optical parametric amplifiers
Longhi, S; Laporta, P
2002-01-01
The dispersive properties of non-degenerate optical parametric amplification in quasi-phase-matched (QPM) nonlinear quadratic crystals with an arbitrary grating profile are theoretically investigated in the no-pump-depletion limit. The spectral group delay curve of the amplifier is shown to be univocally determined by its spectral power gain curve through a Hilbert transform. Such a constraint has important implications on the propagation of spectrally-narrow optical pulses through the amplifier. In particular, it is shown that anomalous transit times, corresponding to superluminal or even negative group velocities, are possible near local minima of the spectral gain curve. A possible experimental observation of such effects using a QPM Lithium-Niobate crystal is suggested.
Wong, C W; Wong, Chun Wa; Yasui, Kosuke
2006-01-01
The one-dimensional falling motion of a bungee chain suspended from a rigid support and of a chain falling from a resting heap on a table is studied. Their Lagrangians are found to contain no explicit time dependence. As a result, these falling chains are conservative systems. Each of their Lagrange's equations of motion is shown to contain a term that enforces energy conservation when masses are transferred between subchains. We show in particular that Cayley's 1857 energy nonconserving solution for a chain falling from a resting heap is incorrect because it neglects the energy gained when the transferred link is emitted by the emitting subchain. The maximum chain tension measured by Calkin and March for the falling bungee chain is given a simple if rough interpretation. In the simplified one-dimensional treatment, the kinetic energy of the center of mass of the falling bungee chain is found to be converted by the chain tension at the rigid support into the internal kinetic energy of the chain. However, as t...
Off-axis multipass amplifier as a large aperture driver stage for fusion lasers.
Murray, J E; Downs, D C; Hunt, J T; Hermes, G L; Warren, W E
1981-03-01
A multipass amplifier configuration is described which has potential as a large aperture, high gain driver stage for fusion laser systems. We avoid the present limitations of large aperture switches by using an off-angle geometry that does not require an optical switch. The saturated gain characteristics of this multipass amplifier are optimized numerically. Three potential problems are investigated experimentally, self-lasing, output beam quality, and amplified spontaneous emission output. The results indicate comparable cost for comparable performance to a linear chain, with some operational advantage for the multipass driver stage. PMID:20309212
Boyd, Robert W
2013-01-01
Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q
Cost optimal allocation of amplifiers and DCMs in WDM ring networks.
Minagar, Amir; Premaratne, Malin; Tran, An V
2006-10-30
Designing metropolitan wavelength division multiplexing (WDM) ring networks with minimum deployment cost is a demanding issue in Telecommunication Network planning . We have already presented amplifier placement methods to minimize the number of amplifiers in WDM rings for the case all amplifiers follow a unique gain model. In this paper, we take into account different types of amplifiers with predefined fixed characteristics and costs. We also formulate fiber dispersion limitations on the ring design, and present two efficient methods for placing amplifiers and Dispersion Compensation Modules (DCMs) in WDM rings to minimize the total deployment cost of the system. The first method deals with both linear and nonlinear equations and uses a mixed integer nonlinear programming (MINLP) solver where the second method applies the linear approximation of nonlinear constraints, and uses a mixed integer linear programming (MILP) solver to minimize the total cost of the system. We carry out Simulation experiments to confirm the applicability of the methods and compare the results for various network configurations.
Goldstein, E. L.; Eskildsen, L.; da Silva, V.; Andrejco, M.; Silberberg, Y.
1995-05-01
The emergence of practical fiber-amplifier chains has swiftly raised the prospect of transparent lightwave networks, in which signals travel from source to destination through a sequence of intermediate nodes without optoelectronic conversion. When such networks employ multiple wavelengths, however, some of the most substantial new research challenges are those posed by the amplifier chains themselves. Such networks suffer from accumulating interchannel power spread, from sensitivity to interamplifier loss variations, and from transient cross saturation, as the network undergoes reconfiguration. All of these difficulties effectively vanish in a chain of saturated lightwave amplifiers whose per-channel gains are decoupled by, e.g., inhomogeneous broadening. Unlike conventional, homogeneously broadened systems, saturated fiber-amplifier chains with decoupled gain dynamics provide automatic channel-by-channel power regulation, tolerance to interamplifier loss variations, and immunity to transient cross saturation. Thus, if amplifiers with such decoupled gain dynamics can be implemented in a practical way, they promise to solve - in a single stroke - several of the most substantial technological challenges facing transparent multiwavelength lightwave networks.
Single conversion stage amplifier - SICAM
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.
2005-12-15
This Ph.D. thesis presents a thorough analysis of the so called SICAM - SIngle Converter stage AMplifier approach to building direct energy conversion audio power amplifiers. The mainstream approach for building isolated audio power amplifiers today consists of isolated DC power supply and Class D amplifier, which essentially represents a two stage solution, where each of the components can be viewed as separate and independent part. The proposed SICAM solution strives for direct energy conversion from the mains to the audio output, by dedicating the operation of the components one to another and integrating their functions, so that the final audio power amplifier represents a single-stage topology with higher efficiency, lower volume, less board space, lower component count and subsequently lower cost. The SICAM approach is both applicable to non-isolated and isolated audio power amplifiers, but the problems encountered in these two cases are different. Non-isolated SICAM solutions are intended for both AC mains-connected and battery-powered devices. In non-isolated mains-connected SICAMs the main idea is to simplify the power supply or even provide integrated power factor correction (PFC) functions, while still maintaining low component stress and good audio performance by generally decreasing the input voltage level to the Class D audio power amplifier. On the other hand, non-isolated battery-powered SICAMs have to cope with the ever changing battery voltage and provide output voltage levels which are both lower and higher than the battery voltage, while still being simple and single-stage energy conversion solutions. In isolated SICAMs the isolation transformer adjusts the voltage level on the secondary side to the desired level, so the main challenges here are decreasing the size of the magnetic core and reducing the number and size of bulky reactive components as much as possible. The main focus of this thesis is directed towards the isolated SICAMs and
Higher order mode optical fiber Raman amplifiers
DEFF Research Database (Denmark)
Rottwitt, Karsten; Friis, Søren Michael Mørk; Usuga Castaneda, Mario A.;
2016-01-01
We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations.......We review higher order mode Raman amplifiers and discuss recent theoretical as well as experimental results including system demonstrations....
Analog circuit design designing high performance amplifiers
Feucht, Dennis
2010-01-01
The third volume Designing High Performance Amplifiers applies the concepts from the first two volumes. It is an advanced treatment of amplifier design/analysis emphasizing both wideband and precision amplification.
Challenges in higher order mode Raman amplifiers
DEFF Research Database (Denmark)
Rottwitt, Karsten; Nielsen, Kristian; Friis, Søren Michael Mørk;
2015-01-01
A higher order Raman amplifier model that take random mode coupling into account ispresented. Mode dependent gain and signal power fluctuations at the output of the higher order modeRaman amplifier are discussed...
Quantum Theory of Laser Amplifiers.
Mander, Gillian Linda
Available from UMI in association with The British Library. Requires signed TDF. We calculate the input-output characteristics of a below threshold laser amplifier. Expressions are derived for the output second- and fourth-order spectral and temporal correlation functions in terms of the corresponding input quantities, and for the photocount first and second factorial moments for both homodyne and direct detection. The general results are applied to several cases of practical interest, including specific non-classical input states. We show that a maximum of twofold amplification is permitted if squeezing in the input is to survive at the output. Similarly, for preservation of photon antibunching in amplification we show that only very small gains are allowed. The model treated here provides a detailed example of the amplifier noise limitations imposed by quantum mechanics. In particular, we show that minimum noise occurs in a cavity that is asymmetric with respect to the mirror reflectivities. The latter part of this work treats the above threshold laser amplifier. The laser output is back-scattered from a moving target to provide a weak Doppler-shifted signal which re-enters the laser cavity and is amplified. We show that the three-level atomic lasing medium is equivalent to a two-level medium pumped by an inverted bath. We use the methods of quantum statistical analysis to obtain time -evolution equations for the c-number amplitudes of the laser and signal fields. We show that the results may be applied to the below threshold regime for appropriate values of the pump parameter. By considering the amplitude differential gain we show explicitly that the behaviour of the laser around threshold is characteristic of a second -order phase transition. We calculate the output intensity gain appropriate to a heterodyne detection process, and find good agreement between the predicted gain profiles and measured data for both carbon dioxide and argon-ion lasers.
338-GHz Semiconductor Amplifier Module
Samoska, Lorene A.; Gaier, Todd C.; Soria, Mary M.; Fung, King Man; Rasisic, Vesna; Deal, William; Leong, Kevin; Mei, Xiao Bing; Yoshida, Wayne; Liu, Po-Hsin; Uyeda, Jansen; Lai, Richard
2010-01-01
Research findings were reported from an investigation of new gallium nitride (GaN) monolithic millimeter-wave integrated circuit (MMIC) power amplifiers (PAs) targeting the highest output power and the highest efficiency for class-A operation in W-band (75-110 GHz). W-band PAs are a major component of many frequency multiplied submillimeter-wave LO signal sources. For spectrometer arrays, substantial W-band power is required due to the passive lossy frequency multipliers.
X-Parameter Based Modelling of Polar Modulated Power Amplifiers
DEFF Research Database (Denmark)
Wang, Yelin; Nielsen, Troels Studsgaard; Sira, Daniel;
2013-01-01
X-parameters are developed as an extension of S-parameters capable of modelling non-linear devices driven by large signals. They are suitable for devices having only radio frequency (RF) and DC ports. In a polar power amplifier (PA), phase and envelope of the input modulated signal are applied at...... PA for simulations. The simulated error vector magnitude (EVM) and adjacent channel power ratio (ACPR) were compared with the measured data to validate the model. The maximum differences between the simulated and measured EVM and ACPR are less than 2% point and 3 dB, respectively....
High power regenerative laser amplifier
Miller, J.L.; Hackel, L.A.; Dane, C.B.; Zapata, L.E.
1994-02-08
A regenerative amplifier design capable of operating at high energy per pulse, for instance, from 20-100 Joules, at moderate repetition rates, for instance from 5-20 Hertz is provided. The laser amplifier comprises a gain medium and source of pump energy coupled with the gain medium; a Pockels cell, which rotates an incident beam in response to application of a control signal; an optical relay system defining a first relay plane near the gain medium and a second relay plane near the rotator; and a plurality of reflectors configured to define an optical path through the gain medium, optical relay and Pockels cell, such that each transit of the optical path includes at least one pass through the gain medium and only one pass through the Pockels cell. An input coupler, and an output coupler are provided, implemented by a single polarizer. A control circuit coupled to the Pockels cell generates the control signal in timed relationship with the input pulse so that the input pulse is captured by the input coupler and proceeds through at least one transit of the optical path, and then the control signal is applied to cause rotation of the pulse to a polarization reflected by the polarizer, after which the captured pulse passes through the gain medium at least once more and is reflected out of the optical path by the polarizer before passing through the rotator again to provide an amplified pulse. 7 figures.
1977-01-01
The picture shows a 2 MW, 200 MHz amplifier plant with feeder lines. The main RF-system of the SPS comprises four cavities: two of 20 m length and two of 16.5 m length. They are all installed in one long straight section (LSS 3). These cavities are of the travelling-wave type operating at a centre frequency of 200.2 MHz. They are wideband, filling time about 700 ns and untuned. The power amplifiers, using tetrodes are installed in a surface building 200 m from the cavities. Initially only two cavities were installed, a third cavity was installed in 1978 and a forth one in 1979. The number of power amplifiers was also increased: to the first 2 MW plant a second 2 MW plant was added and by end 1979 there were 8 500 kW units combined in pairs to feed each of the 4 cavities with up to about 1 MW RF power, resulting in a total accelerating voltage of about 8 MV. See also 7412016X, 7412017X, 7411048X.
Sub-picosecond pulse distortion in an InGaAsP optical amplifier
DEFF Research Database (Denmark)
Romstad, Francis Pascal; Borri, Paola; Bischoff, Svend;
1999-01-01
We observe strong distortion of -150 fs pulses after propagation through a semiconductor optical amplifier. Both pulse narrowing and breakup is seen. The distortion is due to the interplay of the Kerr non-linearity and gain dispersion and is important for the use of SOAs in ultrafast signal...
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
The input power tolerance of a single-pump fiber-optic parametric amplifier (FOPA) is experimentally shown to be enhanced for return-to-zero differential phase-shift keying (RZ-DPSK) modulation compared to RZ ON–OFF keying modulation at 40 Gb/s. The improved nonlinear tolerance is exploited...
Improved charge amplifier using hybrid hysteresis compensation
Amin-Shahidi, Darya; Trumper, David L.
2013-08-01
We present a novel charge amplifier, with a robust feedback circuit and a method for compensating piezoelectric actuator's hysteresis at low frequencies. The amplifier uses a modified feedback circuit which improves robustness to the addition of series load impedance such as in cabling. We also describe a hybrid hysteresis compensation method for enabling the charge amplifier to reduce hysteresis at low frequencies. Experimental results demonstrate the utility of the new amplifier design.
Institute of Scientific and Technical Information of China (English)
李慧瑾; 胡军; 李研; 孙晶莹; 高锦伟; 赵向绒; 封青; 谭天天; 胡巧侠; 李元
2013-01-01
Objective: To clone and analysis light and heavy chain genes of monoclonal antibody against H1N1 influenza virus hemagglutinin by Nested PCR, then construct a common method for cloning light and heavy chain variable region genes of mouse anti-human H1N1 influenza virus hemagglutinin monoclonal antibody. Methods:We designed 22 pairs of primers for amplifying Igκ light and heavy chain variable region gene, and cloned light and heavy chain variable region genes of 6 mouse anti-human H1N1 influenza virus hemagglutinin monoclonal anti⁃bodies. Cloning and subsequent sequences analysis of immunoglobulin gene were performed, sequence alignment with mouse immunoglobulin in NCBI. Results: The nucleotide and corresponding amino acid sequences were in line with characteristics of mouse immunoglobulin variable region. Conclusion: In this study, we cloned 6 mouse antibody variable region genes, and found a common method for cloning immunoglobulin light and heavy chain variable region genes. It provides a basis for late amplifying monoclonal antibody variable region, and experimental data for analysis of H1N1 influenza virus hemagglutinin and antibody binding sites.% 目的：采用巢式PCR对甲型H1N1流感病毒血凝素单克隆抗体的轻链和重链基因进行扩增，对获得的基因进行序列分析，并找出克隆鼠Igκ轻链和重链可变区基因的通用方法。方法：设计22对扩增鼠Igκ轻链可变区和重链可变区基因的引物，对6株鼠抗人甲型H1N1流感病毒血凝素单克隆抗体的轻链和重链可变区基因进行克隆并测序，与NCBI公布的鼠免疫球蛋白序列比对分析。结果：巢式PCR方法可以有效避免单克隆抗体克隆过程的假基因，并且得到的单克隆抗体的氨基酸序列均符合鼠免疫球蛋白可变区特征。结论：建立了克隆鼠免疫球蛋白轻链和重链可变区基因的通用方法，为后期克隆鼠源性单克隆抗体的可变区基因提供了
Enhanced Dynamic Range in N-SQUID Lumped Josephson Parametric Amplifiers
Eddins, A.; Levenson-Falk, E. M.; Toyli, D. M.; Vijay, R.; Minev, Z.; Siddiqi, I.
2014-03-01
Simultaneously providing high gain and nearly quantum-limited noise performance, superconducting parametric amplifiers (paramps) have been used successfully for high fidelity qubit readout, quantum feedback, and microwave quantum optics experiments. The Lumped Josephson Parametric Amplifier (LJPA) consists of a capacitively shunted SQUID coupled to a transmission line to form a nonlinear resonator. Like other paramps employing a resonant circuit, the LJPA's dynamic range-a potentially key ingredient for multiplexing-is limited. Simple theory predicts that the dynamic range can be increased without any reduction in bandwidth or gain by distributing the resonator nonlinearity over a series array of SQUIDs. We fabricated such array devices with up to 5 SQUIDs and observed a clear increase in the critical power for bifurcation about which parametric gain occurs. We discuss in detail amplifier performance as a function of the number of SQUIDs in the array. This research was supported by the Army Research Office under a QCT grant.
All chalcogenide Raman parametric Laser, Wavelength Converter and Amplifier in a Single Microwire
Ahmad, Raja
2013-01-01
Compact, power efficient and fiber compatible lasers, wavelength converters and amplifiers are vital ingredients for the future fiber optic systems and networks. Nonlinear optical effects, like Raman scattering and parametric four wave mixing, offer a way to realize such devices. Here we use a single chalcogenide microwire to realize a device that provides the functions of a Stokes Raman parametric laser, a four wave mixing anti Stokes wavelength converter, and an ultra broadband Stokes/anti Stokes Raman amplifier or supercontinuum generator. The device operation relies on ultrahigh Raman and Kerr gain (upto five orders of magnitude larger than in silica fibers), precisely engineered chromatic dispersion and high photosensitivity of the chalcogenide microwire. The Raman parametric laser operates at a record low threshold average (peak) pump power of 52 \\muW (207 mW) and a slope efficiency of >2%. A powerful anti Stokes signal is generated via the nonlinear four wave mixing process. As amplifier or the broadba...
Ruszczynski, Andrzej
2011-01-01
Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t
Ways to suppress click and pop for class D amplifiers
Institute of Scientific and Technical Information of China (English)
Wang Haishi; Zhang Bo; Sun Jiang
2012-01-01
Undesirable audio click and pop may be generated in a speaker or headphone.Compared to linear (class A/B/AB) amplifiers,class D amplifiers that comprise of an input stage and a modulation stage are more prone to producing click and pop.This article analyzes sources that generate click and pop in class D amplifiers,and corresponding ways to suppress them.For a class D amplifier with a single-ended input,click and pop is likely to be due to two factors.One is from a voltage difference (VDIF) between the voltage of an input capacitance (VCIN)and a reference voltage (VREF) of the input stage,and the other one is from the non-linear switching during the setting up of the bias and feedback voltages/currents (BFVC) of the modulation stage.In this article,a fast charging loop is introduced into the input stage to charge VCIN to roughly near VREF.Then a correction loop further charges or discharges VCIN,substantially equalizing it with VREF.Dummy switches are introduced into the modulation stage to provide switching signals for setting up BFVC,and the power switches are disabled until the BFVC are set up successfully.A two channel single-ended class D amplifier with the above features is fabricated with 0.5 μm Bi-CMOS process.Road test and fast Fourier transform analysis indicate that there is no noticeable click and pop.
Nonlinear Propagation of Coupling Optical Pulse under Compton Scattering in Laser Medium
Institute of Scientific and Technical Information of China (English)
HAO Dong-shan; ZHANG Xiao-fu
2006-01-01
After considering Kerr nonlinear effect,group velocity dispersion of host and gain distribution of active particle in laser amplifying medium,a basic equation describing propagation of the coupling optical pulse under the multi-photon nonlinear Compton scattering in the laser amplifying medium has been deduced. Besides,the profile and power spectrum of a picosecond-level super-Gaussian coupling pulse in the laser amplifying medium have been discussed when its central frequency coincides with the gain peak frequency of the laser amplifying medium.
Spontaneous emission from saturated parametric amplifiers
DEFF Research Database (Denmark)
Rottwitt, Karsten; Ott, Johan Raunkjær; Steffensen, Henrik;
2009-01-01
Noise performance of parametric amplifiers is typically calculated assuming un-depleted operation. However, in many applications especially when applied as regenerative amplifiers in systems based on phase shift keyed modulation schemes, this assumption is not valid. Here we show the impact on ac...... on accumulated spontaneous emission for a parametric amplifier operated in saturation....
European Research on THz Vacuum Amplifiers
DEFF Research Database (Denmark)
Brunetti, F.; Cojocarua, C.-S.; de Rossi, A.;
2010-01-01
The OPTHER (OPtically Driven TeraHertz AmplifiERs) project represents a considerable advancement in the field of high frequency amplification. The design and realization of a THz amplifier within this project is a consolidation of efforts at the international level from the main players of the Eu...
A High-performance Small Signal Amplifier
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
According to questions in the design of high quality small signal amplifier, this paper gave a new-type high performance small signal amplifier. The paper selected the operational amplifier of ICL Company and designed a new-type circuit with simple, low cost and excellent performance.
Radio frequency amplifier with effective decoupling
Besling, W.F.A.; Bakker, T.W.; Lamy, Y.; Kochupurackal, J.; Roozeboom, F.
2011-01-01
A variety of circuits, methods and devices are implemented for radiofrequency amplifiers. According to one such implementation, a radiofrequency amplifier circuit is implemented in a SMD package. The circuit amplifies a radiofrequency signal having a base-band portion and a plurality of carrier sign
low pump power photonic crystal fibre amplifiers
DEFF Research Database (Denmark)
Hougaard, Kristian G.; Broeng, Jes; Bjarklev, Anders Overgaard
2003-01-01
Designs of low pump power optical amplifiers, based on photonic crystal fibres are presented. The potential of these fibre amplifiers is investigated, and it is demonstrated that such amplifiers may deliver gains of more than 15 dB at 1550 nm with less than 1 mW of optical pump power....
Tuning the elastic nonlinearities in composite nanomaterials
International Nuclear Information System (INIS)
The possibility of tuning the nonlinear effective response of composite materials and structures is of great importance for developing new concepts such as soft metamaterials, acoustic diodes, nonlinear waveguides and phononic crystals. In this paper we develop a homogenization technique for dispersions of nonlinear particles in a soft matrix able to take account of second and third order elastic nonlinearities. Based on this method, we prove the possibility to strongly amplify a given particles nonlinearity (either the second or the third one) under specific conditions concerning the linear response of the two constituents (particles and matrix). We finally give a realistic example based on a population of porous polymer particles embedded in a PDMS matrix. (paper)
In-line phase sensitive amplifier based on PPLN waveguides.
Umeki, Takeshi; Asobe, Masaki; Takenouchi, Hirokazu
2013-05-20
We demonstrate a χ(2)-based in-line PSA with a carrier-recovery and phase-locking system for a phase shift keying (PSK) signal. By doubling the signal phase using a wavelength conversion technique, the carrier was recovered from a PSK signal. The carrier phase was synchronized to a local oscillator using optical injection locking. Phase sensitive amplification with a wide phase sensitive dynamic range of 20 dB was achieved using degenerate parametric amplification in a periodically poled LiNbO(3) (PPLN) waveguide. The phase regeneration effect was examined for a degraded signal by means of constellation analyses and bit-error rate measurements. The in-line PSA also operated successfully as a repeater amplifier in a 160 km fiber link without a power penalty. Finally, we demonstrate the regeneration of non-linear impairments induced by fiber non-linearity.
Directory of Open Access Journals (Sweden)
Gaurav Solanki
2012-10-01
Full Text Available The polymerase chain reaction (PCR is a technique in molecular biology to amplify a single or a few copies of a piece of DNA across several orders of magnitude, generating thousands to millions of copies of a particular DNA sequence. PCR is now a common and often indispensable technique used in medical and biological research labs for a variety of applications. There are three major steps involved in the PCR technique: denaturation, annealing and extension. PCR is useful in the investigation and diagnosis of a growing number of diseases. PCR is also used in forensics laboratories. PCR can identify genes that have been implicated in the development of cancer. The present paper is an attempt to review basics of PCR in relation to its methods, application and use.
Log amplifier with pole-zero compensation
Brookshier, William
1987-01-01
A logarithmic amplifier circuit provides pole-zero compensation for improved stability and response time over 6-8 decades of input signal frequency. The amplifier circuit includes a first operational amplifier with a first feedback loop which includes a second, inverting operational amplifier in a second feedback loop. The compensated output signal is provided by the second operational amplifier with the log elements, i.e., resistors, and the compensating capacitors in each of the feedback loops having equal values so that each break point or pole is offset by a compensating break point or zero.
Semiconductor quantum-dot lasers and amplifiers
DEFF Research Database (Denmark)
Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.;
2002-01-01
-power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...
Status Report on the Energy Amplifier
Rubbia, Carlo
1994-01-01
0ne year after its first presentation,the Energy Amplifier (EA) Project holds its promises for a environmentally acceptable form of energy extraction from nuclei, namely to eliminate or at least greatly reduce(i) the environmental impact of the long-lived highly radioactive waste;(ii) the possibility of diversions toward military applications;(iii) the risks of an accidental divergence related to the critical operation of the chain reaction and (iv) make a more efficient use of a fuel which is less radio-toxic to extract and more abundant on Earth than Uranium. In these respects the EA (or equivalent scenarios from Los Alamos and elsewhere) is comparable in performance to Thermonuclear Fusion. Bot h approches offer pratically unl;imited fuel resources: the energetic content of Lithium on the Earth's crust needed by Fusion is estimated to be seven times the one of Thorium and they are both adequate for millions of years of very intensived utilisation.However the EA can be built economically,in a variety of siz...
Liu, Bin; Liu, Chong; Shen, Lifeng; Wang, Chunhua; Ye, Zhibin; Liu, Dong; Xiang, Zhen
2016-04-18
A method for beam quality management is presented in a master oscillator power amplifier (MOPA) using Nd:YVO4 as the gain medium by extra-cavity periodic reproduction of wavefront aberrations. The wavefront aberration evolution of the intra-cavity beams is investigated for both symmetrical and asymmetrical resonators. The wavefront aberration reproduction process is successfully realized outside the cavity in four-stage amplifiers. In the MOPA with a symmetrical oscillator, the laser power increases linearly and the beam quality hardly changes. In the MOPA with an asymmetrical oscillator, the beam quality is deteriorated after the odd-stage amplifier and is improved after the even-stage amplifier. The wavefront aberration reproduction during the extra-cavity beam propagation in the amplifiers is equivalent to that during the intra-cavity propagation. This solution helps to achieve the effective beam quality management in laser amplifier chains. PMID:27137329
Liu, Bin; Liu, Chong; Shen, Lifeng; Wang, Chunhua; Ye, Zhibin; Liu, Dong; Xiang, Zhen
2016-04-18
A method for beam quality management is presented in a master oscillator power amplifier (MOPA) using Nd:YVO4 as the gain medium by extra-cavity periodic reproduction of wavefront aberrations. The wavefront aberration evolution of the intra-cavity beams is investigated for both symmetrical and asymmetrical resonators. The wavefront aberration reproduction process is successfully realized outside the cavity in four-stage amplifiers. In the MOPA with a symmetrical oscillator, the laser power increases linearly and the beam quality hardly changes. In the MOPA with an asymmetrical oscillator, the beam quality is deteriorated after the odd-stage amplifier and is improved after the even-stage amplifier. The wavefront aberration reproduction during the extra-cavity beam propagation in the amplifiers is equivalent to that during the intra-cavity propagation. This solution helps to achieve the effective beam quality management in laser amplifier chains.
HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS
International Nuclear Information System (INIS)
Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department
High temperature charge amplifier for geothermal applications
Lindblom, Scott C.; Maldonado, Frank J.; Henfling, Joseph A.
2015-12-08
An amplifier circuit in a multi-chip module includes a charge to voltage converter circuit, a voltage amplifier a low pass filter and a voltage to current converter. The charge to voltage converter receives a signal representing an electrical charge and generates a voltage signal proportional to the input signal. The voltage amplifier receives the voltage signal from the charge to voltage converter, then amplifies the voltage signal by the gain factor to output an amplified voltage signal. The lowpass filter passes low frequency components of the amplified voltage signal and attenuates frequency components greater than a cutoff frequency. The voltage to current converter receives the output signal of the lowpass filter and converts the output signal to a current output signal; wherein an amplifier circuit output is selectable between the output signal of the lowpass filter and the current output signal.
Audio power amplifier design handbook
Self, Douglas
2013-01-01
This book is essential for audio power amplifier designers and engineers for one simple reason...it enables you as a professional to develop reliable, high-performance circuits. The Author Douglas Self covers the major issues of distortion and linearity, power supplies, overload, DC-protection and reactive loading. He also tackles unusual forms of compensation and distortion produced by capacitors and fuses. This completely updated fifth edition includes four NEW chapters including one on The XD Principle, invented by the author, and used by Cambridge Audio. Cro
Cathode-follower power amplifier
International Nuclear Information System (INIS)
In circular accelerators and particularly in storage rings it is essential that the total impedance, as seen by the beam, be kept below some critical value. A model of the accelerating system was built using a single-ended cathode-follower amplifier driving a ferrite-loaded cavity. The system operated at 234.5 kHz with a peak output voltage of +-10 kV on the gap. The dynamic output impedance, as measured on the gap, was < 15 ohms
Forward model nonlinearity versus inverse model nonlinearity
Mehl, S.
2007-01-01
The issue of concern is the impact of forward model nonlinearity on the nonlinearity of the inverse model. The question posed is, "Does increased nonlinearity in the head solution (forward model) always result in increased nonlinearity in the inverse solution (estimation of hydraulic conductivity)?" It is shown that the two nonlinearities are separate, and it is not universally true that increased forward model nonlinearity increases inverse model nonlinearity. ?? 2007 National Ground Water Association.
2006-01-01
6 August 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a chain of clustered and battered craters. These were formed by secondary impact. That is, somewhere to the south (beyond the bottom of this image), a large impact crater formed. When this occurred, material ejected from the crater was thrown tens to hundreds of kilometers away. This material then impacted the martian surface, forming clusters and chains of smaller craters. Location near: 15.8oN, 35.6oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Northern Spring
Yousefi, Mehdi; Khosravi-Eghbal, Roya; Hemmati, Azam; Shokri, Fazel
2013-01-01
Background Light chain (LC) and heavy chain carboxyterminal subdomain (HCC) fragments are the most important parts of tetanus neurotoxin (TeNT) which play key roles in toxicity and binding of TeNT, respectively. In the present study, these two fragments were cloned and expressed in a prokaryotic system and their identity was confirmed using anti-TeNT specific polyclonal and monoclonal antibodies. Methods LC and HCC gene segments were amplified from Clostridium tetani genomic DNA by PCR, clone...
Transverse pumped laser amplifier architecture
Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary
2013-07-09
An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.
Locoregional MYCN-amplified neuroblastoma.
Morales La Madrid, Andres; Volchenboum, Samuel; Gastier-Foster, Julie M; Pyatt, Robert; Liu, Don; Pytel, Peter; Lavarino, Cinzia; Rodriguez, Eva; Cohn, Susan L
2012-10-01
MYCN-amplification is strongly associated with other high-risk prognostic factors and poor outcome in neuroblastoma. Infrequently, amplification of MYCN has been identified in localized tumors with favorable biologic features. Outcome for these children is difficult to predict and optimal treatment strategies remain unclear. We report a 5-month-old who presented with an MYCN-amplified INSS stage 3, pelvic neuroblastoma. The tumor had favorable histology, hyperdiploidy, and lacked 1p36 and 11q23 aberrations. Although the patient met the criteria for high-risk neuroblastoma, because of the discordant prognostic markers we elected to treat her according to an intermediate-risk protocol. She remains event-free more than 18 months.
Linearisation of RF Power Amplifiers
DEFF Research Database (Denmark)
Nielsen, Per Asbeck
2001-01-01
This thesis deals with linearisation techniques of RF power amplifiers (PA), PA design techniques and integration of the necessary building blocks in a CMOS technology. The opening chapters introduces the theory of transmitter architectures, RF-signal representation and the principles of digital...... of linearisation systems with focus on polar modulation feedback, and a chip oriented part focusing on integrating of separate building blocks of the system on a chip. The system oriented part of this thesis deals with analog feedback linearisation systems. The Polar modulation feedback system is compared...... that utilize properties of the polar loop are presented. Analysis of the envelope feedback loop shows some fundamental limitations of the loop gain and the loop bandwidth due to the varying PA gain. Based on these observation a set of design guidelines for an envelope feedback loop is given. The guidelines...
Optical latches using optical amplifiers
Li, Wenbo; Hu, Hongyu; Dutta, Niloy K.
2013-05-01
Optical latches are important for a wide range of applications including communication systems, optical logic systems, optical random access memory (RAM) and encryption. All optical logic operations using quantum dot (QD) based semiconductor optical amplifier (SOA) and Mach-Zehnder interferometer (MZI) have been studied. The building block of an optical latch such as NAND gate has been fabricated and their operation experimentally demonstrated at ~ 80 GHz. A rate equation model has been developed for the QD-SOA-MZI and it has been used to analyze the Boolean logic operation. The model has been used to analyze the Set-Reset (S-R) latch and the D-Flip-Flop (DFF) devices. The DFF is the basic device for building larger logic circuits. The results show that the latches would work to speeds of ~ 250 Gb/s.
An Implantable CMOS Amplifier for Nerve Signals
DEFF Research Database (Denmark)
Nielsen, Jannik Hammel; Lehmann, Torsten
2001-01-01
on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard digital 0.5 μm CMOS single poly, n-well process. The prototype amplifier features a gain of 80 dB over a 3.6 kHz bandwidth, a CMRR of more than 87 dB and a PSRR...
Enhanced Gain in Photonic Crystal Amplifiers
DEFF Research Database (Denmark)
Ek, Sara; Semenova, Elizaveta; Hansen, Per Lunnemann;
2012-01-01
study of a 1 QW photonic crystal amplifier. Net gain is achieved which enables laser oscillation in photonic crystal micro cavities. The ability to freely tailor the dispersion in a semiconductor optical amplifier makes it possible to raise the optical gain considerably over a certain bandwidth. These...... results are promising for short and efficient semiconductor optical amplifiers. This effect will also benefit other devices, such as mode locked lasers....
A CONCEPTUAL FRAMEWORK FOR SUSTAINABLE POULTRY SUPPLY CHAIN MODEL
Mohammad SHAMSUDDOHA; Alexandru NEDELEA
2013-01-01
Now a day, sustainable supply chain is the crucially considerable matter for future focused industries. As a result, attention in supply chain management has increasingly amplified since the 1980s when firms discovered its benefits of mutual relationships within and beyond their own organization. This is why, concern researchers are trying hard to develop new theory or model which might help the corporate sector for achieving sustainability in their supply chains. This kind of reflection can ...
Lee, Chien-er
2004-01-01
By means of the idea of measurements on the crossed space-time nonlocal observables, we extend the mechanism for the two-way quantum teleportation to the chain teleportation among N spatially separated spin-1/2 systems. Since in the process only the local interactions are used, the microcausality is automatically satisfied.
Non-linearity in Johnson noise thermometry
White, D. R.
2012-12-01
This paper discusses the effects of non-linearity, some of the mechanisms responsible for non-linearity, and methods for measuring non-linearity in Johnson noise thermometry. Mechanisms considered include quantum tunnelling, bipolar junction transistor and junction field-effect transistor amplifiers, feedback, clipping, output-stage crossover, quantization and dither. It is found that even- and odd-order effects behave differently in correlator-based noise thermometers, with the dominant even-order effects contributing as intermodulation products whereas the dominant odd-order contributions are third-order and at the same frequencies as the parent signals. Possible test methods include the use of discrete tones, changes in spectral shape, and direct measurement using reference noise powers. For correlators operated at constant noise power, direct measurement of non-linearity using reference noise powers enables corrections to be made with negligible additional uncertainty and measurement time.
Nonlinear modeling of MEMS piezoelectric energy harvesters
Wang, Y. C.; Huang, T. W.; Shu, Y. C.; Lin, S. C.; Wu, W. J.
2016-04-01
This article presents the modeling of nonlinear response of micro piezoelectric energy harvesters under amplified base excitation. The micro transducer is a composite cantilever beam made of the PZT thick film deposited on the stainless-steel substrate. The model is developed based on the Euler-Bernoulli beam theory considering geometric and inertia nonlinearities, and the reduced formulation is derived based on the Hamiltonian variational principle. The harmonic balance method is used to simulate the nonlinear frequency response under various magnitudes of excitation and electric loads. The hardening type of nonlinearity is predicted and is found to be in good agreement with experiment. However, the softening response is also observed in different samples fabricated under different conditions. Such disagreement is under investigation.
Reflection amplifiers in self-regulated learning
Verpoorten, Dominique
2012-01-01
Verpoorten, D. (2012). Reflection amplifiers in self-regulated learning. Doctoral thesis. November, 9, 2012, Heerlen, The Netherlands: Open Universiteit (CELSTEC). Datawyse / Universitaire Pers Maastricht.
Design of an 1800nm Raman amplifier
DEFF Research Database (Denmark)
Svane, Ask Sebastian; Rottwitt, Karsten
2013-01-01
We present the experimental results for a Raman amplifier that operates at 1810 nm and is pumped by a Raman fiber laser at 1680 nm. Both the pump laser and the Raman amplifier is polarization maintaining. A challenge when scaling Raman amplifiers to longer wavelengths is the increase...... performance of the amplifier is also investigated for both configurations. Our results show an on/off gain exceeding 20 dB at 1810 nm for which the obtained effective noise figure is below 3 dB....
Dynamics of Soliton Cascades in Fiber Amplifiers
Arteaga-Sierra, F R; Agrawal, Govind P
2016-01-01
We study numerically the formation of cascading solitons when femtosecond optical pulses are launched into a fiber amplifier with less energy than required to form a soliton of equal duration. As the pulse is amplified, cascaded fundamental solitons are created at different distances, without soliton fission, as each fundamental soliton moves outside the gain bandwidth through the Raman-induced spectral shifts. As a result, each input pulse creates multiple, temporally separated, ultrashort pulses of different wavelengths at the amplifier output. The number of pulses depends not only on the total gain of the amplifier but also on the width of input pulses.
Measurements and simulations of non-linear noise re-distribution in an SOA
DEFF Research Database (Denmark)
Öhman, Filip; Tromborg, Bjarne; Mørk, Jesper;
2004-01-01
Measurements and statistical simulations demonstrate that a semiconductor optical amplifier (SOA) induces non-linear noise re-distribution with a strong power and bandwidth dependence. © 2004 Optical Society of America......Measurements and statistical simulations demonstrate that a semiconductor optical amplifier (SOA) induces non-linear noise re-distribution with a strong power and bandwidth dependence. © 2004 Optical Society of America...
Nonlinear interactions between gravity waves and tides
Institute of Scientific and Technical Information of China (English)
LIU Xiao; XU JiYao; MA RuiPing
2007-01-01
In this study, we present the nonlinear interactions between gravity waves (GWs) and tides by using the 2D numerical model for the nonlinear propagation of GWs in the compressible atmosphere. During the propagation in the tidal background, GWs become instable in three regions, that is z = 75-85 km, z =90-110 km and z= 115-130 km. The vertical wavelength firstly varies gradually from the initial 12 km to 27 km. Then the newly generated longer waves are gradually compressed. The longer and shorter waves occur in the regions where GWs propagate in the reverse and the same direction of the horizontal mean wind respectively. In addition, GWs can propagate above the main breaking region (90-110 km). During GWs propagation, not only the mean wind is accelerated, but also the amplitude of tide is amplified. Especially, after GWs become instable, this amplified effect to the tidal amplitude is much obvious.
Nonlinear interactions between gravity waves and tides
Institute of Scientific and Technical Information of China (English)
2007-01-01
In this study, we present the nonlinear interactions between gravity waves (GWs) and tides by using the 2D numerical model for the nonlinear propagation of GWs in the compressible atmosphere. During the propagation in the tidal background, GWs become instable in three regions, that is z = 75―85 km, z = 90―110 km and z = 115―130 km. The vertical wavelength firstly varies gradually from the initial 12 km to 27 km. Then the newly generated longer waves are gradually compressed. The longer and shorter waves occur in the regions where GWs propagate in the reverse and the same direction of the hori-zontal mean wind respectively. In addition, GWs can propagate above the main breaking region (90—110 km). During GWs propagation, not only the mean wind is accelerated, but also the amplitude of tide is amplified. Especially, after GWs become instable, this amplified effect to the tidal amplitude is much obvious.
Distributed feedback laser amplifiers combining the functions of amplifiers and channel filters
DEFF Research Database (Denmark)
Wang, Z.; Durhuus, T.; Mikkelsen, Benny;
1994-01-01
A dynamic model for distributed feedback amplifiers, including the mode coupled equations and the carrier rate equation, is established. The presented mode coupled equations have taken into account the interaction between fast changing optical signal and the waveguide with corrugations. By showin...... the possibility of amplifying 100 ps pulses without pulse broadening, we anticipate that a distributed feedback amplifier can be used as a combined amplifier and channel filter in high bit rate transmission systems....
Amplified spontaneous emission and its restraint in a terawatt Ti:sapphire amplifier
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
Amplified spontaneous emission (ASE) and its restraint in a femtosecond Ti: sapphire chirped_pulse amplifier were investigated. The noises arising from ASE were effectively filtered out in the spatial, temporal and spectral domain. Pulses as short as 38 fs were amplified to peak power of 1.4 TW. The power ratio between the amplified femtosecond pulse and the ASE was higher than 106:1.
Kilowatt high-efficiency narrow-linewidth monolithic fiber amplifier operating at 1034 nm
Naderi, Nader A.; Flores, Angel; Anderson, Brian M.; Rowland, Ken; Dajani, Iyad
2016-03-01
Power scaling investigation of a narrow-linewidth, Ytterbium-doped all-fiber amplifier operating at 1034 nm is presented. Nonlinear stimulated Brillouin scattering (SBS) effects were suppressed through the utilization of an external phase modulation technique. Here, the power amplifier was seeded with a spectrally broadened master oscillator and the results were compared using both pseudo-random bit sequence (PRBS) and white noise source (WNS) phase modulation formats. By utilizing an optical band pass filter as well as optimizing the length of fiber used in the pre-amplifier stages, we were able to appreciably suppress unwanted amplified spontaneous emission (ASE). Notably, through PRBS phase modulation, greater than two-fold enhancement in threshold power was achieved when compared to the WNS modulated case. Consequently, by further optimizing both the power amplifier length and PRBS pattern at a clock rate of 3.5 GHz, we demonstrated 1 kilowatt of power with a slope efficiency of 81% and an overall ASE content of less than 1%. Beam quality measurements at 1 kilowatt provided near diffraction-limited operation (M2 knowledge, the power scaling results achieved in this work represent the highest power reported for a spectrally narrow all-fiber amplifier operating at < 1040 nm in Yb-doped silica-based fiber.
Investigations on high power solid state RF and microwave amplifiers for superconducting structures
International Nuclear Information System (INIS)
The radio frequency (RF) and microwave power amplifiers are key systems for many strategic applications. In recent years, the cutting-edge technology of solid-state RF amplifier has outshined as compared to vacuum tube counterparts, due to its numerous advantages offered for particle accelerator's systems. Major constituent blocks of a typical high power solid-state RF amplifier are power amplifier modules, power combiners, dividers and directional couplers. In this thesis, investigations of newer and improved design techniques and topologies, suitable for high power and efficient operation of these blocks, followed by their experimental verification has been carried out. Most of the reported designs for the solid-state amplifier aims for low-power output. At high RF power (> 500 W), such designs and the desired wave-shaping, governed by operating class, of the transistor's terminal voltage do not meet the calculated requisites. The calculated optimum values of the terminal voltage/current often exceed the maximum voltage rating of the transistor. Hence, newer methodology using continuous harmonic-tuned design-space, with the inclusion of the nonlinear output (drain) capacitor of the LDMOS transistor, solves this problem. In this thesis, the traditional and newer continuous harmonic tuned operating modes for amplifier modules, at high power, were suitably investigated
Talbert, Robert
2010-01-01
Catch Chain is a book of poems that traces the journey of a Corrections Officer who attempts to combat issues of isolation, inhumane treatment of inmates and societal rejection in jails by embarking upon a cross-country road trip. However, the same issues the officer initially wrestled with begin cropping up in different cities, on various highways and in a multitude of states. The excitement and adventure of the open road runs parallel to the recurring imprisonment of the guard's mind.
An Implantable CMOS Amplifier for Nerve Signals
DEFF Research Database (Denmark)
Nielsen, Jannik Hammel; Lehmann, Torsten
2003-01-01
. A continuous-time current-steering offset-compensation technique is utilized in order to minimize the noise contribution and to minimize dynamic impact on the amplifier input nodes. The method for signal recovery from noisy nerve signals is presented. A prototype amplifier is realized in a standard digital 0...
Self-pulsation in Raman fiber amplifiers
DEFF Research Database (Denmark)
Pedersen, Martin Erland Vestergaard; Ott, Johan Raunkjær; Rottwitt, Karsten
2009-01-01
Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated.......Dynamic behavior caused by Brillouin scattering in Raman fiber amplifiers is studied. Modes of self-pulsation steady state oscillations are found. Their dependence on amplification scheme is demonstrated....
Waveguide optical amplifier for telecom applications
Taccheo, Stefano; Zannin, Marcelo; Ennser, Karin; Careglio, Davide; Solé Pareta, Josep; Aracil Rico, Javier
2009-01-01
In this paper we review progress in optical gain clamped waveguide amplifiers for applications to optical communications. We demonstrate that compact waveguide devices may offer advantages compared to standard fiber amplifiers. In particular we focus on the application of gain clamping and optical burst switching networks where physical impairments may occur due to variation of the input power. Peer Reviewed
BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER
DEFF Research Database (Denmark)
2010-01-01
Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted...
Design and performance of the beamlet amplifiers
Energy Technology Data Exchange (ETDEWEB)
Erlandson, A.C.; Rotter, M.D.; Frank, M.D.; McCracken, R.W.
1996-06-01
In future laser systems, such as the National Ignition Facility (NIF), multi-segment amplifiers (MSAs) will be used to amplify the laser beam to the required levels. As a prototype of such a laser architecture, the authors have designed, built, and tested flash-lamp-pumped, Nd:Glass, Brewster-angle slab MSAs for the Beamlet project. In this article, they review the fundamentals of Nd:Glass amplifiers, describe the MSA geometry, discuss parameters that are important in amplifier design, and present our results on the characterization of the Beamlet MSAs. In particular, gain and beam steering measurements show that the Beamlet amplifiers meet all optical performance specifications and perform close to model predictions.
Qubit readout with a directional parametric amplifier
Sliwa, K. M.; Abdo, B.; Narla, A.; Shankar, S.; Hatridge, M.; Frunzio, L.; Schoelkopf, R. J.; Devoret, M. H.
2014-03-01
Josephson junction based quantum limited parametric amplifiers play an essential role in superconducting qubit measurements. These measurements necessitate circulators and isolators between the amplifier and qubit to add directionality and/or isolation. Unfortunately, this extra hardware limits both quantum measurement efficiency and experimental scalability. Here we present a quantum-limited Josephson-junction-based directional amplifier (JDA) based on a novel coupling between two nominally identical Josephson parametric converters (JPCs). The device achieves a forward gain of 11 dB with a 15 MHz dynamical bandwidth, but higher gains are possible at the expense of bandwidth. We also present measurements of a transmon qubit made with the JDA, and show minimal measurement back-action despite the absence of any isolator or circulator before the amplifier. These results provide a first step toward realizing on-chip integration of qubits and parametric amplifiers. Work supported by: IARPA, ARO, and NSF.
Detection of Non-Amplified Genomic DNA
Corradini, Roberto
2012-01-01
This book offers a state-of-the-art overview on non amplified DNA detection methods and provides chemists, biochemists, biotechnologists and material scientists with an introduction to these methods. In fact all these fields have dedicated resources to the problem of nucleic acid detection, each contributing with their own specific methods and concepts. This book will explain the basic principles of the different non amplified DNA detection methods available, highlighting their respective advantages and limitations. The importance of non-amplified DNA sequencing technologies will be also discussed. Non-amplified DNA detection can be achieved by adopting different techniques. Such techniques have allowed the commercialization of innovative platforms for DNA detection that are expected to break into the DNA diagnostics market. The enhanced sensitivity required for the detection of non amplified genomic DNA has prompted new strategies that can achieve ultrasensitivity by combining specific materials with specifi...
Ultrafast disk lasers and amplifiers
Sutter, Dirk H.; Kleinbauer, Jochen; Bauer, Dominik; Wolf, Martin; Tan, Chuong; Gebs, Raphael; Budnicki, Aleksander; Wagenblast, Philipp; Weiler, Sascha
2012-03-01
Disk lasers with multi-kW continuous wave (CW) output power are widely used in manufacturing, primarily for cutting and welding applications, notably in the automotive industry. The ytterbium disk technology combines high power (average and/or peak power), excellent beam quality, high efficiency, and high reliability with low investment and operating costs. Fundamental mode picosecond disk lasers are well established in micro machining at high throughput and perfect precision. Following the world's first market introduction of industrial grade 50 W picosecond lasers (TruMicro 5050) at the Photonics West 2008, the second generation of the TruMicro series 5000 now provides twice the average power (100 W at 1030 nm, or 60 W frequency doubled, green output) at a significantly reduced footprint. Mode-locked disk oscillators achieve by far the highest average power of any unamplified lasers, significantly exceeding the 100 W level in laboratory set-ups. With robust long resonators their multi-microjoule pulse energies begin to compete with typical ultrafast amplifiers. In addition, significant interest in disk technology has recently come from the extreme light laser community, aiming for ultra-high peak powers of petawatts and beyond.
Locally Controlled Deeply Saturated Fiber Optic Parametric Amplifiers
Nissim, Ron Reuven
A new class of highly efficient Optical Parametric Amplifiers (OPA) is explored in this dissertation, which have the potential to reduce the power requirement on the pump and enable new functionalities. This originates from the simple notion that figure of merit (FoM) of an OPA is proportional to the product of the pump power and amplifier's length and nonlinearity. Silica fibers have been developed for over five decades and offer unparalleled transparency. By merely extending the fiber, i.e. the amplifier's length, a high FoM amplifier can be formed while keeping the pump at a moderate, sub-Watt power level. Unfortunately, optical fibers are inherently non-uniform. Their core size fluctuates along the fiber on a nanometer scale which is on the order of the fiber's molecular constituents. It is currently established that the performance of a fiber-based OPA (FOPA) is dictated by its stochastic nature. In fact, given a moderate pump power level, the highly efficient OPA will be required to maintain a strict phase matching condition across hundreds of meters. Facing this challenge, this dissertation focuses on a locally-controlled, high FoM FOPA. A high FoM FOPA operates in the deeply saturated regime in which a weak signal saturates the amplifier and depletes the pump power, effectively generating an inverse response of the pump output power to the signal input power. Given FOPAs' inhomogeneous nature, the performance limit of deeply saturated FOPAs is studied. So far, FOPAs have been commonly treated as a uniform entity; however, this study discovers unique features of the system which originate from and are strongly influenced by the fiber's inhomogeneous nature. One major example is the non-reciprocal response of deeply saturated FOPAs. It was found that deeply saturated FOPAs perform very highly, as the pump can respond to a rapidly varying (sub-THz) weak (sub-muW) signal. This is a novel method which obtained orders of magnitude improvement over current
Dawson, Jay W; Messerly, Michael J; Beach, Raymond J; Shverdin, Miroslav Y; Stappaerts, Eddy A; Sridharan, Arun K; Pax, Paul H; Heebner, John E; Siders, Craig W; Barty, C P J
2008-08-18
We analyze the scalability of diffraction-limited fiber lasers considering thermal, non-linear, damage and pump coupling limits as well as fiber mode field diameter (MFD) restrictions. We derive new general relationships based upon practical considerations. Our analysis shows that if the fiber's MFD could be increased arbitrarily, 36 kW of power could be obtained with diffraction-limited quality from a fiber laser or amplifier. This power limit is determined by thermal and non-linear limits that combine to prevent further power scaling, irrespective of increases in mode size. However, limits to the scaling of the MFD may restrict fiber lasers to lower output powers. PMID:18711562
Directory of Open Access Journals (Sweden)
Sergio Ruíz-Hernández
2015-01-01
Full Text Available This paper addresses an adaptive control approach for synchronizing two chaotic oscillators with saturated nonlinear function series as nonlinear functions. Mathematical models to characterize the behavior of the transmitter and receiver circuit were derived, including in the latter the adaptive control and taking into account, for both chaotic oscillators, the most influential performance parameters associated with operational amplifiers. Asymptotic stability of the full synchronization system is studied by using Lyapunov direct method. Theoretical derivations and related results are experimentally validated through implementations from commercially available devices. Finally, the full synchronization system can easily be reproducible at a low cost.
Marini, A; Roy, S; Longhi, S; Biancalana, F
2013-01-01
We study analytically and numerically an optical analogue of tachyon condensation in amplifying plasmonic arrays. Optical propagation is modeled through coupled-mode equations, which in the continuous limit can be converted into a nonlinear one-dimensional Dirac-like equation for fermionic particles with imaginary mass, i.e. fermionic tachyons. We demonstrate that the vacuum state is unstable and acquires an expectation value with broken chiral symmetry, corresponding to the homogeneous nonlinear stationary solution of the system. The quantum field theory analogue of this process is the condensation of unstable fermionic tachyons into massive particles. This paves the way for using amplifying plasmonic arrays as a classical laboratory for spontaneous symmetry breaking effects in quantum field theory.
Simulation of planar FEL-amplifier with tape relativistic electron beam
Ginzburg, N S; Peskov, N Yu; Arzhannikov, A V; Sinitskij, S L
2001-01-01
The simulation of the planar microwave (4 mm) amplifier on the basis of the powerful laser on free electrons (FEL- amplifier) is carried out. The tape relativistic electron beam with the energy up to 1 MeV and operating current up to 2 kA is formed by the Y-3 accelerators. The complete nonaveraging system of the self-consistent equations describing the process of interaction of the particles, moving in the plane ondulator field is obtained. Thereafter the averaging of the above-mentioned equations was carried out and the linear and nonlinear stages of the amplification process were studied. The additional simulation of the FEL-amplifier is carried out on the basis of the two-dimensional version of the KARAT PIC-code. It is shown that the applied approaches give sufficiently close results
Static thermo-optic instability in double-pass fiber amplifiers
DEFF Research Database (Denmark)
Lægsgaard, Jesper
2016-01-01
A coupled-mode formalism, earlier used to describe transverse mode instabilities in single-pass optical fiber amplifiers, is extended to the case of double-pass amplifiers. Contrary to the single-pass case, it is shown that the thermo-optic nonlinearity can couple light at the same frequency...... between the LP01 and LP11 modes, leading to a static deformation of the output beam profile. This novel phenomenon is caused by the interaction of light propagating in either direction with thermo-optic index perturbations caused by light propagating in the opposite direction. The threshold power...... for the static deformation is found to be several times lower than what is typically found for the dynamic modal instabilities observed in single-pass amplifiers. (C) 2016 Optical Society of America...
Andersen, T V; Schmidt, O; Bruchmann, C; Limpert, J; Aguergaray, C; Cormier, E; Tünnermann, A
2006-05-29
We report on the generation of high energy femtosecond pulses at 1 MHz repetition rate from a fiber laser pumped optical parametric amplifier (OPA). Nonlinear bandwidth enhancement in fibers provides the intrinsically synchronized signal for the parametric amplifier. We demonstrate large tunability extending from 700 nm to 1500 nm of femtosecond pulses with pulse energies as high as 1.2 muJ when the OPA is seeded by a supercontinuum generated in a photonic crystal fiber. Broadband amplification over more than 85 nm is achieved at a fixed wavelength. Subsequent compression in a prism sequence resulted in 46 fs pulses. With an average power of 0.5 W these pulses have a peak-power above 10 MW. In particular, the average power and pulse energy scalability of both involved concepts, the fiber laser and the parametric amplifier, will enable easy up-scaling to higher powers.
CALCULATION OF CONFORMATIONAL ENTROPY AND FREE ENERGY OF POLYSILANE CHAIN
Institute of Scientific and Technical Information of China (English)
Meng-bo Luo; Ying-cai Chen; Jian-hua Huang; Jian-min Xu
2001-01-01
The conformational entropy S and free energy F were calculated by exact enumeration of polysilane chain up to 23 segments with excluded volume (EV) and long-range van der Waals (VW) interaction. A nonlinear relation between SEV+VW and chain length n was found though SEV was found to vary linearly with n. We found that the second-order transition temperature of polysilane chain with VW interaction increases with the increase of chain length, while that of polysilane chain without VW interaction is chain length independent. Moreover, the free energies FEV+VW and FEV are both linearly related with n, and FEV+VW＜FEV for all temperatures.``
Mechanically Amplified Piezoelectric Tunable 3D Microwave Superconducting Cavity
Carvalho, N C; Tobar, M E
2016-01-01
In the context of hybrid quantum systems, there is a demand for superconducting tunable devices able to operate in the single-photon regime. In this work, we developed a 3D microwave reentrant cavity with such characteristics ready to provide a very fine-tuning of a high-Q resonant mode over a large dynamic range. This system has an electronic tuning mechanism based on a mechanically amplified piezoelectric actuator, which can set the cavity resonance with a large dynamic range of order 1 GHz at 10 mK. At elevated microwave power, nonlinear thermal e effects were observed to destroy the superconductivity of the cavity due to the large electric fields generated in the small gap of the reentrant cavity.
Application of Taguchi's method to optimize fiber Raman amplifier
Zaman, Mohammad Asif
2016-04-01
Taguchi's method is introduced to perform multiobjective optimization of fiber Raman amplifier (FRA). The optimization requirements are to maximize gain and keep gain ripple minimum over the operating bandwidth of a wavelength division multiplexed (WDM) communication link. Mathematical formulations of FRA and corresponding numerical solution techniques are discussed. A general description of Taguchi's method and how it can be integrated with the FRA optimization problem are presented. The proposed method is used to optimize two different configurations of FRA. The performance of Taguchi's method is compared with genetic algorithm and particle swarm optimization in terms of output performance and convergence rate. Taguchi's method is found to produce good results with fast convergence rate, which makes it well suited for the nonlinear optimization problems.
Stimulated Raman Effect in Bi—driectionally Amplified and Transmission WDM Systems
Institute of Scientific and Technical Information of China (English)
KanZHANG; AnshiXU
1997-01-01
One of the nonlinear effect-SRS effect in bi-directional WDM transmission systems is studied in this paper,Analytical and numerical results are given to show the effect of SRS.Systems with uni-and bi-directional EDFAs(Erbium doped fiber amplifiers0 are also considered.And a new method to deal with SRS effect in bi-directional systems is drawn out.
An analytical study on bistability of Fabry-Perot semiconductor optical amplifiers
Wang, Gang; Chen, Shuqiang; Yang, Huajun
2016-09-01
Optical bistabilities have been considered to be useful for sensor applications. As a typical nonlinear device, Fabry-Perot semiconductor optical amplifiers (FPSOAs) exhibit bistability under certain conditions. In this paper, the bistable characteristics in FPSOAs are investigated theoretically. Based on Adams's relationship between the incident optical intensity I in and the z-independent average intracavity intensity I av, an analytical expression of the bistable loop width in SOAs is derived. Numerical simulations confirm the accuracy of the analytical result.
Institute of Scientific and Technical Information of China (English)
Pasu; Kaewplung; Tuptim; Angkaew
2003-01-01
We realized a 200-Gbit/s 10,000-km data transmission by employing distributed Raman amplifiers to construct reverse power distribution in the second half of midway optical phase conjugation transmission system in order to compensate nonlinear waveform distortion.
Quantum electronics maser amplifiers and oscillators
Fain, V M; Sanders, J H
2013-01-01
Quantum Electronics, Volume 2: Maser Amplifiers and Oscillators deals with the experimental and theoretical aspects of maser amplifiers and oscillators which are based on the principles of quantum electronics. It shows how the concepts and equations used in quantum electronics follow from the basic principles of theoretical physics.Comprised of three chapters, this volume begins with a discussion on the elements of the theory of quantum oscillators and amplifiers working in the microwave region, along with the practical achievements in this field. Attention is paid to two-level paramagnetic ma
Laser Cooled High-Power Fiber Amplifier
Nemova, Galina
2009-01-01
A theoretical model for laser cooled continuous-wave fiber amplifier is presented. The amplification process takes place in the Tm3+-doped core of the fluoride ZBLAN (ZrF4-BaF2-LaF3-AlF3-NaF) glass fiber. The cooling process takes place in the Yb3+:ZBLAN fiber cladding. It is shown that for each value of the pump power and the amplified signal there is a distribution of the concentration of the Tm3+ along the length of the fiber amplifier, which provides its athermal operation. The influence ...
Fundamentals of RF and microwave transistor amplifiers
Bahl, Inder J
2009-01-01
A Comprehensive and Up-to-Date Treatment of RF and Microwave Transistor Amplifiers This book provides state-of-the-art coverage of RF and microwave transistor amplifiers, including low-noise, narrowband, broadband, linear, high-power, high-efficiency, and high-voltage. Topics covered include modeling, analysis, design, packaging, and thermal and fabrication considerations. Through a unique integration of theory and practice, readers will learn to solve amplifier-related design problems ranging from matching networks to biasing and stability. More than 240 problems are included to help read
Testing methodologies and systems for semiconductor optical amplifiers
Wieckowski, Michael
Semiconductor optical amplifiers (SOA's) are gaining increased prominence in both optical communication systems and high-speed optical processing systems, due primarily to their unique nonlinear characteristics. This in turn, has raised questions regarding their lifetime performance reliability and has generated a demand for effective testing techniques. This is especially critical for industries utilizing SOA's as components for system-in-package products. It is important to note that very little research to date has been conducted in this area, even though production volume and market demand has continued to increase. In this thesis, the reliability of dilute-mode InP semiconductor optical amplifiers is studied experimentally and theoretically. The aging characteristics of the production level devices are demonstrated and the necessary techniques to accurately characterize them are presented. In addition, this work proposes a new methodology for characterizing the optical performance of these devices using measurements in the electrical domain. It is shown that optical performance degradation, specifically with respect to gain, can be directly qualified through measurements of electrical subthreshold differential resistance. This metric exhibits a linear proportionality to the defect concentration in the active region, and as such, can be used for prescreening devices before employing traditional optical testing methods. A complete theoretical analysis is developed in this work to explain this relationship based upon the device's current-voltage curve and its associated leakage and recombination currents. These results are then extended to realize new techniques for testing semiconductor optical amplifiers and other similarly structured devices. These techniques can be employed after fabrication and during packaged operation through the use of a proposed stand-alone testing system, or using a proposed integrated CMOS self-testing circuit. Both methods are capable
A CHI wiggler ubitron amplifier experiment: Wiggler characterization
Energy Technology Data Exchange (ETDEWEB)
Taccetti, J.M.; Jackson, R.H.; Freund, H.P. [Naval Research Lab., Washington, DC (United States)] [and others
1995-12-31
A 35 GHz CHI (Coaxial Hybrid Iron) wiggler ubitron amplifier experiment is under construction at the Naval Research Laboratory. The CHI wiggler configuration has the potential of generating high wiggler magnetic fields at short periods with excellent beam focusing and transport properties. This makes it a desirable configuration for the generation of high power coherent radiation in relatively compact systems. The CHI wiggler consists of alternating rings of magnetic and non-magnetic materials concentric with a central rod of similar alternating design but shifted along the axis by half a period. Once inserted in a solenoidal magnetic field, the CHI structure deforms the axial field to create a radial field oscillating with the same periodicity as the rings. An annular electron beam is propagated through the coaxial gap where the oscillating radial field imparts an azimuthal wiggle motion. The principal goals of the experiment are to investigate the performance tradeoffs involved in the CHI configuration for high frequency amplifiers operating at low voltages with small wiggler periods. The nominal design parameters are a center frequency of 35 GHz, wiggler period of 0.75 cm, and beam voltage of approximately 150 kV. Calculations have shown an intrinsic (untapered) efficiency of {approximately} 7% when operating at 6.3 kG axial field (wiggler field, B{sub w}{approximately}1270 G). The calculated gain was 36 dB, saturating at a distance of 46 cm. These parameters yield an instantaneous amplifier bandwidth of {approximately} 25%. There appears to be room for further improvement in efficiency, a matter which will be scrutinized more closely in the final design. A prototype CHI wiggler is presently being fabricated for use in conjunction with an existing 30 kG superconducting solenoid. The performance properties of the prototype will be characterized and compared with linear and non-linear calculations.
Mismatch Calibration in LINC Power Amplifiers Using Modified Gradient Algorithm
Directory of Open Access Journals (Sweden)
Hosein Miar-Naimi
2013-09-01
Full Text Available One of the power amplifiers linearization technique is linear amplification with nonlinear components (LINC.The effects of phase and gain imbalances between two signal branches in LINC transmitters have been analyzed in this paper. Then a feedback path has been added to compensate this mismatches, using two complex gain in each path.This complex gains are controlled in a way to calibrate any gain and phase mismatches between two path using Modified Gradient Algorithm (MGA adaptively. The main advantages of this algorithm over other algorithms are zero residual error and fast convergence time. In the proposedarchitecture power amplifiers in each path are modeled as a complex gain which its phase and amplitude depend on input signal level. Many simulations have been performed to validate the proposed self calibrating LINC transmitter. Simulation results have confirmed the analyticalpredictions. According to simulation results the proposed structure has around 40 dB/Hz improvement in the first adjacent channel of the output signal spectrum.
Dye laser chain for laser isotope separation
Doizi, Denis; Jaraudias, Jean; Pochon, E.; Salvetat, G.
1993-05-01
Uranium enrichment by laser isotope separation uses a three step operation which requires four visible wavelengths to boost an individual U235 isotope from a low lying atomic energy level to an autoionizing state. The visible wavelengths are delivered by dye lasers pumped by copper vapor lasers (CVL). In this particular talk, a single dye chain consisting of a master oscillator and amplifier stages will be described and some of its performance given.
Rajasekar, Shanmuganathan
2016-01-01
This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...
Measurements and Simulations of nonlinear noise redistribution in an SOA
DEFF Research Database (Denmark)
Öhman, Filip; Tromborg, Bjarne; Mørk, Jesper;
2005-01-01
Measurements and numerical simulations of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate nonlinear noise redistribution. The redistribution, which relies on self-modulation due to gain saturation and carrier dynamics, shows a strong power and bandwidth dependence...... and can be important for SOA-based regenerators....
Sensor/amplifier for weak light sources
Desmet, D. J.; Jason, A. J.; Parr, A. C.
1980-01-01
Light sensor/amplifier circuit detects weak light converts it into strong electrical signal in electrically noisy environment. Circuit is relatively simple and uses inexpensive, readily available components. Device is useful in such applications as fire detection and photographic processing.
High Energy Single Frequency Resonant Amplifier Project
National Aeronautics and Space Administration — This SBIR phase I project proposes a single frequency high energy resonant amplifier for remote sensing. Current state-of-art technologies can not provide all...
Multiple excitation regenerative amplifier inertial confinement system
International Nuclear Information System (INIS)
The invention relates to apparatus and methods for producing high intensity laser radiation generation which is achieved through an optical amplifier-storage ring design. One or two synchronized, counterpropagating laser pulses are injected into a regenerative amplifier cavity and amplified by gain media which are pumped repetitively by electrical or optical means. The gain media excitation pulses are tailored to efficiently amplify the laser pulses during each transit. After the laser pulses have been amplified to the desired intensity level, they are either switched out of the cavity by some switch means, as for example an electro-optical device, for any well known laser end uses, or a target means may be injected into the regenerative amplifier cavity in such a way as to intercept simultaneously the counterpropagating laser pulses. One such well known end uses to which this invention is intended is for production of high density and temperature plasmas suitable for generating neutrons, ions and x-rays and for studying matter heated by high intensity laser radiation
Proposal of Switching Power Amplifier Using Small Capacity Linear Amplifier and LC Filter
Kamada, Jo; Funato, Hirohito; Ogasawara, Satoshi
The higher efficiency and the low noise in output voltage and current has been required in some applications, i.e. audio-video equipment, medical equipment and so on. This paper proposes a power amplifier in which a PWM inverter is used as a main circuit. In the proposed power amplifier, a hybrid filter composed of a simple and general LC filter and a small capacity linear amplifier is connected to the output of the inverter. The linear amplifier is inserted in series to the filter capacitor to improve the filtering effect of the LC filter. Switching ripples and LC resonances are considerably suppressed by controlling the amplifier using the proposed method and a low distortion switching power amplifier is realized. The effects of the proposal circuit are verified by simulations and experiments. As a result, the proposed circuit achieves low noise about THD=0.68% in simulation and THD=1.7% in experiment.
Lei, Chengmin; Jin, Aijun; Song, Rui; Chen, Zilun; Hou, Jing
2016-05-01
The theoretical research of supercontinuum (SC) generation in a fiber amplifier system has been seldom reported. For the purpose of further understanding the mechanism of SC generation in fiber amplifiers, we propose a combined numerical model of the laser rate equations and the generalized non-linear Schrödinger equation to simulate the amplification of 1060 nm picosecond pulses and their spectral broadening in an ytterbium-doped fiber amplifier. The calculation results of this model are compared with the experimental results under the same conditions and a good agreement is achieved. We find that the pulse is gain amplified initially, and then dominated by stimulated Raman scattering in the normal dispersion region. In anomalous dispersion region, modulation instability, higher-order soliton fission and soliton self-frequency shift dominates the spectral broadening. It is found numerically and experimentally that the length of the gain fiber and the 976 nm pump power are the most imperative parameters to control the output power, spectral range and flatness of the SC. The pulse width of signal pulse also plays a part in influencing SC generation. The results verify that our model is promising for analyzing the physical processes of pulse evolution and SC generation in a fiber amplifier system. PMID:27137540
Femtosecond pulse generation and amplification in Yb-doped fibre oscillator–amplifier system
Indian Academy of Sciences (India)
P K Mukhopadhyay
2010-11-01
In recent times ytterbium (Yb) doped fibre-based mode-locked master oscillator and power amplifier have attracted a great deal of interest because of their inherent advantages like flexibility, reliability, compactness, high power handling capability and diffraction limited output beam quality as compared to the solid-state counterpart. But, to successfully develope of high-power femtosecond oscillator–amplifier system based on Yb- doped fibre, an appropriate choice of the mode-locking regime and the amplifier geometry are required. Development of an all-fibre integrated high-power Yb-doped fibre oscillator–amplifier system in which the advantages of a fibre-based system can be fully exploited remained a challenge as it requires the careful optimization of dispersion, nonlinearity, gain and ASE contribution. In this article, femto-second pulse generation in Yb-doped fibre oscillator in different mode-locking regimes are reviewed and the details of development and characterization of an all-fibre, high-power, low-noise amplifier system seeded by an all-normal-dispersion mode-locked Yb-doped fibre laser oscillator is described. More than 10 W of average power is obtained from the fibre oscillator–amplifier system at a repetition rate of 43 MHz with diffraction-limited beam quality. Amplified pulses are de-chirped to sub-160 fs duration in a grating compressor. This is the first 10 W-level source of femtosecond pulses with completely fibre-integrated amplification comprised of commercially available components.
VDMOS transistors for power amplifier in UHF band
Kassmi, Kamal
Modeling of power VDMOSFET transistors working in the UHF band is considered. VDMOSFET power structures suited to mobile radiotelephony power amplification are described. A nonlinear physical model suitable for all working regimes is developed. The elements of this model only depend on physical and technological data and bias voltages of the device. A reduced model compatible with SPICE (Simulation Program with Integrated Circuit Emphasis) is presented. A first comparison between measured and computed characteristics is presented under DC switching and small signal conditions. A methodology for the study and design of radio frequency power amplifiers in a nonlinear regime is described. The performance of these devices in terms of power gain, output power, efficiency, linearity and the drain bias influence as well as third order Intermodulation Distortion (IMD3) are considered. It is shown that IMD and power gain performances are controlled by DC output characteristics in the ohmic zone. Practical conclusions with respect to the intrinsic qualities and drawbacks of these products for UHF power amplification are drawn.
Mid-infrared optical parametric amplifier using silicon nanophotonic waveguides
Liu, Xiaoping; Vlasov, Yurii A; Green, William M J
2010-01-01
All-optical signal processing is envisioned as an approach to dramatically decrease power consumption and speed up performance of next-generation optical telecommunications networks. Nonlinear optical effects, such as four-wave mixing (FWM) and parametric gain, have long been explored to realize all-optical functions in glass fibers. An alternative approach is to employ nanoscale engineering of silicon waveguides to enhance the optical nonlinearities by up to five orders of magnitude, enabling integrated chip-scale all-optical signal processing. Previously, strong two-photon absorption (TPA) of the telecom-band pump has been a fundamental and unavoidable obstacle, limiting parametric gain to values on the order of a few dB. Here we demonstrate a silicon nanophotonic optical parametric amplifier exhibiting gain as large as 25.4 dB, by operating the pump in the mid-IR near one-half the band-gap energy (E~0.55eV, lambda~2200nm), at which parasitic TPA-related absorption vanishes. This gain is high enough to comp...
A tentative programme towards a full scale energy amplifier
Rubbia, Carlo
1996-01-01
We present a proposal of a full scale demonstration plant of the Energy Amplifier (EA), following the conceptual design of Ref. [1]. Unlike the presently on going CERN experiments, reaction rates will be sufficiently massive to permit demonstrating the practical feasibility of energy generation on an industrial scale and to tackle the complete family chains of [1] the breeding process in Thorium fuel, [2] the burning of the self-generated Actinides, [3] the Plutonium (higher Actinides) burning of spent fuel from ordinary Reactors and [4] Fuel reprocessing/regeneration. The accelerator must provide a beam power which is commensurate to the rate of transformations which are sought. No existing accelerator can meet such a performance and a dedicated facility must be built. We describe an alternative based on the superconducting cavities (SC) now in standard use at the LEP \\[e^+-e^-\\] collider which is scheduled to terminate its operation by year 200 After this time, with reasonable modifications, the fully opera...
An Electronically Tunable Transconductance Amplifier for Use in Auditory Prostheses
Directory of Open Access Journals (Sweden)
FARAGO, P.
2015-11-01
Full Text Available Low-voltage and low-power trends in analog electronics enable novel features in modern bio-medical devices, such as extensive portability, autonomy and even battery-less operation. One specific example is the cochlear implant (CI, which emulates the physiology of hearing to produce auditory sensations via neural stimulation. Besides low-voltage and low-power operation, a key feature in modern CIs is wide-range programmability of the speech processing parameters. This paper proposes an operational transconductance amplifier (OTA for use in CIs, with wide-range electronic tuning of the transconductance value. The proposed OTA is developed around a cascade of two transconductor stages, making the transconductance dependent on the bias current ratio. A combination of linearization techniques: bulk input, parallel differential pairs and feedback, is used to achieve sufficient linear range for CI speech processing. Wide-range parameter tuning of the speech processing sections is illustrated on a variable gain amplifier, a bandpass Tow-Thomas biquad and an envelope detector. Finally, the complete CI speech processing chain is illustrated. The proposed OTA and its employment in CI analog speech processing are validated on a 350 nm CMOS process.
Freezing of nonlinear Bloch oscillations in the generalized discrete nonlinear Schrödinger equation.
Cao, F J
2004-09-01
The dynamics in a nonlinear Schrödinger chain in a homogeneous electric field is studied. We show that discrete translational invariant integrability-breaking terms can freeze the Bloch nonlinear oscillations and introduce new faster frequencies in their dynamics. These phenomena are studied by direct numerical integration and through an adiabatic approximation. The adiabatic approximation allows a description in terms of an effective potential that greatly clarifies the phenomena.
Optimization of Signal-to-Noise-and-Distortion Ratio for Dynamic Range Limited Nonlinearities
Ying, Kai; Yu, Zhenhua; Baxley, Robert J.; Zhou, G. Tong
2014-01-01
Many components used in signal processing and communication applications, such as power amplifiers and analog-to-digital converters, are nonlinear and have a finite dynamic range. The nonlinearity associated with these devices distorts the input, which can degrade the overall system performance. Signal-to-noise-and-distortion ratio (SNDR) is a common metric to quantify the performance degradation. One way to mitigate nonlinear distortions is by maximizing the SNDR. In this paper, we analyze h...
Analysis and application of nonlinear amplification effects in single-mode optical fibers
Chiarello, Fabrizio
2014-01-01
This thesis focuses on all-optical signal generation and processing through nonlinear amplification phenomena in single-mode fibers. Three different nonlinear fiber optical oscillators are investigated and experimentally demonstrated. A continuous-wave pump for fiber Raman amplifiers, developed with the goal of achieving high degree of polarization, tunability and suppression of stimulated Brillouin scattering, is presented, discussed and used to achieve nonlinear polarization attraction....
International Nuclear Information System (INIS)
Chain Reaction is a work of recent American political history. It seeks to explain how and why America came to depend so heavily on its experts after World War II, how those experts translated that authority into political clout, and why that authority and political discretion declined in the 1970s. The author's research into the internal memoranda of the Atomic Energy Commission substantiates his argument in historical detail. It was not the ravages of American anti-intellectualism, as so many scholars have argued, that brought the experts back down to earth. Rather, their decline can be traced to the very roots of their success after World War II. The need to over-state anticipated results in order to garner public support, incessant professional and bureaucratic specialization, and the sheer proliferation of expertise pushed arcane and insulated debates between experts into public forums at the same time that a broad cross section of political participants found it easier to gain access to their own expertise. These tendencies ultimately undermined the political influence of all experts. (author)
Modeling and compensation of transmitter nonlinearity in coherent optical OFDM.
Amiralizadeh, Siamak; Nguyen, An T; Rusch, Leslie A
2015-10-01
We present a comprehensive study of nonlinear distortions from an optical OFDM transmitter. Nonlinearities are introduced by the combination of effects from the digital-to-analog converter (DAC), electrical power amplifier (PA) and optical modulator in the presence of high peak-to-average power ratio (PAPR). We introduce parameters to quantify the transmitter nonlinearity. High input backoff avoids OFDM signal compression from the PA, but incurs high penalties in power efficiency. At low input backoff, common PAPR reduction techniques are not effective in suppressing the PA nonlinear distortion. A bit error distribution investigation shows a technique combining nonlinear predistortion with PAPR mitigation could achieve good power efficiency by allowing low input backoff. We use training symbols to extract the transmitter nonlinear function. We show that piecewise linear interpolation (PLI) leads to an accurate transmitter nonlinearity characterization. We derive a semi-analytical solution for bit error rate (BER) that validates the PLI approximation accurately captures transmitter nonlinearity. The inverse of the PLI estimate of the nonlinear function is used as a predistorter to suppress transmitter nonlinearity. We investigate performance of the proposed scheme by Monte Carlo simulations. Our simulations show that when DAC resolution is more than 4 bits, BER below forward error correction limit of 3.8 × 10(-3) can be achieved by using predistortion with very low input power backoff for electrical PA and optical modulator. PMID:26480133
Nonlinear singular vectors and nonlinear singular values
Institute of Scientific and Technical Information of China (English)
穆穆
2000-01-01
A novel concept of nonlinear singular vector and nonlinear singular value is introduced, which is a natural generalization of the classical linear singular vector and linear singular value to the nonlinear category. The optimization problem related to the determination of nonlinear singular vectors and singular values is formulated. The general idea of this approach is demonstrated by a simple two-dimensional quasigeostrophic model in the atmospheric and oceanic sciences. The advantage and its applications of the new method to the predictability, ensemble forecast and finite-time nonlinear instability are discussed. This paper makes a necessary preparation for further theoretical and numerical investigations.
Energy Technology Data Exchange (ETDEWEB)
Kozlowski, K.K.; Teschner, J.
2010-06-15
We give a direct derivation of a proposal of Nekrasov-Shatashvili concerning the quantization conditions of the Toda chain. The quantization conditions are formulated in terms of solutions to a nonlinear integral equation similar to the ones coming from the thermodynamic Bethe ansatz. This is equivalent to extremizing a certain function called Yang's potential. It is shown that the Nekrasov-Shatashvili formulation of the quantization conditions follows from the solution theory of the Baxter equation, suggesting that this way of formulating the quantization conditions should indeed be applicable to large classes of quantized algebraically integrable models. (orig.)
High power, high beam quality regenerative amplifier
Hackel, L.A.; Dane, C.B.
1993-08-24
A regenerative laser amplifier system generates high peak power and high energy per pulse output beams enabling generation of X-rays used in X-ray lithography for manufacturing integrated circuits. The laser amplifier includes a ring shaped optical path with a limited number of components including a polarizer, a passive 90 degree phase rotator, a plurality of mirrors, a relay telescope, and a gain medium, the components being placed close to the image plane of the relay telescope to reduce diffraction or phase perturbations in order to limit high peak intensity spiking. In the ring, the beam makes two passes through the gain medium for each transit of the optical path to increase the amplifier gain to loss ratio. A beam input into the ring makes two passes around the ring, is diverted into an SBS phase conjugator and proceeds out of the SBS phase conjugator back through the ring in an equal but opposite direction for two passes, further reducing phase perturbations. A master oscillator inputs the beam through an isolation cell (Faraday or Pockels) which transmits the beam into the ring without polarization rotation. The isolation cell rotates polarization only in beams proceeding out of the ring to direct the beams out of the amplifier. The diffraction limited quality of the input beam is preserved in the amplifier so that a high power output beam having nearly the same diffraction limited quality is produced.
A naturally stable Sagnac-Michelson nonlinear interferometer
Lukens, Joseph M; Pooser, Raphael C
2016-01-01
Interferometers measure a wide variety of dynamic processes by converting a phase change into an intensity change. Nonlinear interferometers, making use of nonlinear media in lieu of beamsplitters, promise substantial improvement in the quest to reach the ultimate sensitivity limits. Here we demonstrate a new nonlinear interferometer utilizing a single parametric amplifier for mode mixing---conceptually, a nonlinear version of the conventional Michelson interferometer with its arms collapsed together. We observe up to 99.9\\% interference visibility and find evidence for noise reduction based on phase-sensitive gain. Our configuration utilizes fewer components than previous demonstrations and requires no active stabilization, offering new capabilities for practical nonlinear interferometric-based sensors.
Adaptive Predistortion Using Cubic Spline Nonlinearity Based Hammerstein Modeling
Wu, Xiaofang; Shi, Jianghong
In this paper, a new Hammerstein predistorter modeling for power amplifier (PA) linearization is proposed. The key feature of the model is that the cubic splines, instead of conventional high-order polynomials, are utilized as the static nonlinearities due to the fact that the splines are able to represent hard nonlinearities accurately and circumvent the numerical instability problem simultaneously. Furthermore, according to the amplifier's AM/AM and AM/PM characteristics, real-valued cubic spline functions are utilized to compensate the nonlinear distortion of the amplifier and the following finite impulse response (FIR) filters are utilized to eliminate the memory effects of the amplifier. In addition, the identification algorithm of the Hammerstein predistorter is discussed. The predistorter is implemented on the indirect learning architecture, and the separable nonlinear least squares (SNLS) Levenberg-Marquardt algorithm is adopted for the sake that the separation method reduces the dimension of the nonlinear search space and thus greatly simplifies the identification procedure. However, the convergence performance of the iterative SNLS algorithm is sensitive to the initial estimation. Therefore an effective normalization strategy is presented to solve this problem. Simulation experiments were carried out on a single-carrier WCDMA signal. Results show that compared to the conventional polynomial predistorters, the proposed Hammerstein predistorter has a higher linearization performance when the PA is near saturation and has a comparable linearization performance when the PA is mildly nonlinear. Furthermore, the proposed predistorter is numerically more stable in all input back-off cases. The results also demonstrate the validity of the convergence scheme.
The OPTHER Project: Progress toward the THz Amplifier
DEFF Research Database (Denmark)
Paoloni, C; Brunetti, F; Di Carlo, A;
2011-01-01
This paper describes the status of the OPTHER (OPtically driven TeraHertz AmplifiERs) project and progress toward the THz amplifier realization. This project represents a considerable advancement in the field of high frequency amplification. The design and realization of a THz amplifier within th...
Xiao, Xue; Tao, Jing; Zhang, Hong Zhi; Huang, Cheng Zhi; Zhen, Shu Jun
2016-11-15
Graphene oxide (GO) is an excellent fluorescence anisotropy (FA) amplifier. However, in the conventional GO amplified FA strategy, one target can only induce the FA change of one fluorophore on probe, which limits the detection sensitivity. Herein, we developed an exonuclease III (Exo III) aided GO amplified FA strategy by using aptamer as an recognition element and ricin B-chain as a proof-of-concept target. The aptamer was hybridized with a blocker sequence and linked onto the surface of magnetic beads (MBs). Upon the addition of ricin B-chain, blocker was released from the surface of MBs and hybridized with the dye-modified probe DNA on the surface of GO through the toehold-mediated strand exchange reaction. The formed blocker-probe DNA duplex triggered the Exo III-assisted cyclic signal amplification by repeating the hybridization and digestion of probe DNA, liberating the fluorophore with several nucleotides (low FA value). Thus, ricin B-chain could be sensitively detected by the significantly decreased FA. The linear range was from 1.0μg/mL to 13.3μg/mL and the limit of detection (LOD) was 400ng/mL. This method improved the sensitivity of FA assay and it could be generalized to any kind of target detection based on the use of an appropriate aptamer. PMID:27295569
Design Of A Doherty Power Amplifier For GSM Systems
Directory of Open Access Journals (Sweden)
Saad Wasmi Osman
2013-04-01
Full Text Available This paper presents the design and analysis of Doherty power amplifier. The Doherty amplifier is used in a base station for mobile system because of its high efficiency. The class AB power amplifier used in the configuration of the main and auxiliary amplifier. The result obtained shows that the Doherty power amplifier can be used on a wide band spectrum, the amplifier works at 900MHz and has very good power added efficiency (PAE and gain. The amplifier can also work at 1800MHz at input power greater than 20dBm.
The Electron Beam Semiconductor (EBS) amplifier
True, R. M.; Baxendale, J. F.
1980-07-01
The Electron Beam Semiconductor (EBS) concept has existed for three decades; but only within the last decade has an active, well-defined program been underway to develop devices that can operate as high-power radio frequency(RF) amplifiers, fast risetime switches, and current and voltage pulse amplifiers. This report discusses the test procedures, data and results of reliability testing of RF and video pulse EBS amplifiers at Electronics Research and Development Command (ERADCOM), Fort Monmouth, New Jersey. Also, the experimental analysis of the series connected diode EBS device is described in detail. Finally, the report concludes with a discussion of the state-of-the-art of EBS and future trends of the technology.
An automated test facility for neutronic amplifiers
International Nuclear Information System (INIS)
Neutronic amplifiers are used at the Chalk River Laboratory in applications such as neutron flux monitoring and reactor control systems. Routine preventive maintenance of control and safety systems included annual calibration and characterization of the neutronic amplifiers. An investigation into the traditional methods of annual routine maintenance of amplifiers concluded that frequency and phase response measurements in particular were labour intensive and subject to non-repeatable errors. A decision was made to upgrade testing methods and facilities by using programmable test equipment under the control of a computer. In order to verify the results of the routine measurements, expressions for the transfer functions were derived from the circuit diagrams. Frequency and phase responses were then calculated and plotted thus providing a bench-mark to which the test results can be compared. (author)
Use of polymerase chain reaction for detection of Chlamydia trachomatis
DEFF Research Database (Denmark)
Østergaard, Lars; Birkelund, Svend; Christiansen, Gunna
1990-01-01
A polymerase chain reaction (PCR) assay was developed for detection of Chlamydia trachomatis DNA. From the published sequence of the common C. trachomatis plasmid, two primer sets were selected. Detection of amplified sequences was done by agarose gel electrophoresis of cleaved or uncleaved...
Brox, Thomas; Weickert, Joachim; Burgeth, Bernhard; Mrázek, Pavel
2004-01-01
In this article we introduce nonlinear versions of the popular structure tensor, also known as second moment matrix. These nonlinear structure tensors replace the Gaussian smoothing of the classical structure tensor by discontinuity-preserving nonlinear diffusions. While nonlinear diffusion is a well-established tool for scalar and vector-valued data, it has not often been used for tensor images so far. Two types of nonlinear diffusion processes for tensor data are studied: an isotropic one w...
Deformations and Nonlinear Systems
Man'ko, V. I.; Marmo, G.; F. Zaccaria
1997-01-01
The q-deformation of harmonic oscillators is shown to lead to q-nonlinear vibrations. The examples of q-nonlinearized wave equation and Schr\\"odinger equation are considered. The procedure is generalized to broader class of nonlinearities related to other types of deformations. The nonlinear noncanonical transforms used in the deformation procedure are shown to preserve in some cases the linear dynamical equations, for instance, for the harmonic oscillators. The nonlinear coherent states and ...
Linear Amplifier Model for Optomechanical Systems
Botter, Thierry; Brahms, Nathan; Schreppler, Sydney; Stamper-Kurn, Dan M
2011-01-01
We model optomechanical systems as linear optical amplifiers. This provides a unified treatment of diverse optomechanical phenomena. We emphasize, in particular, the relationship between ponderomotive squeezing and optomechanically induced transparency, two foci of current research. We characterize the amplifier response to quantum and deliberately applied fluctuations, both optical and mechanical. Further, we apply these results to establish quantum limits on external force sensing both on and off cavity resonance. We find that the maximum sensitivity attained on resonance constitutes an absolute upper limit, not surpassed when detuning off cavity resonance. The theory can be extended to a two-sided cavity with losses and limited detection efficiency.
Operational amplifier circuits analysis and design
Nelson, J C C
1995-01-01
This book, a revised and updated version of the author's Basic Operational Amplifiers (Butterworths 1986), enables the non-specialist to make effective use of readily available integrated circuit operational amplifiers for a range of applications, including instrumentation, signal generation and processing.It is assumed the reader has a background in the basic techniques of circuit analysis, particularly the use of j notation for reactive circuits, with a corresponding level of mathematical ability. The underlying theory is explained with sufficient but not excessive, detail. A range of compu
Optimization of Pr3+:ZBLAN fiber amplifiers
DEFF Research Database (Denmark)
Pedersen, B.; Miniscalco, J. W.; Quimby, R. S.
1992-01-01
Experimental parameters have been measured and used in a quantitative model of Pr3+-doped fluorozirconate fiber amplifiers. The optimum cutoff wavelength was determined to be 800 nm and the gain for 400 mW of pump was found to increase from 12 to 34 dB if the NA was increased from 0.15 to 0.......25. Lengthening the metastable state lifetime from 110 to 300 μs would significantly improve amplifier performance while concentration quenching can appreciably degrade it...
2-μm wavelength, high-energy Ho:YLF chirped-pulse amplifier for mid-infrared OPCPA.
Hemmer, M; Sánchez, D; Jelínek, M; Smirnov, Vadim; Jelinkova, H; Kubeček, V; Biegert, J
2015-02-15
A 2-μm wavelength laser delivering up to 39-mJ energy, ∼10 ps duration pulses at 100-Hz repetition rate is reported. The system relies on chirped pulse amplification (CPA): a modelocked Er:Tm:Ho fiber-seeder is followed by a Ho:YLF-based regenerative amplifier and a cryogenically cooled Ho:YLF single pass amplifier. Stretching and compressing are performed with large aperture chirped volume Bragg gratings (CVBG). At a peak power of 3.3 GW, the stability was <1% rms over 1 h, confirming high suitability for OPCPA and extreme nonlinear optics applications. PMID:25680122
Ultra-Broad-Band Optical Parametric Amplifier or Oscillator
Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatolly; Maleki, Lute
2009-01-01
A concept for an ultra-broad-band optical parametric amplifier or oscillator has emerged as a by-product of a theoretical study in fundamental quantum optics. The study was originally intended to address the question of whether the two-photon temporal correlation function of light [in particular, light produced by spontaneous parametric down conversion (SPDC)] can be considerably narrower than the inverse of the spectral width (bandwidth) of the light. The answer to the question was found to be negative. More specifically, on the basis of the universal integral relations between the quantum two-photon temporal correlation and the classical spectrum of light, it was found that the lower limit of two-photon correlation time is set approximately by the inverse of the bandwidth. The mathematical solution for the minimum two-photon correlation time also provides the minimum relative frequency dispersion of the down-converted light components; in turn, the minimum relative frequency dispersion translates to the maximum bandwidth, which is important for the design of an ultra-broad-band optical parametric oscillator or amplifier. In the study, results of an analysis of the general integral relations were applied in the case of an optically nonlinear, frequency-dispersive crystal in which SPDC produces collinear photons. Equations were found for the crystal orientation and pump wavelength, specific for each parametric-down-converting crystal, that eliminate the relative frequency dispersion of collinear degenerate (equal-frequency) signal and idler components up to the fourth order in the frequency-detuning parameter
Feedback analysis of transimpedance operational amplifier circuits
DEFF Research Database (Denmark)
Bruun, Erik
1993-01-01
The transimpedance or current feedback operational amplifier (CFB op-amp) is reviewed and compared to a conventional voltage mode op-amp using an analysis emphasizing the basic feedback characteristics of the circuit. With this approach the paradox of the constant bandwidth obtained from CFB op...
Ultra-low Voltage CMOS Cascode Amplifier
DEFF Research Database (Denmark)
Lehmann, Torsten; Cassia, Marco
2000-01-01
In this paper, we design a folded cascode operational transconductance amplifier in a standard CMOS process, which has a measured 69 dB DC gain, a 2 MHz bandwidth and compatible input- and output voltage levels at a 1 V power supply. This is done by a novel Current Driven Bulk (CDB) technique, wh...
Stereoscopy Amplifies Emotions Elicited by Facial Expressions.
Hakala, Jussi; Kätsyri, Jari; Häkkinen, Jukka
2015-12-01
Mediated facial expressions do not elicit emotions as strongly as real-life facial expressions, possibly due to the low fidelity of pictorial presentations in typical mediation technologies. In the present study, we investigated the extent to which stereoscopy amplifies emotions elicited by images of neutral, angry, and happy facial expressions. The emotional self-reports of positive and negative valence (which were evaluated separately) and arousal of 40 participants were recorded. The magnitude of perceived depth in the stereoscopic images was manipulated by varying the camera base at 15, 40, 65, 90, and 115 mm. The analyses controlled for participants' gender, gender match, emotional empathy, and trait alexithymia. The results indicated that stereoscopy significantly amplified the negative valence and arousal elicited by angry expressions at the most natural (65 mm) camera base, whereas stereoscopy amplified the positive valence elicited by happy expressions in both the narrowed and most natural (15-65 mm) base conditions. Overall, the results indicate that stereoscopy amplifies the emotions elicited by mediated emotional facial expressions when the depth geometry is close to natural. The findings highlight the sensitivity of the visual system to depth and its effect on emotions. PMID:27551358
International Nuclear Information System (INIS)
We present a high-energy, high-average-power picosecond laser system based on a hybrid chain in a master oscillator power amplifier configuration. The chain is seeded by a Ti:sapphire oscillator, followed by a Yb doped fiber preamplifier, a Nd:YAG-based regenerate amplifier, and a Nd:YVO4-based single-pass amplifier. The final diode-pumped, solid-state amplifier is detailed and produces pulses with more than 10 mJ energy at 32 W average power with 207 ps duration, corresponding to 50 MW peak power. The picosecond pulse output is seeded and optically synchronized with the sub-5-fs oscillator for optical parametric chirped-pulse amplification pumping. (authors)
Modelling proton transfer in water molecule chains
Korzhimanov, Artem; Shutova, Tatiana; Samuelsson, Goran
2011-01-01
The process of protons transport in molecular water chains is of fundamental interest for many biological systems. Although many features of such systems can be analyzed using large-scale computational modeling, other features are better understood in terms of simplified model problems. Here we have tested, analytically and numerically, a model describing the classical proton hopping process in molecular water chains. In order to capture the main features of the proton hopping process in such molecular chains, we use a simplified model for our analysis. In particular, our discrete model describes a 1D chain of water molecules situated in an external protein channel structure, and each water molecule is allowed to oscillate around its equilibrium point in this system, while the protons are allowed to move along the line of neighboring oxygen atoms. The occurrence and properties of nonlinear solitary transport structures, allowing for much faster proton transport, are discussed, and the possible implications of...
Network science, nonlinear science and infrastructure systems
2007-01-01
Network Science, Nonlinear Science and Infrastructure Systems has been written by leading scholars in these areas. Its express purpose is to develop common theoretical underpinnings to better solve modern infrastructural problems. It is felt by many who work in these fields that many modern communication problems, ranging from transportation networks to telecommunications, Internet, supply chains, etc., are fundamentally infrastructure problems. Moreover, these infrastructure problems would benefit greatly from a confluence of theoretical and methodological work done with the areas of Network Science, Dynamical Systems and Nonlinear Science. This book is dedicated to the formulation of infrastructural tools that will better solve these types of infrastructural problems. .
Higher-order effects on self-similar parabolic pulse in the microstructured fibre amplifier
Institute of Scientific and Technical Information of China (English)
Liu Wei-Ci; Xu Wen-Cheng; Feng Jie; Chen Wei-Cheng; Li Shu-Xian; Lin Song-Hao
2008-01-01
By considering higher-order effects, the properties of self-similar parabolic pulses propagating in the microstructured fibre amplifier with a normal group-velocity dispersion have been investigated. The numerical results indicate that the higher-order effects can badly distort self-similar parabolic pulse shape and optical spectrum, and at the same time the peak shift and oscillation appear, while the pulse still reveals highly linear chirp but grows into asymmetry. The influence of different higher-order effects on self-similar parabolic pulse propagation has been analysed. It shows thatthe self-steepening plays a more important role. We can manipulate the geometrical parameters of the microstructured fibre amplifier to gain a suitable dispersion and nonlinearity coefficient which will keep high-quality self-similar parabolic pulse propagation. These results are significant for the further study of self-similar parabolic pulse propagation.
Energy localization in weakly dissipative resonant chains
Kovaleva, Agnessa
2016-08-01
Localization of energy in oscillator arrays has been of interest for a number of years, with special attention paid to the role of nonlinearity and discreteness in the formation of localized structures. This work examines a different type of energy localization arising due to the presence of dissipation in nonlinear resonance arrays. As a basic model, we consider a Klein-Gordon chain of finite length subjected to a harmonic excitation applied at an edge of the chain. It is shown that weak dissipation may be a key factor preventing the emergence of resonance in the entire chain, even if its nondissipative analog is entirely captured into resonance. The resulting process in the dissipative oscillator array represents large-amplitude resonant oscillations in a part of the chain adjacent to the actuator and small-amplitude oscillations in the distant part of the chain. The conditions of the emergence of resonance as well as the conditions of energy localization are derived. An agreement between the obtained analytical results and numerical simulations is demonstrated.
Numerical simulations for parabolic pulse shaping in non-linear media
Nora, R. C.; Durfee, C. G.; Carr, L. D.
2007-03-01
Pulses with parabolic temporal profiles have the property that they can propagate through non-linear media in a self similar manner. Parabolic pulses have been generated experimentally in fiber amplifiers. Input pulses develop into parabolic pulses by the combined action of group velocity dispersion, non-linear refractive index, and gain. In this work, we are exploring the feasibility of generating ultrafast parabolic pulses in laser resonators. We have successfully numerically simulated the generation of parabolic pulses in fiber amplifiers using two different algorithms, the Cayley method, and fourth order Runge-Kutta, to solve the Nonlinear Schrodinger equation with gain and periodic boundary conditions. In contrast to fiber amplifiers, pulses in laser resonators must maintain a stable pulse shape on each round trip through the optical cavity. We are exploring the prediction that a time dependent saturable gain will stabilize the pulse in the oscillator and yield parabolic pulses.
Institute of Scientific and Technical Information of China (English)
Wang Hanchao; Huang Lirong; Shi Zhongwei
2011-01-01
A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated. The amplified spontaneous emission (ASE) spectrum and gain were measured and analyzed. It is shown that the ASE spectrum and gain characteristic are greatly influenced by the distribution of the injection current density. By changing the injection current density of two electrodes, the full width at half maximum, peak wavelength, peak power of the ASE spectrum and the gain characteristic can be easily controlled.
DEFF Research Database (Denmark)
2015-01-01
The present invention relates to a silicone chain extender, more particularly a chain extender for silicone polymers and copolymers, to a chain extended silicone polymer or copolymer and to a functionalized chain extended silicone polymer or copolymer, to a method for the preparation thereof and...
Health supply chain management.
Zimmerman, Rolf; Gallagher, Pat
2010-01-01
This chapter gives an educational overview of: * The actual application of supply chain practice and disciplines required for service delivery improvement within the current health environment. * A rationale for the application of Supply Chain Management (SCM) approaches to the Health sector. * The tools and methods available for supply chain analysis and benchmarking. * Key supply chain success factors. PMID:20407173
Malevich, Pavel; Kanai, Tsuneto; Hoogland, Heinar; Holzwarth, Ronald; Baltuška, Andrius; Pugžlys, Audrius
2016-03-01
We present a concept of a white-light-seeded-cascaded mid-infrared (mid-IR) optical parametric amplifier (OPA) based on potassium titanyl arsenate and zinc germanium phosphate nonlinear optical crystals and producing 100-μJ level pulses centered at 5300 nm, with the spectrum supporting four-optical-cycle pulse duration. The OPA is pumped by 2090-nm master oscillator/power amplifier based on a Tm,Ho-fiber laser seeder and a Ho:YAG regenerative amplifier delivering 3.8-mJ sub-ps pulses at a repetition rate of 1 kHz. We validate that output parameters of the OPA are scalable by means of increasing the pulse energy, decreasing the pulse duration and redshifting the central wavelength. PMID:26974083
DEFF Research Database (Denmark)
Nguyen-Duy, Khiem
of a proposed NSE system with high dynamic performance. The goal of the work is to achieve a state-of-the art transient time of 10 µs. In order to produce the arbitrary nonlinear curve, the exponential function of a typical diode is used, but the diode can be replaced by other nonlinear curve reference...... generator unit. Because nonlinear energy sources come in different sizes and power rating, a single NSE may not be sufficient to simulate a wide selection of nonlinear sources. For this reason, the proposed NSE system is realized as modules. Stacking or connecting multiple modules in parallel will allow...... nonlinear curve reference generator based on diode curve. Even though the nonlinear curve is based on diode p-n junction, the proposed NSE can simulate other arbitrary nonlinear sources if the diode is replaced by other appropriate nonlinear curve reference generator units. The prototype is 200-W rating...
Localized Waves in Nonlinear Systems with Spatially Inhomogeneous Nonlinearity
Institute of Scientific and Technical Information of China (English)
GAO Yuan; TANG Xiao-Yan; LOU Sen-Yue
2009-01-01
A type of (2+1)-dimensional nonlinear SchrSdinger equation with spatially inhomogeneous nonlinearity and an external potential is studied.It is found that special external potentials and spatially nonlinearities can support nonlinear localized waves.
Strauch, Paul E
1997-01-01
Noise or interference is often assumed to be a random process. Conventional linear filtering, control or prediction techniques are used to cancel or reduce the noise. However, some noise processes have been shown to be nonlinear and deterministic. These nonlinear deterministic noise processes appear to be random when analysed with second order statistics. As nonlinear processes are widespread in nature it may be beneficial to exploit the coherence of the nonlinear deterministic no...
International Nuclear Information System (INIS)
We investigate the effect of intraband carrier dynamics on a nonlinear phase shift induced in a semiconductor optical amplifier (SOA) in terms of its applicability to the Symmetric Mach - Zehnder (SMZ) all-optical switch. Nonlinear phase shifts in an SOA and a passive semiconductor waveguide are compared under control-pulse durations ranging from 3.2 to 0.4 ps. The results show that femtosecond switching with higher efficiency is still possible by using the SOA. We experimentally achieve femtosecond (670 fs), femtojoule (140 fJ) switching with the SOA-based SMZ all-optical switch. [copyright] 2001 American Institute of Physics
MARKOV CHAIN PORTFOLIO LIQUIDITY OPTIMIZATION MODEL
Directory of Open Access Journals (Sweden)
Eder Oliveira Abensur
2014-05-01
Full Text Available The international financial crisis of September 2008 and May 2010 showed the importance of liquidity as an attribute to be considered in portfolio decisions. This study proposes an optimization model based on available public data, using Markov chain and Genetic Algorithms concepts as it considers the classic duality of risk versus return and incorporating liquidity costs. The work intends to propose a multi-criterion non-linear optimization model using liquidity based on a Markov chain. The non-linear model was tested using Genetic Algorithms with twenty five Brazilian stocks from 2007 to 2009. The results suggest that this is an innovative development methodology and useful for developing an efficient and realistic financial portfolio, as it considers many attributes such as risk, return and liquidity.
Institute of Scientific and Technical Information of China (English)
Feng Liu; Qing Ye; Aiping Luo; Jianrong Qiu; Congshan Zhu; Ronghui Qu; Zujie Fang
2005-01-01
The nonlinear switching characteristics of fused fiber directional couplers were studied experimentally. By using femtosecond laser pulses with pulse width of 100 fs and wavelength of about 1550 nm from a system of Ti:sapphire laser and optical parametric amplifier (OPA), the nonlinear switching properties of a null coupler and a 100% coupler were measured. The experimental results were coincident with the simulations based on nonlinear propagation equations in fiber by using super-mode theory. Nonlinear loss in fiber was also measured to get the injected power at the coupler. After deducting the nonlinear loss and input efficiency, the nonlinear switching critical peak powers for a 100% and a null fused couplers were calculated to be 9410 and 9440 W, respectively. The nonlinear loss parameter PN in an expression of αNL = αP/PN was obtained to be PN = 0.23 W.
Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong
2015-01-01
This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.
Noncommutative Nonlinear Supersymmetry
Nishino, H; Nishino, Hitoshi; Rajpoot, Subhash
2002-01-01
We present noncommutative nonlinear supersymmetric theories. The first example is a non-polynomial Akulov-Volkov-type lagrangian with noncommutative nonlinear global supersymmetry in arbitrary space-time dimensions. The second example is the generalization of this lagrangian to Dirac-Born-Infeld lagrangian with nonlinear supersymmetry realized in dimensions D=2,3,4 and 6 (mod 8).
Fiber Nonlinearities: A Tutorial
Institute of Scientific and Technical Information of China (English)
Govind; P.; Agrawal
2003-01-01
Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications, the Raman amplification being only one of the recent examples. In this tutorial I review the various nonlinear effects occurring in optical fibers from both standpoints..
Fiber Nonlinearities: A Tutorial
Institute of Scientific and Technical Information of China (English)
Govind P. Agrawal
2003-01-01
Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications,the Raman amplification being only one of the recent examples. In this tutorial I review the vario us nonlinear effects occurring in optical fibers from both standpoints..
Optimal beamforming in MIMO systems with HPA nonlinearity
Qi, Jian
2010-09-01
In this paper, multiple-input multiple-output (MIMO) transmit beamforming (TB) systems under the consideration of nonlinear high-power amplifiers (HPAs) are investigated. The optimal beamforming scheme, with the optimal beamforming weight vector and combining vector, is proposed for MIMO systems with HPA nonlinearity. The performance of the proposed MIMO beamforming scheme in the presence of HPA nonlinearity is evaluated in terms of average symbol error probability (SEP), outage probability and system capacity, considering transmission over uncorrelated quasi-static frequency-flat Rayleigh fading channels. Numerical results are provided and show the effects of several system parameters, namely, parameters of nonlinear HPA, numbers of transmit and receive antennas, and modulation order of phase-shift keying (PSK), on performance. ©2010 IEEE.
Nonlinear optical cryptosystem resistant to standard and hybrid attacks
Sinha, Aloka
2016-06-01
We propose a nonlinear optical cryptosystem that is resistant to amplitude-phase retrieval attacks, known-plaintext attack and chosen-plaintext attack. A squaring operation is introduced in the encryption path, which thwarts the iterative attacks. This nonlinear operation tends to amplify the error in the estimation during an iterative attack. The decryption process requires the use of a square-root operation. Thus, in the reverse path also, the attacks encounter the nonlinear square-root operation. These two nonlinearities make the iterative attacks unstable, thereby leading to non-convergence of the mean square error (MSE). Our technique is also resistant to hybrid attacks. The technique is general and is shown to work on a variety of images of the type grayscale and binary. Numerical simulation results corroborate the effectiveness of the proposed cryptosystem.
Optical Nonlinearities in Chalcogenide Glasses and their Applications
Zakery, A
2007-01-01
Photonics, which uses photons for information and image processing, has been labeled the technology of the 21st century, for which non-linear optical processes provide the key functions of frequency conversion and optical switching. Chalcogenide glass fiber is one of the most promising candidates for use as a non-linear optical medium because of its high optical nonlinearity and long interaction length. Since the chalcogenide glass fibers transmit into the IR, there are numerous potential applications in the civil, medical and military areas. One of the most exciting developments in the future is going to be in the area of rare-earth ion doping of chalcogenide fibers for IR fluorescence emission. The IR light sources, lasers and amplifiers developed using this phenomena will be very useful in civil, medical and military applications. Remote IR spectroscopy and imaging using flexible fibers will be realized for applications. Other future research areas which will inevitably be explored includes non-linear opti...
Design of advanced materials for linear and nonlinear dynamics
DEFF Research Database (Denmark)
Frandsen, Niels Morten Marslev
but general model of inhomogeneous structural materials with nonlinear material characteristics. The second material system is an “engineered” material in the sense that a classical structural element, a linear elastic and homogeneous rod, is “enhanced” by applying a mechanism on its surface, amplifying....... This is demonstrated both analytically, numerically and experimentally. This makes the material a strong candidate for mechanical filtering for sound and vibration isolation purposes, not least for systems with varying natural frequencies such as nonlinear structures or structures with variable mass due to, e......The primary catalyst of this PhD project has been an ambition to design advanced materials and structural systems including, and possibly even exploiting, nonlinear phenomena such as nonlinear modal interaction leading to energy conversion between modes. An important prerequisite for efficient...
Reducing the impact of demand process variability within a multi-echelon supply chain
Campuzano Bolarín, Francisco; Ros Mcdonnell, Lorenzo Brian; Martín García, Juan
2008-01-01
Forrester analyzed Supply Chain and the different levels existing in it, as well as the participant companies and the role played by each of them inside the chain as a global group, and observed that small variations in end item demand caused oscillations that are amplified throughout the chain. This phenomenon, called the Bullwhip effect, has detrimental consequences on inventory levels and on all kind of inventory costs that may affect the added value of the activities throughout the logist...
Inventory cost consequences of variability demand process within a multi-echelon supply chain
Campuzano Bolarín, Francisco; Lisec, Andrej; Lario Esteban, Francisco Cruz
2012-01-01
The bullwhip effect (Lee et al, 1997a) is a known supply chain phenomenon where small variations in end item demand create oscillations that amplify throughout the chain. Different price elasticity of demand influence different changes of demand when prices of items are changing on the time horizon. The variance of the orders at the end user placed on suppliers or on manufacturer increases with the orders flow upstream in the logistics chain. This creates harmful consequences in i...
Reducing the impact of demand process variability within a multi-echelon supply chain. Poster
Campuzano Bolarín, Francisco; Ros Mcdonnell, Lorenzo Brian; Martín García, Juan
2008-01-01
Forrester analyzed Supply Chain and the different levels existing in it, as well as the participant companies and the role played by each of them inside the chain as a global group, and observed that small variations in end item demand caused oscillations that are amplified throughout the chain. This phenomenon, called the Bullwhip effect, has detrimental consequences on inventory levels and on all kind of inventory costs that may affect the added value of the activities throughout the logist...
First lasing of the regenerative amplifier FEL
International Nuclear Information System (INIS)
The regenerative amplifier free-electron laser (RAFEL) is a high-gain RF-linac FEL capable of producing high optical power from a compact design. The combination of a high-gain and small optical feedback enables the FEL to reach saturation and produce a high optical power and high extraction efficiency without the risk of optical damage to the mirrors. This paper summarizes the first lasing of the regenerative amplifier FEL and describes recent experimental results. The highest optical energy achieved thus far at 16.3 μm is 1.7 J over a train of 900 micropulses. We infer pulse energy of 1.9 mJ in each 16 ps micropulse, corresponding to a peak power of 120 MW
Behavioral modeling of Digitally Adjustable Current Amplifier
Directory of Open Access Journals (Sweden)
Josef Polak
2015-03-01
Full Text Available This article presents the digitally adjustable current amplifier (DACA and its analog behavioral model (ABM, which is suitable for both ideal and advanced analyses of the function block using DACA as active element. There are four levels of this model, each being suitable for simulation of a certain degree of electronic circuits design (e.g. filters, oscillators, generators. Each model is presented through a schematic wiring in the simulation program OrCAD, including a description of equations representing specific functions in the given level of the simulation model. The design of individual levels is always verified using PSpice simulations. The ABM model has been developed based on practically measured values of a number of DACA amplifier samples. The simulation results for proposed levels of the ABM model are shown and compared with the results of the real easurements of the active element DACA.
High power single-frequency Innoslab amplifier.
Han, Ke-Zhen; Ning, Jian; Zhang, Bai-Tao; Wang, Yi-Ran; Zhang, Hai-Kun; Nie, Hong-Kun; Sun, Xiao-Li; He, Jing-Liang
2016-07-10
A laser diode array (LDA) end-pumped continuous-wave single-frequency Innoslab amplifier has been demonstrated. The Gaussian ray bundle method was used to model the light propagation in the Innoslab amplifier for the first time to the best of our knowledge. With discrete reflectors, the maximum output of 60 W with a linewidth of 44 MHz was achieved under the pump power of 245 W, corresponding to the optical-optical efficiency of 24.5%. The beam quality factor M2 at the output power of 51 W in the horizontal and vertical direction was measured to be 1.4 and 1.3, respectively. The long-term power instability in 2 h was less than 0.25%. PMID:27409308
Linear control of oscillator and amplifier flows*
Schmid, Peter J.; Sipp, Denis
2016-08-01
Linear control applied to fluid systems near an equilibrium point has important applications for many flows of industrial or fundamental interest. In this article we give an exposition of tools and approaches for the design of control strategies for globally stable or unstable flows. For unstable oscillator flows a feedback configuration and a model-based approach is proposed, while for stable noise-amplifier flows a feedforward setup and an approach based on system identification is advocated. Model reduction and robustness issues are addressed for the oscillator case; statistical learning techniques are emphasized for the amplifier case. Effective suppression of global and convective instabilities could be demonstrated for either case, even though the system-identification approach results in a superior robustness to off-design conditions.
Design of an 1800 nm Raman Amplifier
DEFF Research Database (Denmark)
Svane, Ask Sebastian; Rottwitt, Karsten
Different approaches are being explored to increase the capacity of communication systems [1,2], both long and short range systems. One approach is by exploiting new optical wavelength bands, outside the conventional communication window from 1530 nm to 1625 nm. Hollow core fibers have been...... in the pump power requirement and deteriorated noise properties. Here we demonstrate a Raman amplifier designed for signal wavelengths around 1800 nm. The amplification fiber is an OFS PM Raman fiber, and is pumped by a Raman fiber laser emitting at 1680 nm [4]. The amplifier was pumped co......-polarized and backward, with respect to the singal. In Fig. 2 a measured Raman on/off gain exceeding 9 dB for 285 mW of injected pump power is obtained in a 4.35 km long fiber. A broadband supercontinuum source was used as a signal from 1700 nm to 1900 nm....
Noise Gain Features of Fiber Raman Amplifier
Directory of Open Access Journals (Sweden)
Georgii S. Felinskyi
2016-01-01
Full Text Available The formation dynamics of the optical noise in a silica single mode fiber (SMF as function of the pump power variation in the counter pumped fiber Raman amplifier (FRA is experimentally studied. The ratio between the power of amplified spontaneous emission and the power of incoherent optical noise is quantitatively determined by detailed analysis of experimental data in the pump powers range of 100–300 mW within the full band of Stokes frequencies, including FRA working wavelengths over the C + L transparency windows. It is found out the maximum of Raman gain coefficient for optical noise does not exceed ~60% of corresponding peak at the gain profile maximum of coherent signal. It is shown that the real FRA noise figure may be considerably less than 3 dB over a wide wavelength range (100 nm at a pump power of several hundreds of mW.
Cryogenic cooling for high power laser amplifiers
Directory of Open Access Journals (Sweden)
Perin J.P.
2013-11-01
Full Text Available Using DPSSL (Diode Pumped Solid State Lasers as pumping technology, PW-class lasers with enhanced repetition rates are developed. Each of the Yb YAG amplifiers will be diode-pumped at a wavelength of 940 nm. This is a prerequisite for achieving high repetition rates (light amplification duration 1 millisecond and repetition rate 10 Hz. The efficiency of DPSSL is inversely proportional to the temperature, for this reason the slab amplifier have to be cooled at a temperature in the range of 100 K–170 K with a heat flux of 1 MW*m−2. This paper describes the thermo-mechanical analysis for the design of the amplification laser head, presents a preliminary proposal for the required cryogenic cooling system and finally outlines the gain of cryogenic operation for the efficiency of high pulsed laser.
Wang, Fuan; Lu, Chun-Hua; Liu, Xiaoqing; Freage, Lina; Willner, Itamar
2014-02-01
The amplified, highly sensitive detection of DNA using the dendritic rolling circle amplification (RCA) is introduced. The analytical platform includes a circular DNA and a structurally tailored hairpin structure. The circular nucleic acid template includes a recognition sequence for the analyte DNA (the Tay-Sachs mutant gene), a complementary sequence to the Mg(2+)-dependent DNAzyme, and a sequence identical to the loop region of the coadded hairpin structure. The functional hairpin in the system consists of the analyte-sequence that is caged in the stem region and a single-stranded loop domain that communicates with the RCA product. The analyte activates the RCA process, leading to DNA chains consisting of the Mg(2+)-dependent DNAzyme and sequences that are complementary to the loop of the functional hairpin structure. Opening of the coadded hairpin releases the caged analyte sequence, resulting in the dendritic RCA-induced synthesis of the Mg(2+)-dependent DNAzyme units. The DNAzyme-catalyzed cleavage of a fluorophore/quencher-modified substrate leads to a fluorescence readout signal. The method enabled the analysis of the target DNA with a detection limit corresponding to 1 aM. By the design of two different circular DNAs that include recognition sites for two different target genes, complementary sequences for two different Mg(2+)-dependent DNAzyme sequences and two different functional hairpin structures, the dendritic RCA-stimulated multiplexed analysis of two different genes is demonstrated. The amplified dendritic RCA detection of DNA is further implemented to yield the hemin/G-quadruplex horseradish peroxidase (HRP)-mimicking DNAzyme as catalytic labels that provide colorimetric or chemiluminescent readout signals. PMID:24377284
Optimisation of semiconductor optical amplifiers for optical networks
International Nuclear Information System (INIS)
This thesis is concerned with the design, fabrication and testing of Multiple Quantum Well Semiconductor Optical Amplifiers (SOAs) in the Indium Phosphide (InP) material system at a wavelength of 1.55μm. Following an introduction to optical communication systems and an overview of SOAs, the realisation of two SOAs is described. First, the design and fabrication of an SOA for linear amplification is presented, which uses integrated mode expanders to match the output mode to that of an optical fibre. In conjunction with angled facets, these mode expanders allow the reduction of the intrinsic facet reflectivity so that anti-reflection (AR) coatings are not required for travelling wave operation. It is shown that despite the effective reflectivity being very low, the mirror loss can be improved by the application of a single layer AR coating. Devices with this AR coating are shown to have state of the art performance in terms of gain and noise. Secondly, the requirements for non-linear switching using SOAs are investigated, through a combination of theory and experiment. From these findings, methods for optimisation are outlined, and an SOA is designed and fabricated which incorporates these changes. Following basic characterisation, the SOA is shown to have improved characteristics through CW measurements. The performance is demonstrated by world leading wavelength conversion experiments at 100Gbit/s and finally the prospects for operation of a 100Gbit/s interferometer using this device are investigated. (author)
International Nuclear Information System (INIS)
Supercontinuum generation with considerable flatness and low fluctuation is investigated in nonlinear fibers by amplification of pulsed seed signal of a stable mode locked bismuth oxide based erbium doped fiber laser. Spectral expansion from 980 to 1750 nm is obtained by 340 fs pulses at 1560 nm amplified up to 177 kW in a dispersion flattened highly non-linear fiber. A comparison is made for different types of nonlinear fibers and evaluation of spectral bandwidth at high powers is probed
Amplifying the Hawking Signal in BECs
Directory of Open Access Journals (Sweden)
Roberto Balbinot
2014-01-01
Full Text Available We consider simple models of Bose-Einstein condensates to study analog pair-creation effects, namely, the Hawking effect from acoustic black holes and the dynamical Casimir effect in rapidly time-dependent backgrounds. We also focus on a proposal by Cornell to amplify the Hawking signal in density-density correlators by reducing the atoms’ interactions shortly before measurements are made.
Electrically Pumped Vertical-Cavity Amplifiers
DEFF Research Database (Denmark)
Greibe, Tine
2007-01-01
In this work, the design of electrically pumped vertical cavity semiconductor optical amplifiers (eVCAs) for use in a mode-locked external-cavity laser has been developed, investigated and analysed. Four different eVCAs, one top-emitting and three bottom emitting structures, have been designed...... and discussed. The thesis concludes with recommendations for further work towards the realisation of compact electrically pumped mode-locked vertical externalcavity surface emitting lasers....
Quantum noise in ideal operational amplifiers
Courty, Jean-Michel; Grassia, Francesca; Reynaud, Serge
1998-01-01
We consider a model of quantum measurement built on an ideal operational amplifier operating in the limit of infinite gain, infinite input impedance and null output impedance and with a feddback loop. We evaluate the intensity and voltage noises which have to be added to the classical amplification equations in order to fulfill the requirements of quantum mechanics. We give a description of this measurement device as a quantum network scattering quantum fluctuations from input to output ports.
Fundamental design of a distributed erbium-doped fiber amplifier for long-distance transmission
DEFF Research Database (Denmark)
Rottwitt, Karsten; Bjarklev, Anders Overgaard; Povlsen, Jørn Hedegaard;
1992-01-01
. Designs based on a bidirectional pumping scheme are evaluated, taking nonlinearities into account. The optimum value of the numerical aperture will be evaluated for cutoff wavelengths where the propagating pump power is single moded. For distances between each pumping station in the region between 10......Comprehensive theoretical analysis on the design of a distributed erbium-doped fiber amplifier for long-distance transmission has been carried out, using a highly accurate model. The dispersion of the optical fiber as a function of the numerical aperture and the cutoff wavelength is included...... and 100 km, the optimum ratio of copropagating and counterpropagating pump power will also be evaluated...
Generation of Squeezing in Higher Order Hermite-Gaussian Modes with an Optical Parametric Amplifier
DEFF Research Database (Denmark)
Lassen, Mikael Østergaard; Delaubert, Vincent; Harb, Charles C.;
2006-01-01
We demonstrate quantum correlations in the transverse plane of continuous wave light beams by producing -4.0 dB, -2.6 dB and -1.5 dB of squeezing in the TEM_{00}, TEM_{10} and TEM_{20} Hermite-Gauss modes with an optical parametric amplifier, respectively. This has potential applications in quantum...... information networking, enabling parallel quantum information processing. We describe the setup for the generation of squeezing and analyse the effects of various experimental issues such as mode overlap between pump and seed and nonlinear losses. © The Authors. All rights reserved...
Directory of Open Access Journals (Sweden)
Zhou G Tong
2007-01-01
Full Text Available Many modern communication signal formats, such as orthogonal frequency-division multiplexing (OFDM and code-division multiple access (CDMA, have high peak-to-average power ratios (PARs. A signal with a high PAR not only is vulnerable in the presence of nonlinear components such as power amplifiers (PAs, but also leads to low transmission power efficiency. Selected mapping (SLM and clipping are well-known PAR reduction techniques. We propose to combine SLM with threshold clipping and digital baseband predistortion to improve the overall efficiency of the transmission system. Testbed experiments demonstrate the effectiveness of the proposed approach.
High efficiency, high energy, CEP-stabilized infrared optical parametric amplifier
Ling, Weijun; Geng, Xiaotao; Guo, Shuyan; Wei, Zhiyi; Krausz, F.; Kim, D.
2014-10-01
A high efficiency, tunable, carrier-envelope-phase (CEP) stabilized near-infrared optical parametric amplifier (OPA) is demonstrated with just a single BBO crystal. A white-light continuum produced by a CEP-stabilized laser is seeded into the two stages of the type II OPA system. We achieved a pump-to-signal conversion efficiency of 34% with a single nonlinear crystal. To our knowledge this is the highest conversion efficiency reported in broadband optical parametric amplification, using the two stages. This work demonstrates a compact way to for tunable femtosecond pulses with CEP stabilization.
Charge sensitive amplifies. The state of arts
Energy Technology Data Exchange (ETDEWEB)
Mori, Kunishiro [Clear Pulse Co., Tokyo (Japan)
1996-07-01
In the radiation detectors, signals are essentially brought with charges produced by radiation, then it is naturally the best way to use a charge sensitive amplifier (CSA) system to extract those signals. The CSA is thought to be the best amplifier suitable to almost all the radiation detectors, if neglecting economical points of view. The CSA has been only applied to special fields like radiation detection because the concept of `charges` is not so universal against the concepts of `voltage` and `current`. The CSA, however, is low in noise and a high speed amplifier and may be applicable not only to radiation measurement but also piezoelectric devices and also bolometers. In this article, noise in the CSA, basic circuit on the CSA, concepts of `equivalent noise charge` (ENC), a method for the ENC, and importance of the `open-loop gain` in the CSA to achieve better performance of it and how to realize in a practical CSA were described. And, characteristics on a counting rate of the CSA, various circuit used in the CSA, and CSAs which are commercially available at present and special purpose CSAs were also introduced. (G.K.)
Microstrip SQUID amplifiers for quantum information science
Defeo, M. P.; Plourde, B. L. T.
2012-02-01
Recent progress in SQUID amplifiers suggests that these devices might approach quantum-limited sensitivity in the microwave range, thus making them a viable option for measurement of superconducting quantum systems. In the microstrip SQUID amplifier configuration, gains of around 20dB are possible at frequencies of several hundred MHz, and the gain is limited by the maximum voltage modulation available from the SQUID. One route for increasing the voltage modulation involves using larger resistive shunts, however maintaining non-hysteretic device operation requires smaller junction capacitances than is possible with conventional photolithographically patterned junctions. Operating at higher frequencies requires a shorter input coil which reduces mutual inductance between the coil and washer and therefore gain. We have fabricated microstrip SQUID amplifiers using submicron Al-AlOx-Al junctions and large shunts. The input coil and SQUID washer are optimized for producing high gain at frequencies in the gigahertz range. Recent measurements of gain and noise temperature will be discussed as well as demonstrations of these devices as a first stage of amplification for a superconducting system
Parallel reservoir computing using optical amplifiers.
Vandoorne, Kristof; Dambre, Joni; Verstraeten, David; Schrauwen, Benjamin; Bienstman, Peter
2011-09-01
Reservoir computing (RC), a computational paradigm inspired on neural systems, has become increasingly popular in recent years for solving a variety of complex recognition and classification problems. Thus far, most implementations have been software-based, limiting their speed and power efficiency. Integrated photonics offers the potential for a fast, power efficient and massively parallel hardware implementation. We have previously proposed a network of coupled semiconductor optical amplifiers as an interesting test case for such a hardware implementation. In this paper, we investigate the important design parameters and the consequences of process variations through simulations. We use an isolated word recognition task with babble noise to evaluate the performance of the photonic reservoirs with respect to traditional software reservoir implementations, which are based on leaky hyperbolic tangent functions. Our results show that the use of coherent light in a well-tuned reservoir architecture offers significant performance benefits. The most important design parameters are the delay and the phase shift in the system's physical connections. With optimized values for these parameters, coherent semiconductor optical amplifier (SOA) reservoirs can achieve better results than traditional simulated reservoirs. We also show that process variations hardly degrade the performance, but amplifier noise can be detrimental. This effect must therefore be taken into account when designing SOA-based RC implementations.
Moreno, Vanessa; Rius, Manuel; Mora, José; Muriel Fernández, Miguel Ángel; Capmany, José
2013-01-01
In this paper, a novel method to generate ultrawideband (UWB) doublets is proposed and experimentally demonstrated, which is based on exploiting the cross-phase modulation in a semiconductor optical amplifier (SOA). The key component is an integrated SOA Mach-Zehnder interferometer pumped with an optical carrier modulated by a Gaussian pulse. The transfer function of the nonlinear conversion process leads to the generation of UWB doublet pulses by tuning the SOA currents to different values. ...
300 microJ noncollinear optical parametric amplifier in the visible at 1 kHz repetition rate.
Tzankov, Pancho; Zheng, Jiaan; Mero, Mark; Polli, Dario; Manzoni, Cristian; Cerullo, Giulio
2006-12-15
We demonstrate an order-of-magnitude energy scaling of a white-light seeded noncollinear optical parametric amplifier in the visible. The generated pulses, tunable between 520 and 650 nm with sub-25-fs duration, had energies up to 310 microJ with 20% blue-pump-to-signal energy conversion efficiency at 540 nm. This new ultrafast source will make possible numerous extreme nonlinear optics applications. As a first application, we demonstrate the generation of tunable vacuum ultraviolet pulses.
Application module of universal amplifier in education process
CHALOUPEK, Pavel
2013-01-01
This thesis deals with the teaching and implementation module for teaching in secondary schools and their role in education. Following the theory being discussed in relation to a valid educational program. Learning amplifier module implemented by the assignment to DPS. The activity of the amplifier module to simulate in Multisim simulation program. Next is made circuitry design in discrete amplifier module. There evaluated the feasibility and simulation of realizations amplifier module in sec...
Noise and saturation properties of semiconductor quantum dot optical amplifiers
DEFF Research Database (Denmark)
Berg, Tommy Winther; Mørk, Jesper
2002-01-01
We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved.......We present a detailed theoretical analysis of quantum dot optical amplifiers. Due to the presence of a reservoir of wetting layer states, the saturation and noise properties differ markedly from bulk or QW amplifiers and may be significantly improved....
Efficiency of low power audio amplifiers and loudspeakers
Burrow, SG; Grant, Duncan A
2001-01-01
In this paper we look at the load presented to audio amplifiers by real transducers. We consider the power losses in Class-AB and Class-D amplifier topologies, and determine that in order to predict efficiency it is necessary to consider the amplifier/transducer combination. The ability of the class-D amplifier to recycle quadrature load current offers new ways to improve efficiency.
A CONCEPTUAL FRAMEWORK FOR SUSTAINABLE POULTRY SUPPLY CHAIN MODEL
Directory of Open Access Journals (Sweden)
Mohammad SHAMSUDDOHA
2013-12-01
Full Text Available Now a day, sustainable supply chain is the crucially considerable matter for future focused industries. As a result, attention in supply chain management has increasingly amplified since the 1980s when firms discovered its benefits of mutual relationships within and beyond their own organization. This is why, concern researchers are trying hard to develop new theory or model which might help the corporate sector for achieving sustainability in their supply chains. This kind of reflection can be seen by the number of papers published and in particular by journal since 1980. The objectives of this paper are twofold. First, it offers a literature review on sustainable supply chain management taking papers published in last three decades. Second, it offers a conceptual sustainable supply chain process model in light of triple bottom line theory. The model has been developed by taking in-depth interview of an entrepreneur from a Poultry case industry in Bangladesh.
Nonlinear dynamics and complexity
Luo, Albert; Fu, Xilin
2014-01-01
This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.
Matched wideband low-noise amplifiers for radio astronomy.
Weinreb, S; Bardin, J; Mani, H; Jones, G
2009-04-01
Two packaged low noise amplifiers for the 0.3-4 GHz frequency range are described. The amplifiers can be operated at temperatures of 300-4 K and achieve noise temperatures in the 5 K range (radio astronomy systems or as i.f. amplifiers following superconducting mixers operating in the millimeter and submillimeter frequency range. PMID:19405681
Digital system provides superregulation of nanosecond amplifier-discriminator circuit
Forges, K. G.
1966-01-01
Feedback system employing a digital logic comparator to detect and correct amplifier drift provides stable gain characteristics for nanosecond amplifiers used in counting applications. Additional anticoincidence logic enables application of the regulation circuit to the amplifier and discriminator while they are mounted in an operable circuit.
The Dynamics of Semiconductor Optical Amplifiers – Modeling and Applications
DEFF Research Database (Denmark)
Mørk, Jesper; Nielsen, Mads Lønstrup; Berg, Tommy Winther
2003-01-01
The importance of semiconductor optical amplifiers is discussed. A semiconductor optical amplifier (SOA) is a semiconductor laser with anti-reflection coated facets that amplifies an injected light signal by means of stimulated emission. SOAs have a number of unique properties that open up...
Fiber optical parametric amplifiers in optical communication systems
DEFF Research Database (Denmark)
Marhic, Michel E.; Andrekson, Peter A.; Petropoulos, Periklis;
2015-01-01
The prospects for using fiber optical parametric amplifiers (OPAs) in optical communication systems are reviewed. Phase-insensitive amplifiers (PIAs) and phase-sensitive amplifiers (PSAs) are considered. Low-penalty amplification at/or near 1 Tb/s has been achieved, for both wavelength- and time...
Polarization of Tapered Semiconductor Travelling-Wave Amplifiers
Institute of Scientific and Technical Information of China (English)
焦明星; 张书练; 梁晋文
2001-01-01
The polarization of a tapered semi-conductor travelling-wave amplifier has been investigated with the transfer matrix method based on convective equation. It is shown that the apparent polarization mode competition exists, and polarization-independent tapered semiconductor travellingwave amplifiers can be obtained through the optimization of amplifier parameters.
Distributed nonlinear optical response
DEFF Research Database (Denmark)
Nikolov, Nikola Ivanov
2005-01-01
The purpose of the research presented here is to investigate basic physical properties in nonlinear optical materials with delayed or nonlocal nonlinearity. Soliton propagation, spectral broadening and the influence of the nonlocality or delay of the nonlinearity are the main focusses in the work....... The research presented in Chapter 3 and papers B and C is concerned with the properties and the stable dark soliton propagation and their bound states in nonlocal nonlinear optical media. It is shown that nonlocality of the nonlinearity induces attractive forces between solitons, that leads to the formation...... of bound states of out of phase bright solitons and dark solitons. Also, the newly introduced analogy between the nonlocal cubic nonlinear and the quadratic nonlinear media, presented in paper B and Chapter 3 is discussed. In particular it supplies intuitive physical meaning of the formation of solitons...
Asymmetric Wave Propagation Through Saturable Nonlinear Oligomers
Directory of Open Access Journals (Sweden)
Daniel Law
2014-10-01
Full Text Available In the present paper we consider nonlinear dimers and trimers (more generally, oligomers embedded within a linear Schrödinger lattice where the nonlinear sites are of saturable type. We examine the stationary states of such chains in the form of plane waves, and analytically compute their reflection and transmission coefficients through the nonlinear oligomer, as well as the corresponding rectification factors which clearly illustrate the asymmetry between left and right propagation in such systems. We examine not only the existence but also the dynamical stability of the plane wave states. Lastly, we generalize our numerical considerations to the more physically relevant case of Gaussian initial wavepackets and confirm that the asymmetry in the transmission properties also persists in the case of such wavepackets.
Robust Transceiver with Tomlinson-Harashima Precoding for Amplify-and-Forward MIMO Relaying Systems
Xing, Chengwen; Gao, Feifei; Wu, Yik-Chung
2011-01-01
In this paper, robust transceiver design with Tomlinson-Harashima precoding (THP) for multi-hop amplify-and-forward (AF) multiple-input multiple-output (MIMO) relaying systems is investigated. At source node, THP is adopted to mitigate the spatial intersymbol interference. However, due to its nonlinear nature, THP is very sensitive to channel estimation errors. In order to reduce the effects of channel estimation errors, a joint Bayesian robust design of THP at source, linear forwarding matrices at relays and linear equalizer at destination is proposed. With novel applications of elegant characteristics of multiplicative convexity and matrix-monotone functions, the optimal structure of the nonlinear transceiver is first derived. Based on the derived structure, the transceiver design problem reduces to a much simpler one with only scalar variables which can be efficiently solved. Finally, the performance advantage of the proposed robust design over non-robust design is demonstrated by simulation results.
Study of all-optical sampling using a semiconductor optical amplifier
Wu, Chen; Wang, Yongjun; Wang, Lina; Wang, Fu
2016-08-01
All-optical sampling is an important research content of all-optical signal processing. In recent years, the application of the semiconductor optical amplifier (SOA) in optical sampling has attracted lots of attention because of its small volume and large nonlinear coefficient. We propose an optical sampling model based on nonlinear polarization rotation effect of the SOA. The proposed scheme has the advantages of high sampling speed and small input pump power, and a transfer curve with good linearity was obtained through simulation. To evaluate the performance of sampling, we analyze the linearity and efficiency of sampling pulse considering the impact of pulse width and analog signal frequency. We achieve the sampling of analog signal to high frequency pulse and exchange the positions of probe light and pump light to study another sampling.
Nonlinear Transaction Pricing in the Securities Trading Value Chain
Burghardt, Matthias
2007-01-01
Most of the research on transaction costs in the market microstructure literature focuses on implicit transaction costs. Research on the design of price schedules for explicit transaction fees is rare. This paper analyzes and classifies different price schedules and discusses their application to the market transaction business. The discussion highlights design issues and the need for a structured approach for price schedule design in the context of market engineering. In order to get some...
Endogenous Contracts Under Bargaining in Competing Vertical Chains
Milliou, Chrysovalantou; Petrakis, Emmanuel; Vettas, Nikolaos
2003-01-01
We investigate the endogenous determination of contracts in competing vertical chains where upstream and downstream firms bargain first over the type of contract and then over the contract terms. Upstream firms always opt for non-linear contracts, which specify the input quantity and its total price. Downstream firms also opt for non-linear contracts, unless their bargaining power is low, in which case they prefer wholesale price contracts. While welfare is maximized under two-part tariffs, t...
Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities
Indian Academy of Sciences (India)
Antonella Fiacca; Nikolaos Matzakos; Nikolaos S Papageorgiou; Raffaella Servadei
2001-11-01
In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all $\\mathbb{R}$. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of $\\mathbb{R}$. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).
Analysis of multipass laser amplifier systems for storage laser media
International Nuclear Information System (INIS)
The performance characteristics of single pass and multipass storage laser amplifiers are presented and compared. The effects of the multipass amplifier parameters on the extraction characteristics are examined. For a wide range of conditions the multipass amplifier is found to provide high energy gain and high efficiency simultaneously. This is a significant advantage over the single pass laser amplifier. Finally, three specific storage laser amplifier systems, flashlamp pumped V:MgF2, XeF laser pumped Tm:Glass, and photolytically pumped Selenium, are examined. The performance characteristics for each of the three systems are calculated and compared
Analysis of multipass laser amplifier systems for storage laser media
Energy Technology Data Exchange (ETDEWEB)
Harvey, J.F.
1980-03-25
The performance characteristics of single pass and multipass storage laser amplifiers are presented and compared. The effects of the multipass amplifier parameters on the extraction characteristics are examined. For a wide range of conditions the multipass amplifier is found to provide high energy gain and high efficiency simultaneously. This is a significant advantage over the single pass laser amplifier. Finally, three specific storage laser amplifier systems, flashlamp pumped V:MgF/sub 2/, XeF laser pumped Tm:Glass, and photolytically pumped Selenium, are examined. The performance characteristics for each of the three systems are calculated and compared.
Characterization of a Common-Gate Amplifier Using Ferroelectric Transistors
Hunt, Mitchell; Sayyah, Rana; MacLeod, Todd C.; Ho, Fat D.
2011-01-01
In this paper, the empirical data collected through experiments performed using a FeFET in the common-gate amplifier circuit is presented. The FeFET common-gate amplifier was characterized by varying all parameters in the circuit, such as load resistance, biasing of the transistor, and input voltages. Due to the polarization of the ferroelectric layer, the particular behavior of the FeFET common-gate amplifier presents interesting results. Furthermore, the differences between a FeFET common-gate amplifier and a MOSFET common-gate amplifier are examined.
Characterization of a Common-Source Amplifier Using Ferroelectric Transistors
Hunt, Mitchell; Sayyah, Rana; MacLeond, Todd C.; Ho, Pat D.
2010-01-01
This paper presents empirical data that was collected through experiments using a FeFET in the established common-source amplifier circuit. The unique behavior of the FeFET lends itself to interesting and useful operation in this widely used common-source amplifier. The paper examines the effect of using a ferroelectric transistor for the amplifier. It also examines the effects of varying load resistance, biasing, and input voltages on the output signal and gives several examples of the output of the amplifier for a given input. The difference between a commonsource amplifier using a ferroelectric transistor and that using a MOSFET is addressed.
Solitons in an isolated helix chain
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Zolotaryuk, Alexander; Savin, A.V.
1997-01-01
propagating together with localized transverse thickening (bulge) and torsional stretching (untwisting) have been found. The stability properties of these (three-component) soliton solutions have been studied by using numerical techniques developed for seeking solitary-wave solutions in complex molecular...... as a generalization of the well-known one-dimensional Fermi-Pasta-Ulam model to include transverse degrees of freedom of the chain molecules. In the particular case of the alpha-helix molecular chain, the intermolecular interactions involved into the model are the point-point bonds connecting the first-, second......-, and third-nearest neighbors. The set of nonlinear field equations with respect to the longitudinal and transverse (torsional and radial) displacements of the chain molecules has been derived and treated. Stable nontopological soliton solutions which describe supersonic pulses of longitudinal compression...
Low power RF amplifier circuit for ion trap applications
Noriega, J. R.; García-Delgado, L. A.; Gómez-Fuentes, R.; García-Juárez, A.
2016-09-01
A low power RF amplifier circuit for ion trap applications is presented and described. The amplifier is based on a class-D half-bridge amplifier with a voltage mirror driver. The RF amplifier is composed of an RF class-D amplifier, an envelope modulator to ramp up the RF voltage during the ion analysis stage, a detector or amplitude demodulation circuit for sensing the output signal amplitude, and a feedback amplifier that linearizes the steady state output of the amplifier. The RF frequency is set by a crystal oscillator and the series resonant circuit is tuned to the oscillator frequency. The resonant circuit components have been chosen, in this case, to operate at 1 MHz. In testings, the class-D stage operated at a maximum of 78 mW at 1.1356 MHz producing 225 V peak.
Investigations of electronic amplifiers supplying a piezobimorph actuator
Milecki, Andrzej; Regulski, Roman
2016-10-01
Piezoelectric bending actuators, also known as bimorphs, are characterized by very good dynamic properties and by displacements in a range of a few millimeters. Therefore these actuators are used in a wide range of applications. However their usage is limited because they require supplying amplifiers with output voltage of about 200 V, which are rather expensive. This paper presents investigation results of such amplifiers with high voltage output. The model of a piezobending actuator is proposed and implemented in Matlab-Simulink software in order to simulate the behavior of the actuator supplied by the amplifiers. The simulation results are presented and compared with investigation results of high voltage amplifier used for supplying a piezoactuator. The influence of current limitation of operational amplifier on the actuator current is tested. Finally, a low cost audio power amplifier is proposed to control the piezobender actuator (as a cheaper alternative to the high-voltage amplifier) and its investigations results are presented in the paper.
Time amplifying techniques towards atomic time resolution
Institute of Scientific and Technical Information of China (English)
LI JingZhen
2009-01-01
High speed imaging technology has opened applications in many fields,such as collision,detonating,high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and electron dynamics inside atom shell.In principle,all of the transient processes need to be explained theoretically and,st the same time,the time amplifying technique is required for observations of these processes.The present review concerns the atomic time amplifying mechanism of optical information and the extremely-high speed imaging methods,which are expressed in terms of the short time amplifying techniques.It is well-known that for extremely-high speed imaging with the converter tube,the temporal resolution is in the order of sub-picosecond of the streak imaging,and the imaging frequency is 6×10~8-5×10~9 fps(frame per second)of the frame imaging.On the other hand,for the tubeless extremely-high speed imaging,the imaging frequency is 10~7-10~(14) fps,and its mechanism of forming high speed and framing could involve a lot of factors of the light under investigation,for instance,light speed,light parallelism,the parameters of light wave such as amplitude,phase,polarization and wavelength,and even quantum properties of photon.In the cascaded system of electromagnetic wave and particle wave,it is possible to simultaneously realize extremely-high resolution in time and space,which is higher than a kite resolution.Then it would be possible to break the limit of the Heisenberg uncertainty relation of the optical frequency band.
Time amplifying techniques towards atomic time resolution
Institute of Scientific and Technical Information of China (English)
无
2009-01-01
High speed imaging technology has opened applications in many fields,such as collision,detonating, high voltage discharge,disintegration and transfer of phonon and exciton in solid,photosynthesis primitive reaction,and electron dynamics inside atom shell.In principle,all of the transient processes need to be explained theoretically and,at the same time,the time amplifying technique is required for observations of these processes.The present review concerns the atomic time amplifying mechanism of optical information and the extremely-high speed imaging methods,which are expressed in terms of the short time amplifying techniques.It is well-known that for extremely-high speed imaging with the converter tube,the temporal resolution is in the order of sub-picosecond of the streak imaging,and the imaging frequency is 6×10 8 ―5×10 9 fps(frame per second)of the frame imaging.On the other hand,for the tubeless extremely-high speed imaging,the imaging frequency is 10 7 ―10 14 fps,and its mechanism of forming high speed and framing could involve a lot of factors of the light under investigation,for instance,light speed,light parallelism,the parameters of light wave such as amplitude,phase,polari- zation and wavelength,and even quantum properties of photon.In the cascaded system of electro- magnetic wave and particle wave,it is possible to simultaneously realize extremely-high resolution in time and space,which is higher than a kite resolution.Then it would be possible to break the limit of the Heisenberg uncertainty relation of the optical frequency band.
High sensitivity amplifier/discriminator for PWC's
International Nuclear Information System (INIS)
The facility support group at Fermilab is designing and building a general purpose beam chamber for use in several locations at the laboratory. This pwc has 128 wires per plane spaced 1 mm apart. An initial production of 25 signal planes is anticipated. In proportional chambers, the size of the signal depends exponentially on the charge stored per unit of length along the anode wire. As the wire spacing decreases, the capacitance per unit length decreases, thereby requiring increased applied voltage to restore the necessary charge per unit length. In practical terms, this phenomenon is responsible for difficulties in constructing chambers with less than 2 mm wire spacing. 1 mm chambers, therefore, are frequently operated very near to their breakdown point and/or a high gain gas containing organic compounds such as magic gas is used. This argon/iso-butane mixture has three drawbacks: it is explosive when exposed to the air, it leaves a residue on the wires after extended use and is costly. An amplifier with higher sensitivity would reduce the problems associated with operating chambers with small wire spacings and allow them to be run a safe margin below their breakdown voltage even with an inorganic gas mixture such as argon/CO2, this eliminating the need to use magic gas. Described here is a low cost amplifier with a usable threshold of less than 0.5 μA. Data on the performance of this amplifier/discriminator in operation on a prototype beam chamber are given. This data shows the advantages of the high sensitivity of this design
Undulations from amplified low frequency surface waves
Coutant, Antonin
2012-01-01
We study the scattering of gravity waves in longitudinal stationary flows. When the flow velocity becomes supercritical, counterflow propagating waves are amplified in such a way that, in the zero-frequency limit, the free surface develops an undu- lation, i.e., a zero-frequency wave of large amplitude with nodes located at specific places. From this, we show that the unperturbed flat surface is unstable against perturbations of arbitrary small amplitude. We then show that this instability also appears when treating low frequency waves by a stochastic ensemble. The relation between the generation of undulations and black hole radiation (the Hawking effect) is discussed.
Envelope tracking power amplifiers for wireless communications
Wang, Zhancang
2014-01-01
Envelope tracking technology is seen as the most promising efficiency enhancement technology for RF power amplifiers for 4G and beyond wireless communications. More and more organizations are investing and researching on this topic with huge potential in academic and commercial areas.This is the first book on the market to offer complete introduction, theory, and design considerations on envelope tracking for wireless communications. This resource presents you with a full introduction to the subject and covers underlying theory and practical design considerations.
Directory of Open Access Journals (Sweden)
Wei Khim Ng
2009-02-01
Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.
Semiflexible Chains at Surfaces: Worm-Like Chains and beyond
Directory of Open Access Journals (Sweden)
Jörg Baschnagel
2016-08-01
Full Text Available We give an extended review of recent numerical and analytical studies on semiflexible chains near surfaces undertaken at Institut Charles Sadron (sometimes in collaboration with a focus on static properties. The statistical physics of thin confined layers, strict two-dimensional (2D layers and adsorption layers (both at equilibrium with the dilute bath and from irreversible chemisorption are discussed for the well-known worm-like-chain (WLC model. There is mounting evidence that biofilaments (except stable d-DNA are not fully described by the WLC model. A number of augmented models, like the (super helical WLC model, the polymorphic model of microtubules (MT and a model with (strongly nonlinear flexural elasticity are presented, and some aspects of their surface behavior are analyzed. In many cases, we use approaches different from those in our previous work, give additional results and try to adopt a more general point of view with the hope to shed some light on this complex field.
Negative thermal conductivity of chains of rotors with mechanical forcing
IACOBUCCI, Alessandra; Legoll, Frederic; Olla, Stefano; Stoltz, Gabriel
2011-01-01
We consider chains of rotors subjected to both thermal and mechanical forcings,in a nonequilibrium steady-state. Unusual nonlinear profiles of temperature and velocities are observed in the system. In particular, the temperature is maximal in the center, which is an indication of the nonlocal behavior of the system. In spite of that, local equilibrium holds for long enough chains. Our numerical results also show that, when the mechanical forcing is strong enough, the energy current can be inc...
Chain-Chain Based Routing Protocol
Directory of Open Access Journals (Sweden)
Samia A Ali
2011-05-01
Full Text Available Wireless sensor network (WSN is an emerging technology for monitoring physical world. WSNs consist of large numbers of sensor nodes operated by battery mostly in harsh environment. Thus energy conservation is a primary issue for organization of these sensor nodes. Another crucial issue is the data delivery time by sensor nodes to the sink node, especially in Military, medical fields, and security monitoring systems where minimum delay is desirable. Number of protocols has been proposed in the literature for routing. One of such protocols is the cluster based routing protocol LEACH (low energy adaptive clustering hierarchy. LEACH protocol organizes WSN into a set of clusters and a periodic voting for cluster head is performed in order to be evenly distributed among all the sensors of the WSN. This periodical cluster head voting in LEACH, however, consumes an amount of non-negligible energy and other resources. For energy conservation, PEGASIS (power efficient gathering in sensor information systems a near optimal chain-based protocol has been proposed, however, it is faced with the challenge of long delay for the transmitted data. Another routing protocol called CCM (Chain-Cluster based Mixed routing, which is mainly a hybrid of LEACH and PEGASIS is proposed, the consumed energy increases as network size increases. In this paper, we propose an efficient routing protocol called CCBRP (Chain-Chain based routing protocol, it achieves both minimum energy consumption and minimum delay. The CCBRP protocol mainly divides a WSN into a number of chains (Greedy algorithm is used to form each chain as in PEGSIS protocol and runs in two phases. In the first phase, sensor nodes in each chain transmit data to their chain leader nodes in parallel. In the second phase, all chain leader nodes form a chain (also, using Greedy algorithm and choose randomly a leader node then all chain leader nodes send their data to this chosen leader node. This chosen leader node
Nonlinear Integrated Microwave Photonics
Marpaung, David; Eggleton, Benjamin J.
2013-01-01
Harnessing nonlinear optical effects in a photonic chip scale has been proven useful for a number of key applications in optical communications. Microwave photonics can also benefit from the adoption of such a technology, creating a new concept of nonlinear integrated microwave photonics. Here, we discuss the potential of on-chip nonlinear processing towards the creation of robust and multifunctional microwave photonic (MWP) processors. We also highlight key recent results in the field, inclu...
The nonlinear magnetoinductive dimer
Molina, Mario I.
2013-01-01
We examine a nonlinear magnetoinductive dimer and compute its linear and nonlinear symmetric, antisymmetric and asymmetric modes in closed-form, in the rotating-wave approximation. A linear stability analysis of these modes reveals that the asymmetric mode is always stable, for any allowed value of the coupling parameter and for both, hard and soft nonlinearity. A numerical computation of the dimer dynamics reveals a magnetic energy selftrapping whose threshold increases for increasing dimer ...
Nonlinear Electrodynamics and QED
Delphenich, David
2003-01-01
The limits of linear electrodynamics are reviewed, and possible directions of nonlinear extension are explored. The central theme is that the qualitative character of the empirical successes of quantum electrodynamics must be used as a guide for understanding the nature of the nonlinearity of electrodynamics at the subatomic level. Some established theories of nonlinear electrodynamics, namely, those of Mie, Born, and Infeld are presented in the language of the modern geometrical and topologi...
Yoneya, Akihiko; Watanabe, Akira
The full-digital audio amplifiers are advantageous with the points of its high power efficiency and its possibility of high fidelity due to the digital signal processing. With the full-digital amplifier, class-D amplifiers are used to drive the load with PWM signals produced from the source signal. Unfortunately, the signals are distorted when the PCM signals are converted to the PWM signals because the pulse-width modulation is a nonlinear conversion from the viewpoint of transient responses. This paper proposes a way to compensate the distortion caused by the pulse-width modulation. A feedforward compensation approach is used because of the simplicity of implementation. The distortion components are estimated with the source signals and its time-derivative signals and used to cancel out them by subtracting them from the source signals. A numerical example with two-tone test is performed to show the effectiveness of the proposed method. The distortion compensation scheme used here may be applicative to other applications.
Vertical coupling in multiple stacks quantum-dot semiconductor optical amplifiers
International Nuclear Information System (INIS)
The characteristics of vertically coupled multiple stacks quantum-dot (QD) semiconductor optical amplifiers (SOAs) are studied taking into account the effect of carrier coupling between adjacent stacks. We find that QD-SOAs that consist of a few numbers of stacks provide higher optical gain at lower applied current. Our analysis shows that the optical gain of the amplifier can be considerably enhanced due to short tunnelling lifetimes between adjacent stacks. Also, our analysis reveals that short coupling lifetimes can significantly reduce the transparency current and improve the uniformity of the active region since the net coupling rate is a linear function of the injection rate. Long coupling lifetime, on the other hand, produces non-linear and non-uniform coupling rates, which reduce the optical gain and increase the transparency current of the amplifier. We also find that the degradation in the unsaturated optical gain due to long coupling lifetimes is more severe in p-type doped QD-SOA compared with un-doped QD-SOA.
Coupling Two Different Nucleic Acid Circuits in an Enzyme-Free Amplifier
Directory of Open Access Journals (Sweden)
Andrew D. Ellington
2012-11-01
Full Text Available DNA circuits have proven to be useful amplifiers for diagnostic applications, in part because of their modularity and programmability. In order to determine whether different circuits could be modularly stacked, we used a catalytic hairpin assembly (CHA circuit to initiate a hybridization chain reaction (HCR circuit. In response to an input nucleic acid sequence, the CHA reaction accumulates immobilized duplexes and HCR elongates these duplexes. With fluorescein as a reporter each of these processes yielded 10-fold signal amplification in a convenient 96-well format. The modular circuit connections also allowed the output reporter to be readily modified to a G-quadruplex-DNAzyme that yielded a fluorescent signal.
Kono, Mitsuo
2010-01-01
A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.
Nonlinearity Induced Critical Coupling
Reddy, K Nireekshan; Gupta, S Dutta
2013-01-01
We study a critically coupled system (Opt. Lett., \\textbf{32}, 1483 (2007)) with a Kerr-nonlinear spacer layer. Nonlinearity is shown to inhibit null-scattering in a critically coupled system at low powers. However, a system detuned from critical coupling can exhibit near-complete suppression of scattering by means of nonlinearity-induced changes in refractive index. Our studies reveal clearly an important aspect of critical coupling as a delicate balance in both the amplitude and the phase relations, while a nonlinear resonance in dispersive bistability concerns only the phase.
Curvature-induced symmetry breaking in nonlinear Schrodinger models
DEFF Research Database (Denmark)
Gaididei, Yuri Borisovich; Mingaleev, S. F.; Christiansen, Peter Leth
2000-01-01
We consider a curved chain of nonlinear oscillators and show that the interplay of curvature and nonlinearity leads to a symmetry breaking when an asymmetric stationary state becomes energetically more favorable than a symmetric stationary state. We show that the energy of localized states...... decreases with increasing curvature, i.e., bending is a trap for nonlinear excitations. A violation of the Vakhitov-Kolokolov stability criterion is found in the case where the instability is due to the softening of the Peierls internal mode....
Analysis of nonlinear behavior of loudspeakers using the instantaneous frequency
DEFF Research Database (Denmark)
Huang, Hai; Jacobsen, Finn
2003-01-01
It is well know that the weakest link in a sound reproduction chain is the loudspeaker. The most significant effect on the sound quality is nonlinear distortion of loudspeakers. Many methods are applied to analyze the nonlinear distortion of loudspeakers. Almost all of the methods are based on the...... loudspeakers. It will also be helpful for compensating for the nonlinearities and for improving the quality of sound reproduction. [Work supported by Sino-Danish International Co-operative Project, No. AM13: 66 and DANIDA (Denmark).]...
Silicon on Insulator MESFETs for RF Amplifiers.
Wilk, Seth J; Balijepalli, Asha; Ervin, Joseph; Lepkowski, William; Thornton, Trevor J
2010-03-01
CMOS compatible, high voltage SOI MESFETs have been fabricated using a standard 3.3V CMOS process without any changes to the process flow. A 0.6μm gate length device operates with a cut-off frequency of 7.3GHz and a maximum oscillation frequency of 21GHz. There is no degradation in device performance up to its breakdown voltage, which greatly exceeds that of CMOS devices on the same process. Other figures of merit of relevance to RF front-end design are presented, including the maximum stable gain and noise figure. An accurate representation of the device in SPICE has been developed using the commercially available TOM3 model. Using the SOI MESFET model, a source degenerated low noise RF amplifier targeting operation near 1GHz has been designed. The amplifier was fabricated on a PCB board and operates at 940MHz with a minimum NF of 3.8dB and RF gain of 9.9dB while only consuming 5mW of DC power. PMID:20657816
Ultrastable low-noise current amplifier
Drung, Dietmar; Becker, Ulrich; Scherer, Hansjörg; Ahlers, Franz Josef
2014-01-01
An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MOhm reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is extremely stable versus time, temperature and current amplitude within the full dynamic range of +/-5 nA. A low noise level of 2.4 fA/sqrt(Hz) helps to keep averaging times low at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Typically, within one day after calibration, the uncertainty contribution from short-term fluctuations of the transresistance is below one part in 10^7. The long-term stability is expected to be better than one part in 10^5 over a year. A ...
Discrete Quantum Markov Chains
Faigle, Ulrich
2010-01-01
A framework for finite-dimensional quantum Markov chains on Hilbert spaces is introduced. Quantum Markov chains generalize both classical Markov chains with possibly hidden states and existing models of quantum walks on finite graphs. Quantum Markov chains are based on Markov operations that may be applied to quantum systems and include quantum measurements, for example. It is proved that quantum Markov chains are asymptotically stationary and hence possess ergodic and entropic properties. With a quantum Markov chain one may associate a quantum Markov process, which is a stochastic process in the classical sense. Generalized Markov chains allow a representation with respect to a generalized Markov source model with definite (but possibly hidden) states relative to which observables give rise to classical stochastic processes. It is demonstrated that this model allows for observables to violate Bell's inequality.
Nonlinear theory of dust lattice mode coupling in dust crystals
Kourakis, I; Kourakis, Ioannis; Shukla, Padma Kant
2004-01-01
Quasi-crystals formed by charged mesoscopic dust grains (dust lattices), observed since hardly a decade ago, are an exciting paradigm of a nonlinear chain. In laboratory discharge experiments, these quasi-lattices are formed spontaneously in the sheath region near a negative electrode, usually at a levitated horizontal equilibrium configuration where gravity is balanced by an electric field. It is long known (and experimentally confirmed) that dust-lattices support linear oscillations, in the longitudinal (acoustic mode) as well as in the transverse, in plane (acoustic-) or off-plane (optic-like mode) directions. Either due to the (typically Yukawa type) electrostatic inter-grain interaction forces or to the (intrinsically nonlinear) sheath environment, nonlinearity is expected to play an important role in the dynamics of these lattices. Furthermore, the coupling between the different modes may induce coupled nonlinear modes. Despite this evidence, the elucidation of the nonlinear mechanisms governing dust cr...
The Nonlinear Field Space Theory
Mielczarek, Jakub; Trześniewski, Tomasz
2016-08-01
In recent years the idea that not only the configuration space of particles, i.e. spacetime, but also the corresponding momentum space may have nontrivial geometry has attracted significant attention, especially in the context of quantum gravity. The aim of this letter is to extend this concept to the domain of field theories, by introducing field spaces (i.e. phase spaces of field values) that are not affine spaces. After discussing the motivation and general aspects of our approach we present a detailed analysis of the prototype (quantum) Nonlinear Field Space Theory of a scalar field on the Minkowski background. We show that the nonlinear structure of a field space leads to numerous interesting predictions, including: non-locality, generalization of the uncertainty relations, algebra deformations, constraining of the maximal occupation number, shifting of the vacuum energy and renormalization of the charge and speed of propagation of field excitations. Furthermore, a compact field space is a natural way to implement the "Principle of finiteness" of physical theories, which once motivated the Born-Infeld theory. Thus the presented framework has a variety of potential applications in the theories of fundamental interactions (e.g. quantum gravity), as well as in condensed matter physics (e.g. continuous spin chains), and can shed new light on the issue of divergences in quantum field theories.
L.J. Pegler (Lee)
2009-01-01
textabstractThe co-ordination of global production and trade within value chains has amplified debates concerning the impact of globalisation on labour, especially for developing countries. Whilst many development agencies argue for value chain insertion and upgrading as optimistic development pathw
Phonon-assisted nonlinear optical processes in ultrashort-pulse pumped optical parametric amplifiers
Oleksandr Isaienko; István Robel
2016-01-01
Optically active phonon modes in ferroelectrics such as potassium titanyl phosphate (KTP) and potassium titanyl arsenate (KTA) in the ~7–20 THz range play an important role in applications of these materials in Raman lasing and terahertz wave generation. Previous studies with picosecond pulse excitation demonstrated that the interaction of pump pulses with phonons can lead to efficient stimulated Raman scattering (SRS) accompanying optical parametric oscillation or amplification processes (OP...
Nonlinear properties of quantum dot semiconductor optical amplifiers at 1.3 μm: errata
Institute of Scientific and Technical Information of China (English)
D. Bimberg; C. Meuer; M. L(a)mmlin; S. Liebich; J. Kim; E. Varene; A. Kovsh; I. Krestnikov; G. Eisenstein
2009-01-01
@@ The authors regret that one of the coauthors was inad-vertently omitted in the previous paper[1]. E. Varene was a member of the Institut für Festkorperphysik at the Technische Universitat Berlin and contributed to the results on cross-phase modulation.
Direct coupled amplifiers using field effect transistors
International Nuclear Information System (INIS)
The concept of the uni-polar field effect transistor (P.E.T.) was known before the invention of the bi-polar transistor but it is only recently that they have been made commercially. Being produced as yet only in small quantities, their price imposes a restriction on use to circuits where their peculiar properties can be exploited to the full. One such application is described here where the combination of low voltage drift and relatively low input leakage current are necessarily used together. One of the instruments used to control nuclear reactors has a logarithmic response to the mean output current from a polarised ionisation chamber. The logarithmic signal is then differentiated electrically, the result being displayed on a meter calibrated to show the reactor divergence or doubling time. If displayed in doubling time the scale is calibrated reciprocally. Because of the wide range obtained in the logarithmic section and the limited supply voltage, an output of 1 volt per decade change in ionisation current is used. Differentiating this gives a current of 1.5 x 10-8 A for p.s.D. (20 sec. doubling time) in the differentiating amplifier. To overcome some of the problems of noise due to statistical variations in input current, the circuit design necessitates a resistive path to ground at the amplifier input of 20 M.ohms. A schematic diagram is shown. 1. It is evident that a zero drift of 1% can be caused by a leakage current of 1.5 x 10-10 A or an offset voltage of 3 mV at the amplifier input. Although the presently used electrometer valve is satisfactory from the point of view of grid current, there have been sudden changes in grid to grid voltage (the valve is a double triode) of up to 10 m.V. It has been found that a pair of F.E.T's. can be used to replace the electrometer valve so long as care is taken in correct balance of the two devices. An investigation has been made into the characteristics of some fourteen devices to see whether those with very different
Sarvestani Alireza
2010-01-01
Abstract A scaling model is presented to analyze the nonlinear rheology of unentangled polymer melts filled with high concentration of small spherical particles. Assuming the majority of chains to be reversibly adsorbed to the surface of the particles, we show that the emergence of nonlinearity in the viscoelastic response of the composite system subjected to a 2D shear flow results from stretching of the adsorbed chains and increasing desorption rate of the adsorbed segments due to the impos...
DEFF Research Database (Denmark)
Clausen, Carl A. Balslev; Christiansen, Peter Leth; Torner, L.;
1999-01-01
We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear...
Nonlinearity in nanomechanical cantilevers
DEFF Research Database (Denmark)
Villanueva Torrijo, Luis Guillermo; Karabalin, R. B.; Matheny, M. H.;
2013-01-01
. In this article, we report the first highly controlled measurements of the nonlinear response of nanomechanical cantilevers using an ultralinear detection system. This is performed for an extensive range of devices to probe the validity of Euler-Bernoulli theory in the nonlinear regime. We find that its...
Friction and Nonlinear Dynamics
Manini, N.; Braun, O. M.; E. Tosatti; Guerra, R.; Vanossi, A.
2016-01-01
The nonlinear dynamics associated with sliding friction forms a broad interdisciplinary research field that involves complex dynamical processes and patterns covering a broad range of time and length scales. Progress in experimental techniques and computational resources has stimulated the development of more refined and accurate mathematical and numerical models, capable of capturing many of the essentially nonlinear phenomena involved in friction.
Friction and nonlinear dynamics
Manini, N.; Braun, O. M.; Tosatti, E.; Guerra, R.; Vanossi, A.
2016-07-01
The nonlinear dynamics associated with sliding friction forms a broad interdisciplinary research field that involves complex dynamical processes and patterns covering a broad range of time and length scales. Progress in experimental techniques and computational resources has stimulated the development of more refined and accurate mathematical and numerical models, capable of capturing many of the essentially nonlinear phenomena involved in friction.
Measurements and simulations of non-linear noise re-distribution in an SOA
DEFF Research Database (Denmark)
Öhman, Filip; Tromborg, Bjarne; Mørk, Jesper;
2005-01-01
Measurements and numerical simulations of the noise statistics after a semiconductor optical amplifier (SOA) demonstrate non-linear noise re-distribution. The re-distribution, which depends on self-modulation due to gain saturation and carrier dynamics, show a strong power and bandwidth dependence...... and can be important for SOA based regenerators....
Gender Differences on the Use of Amplifiers in Academic Writings
Institute of Scientific and Technical Information of China (English)
申利芬
2012-01-01
This study aims to investigate the use of amplifiers in term of gender and disciplinary groups in academic research arti⁃cles, which is based on the British Academic Written English Corpus (BAWE).18 amplifiers were examined across two dimen⁃sions:gender and disciplinary groups. The results show amplifiers are more common in males’ academic writings than in those of females in general, amplifiers are used more often in AH discipline. However, not all amplifiers show significant gender differ⁃ences between men and women. Six words show a significant difference between male and female writers:pretty, by far, perfect⁃ly, quite, a great deal, totally, which are used more often by males. However, the interesting is in LS discipline, most amplifiers are used more often by female than male writers and males tend to use by far more frequently than females.
ANALYSIS OF INTERNALLY GENERATED NOISE OF BIOELECTRIC AMPLIFIERS
Institute of Scientific and Technical Information of China (English)
Mashhour Mustafa; Bani Amer
2003-01-01
This paper deals with internally generated noise of bioelectric amplifiers that are usually used for processing of bioelectric events. The main purpose of this paper is to present a procedure for analysis of the effects of internal noise generated by the active circuits and to evaluate the output noise of the author's new designed bioelectric amplifier that caused by internal effects to the amplifier circuit itself in order to compare it with the noise generated by conventional amplifiers. The obtained analysis results of internally generated noise showed that the total output noise of bioelectric active circuits does not increase when some of their resistors have a larger value. This behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors. Moreover, the new designed bioelectric amplifier has an output noise less than that for conventional amplifiers. The obtained analysis results were also experimentally verified and the final conclusions were drawn.
Measurement of microdosimetric spectra using an amplifier with logarithmic response
International Nuclear Information System (INIS)
A 3-1/2 decade logarithmic pulse amplifier was developed for use in microdosimetry. A block diagram of the instrument is given. The input shaping amplifier is designed to accept output pulses from a charge sensitive preamplifier with a maximum full scale amplitude of 8 volts. Output of the shaping amplifier is a bipolar, positive lobe leading RC shaped pulse with a maximum linear range approximately 200 millivolts. Following the logarithmic converter is a voltage amplifier which is used to increase the signal level before it is applied through the linear gate to the output buffer-amplifier. The signal at the output connector is a positive pulse compatible with most conventional pulse height analyzers. The gain of the linear amplifier is adjustable over 10 to 1 range by means of front panel controls
Josephson parametric amplifiers for the ADMX-HF experiment
Malnou, Maxime; Palken, Daniel; Hilton, Gene; Vale, Leila; Lehnert, Konrad
2016-03-01
Dark matter search in the ADMX-HF experiment aims at detecting power generated by the axion-photon conversion, of a few hundred of yoctowatts, in the 4 - 12 GHz band. The sensitivity of detection directly depends on the amplifier noise temperature, and therefore requires state of the art microwave amplifiers. In contrast to amplifiers with dissipation on-chip, superconducting Josephson parametric amplifiers (JPA) reach and even circumvent the quantum limit. Over the past years, we have developed JPAs fabricated with arrays of superconducting quantum interference devices. Their gain, bandwidth and tunability are particularly well suited for efficient amplification in the band of interest. In this talk we will present numerical modeling of the behavior of our amplifiers, along with the first results from new designs that cover the 4-12 GHz band. Finally, we will present the ongoing work to increase the gain-bandwidth product and gain stability of our amplifiers.
Nonlinear optics and photonics
He, Guang S
2015-01-01
This book provides a comprehensive presentation on most of the major topics in nonlinear optics and photonics, with equal emphasis on principles, experiments, techniques, and applications. It covers many major new topics including optical solitons, multi-photon effects, nonlinear photoelectric effects, fast and slow light , and Terahertz photonics. Chapters 1-10 present the fundamentals of modern nonlinear optics, and could be used as a textbook with problems provided at the end of each chapter. Chapters 11-17 cover the more advanced topics of techniques and applications of nonlinear optics and photonics, serving as a highly informative reference for researchers and experts working in related areas. There are also 16 pages of color photographs to illustrate the visual appearances of some typical nonlinear optical effects and phenomena. The book could be adopted as a textbook for both undergraduates and graduate students, and serve as a useful reference work for researchers and experts in the fields of physics...
Enhanced nonlinear interactions in quantum optomechanics via mechanical amplification
Lemonde, Marc-Antoine; Didier, Nicolas; Clerk, Aashish A.
2016-04-01
The quantum nonlinear regime of optomechanics is reached when nonlinear effects of the radiation pressure interaction are observed at the single-photon level. This requires couplings larger than the mechanical frequency and cavity-damping rate, and is difficult to achieve experimentally. Here we show how to exponentially enhance the single-photon optomechanical coupling strength using only additional linear resources. Our method is based on using a large-amplitude, strongly detuned mechanical parametric drive to amplify mechanical zero-point fluctuations and hence enhance the radiation pressure interaction. It has the further benefit of allowing time-dependent control, enabling pulsed schemes. For a two-cavity optomechanical set-up, we show that our scheme generates photon blockade for experimentally accessible parameters, and even makes the production of photonic states with negative Wigner functions possible. We discuss how our method is an example of a more general strategy for enhancing boson-mediated two-particle interactions and nonlinearities.
Energy Technology Data Exchange (ETDEWEB)
Moraes, Marco Antonio Proenca Vieira de; Pugliesi, Reinaldo [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)
1996-07-01
The objective of the present work was to establish simple criteria to choose the best combination of electronic modules to achieve an adequate high resolution gamma spectrometer. Linearity, live time correction factors and softwares of a gamma spectrometric system composed by a Hp Ge detector have been studied by using several kinds of spectrometric amplifiers: Canberra 2021, Canberra 2025, Ortec 673 and Tennelec 244 and the MCA cards Ortec and Nucleus. The results showed low values of integral non-linearity for all spectrometric amplifiers connected to the Ortec and Nucleus boards. The MCA card should be able to correct amplifier dead time for 17 kcps count rates. (author)
Low-noise amplifiers for satellite communications
Whelehan, J.
1984-02-01
It is pointed out that over the past several years significant advances have been made in the overall capability of both microwave and mm-wave receivers. This is particularly apparent in the telecom market. Integral parts of advanced receiver technology are low-noise receivers. The advances currently being achieved in low-noise technology are partly based on developments in GaAs semiconductor technology. The development of high-cutoff-frequency beam lead mixer diodes has led to the development of mm-wave low-noise mixers with excellent low-noise capability. The advanced techniques are now being employed in field-deployable systems. Low noise is an important factor in satellite communications applications. Attention is given to C-band fixed satellite service, C-band parametric amplifiers, C-band FET, and X band, the Ku band, and the 30/20 GHz band.
The spectacular human nose: An amplifier of individual quality?
Åse Kristine Rognmo Mikalsen; Ivar Folstad; Nigel Gilles Yoccoz; Bruno Laeng
2014-01-01
Amplifiers are signals that improve the perception of underlying differences in quality. They are cost free and advantageous to high quality individuals, but disadvantageous to low quality individuals, as poor quality is easier perceived because of the amplifier. For an amplifier to evolve, the average fitness benefit to the high quality individuals should be higher than the average cost for the low quality individuals. The human nose is, compared to the nose of most other primates, extraordi...
Modeling and design techniques for RF power amplifiers
Raghavan, Arvind; Laskar, Joy
2008-01-01
The book covers RF power amplifier design, from device and modeling considerations to advanced circuit design architectures and techniques. It focuses on recent developments and advanced topics in this area, including numerous practical designs to back the theoretical considerations. It presents the challenges in designing power amplifiers in silicon and helps the reader improve the efficiency of linear power amplifiers, and design more accurate compact device models, with faster extraction routines, to create cost effective and reliable circuits.
Supply Chain Management og Supply Chain costing
DEFF Research Database (Denmark)
Nielsen, Steen; Mortensen, Ole
2002-01-01
Formålet med denne artikel er at belyse de muligheder som ligger i at integrere virksomhedens økonomiske styring med begrebet Supply Chain Management (SCM). Dette søges belyst ved først at beskrive den teoretiske ramme, hvori SCM indgår. Herefter analyseres begrebet Supply Chain Costing (SCC) som...... Århus. Et resultat er, at via begrebet Supply Chain Costing skabes der mulighed for at måle logistikkædens aktiviteter i kr./øre. Anvendelsen af denne information har også strategisk betydning for at kunne vælge kunde og leverandør. Ved hjælp af integrationen skabes der også helt nye mulighed...
Understanding the Chain Fountain
Biggins, John Simeon
2013-01-01
If a chain is initially at rest in a beaker at a height h1 above the ground, and the end of the chain is pulled over the rim of the beaker and down towards the ground and then released, the chain will spontaneously "flow" out of the beaker under gravity. Furthermore, if h1 is sufficient, the beads do not simply drag over the edge of the beaker but form a fountain reaching a height h2 above it. We show that the formation of a fountain requires that the beads come into motion not only by being pulled upwards by the part of the chain immediately above the pile, but also by being pushed upwards by an anomalous reaction force from the pile of stationary chain. We propose possible origins for this force, argue that its magnitude will be proportional to the square of the chain velocity, and predict and verify experimentally that h2 is proportional to h1.
Nonlinear Damping Identification in Nonlinear Dynamic System Based on Stochastic Inverse Approach
Directory of Open Access Journals (Sweden)
S. L. Han
2012-01-01
Full Text Available The nonlinear model is crucial to prepare, supervise, and analyze mechanical system. In this paper, a new nonparametric and output-only identification procedure for nonlinear damping is studied. By introducing the concept of the stochastic state space, we formulate a stochastic inverse problem for a nonlinear damping. The solution of the stochastic inverse problem is designed as probabilistic expression via the hierarchical Bayesian formulation by considering various uncertainties such as the information insufficiency in parameter of interests or errors in measurement. The probability space is estimated using Markov chain Monte Carlo (MCMC. The applicability of the proposed method is demonstrated through numerical experiment and particular application to a realistic problem related to ship roll motion.
Zhou, Qian
2011-01-01
The dissertation analyses food waste in global supply chain. From the related managerial literature, the process of supply chain operation, from agriculture, manufacturing, warehouses, retailers to customers are explained clearly. Then the reasons and characteristics of food wastes in any point of food supply chain are analyzed. From some case studies and questionnaire investigation, some corresponding methods to reduce food waste are put forward in the following. Lastly, in terms of method s...
Sukkel, W.; Hommes, M.
2009-01-01
In their pursuit of growth and professionalisation, the Dutch organic sector focuses primarily on market development. But how do you stimulate the market for organic foods? This is the subject of many research projects concerning market, consumer preferences and the supply chain. These projects focus specifically at consumer purchasing behaviour, product development, supply chain formation and minimising cost price. As a rule, this research takes place in close cooperation with chain actors
Meca, Ana; Timmer, Judith
2008-01-01
In this chaper, we have reviewed and surveyed the literature on supply chain collaboration. As mentioned above, the game theory models that include cooperative behaviour among retailers seem to be a natural framework to model cooperation (collaboration) in supply chains that consist of a supplier and a finite number of retailers. Various researchers in this area have already adopted several cooperative models dealing with supply chain coordination, and it is expected to see many more in the n...
Sustainable Supply Chain Management
Geentjens, Marlies
2013-01-01
This project investigates the phenomena Sustainable Supply Chain Management. The point of departure is Supply Chain Management, which we analyse in order to lock into an understanding of the development that occur when implementing sustainability. In the quest for higher understanding of the interlocking mechanisms of supply chain management, we combine a theoretical approach to the developmnent of sustainability with some relevant case-examples (mainly depicting IKEA). This focal point g...
Directory of Open Access Journals (Sweden)
Vieraşu, T.
2011-01-01
Full Text Available In this article I will go through three main logistics components, which are represented by: transportation, inventory and facilities, and the three secondary logistical components: information, production location, price and how they determine performance of any supply chain. I will discuss then how these components are used in the design, planning and operation of a supply chain. I will also talk about some obstacles a supply chain manager may encounter.
Vieraşu, T.; Bălăşescu, M.
2011-01-01
In this article I will go through three main logistics components, which are represented by: transportation, inventory and facilities, and the three secondary logistical components: information, production location, price and how they determine performance of any supply chain. I will discuss then how these components are used in the design, planning and operation of a supply chain. I will also talk about some obstacles a supply chain manager may encounter.
Saturation effects in degenerate phase sensitive fiber optic parametric amplifiers
Kakande J.; Parmigiani F.; Slavik R.; Gruner-Nielsen L.; Jakobsen D.; Herstrom S.; Petropoulos P.; Richardson D.J.
2010-01-01
We experimentally study saturation effects in degenerate phase sensitive amplifiers, revealing and explaining a gain regime suitable for all-optical signal processing functions such as phase regeneration.
Nylon Sleeve for Cavity Amplifier Holds Tuning Despite Heat
Derr, Lloyd
1964-01-01
The problem: Detuning of cavity amplifiers with change in temperature. This results in deterioration of the performance of the amplifier at its design frequency. In cavity amplifiers and filters it is desirable that constant performance be maintained regardless of thermal changes. These changes often cause an "off resonance shift" in a cavity filter and a deterioration of performance in a cavity amplifier. The solution: Mount the tuning probe in a nylon sleeve. Thermal expansion and contraction of the nylon nullifies unwanted capacitive and inductive changes in the resonant elements.
Breathers in oscillator chains with Hertzian interactions
James, Guillaume; Cuevas, Jesus
2011-01-01
We prove nonexistence of breathers (spatially localized and time-periodic oscillations) for a class of Fermi-Pasta-Ulam lattices representing an uncompressed chain of beads interacting via Hertz's contact forces. We then consider the setting in which an additional on-site potential is present, motivated by the Newton's cradle under the effect of gravity. Using both direct numerical computations and a simplified asymptotic model of the oscillator chain, the so-called discrete p-Schr\\"odinger (DpS) equation, we show the existence of discrete breathers and study their spectral properties and mobility. Due to the fully nonlinear character of Hertzian interactions, breathers are found to be much more localized than in classical nonlinear lattices and their motion occurs with less dispersion. In addition, we study numerically the excitation of a traveling breather after an impact at one end of a semi-infinite chain. This case is well described by the DpS equation when local oscillations are faster than binary colli...
Exact self-similar solitary waves and collisions in nonlinear optical media
Institute of Scientific and Technical Information of China (English)
Li Hua-Mei
2008-01-01
This paper analyses bright and dark spatial self-similar waves propagation and collision in graded-index nonlinear waveguidc amplifiers with self-focusing and self-defocnsing Kerr nonlinearities.It finds an appropriate transformation for the first time such that the nonlinear Schr'6dinger equation (NLSE) with varying coefficients transform into standard NLSE. It obtains one-solitonlike, two-solitonlike and multi-solitonlike self-similar wave solutions by using the transformation. Furthermore, it analyses the features of the self-similar waves and their collisions.
粒子群优化的RBF神经网络功放行为模型%Behavior models based on the PSORBF Algorithm for power amplifier
Institute of Scientific and Technical Information of China (English)
高明明; 南敬昌; 黄丽娜; 马众
2013-01-01
研究功率放大器的非线性行为模型建模问题。功率放大器既呈现非线性，又呈现记忆效应，为了对具有记忆效应的非线性功率放大器进行精确的行为模型建模，提出了基于粒子群优化的RBF神经网络射频功放行为模型。利用freescale半导体晶体管MRF6S21140器件模型及设计的电路从ADS中导出输入输出数据，对射频功率放大器模型进行了仿真实现，得出了输出电压幅度的拟合曲线以及误差曲线。仿真结果表明：PSO-RBF射频功放模型能够获得较好的精度，能够很好的描述射频功率放大器的非线性和记忆效应，为有效解决精确建立射频功放行为建模的问题提供了参考方法。% Study the power amplifier nonlinear behavior model. Power amplifier presents nonlinear and memory effect. In order to have accurate power nonlinear amplifier behavior model, this study proposes the RBF neural network power amplifier behavior model based on the particle swarm optimization. It derives the input and output data from the RF power amplifier, by using free scale semiconductor device model and MRF6S21140 transistor circuits in the ADS. The results of simulation conclude the amplitude of the output voltage fitting curve and error curve. The results of the simulation indicates that PSO-RBF RF power amplifier model can achieve good precision, and can descript the RF power amplifier nonlinear and memory effects very well. This study provides a reference method of RF power amplifier behavior model.