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Sample records for semiconductor external cavity

  1. Waveguide based external cavity semiconductor lasers

    NARCIS (Netherlands)

    Oldenbeuving, Ruud; Klein, E.J.; Offerhaus, Herman L.; Lee, Christopher James; Verhaegen, M.; Boller, Klaus J.

    2012-01-01

    We report on progress of the project waveguide based external cavity semiconductor laser (WECSL) arrays. Here we present the latest results on our efforts to mode lock an array of tunable, external cavity semiconductor lasers.

  2. Identification of amplitude and timing jitter in external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper; Kroh, Marcel

    2004-01-01

    We theoretically and experimentally investigate the dynamics of external-cavity mode-locked semiconductor lasers, focusing on stability properties, optimization of pulsewidth and timing jitter. A new numerical approach allows to clearly separate timing and amplitude jitter....

  3. Numerical investigations on the performance of external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper

    2004-01-01

    The performance of an external-cavity mode-locked semiconductor laser is analyzed theoretically and numerically. Passive mode-locking is described using a fully-distributed time-domain model including fast effects, spectral hole burning and carrier heating. We provide optimization rules in order ...

  4. Instability of stationary lasing and self-starting mode locking in external-cavity semiconductor lasers

    International Nuclear Information System (INIS)

    Smetanin, Igor V; Vasil'ev, Petr P

    2009-01-01

    Parameters of external-cavity semiconductor lasers, when the stationary lasing becomes unstable, were analysed within the framework of a theoretical model of self-starting mode locking. In this case, a train of ultrashort pulses can be generated due to intrinsic nonlinearities of the laser medium. A decisive role of the transverse optical field nonuniformity, pump rate, and gain spectral bandwidth in the development of the instability of stationary lasing was demonstrated. (control of laser radiation parameters)

  5. Analysis of timing jitter in external-cavity mode-locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Mørk, Jesper

    2006-01-01

    We develop a comprehensive theoretical description of passive mode-locking in external-cavity mode-locked semiconductor lasers based on a fully distributed time-domain approach. The model accounts for the dispersion of both gain and refractive index, nonlinear gain saturation from ultrafast...... processes, self-phase modulation, and spontaneous emission noise. Fluctuations of the mode-locked pulses are characterized from the fully distributed model using direct integration of noise-skirts in the phase-noise spectrum and the soliton perturbations introduced by Haus. We implement the model in order...

  6. Piezo activated mode tracking system for widely tunable mode-hop-free external cavity mid-IR semiconductor lasers

    Science.gov (United States)

    Wysocki, Gerard (Inventor); Tittel, Frank K. (Inventor); Curl, Robert F. (Inventor)

    2010-01-01

    A widely tunable, mode-hop-free semiconductor laser operating in the mid-IR comprises a QCL laser chip having an effective QCL cavity length, a diffraction grating defining a grating angle and an external cavity length with respect to said chip, and means for controlling the QCL cavity length, the external cavity length, and the grating angle. The laser of claim 1 wherein said chip may be tuned over a range of frequencies even in the absence of an anti-reflective coating. The diffraction grating is controllably pivotable and translatable relative to said chip and the effective QCL cavity length can be adjusted by varying the injection current to the chip. The laser can be used for high resolution spectroscopic applications and multi species trace-gas detection. Mode-hopping is avoided by controlling the effective QCL cavity length, the external cavity length, and the grating angle so as to replicate a virtual pivot point.

  7. High-Power Hybrid Mode-Locked External Cavity Semiconductor Laser Using Tapered Amplifier with Large Tunability

    Directory of Open Access Journals (Sweden)

    Andreas Schmitt-Sody

    2008-01-01

    Full Text Available We report on hybrid mode-locked laser operation of a tapered semiconductor amplifier in an external ring cavity, generating pulses as short as 0.5 ps at 88.1 MHz with an average power of 60 mW. The mode locking is achieved through a combination of a multiple quantum well saturable absorber (>10% modulation depth and an RF current modulation. This designed laser has 20 nm tuning bandwidth in continuous wave and 10 nm tuning bandwidth in mode locking around 786 nm center wavelength at constant temperature.

  8. Multistate intermittency on the route to chaos of a semiconductor laser subjected to optical feedback from a long external cavity.

    Science.gov (United States)

    Choi, Daeyoung; Wishon, Michael J; Chang, C Y; Citrin, D S; Locquet, A

    2018-01-01

    We observe experimentally two regimes of intermittency on the route to chaos of a semiconductor laser subjected to optical feedback from a long external cavity as the feedback level is increased. The first regime encountered corresponds to multistate intermittency involving two or three states composed of several combinations of periodic, quasiperiodic, and subharmonic dynamics. The second regime is observed for larger feedback levels and involves intermittency between period-doubled and chaotic regimes. This latter type of intermittency displays statistical properties similar to those of on-off intermittency.

  9. Liquid detection with InGaAsP semiconductor lasers having multiple short external cavities.

    Science.gov (United States)

    Zhu, X; Cassidy, D T

    1996-08-20

    A liquid detection system consisting of a diode laser with multiple short external cavities (MSXC's) is reported. The MSXC diode laser operates single mode on one of 18 distinct modes that span a range of 72 nm. We selected the modes by setting the length of one of the external cavities using a piezoelectric positioner. One can measure the transmission through cells by modulating the injection current at audio frequencies and using phase-sensitive detection to reject the ambient light and reduce 1/f noise. A method to determine regions of single-mode operation by the rms of the output of the laser is described. The transmission data were processed by multivariate calibration techniques, i.e., partial least squares and principal component regression. Water concentration in acetone was used to demonstrate the performance of the system. A correlation coefficient of R(2) = 0.997 and 0.29% root-mean-square error of prediction are found for water concentration over the range of 2-19%.

  10. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  11. Mode locking of an external cavity asymmetric quantum-well GaAs/AlGaAs semiconductor laser

    International Nuclear Information System (INIS)

    Vasil'ev, Petr P; Kan, H; Ohta, H; Hiruma, T; Tanaka, K A

    2006-01-01

    A theoretical model of the optical gain in asymmetric GaAs/AlGaAs quantum-well lasers is developed. It is demonstrated that the emission spectrum of asymmetric GaAs/AlGaAs quantum-well lasers is much broader than that of standard quantum-well lasers. The experimental samples of such lasers and superluminescent diodes with the emission bandwidth exceeding 50 nm are fabricated. Wavelength tunable ultrashort pulses with duration of 1-2 ps at repetition rates of 0.4-1 GHz are obtained by active mode locking of an external cavity laser. (lasers)

  12. Optical cavity furnace for semiconductor wafer processing

    Science.gov (United States)

    Sopori, Bhushan L.

    2014-08-05

    An optical cavity furnace 10 having multiple optical energy sources 12 associated with an optical cavity 18 of the furnace. The multiple optical energy sources 12 may be lamps or other devices suitable for producing an appropriate level of optical energy. The optical cavity furnace 10 may also include one or more reflectors 14 and one or more walls 16 associated with the optical energy sources 12 such that the reflectors 14 and walls 16 define the optical cavity 18. The walls 16 may have any desired configuration or shape to enhance operation of the furnace as an optical cavity 18. The optical energy sources 12 may be positioned at any location with respect to the reflectors 14 and walls defining the optical cavity. The optical cavity furnace 10 may further include a semiconductor wafer transport system 22 for transporting one or more semiconductor wafers 20 through the optical cavity.

  13. Semiconductor micro cavities: half light, half matter

    International Nuclear Information System (INIS)

    Baumberg, Jeremy J.

    2003-01-01

    Quantum wells sandwiched tightly between two mirrors can be used to make a new type of laser that can amplify light more than any other known material. What do you get if you cross light with matter? It is a question that fascinates today's researchers in quantum optoelectronics, who want to see how far the physical states of the world can be intertwined. Although we have a good understanding of the quantum ingredients of optics and solids - photons and atoms - it turns out that assembling these building blocks in deliberately unfamiliar ways can lead to what is new and often quite unexpected behaviour. Consider 'quantum wells', which form the basis of modern semiconductor lasers. First developed in the 1980s, they lie at the heart of optical-communication and optical-storage technologies such as DVD players and they now have a global market of over 10bn British Pounds. Quantum wells consist of a thin sheet of crystalline semiconductor sandwiched between two sheets of another semiconductor. The outer layers squash the wavefunctions of electrons within the central sheet, increasing the electrons' energy and their interaction with light. Engineers can control the colour of the light emitted by the laser simply by adjusting the energy levels within the central sheet, which acts as a potential well. But this bug-sized playground for electrons has not just had technological ramifications. It has also spawned an enormous variety of new physics, including the quantum Hall effect, which can be used as a fundamental standard for measuring the ratio between the charge on the electron and the Planck constant. Over the last ten years researchers have also become increasingly keen to incorporate quantum wells into what are known as 'semiconductor micro cavities'. Physicists have found that these painstakingly layered materials can be used to create new quantum states that resemble superfluids and can be used in interferometric quantum devices. In the March issue of Physics

  14. A compact chaotic laser device with a two-dimensional external cavity structure

    International Nuclear Information System (INIS)

    Sunada, Satoshi; Adachi, Masaaki; Fukushima, Takehiro; Shinohara, Susumu; Arai, Kenichi; Harayama, Takahisa

    2014-01-01

    We propose a compact chaotic laser device, which consists of a semiconductor laser and a two-dimensional (2D) external cavity for delayed optical feedback. The overall size of the device is within 230 μm × 1 mm. A long time delay sufficient for chaos generation can be achieved with the small area by the multiple reflections at the 2D cavity boundary, and the feedback strength is controlled by the injection current to the external cavity. We experimentally demonstrate that a variety of output properties, including chaotic output, can be selectively generated by controlling the injection current to the external cavity.

  15. Optical cavity cooling of mechanical modes of a semiconductor nanomembrane

    DEFF Research Database (Denmark)

    Usami, Koji; Naesby, A.; Bagci, Tolga

    2012-01-01

    Mechanical oscillators can be optically cooled using a technique known as optical-cavity back-action. Cooling of composite metal–semiconductor mirrors, dielectric mirrors and dielectric membranes has been demonstrated. Here we report cavity cooling of mechanical modes in a high-quality-factor and......Mechanical oscillators can be optically cooled using a technique known as optical-cavity back-action. Cooling of composite metal–semiconductor mirrors, dielectric mirrors and dielectric membranes has been demonstrated. Here we report cavity cooling of mechanical modes in a high...

  16. Ring cavity surface emitting semiconductor lasers

    International Nuclear Information System (INIS)

    Mujagic, E.

    2010-01-01

    Quantum cascade lasers (QCLs) are electrically driven semiconductor lasers, which have undergone a steady improvement since the first demonstration in 1994. These are now well established as reliable sources of coherent light in the mid-infrared (MIR) and terahertz (THz)range of the electromagnetic spectrum (3-300 μm). The rapid progress of this type of lasers is based on a high degree of freedom in tailoring the emission wavelength within a large variety of semiconductor heterostructure designs and materials. These properties have attracted the attention of various applications such as gas analysis, chemical sensing, spectral imaging and free-space telecommunication. In order to improve the selectivity, sensitivity and efficiency of today's sensor systems, high optical power, continuous wave and room temperature performance, single-mode operation and low divergence optical beams, are highly desirable qualities of a compact laser source in this field of research. Since all of these features cannot be provided by a conventional edge-emitting device at the same time, research has put focus on the development of surface emitting devices. Nowadays, the vertical cavity surface emitting lasers (VCSELs) are the most prominent representative for this type of light emitters. With its capability of producing narrow circular beams, the feasibility of two-dimensional arrays and on-wafer testing, such a coherent light source results in a reduction of the fabrication effort and production costs. Since the radiation in QCLs is strictly polarized normal to the epitaxial layer plane, fabrication of VCSELs based on QC structures is not viable. The subject of this work is the design and realization of 'ring cavity surface emitting lasers' (ring-CSELs). This type of lasers employs a circular ring cavity and a resonant distributed feedback (DFB) surface grating. Ring-CSELs were fabricated on the basis of MIR and THz QC structures, which cover a wavelength range from 4 μm to 93

  17. Decoherence in semiconductor cavity QED systems due to phonon couplings

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Mørk, Jesper

    2014-01-01

    We investigate the effect of electron-phonon interactions on the coherence properties of single photons emitted from a semiconductor cavity QED (quantum electrodynamics) system, i.e., a quantum dot embedded in an optical cavity. The degree of indistinguishability, governing the quantum mechanical...

  18. Lithographic wavelength control of an external cavity laser with a silicon photonic crystal cavity-based resonant reflector.

    Science.gov (United States)

    Liles, Alexandros A; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of a new design for external cavity hybrid lasers consisting of a III-V semiconductor optical amplifier (SOA) with fiber reflector and a photonic crystal (PhC)-based resonant reflector on SOI. The silicon reflector is composed of an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB.

  19. Porous photonic crystal external cavity laser biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Qinglan [Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Peh, Jessie; Hergenrother, Paul J. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Cunningham, Brian T. [Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

    2016-08-15

    We report the design, fabrication, and testing of a photonic crystal (PC) biosensor structure that incorporates a porous high refractive index TiO{sub 2} dielectric film that enables immobilization of capture proteins within an enhanced surface-area volume that spatially overlaps with the regions of resonant electromagnetic fields where biomolecular binding can produce the greatest shifts in photonic crystal resonant wavelength. Despite the nanoscale porosity of the sensor structure, the PC slab exhibits narrowband and high efficiency resonant reflection, enabling the structure to serve as a wavelength-tunable element of an external cavity laser. In the context of sensing small molecule interactions with much larger immobilized proteins, we demonstrate that the porous structure provides 3.7× larger biosensor signals than an equivalent nonporous structure, while the external cavity laser (ECL) detection method provides capability for sensing picometer-scale shifts in the PC resonant wavelength caused by small molecule binding. The porous ECL achieves a record high figure of merit for label-free optical biosensors.

  20. Modeling and experimental verification of laser self-mixing interference phenomenon with the structure of two-external-cavity feedback

    Science.gov (United States)

    Chen, Peng; Liu, Yuwei; Gao, Bingkun; Jiang, Chunlei

    2018-03-01

    A semiconductor laser employed with two-external-cavity feedback structure for laser self-mixing interference (SMI) phenomenon is investigated and analyzed. The SMI model with two directions based on F-P cavity is deduced, and numerical simulation and experimental verification were conducted. Experimental results show that the SMI with the structure of two-external-cavity feedback under weak light feedback is similar to the sum of two SMIs.

  1. Crystallization of Organic Semiconductor Molecules in Nanosized Cavities

    DEFF Research Database (Denmark)

    Milita, Silvia; Dionigi, Chiara; Borgatti, Francesco

    2008-01-01

    The crystallization of an organic semiconductor, viz., tetrahexil-sexithiophene (H4T6) molecules, confined into nanosized cavities of a self-organized polystyrene beads template, has been investigated by means of in situ grazing incidence X-ray diffraction measurements, during the solvent evapora...

  2. Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

    Science.gov (United States)

    Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and sidemode suppression ratio of more than 25 dB.

  3. A mode-locked external-cavity quantum-dot laser with a variable repetition rate

    International Nuclear Information System (INIS)

    Wu Jian; Jin Peng; Li Xin-Kun; Wei Heng; Wu Yan-Hua; Wang Fei-Fei; Chen Hong-Mei; Wu Ju; Wang Zhan-Guo

    2013-01-01

    A mode-locked external-cavity laser emitting at 1.17-μm wavelength using an InAs/GaAs quantum-dot gain medium and a discrete semiconductor saturable absorber mirror is demonstrated. By changing the external-cavity length, repetition rates of 854, 912, and 969 MHz are achieved respectively. The narrowest −3-dB radio-frequency linewidth obtained is 38 kHz, indicating that the laser is under stable mode-locking operation. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  4. Tunable high-power narrow-spectrum external-cavity diode laser based on tapered amplifier at 668 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Erbert, G.; Sumpf, B.

    2010-01-01

    A 668 nm tunable high-power narrow-spectrum diode laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The laser system is tunable from 659 to 675 nm. As high as 1.38 W output power is obtained at 668.35 nm. The emission spectral bandwidth is less than...

  5. Broadband tunability of gain-flattened quantum-well semiconductor lasers with an external grating

    International Nuclear Information System (INIS)

    Mittelstein, M.; Mehuys, D.; Yariv, A.; Sarfaty, R.; Ungar, J.E.

    1989-01-01

    Semiconductor injection lasers are known to be tunable over a range of order kΒ · T. Quantum-well lasers, in particular, are shown to exhibit flattened, broadband gain spectra at a particular pumping condition. The gain requirement for a grating-tuned external cavity configuration is examined and is applied to a semiconductor quantum-well laser with an optimized length of gain region. The coupled-cavity formalism is employed to examine the conditions for continuous tuning. The possible tuning range of double-heterostructure lasers is compared to that of quantum-well lasers. The predicted broadband tunability of quantum-well lasers is confirmed experimentally by grating-tuning of uncoated lasers exceeding 120 nm, with single, longitudinal mode output power exceeding 300 mW

  6. Controlling spontaneous emission dynamics in semiconductor micro cavities

    Science.gov (United States)

    Gayral, B.

    Spontaneous emission of light can be controlled, cavity quantum electrodynamics tells us, and many experiments in atomic physics demonstrated this fact. In particular, coupling an emitter to a resonant photon mode of a cavity can enhance its spontaneous emission rate: this is the so-called Purcell effect. Though appealing it might seem to implement these concepts for the benefit of light-emitting semiconductor devices, great care has to be taken as to which emitter/cavity system should be used. Semiconductor quantum boxes prove to be good candidates for witnessing the Purcell effect. Also, low volume cavities having a high optical quality in other words a long photon storage time are required. State-of-the-art fabrication techniques of such cavities are presented and discussed.We demonstrate spontaneous emission rate enhancement for InAs/GaAs quantum boxes in time-resolved and continuous-wave photoluminescence experiments. This is done for two kinds of cavities, namely GaAs/AlAs micropillars (global enhancement by a factor of 5), and GaAs microdisks (global enhancement by a factor of 20). Prospects for lasers, light-emitting diodes and single photon sources based on the Purcell effect are discussed. L'émission spontanée de lumière peut être contrôlée, ainsi que nous l'enseigne l'électrodynamique quantique en cavité, ce fait a été démontré expérimentalement en physique atomique. En particulier, coupler un émetteur à un mode photonique résonnant d'une cavité peut exalter son taux d'émission spontanée : c'est l'effet Purcell. Bien qu'il semble très prometteur de mettre en pratique ces concepts pour améliorer les dispositifs semi-conducteurs émetteurs de lumière, le choix du système émetteur/cavité est crucial. Nous montrons que les boîtes quantiques semi-conductrices sont des bons candidats pour observer l'effet Purcell. Il faut par ailleurs des cavités de faible volume ayant une grande qualité optique en d'autres mots un long temps de

  7. Continuous wave room temperature external ring cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Revin, D. G., E-mail: d.revin@sheffield.ac.uk; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W. [Physics and Astronomy Department, The University of Sheffield, S3 7RH Sheffield (United Kingdom); Hempler, N.; Maker, G. T.; Malcolm, G. P. A. [M Squared Lasers Ltd., G20 0SP Glasgow (United Kingdom)

    2015-06-29

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm{sup −1} is realized by the incorporation of a diffraction grating into the cavity.

  8. Continuous wave room temperature external ring cavity quantum cascade laser

    International Nuclear Information System (INIS)

    Revin, D. G.; Hemingway, M.; Vaitiekus, D.; Cockburn, J. W.; Hempler, N.; Maker, G. T.; Malcolm, G. P. A.

    2015-01-01

    An external ring cavity quantum cascade laser operating at ∼5.2 μm wavelength in a continuous-wave regime at the temperature of 15 °C is demonstrated. Out-coupled continuous-wave optical powers of up to 23 mW are observed for light of one propagation direction with an estimated total intra-cavity optical power flux in excess of 340 mW. The uni-directional regime characterized by the intensity ratio of more than 60 for the light propagating in the opposite directions was achieved. A single emission peak wavelength tuning range of 90 cm −1 is realized by the incorporation of a diffraction grating into the cavity

  9. Crisis route to chaos in semiconductor lasers subjected to external optical feedback

    Science.gov (United States)

    Wishon, Michael J.; Locquet, Alexandre; Chang, C. Y.; Choi, D.; Citrin, D. S.

    2018-03-01

    Semiconductor lasers subjected to optical feedback have been intensively used as archetypical testbeds for high-speed (sub-ns) and high-dimensional nonlinear dynamics. By simultaneously extracting all the dynamical variables, we demonstrate that for larger current, the commonly named "quasiperiodic" route is in fact based on mixed external-cavity solutions that lock the oscillation frequency of the intensity, voltage, and separation in optical frequency through a mechanism involving successive rejections along the unstable manifold of an antimode. We show that chaos emerges from a crisis resulting from the inability to maintain locking as the unstable manifold becomes inaccessible.

  10. Evolution of the Novalux extended cavity surface-emitting semiconductor laser (NECSEL)

    Science.gov (United States)

    McInerney, John G.

    2016-03-01

    Novalux Inc was an enterprise founded by Aram Mooradian in 1998 to commercialise a novel electrically pumped vertical extended cavity semiconductor laser platform, initially aiming to produce pump lasers for optical fiber telecommunication networks. Following successful major investment in 2000, the company developed a range of single- and multi-mode 980 nm pump lasers emitting from 100-500 mW with excellent beam quality and efficiency. This rapid development required solution of several significant problems in chip and external cavity design, substrate and DBR mirror optimization, thermal engineering and mode selection. Output coupling to single mode fiber was exceptional. Following the collapse of the long haul telecom market in late 2001, a major reorientation of effort was undertaken, initially to develop compact 60-100 mW hybrid monolithically integrated pumplets for metro/local amplified networks, then to frequency-doubled blue light emitters for biotech, reprographics and general scientific applications. During 2001-3 I worked at Novalux on a career break from University College Cork, first as R&D Director managing a small group tasked with producing new capabilities and product options based on the NECSEL platform, including high power, pulsed and frequency doubled versions, then in 2002 as Director of New Product Realization managing the full engineering team, leading the transition to frequency doubled products.

  11. Resonator modes and mode dynamics for an external cavity-coupled laser array

    Science.gov (United States)

    Nair, Niketh; Bochove, Erik J.; Aceves, Alejandro B.; Zunoubi, Mohammad R.; Braiman, Yehuda

    2015-03-01

    Employing a Fox-Li approach, we derived the cold-cavity mode structure and a coupled mode theory for a phased array of N single-transverse-mode active waveguides with feedback from an external cavity. We applied the analysis to a system with arbitrary laser lengths, external cavity design and coupling strengths to the external cavity. The entire system was treated as a single resonator. The effect of the external cavity was modeled by a set of boundary conditions expressed by an N-by-N frequency-dependent matrix relation between incident and reflected fields at the interface with the external cavity. The coupled mode theory can be adapted to various types of gain media and internal and external cavity designs.

  12. Characteristics of the Single-Longitudinal-Mode Planar-Waveguide External Cavity Diode Laser at 1064 nm

    Science.gov (United States)

    Numata, Kenji; Alalusi, Mazin; Stolpner, Lew; Margaritis, Georgios; Camp, Jordan; Krainak, Michael

    2014-01-01

    We describe the characteristics of the planar-waveguide external cavity diode laser (PW-ECL). To the best of our knowledge, it is the first butterfly-packaged 1064 nm semiconductor laser that is stable enough to be locked to an external frequency reference. We evaluated its performance from the viewpoint of precision experiments. Using a hyperfine absorption line of iodine, we suppressed its frequency noise by a factor of up to 104 at 10 mHz. The PWECL's compactness and low cost make it a candidate to replace traditional Nd:YAG nonplanar ring oscillators and fiber lasers in applications that require a single longitudinal mode.

  13. Pulse properties of external cavity mode locked semiconductor lasers

    DEFF Research Database (Denmark)

    Mulet, Josep; Kroh, Marcel; Mørk, Jesper

    2006-01-01

    picosecond duration with more than 30 dB trailing pulse suppression. The limiting factors to the device performance are investigated on the basis of a fully-distributed time-domain model.We find that ultrafast gain dynamics effectively reduce the pulse-shaping strength and inhibit the generation...

  14. Non-markovian effects in semiconductor cavity QED: Role of phonon-mediated processes

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Nielsen, Torben Roland; Lodahl, Peter

    We show theoretically that the non-Markovian nature of the carrier-phonon interaction influences the dynamical properties of a semiconductor cavity QED system considerably, leading to asymmetries with respect to detuning in carrier lifetimes. This pronounced phonon effect originates from the pola......We show theoretically that the non-Markovian nature of the carrier-phonon interaction influences the dynamical properties of a semiconductor cavity QED system considerably, leading to asymmetries with respect to detuning in carrier lifetimes. This pronounced phonon effect originates from...... the polaritonic quasi-particle nature of the carrier-photon system interacting with the phonon reservoir....

  15. Breath analysis using external cavity diode lasers: a review

    Science.gov (United States)

    Bayrakli, Ismail

    2017-04-01

    Most techniques that are used for diagnosis and therapy of diseases are invasive. Reliable noninvasive methods are always needed for the comfort of patients. Owing to its noninvasiveness, ease of use, and easy repeatability, exhaled breath analysis is a very good candidate for this purpose. Breath analysis can be performed using different techniques, such as gas chromatography mass spectrometry (MS), proton transfer reaction-MS, and selected ion flow tube-MS. However, these devices are bulky and require complicated procedures for sample collection and preconcentration. Therefore, these are not practical for routine applications in hospitals. Laser-based techniques with small size, robustness, low cost, low response time, accuracy, precision, high sensitivity, selectivity, low detection limit, real-time, and point-of-care detection have a great potential for routine use in hospitals. In this review paper, the recent advances in the fields of external cavity lasers and breath analysis for detection of diseases are presented.

  16. High sensitivity detection of NO2 employing cavity ringdown spectroscopy and an external cavity continuously tunable quantum cascade laser.

    Science.gov (United States)

    Rao, Gottipaty N; Karpf, Andreas

    2010-09-10

    A trace gas sensor for the detection of nitrogen dioxide based on cavity ringdown spectroscopy (CRDS) and a continuous wave external cavity tunable quantum cascade laser operating at room temperature has been designed, and its features and performance characteristics are reported. By measuring the ringdown times of the cavity at different concentrations of NO(2), we report a sensitivity of 1.2 ppb for the detection of NO(2) in Zero Air.

  17. Cavity-polariton interaction mediated by coherent acoustic phonons in semiconductor microcavities

    DEFF Research Database (Denmark)

    de Lima, Mauricio; Hey, Rudolf; Santos, Paul

    The strong coupling between excitons in a quantum well (QW) and photons in a semiconductor microcavity leads to the formation of quasi-particles known as cavity-polaritons. In this contribution, we investigate their interaction with coherent acoustic phonons in the form of surface acoustic waves...

  18. Fast tunable blazed MEMS grating for external cavity lasers

    Science.gov (United States)

    Tormen, Maurizio; Niedermann, Philippe; Hoogerwerf, Arno; Shea, Herbert; Stanley, Ross

    2017-11-01

    Diffractive MEMS are interesting for a wide range of applications, including displays, scanners or switching elements. Their advantages are compactness, potentially high actuation speed and in the ability to deflect light at large angles. We have designed and fabricated deformable diffractive MEMS grating to be used as tuning elements for external cavity lasers. The resulting device is compact, has wide tunability and a high operating speed. The initial design is a planar grating where the beams are free-standing and attached to each other using leaf springs. Actuation is achieved through two electrostatic comb drives at either end of the grating. To prevent deformation of the free-standing grating, the device is 10 μm thick made from a Silicon on Insulator (SOI) wafer in a single mask process. At 100V a periodicity tuning of 3% has been measured. The first resonant mode of the grating is measured at 13.8 kHz, allowing high speed actuation. This combination of wide tunability and high operating speed represents state of the art in the domain of tunable MEMS filters. In order to improve diffraction efficiency and to expand the usable wavelength range, a blazed version of the deformable MEMS grating has been designed. A key issue is maintaining the mechanical properties of the original device while providing optically smooth blazed beams. Using a process based on anisotropic KOH etching, blazed gratings have been obtained and preliminary characterization is promising.

  19. An absolute distance interferometer with two external cavity diode lasers

    International Nuclear Information System (INIS)

    Hartmann, L; Meiners-Hagen, K; Abou-Zeid, A

    2008-01-01

    An absolute interferometer for length measurements in the range of several metres has been developed. The use of two external cavity diode lasers allows the implementation of a two-step procedure which combines the length measurement with a variable synthetic wavelength and its interpolation with a fixed synthetic wavelength. This synthetic wavelength is obtained at ≈42 µm by a modulation-free stabilization of both lasers to Doppler-reduced rubidium absorption lines. A stable reference interferometer is used as length standard. Different contributions to the total measurement uncertainty are discussed. It is shown that the measurement uncertainty can considerably be reduced by correcting the influence of vibrations on the measurement result and by applying linear regression to the quadrature signals of the absolute interferometer and the reference interferometer. The comparison of the absolute interferometer with a counting interferometer for distances up to 2 m results in a linearity error of 0.4 µm in good agreement with an estimation of the measurement uncertainty

  20. 3.1 W narrowband blue external cavity diode laser

    Science.gov (United States)

    Peng, Jue; Ren, Huaijin; Zhou, Kun; Li, Yi; Du, Weichuan; Gao, Songxin; Li, Ruijun; Liu, Jianping; Li, Deyao; Yang, Hui

    2018-03-01

    We reported a high-power narrowband blue diode laser which is suitable for subsequent nonlinear frequency conversion into the deep ultraviolet (DUV) spectral range. The laser is based on an external cavity diode laser (ECDL) system using a commercially available GaN-based high-power blue laser diode emitting at 448 nm. Longitudinal mode selection is realized by using a surface diffraction grating in Littrow configuration. The diffraction efficiency of the grating was optimized by controlling the polarization state of the laser beam incident on the grating. A maximum optical output power of 3.1 W in continuous-wave operation with a spectral width of 60 pm and a side-mode suppression ratio (SMSR) larger than 10 dB at 448.4 nm is achieved. Based on the experimental spectra and output powers, the theoretical efficiency and output power of the subsequent nonlinear frequency conversion were calculated according to the Boyd- Kleinman theory. The single-pass conversion efficiency and output power is expected to be 1.9×10-4 and 0.57 mW, respectively, at the 3.1 W output power of the ECDL. The high-power narrowband blue diode laser is very promising as pump source in the subsequent nonlinear frequency conversion.

  1. Novel Cavities in Vertical External Cavity Surface Emitting Lasers for Emission in Broad Spectral Region by Means of Nonlinear Frequency Conversion

    Science.gov (United States)

    Lukowski, Michal L.

    Optically pumped semiconductor vertical external cavity surface emitting lasers (VECSEL) were first demonstrated in the mid 1990's. Due to the unique design properties of extended cavity lasers VECSELs have been able to provide tunable, high-output powers while maintaining excellent beam quality. These features offer a wide range of possible applications in areas such as medicine, spectroscopy, defense, imaging, communications and entertainment. Nowadays, newly developed VECSELs, cover the spectral regions from red (600 nm) to around 5 microm. By taking the advantage of the open cavity design, the emission can be further expanded to UV or THz regions by the means of intracavity nonlinear frequency generation. The objective of this dissertation is to investigate and extend the capabilities of high-power VECSELs by utilizing novel nonlinear conversion techniques. Optically pumped VECSELs based on GaAs semiconductor heterostructures have been demonstrated to provide exceptionally high output powers covering the 900 to 1200 nm spectral region with diffraction limited beam quality. The free space cavity design allows for access to the high intracavity circulating powers where high efficiency nonlinear frequency conversions and wavelength tuning can be obtained. As an introduction, this dissertation consists of a brief history of the development of VECSELs as well as wafer design, chip fabrication and resonator cavity design for optimal frequency conversion. Specifically, the different types of laser cavities such as: linear cavity, V-shaped cavity and patented T-shaped cavity are described, since their optimization is crucial for transverse mode quality, stability, tunability and efficient frequency conversion. All types of nonlinear conversions such as second harmonic, sum frequency and difference frequency generation are discussed in extensive detail. The theoretical simulation and the development of the high-power, tunable blue and green VECSEL by the means of type I

  2. Chaos-based communications using semiconductor lasers subject to feedback from an integrated double cavity

    International Nuclear Information System (INIS)

    Tronciu, V Z; Mirasso, Claudio R; Colet, Pere

    2008-01-01

    We report the results of numerical investigations of the dynamical behaviour of an integrated device composed of a semiconductor laser and a double cavity that provides optical feedback. Due to the influence of the feedback, under the appropriate conditions, the system displays chaotic behaviour appropriate for chaos-based communications. The optimal conditions for chaos generation are identified. It is found that the double cavity feedback requires lower feedback strengths for developing high complexity chaos when compared with a single cavity. The synchronization of two unidirectional coupled (master-slave) systems and the influence of parameters mismatch on the synchronization quality are also studied. Finally, examples of message encoding and decoding are presented and discussed

  3. Anticipated chaos in a nonsymmetric coupled external-cavity-laser system

    International Nuclear Information System (INIS)

    Rees, Paul; Spencer, Paul S.; Pierce, Iestyn; Sivaprakasam, S.; Shore, K. Alan

    2003-01-01

    We explain how the anticipation of chaos in a coupled external cavity laser system described by Sivaprakasam, Shahverdiev, Spencer, and Shore [Phys. Rev. Lett. 87, 154101 (2001)] is obtained. We show that the external cavity induces the required symmetry breaking necessary for the existence of a time delay between the synchronized output of the two laser diodes. The inclusion of a detuning between the two lasers causes one laser to anticipate the chaotic dynamics of the other

  4. Center frequency shift and reduction of feedback in directly modulated external cavity lasers

    DEFF Research Database (Denmark)

    Schiellerup, G.; Pedersen, Rune Johan Skullerud; Olesen, H.

    1989-01-01

    It is shown experimentally and theoretically that a center frequency shift occurs when an external cavity laser is directly modulated. The shift can be observed even when the frequency deviation is small compared to the roundtrip frequency of the external cavity and can qualitatively be explained...... by a reduction in the effective feedback level due to modulation. The frequency shift was measured as a function of modulation frequency and current, and frequency shifts up to 350 MHz were observed...

  5. Mode-locked Pr3+-doped silica fiber laser with an external cavity

    DEFF Research Database (Denmark)

    Shi, Yuan; Poulsen, Christian; Sejka, Milan

    1994-01-01

    We present a Pr3+-doped silica-based fiber laser mode-locked by using a linear external cavity with a vibrating mirror. Stable laser pulses with a FWHM of less than 44 ps, peak power greater than 9 W, and repetition rate up to 100 MHz are obtained. The pulse width versus cavity mismatch ΔL and pump...... power have been investigated. With a short piece of nonlinear fiber included in the external cavity, laser pulses of 45 ps have been measured...

  6. Spectral properties of a broad-area diode laser with off-axis external-cavity feedback

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2013-01-01

    Spectral properties, both the optical spectrum and the intensity noise spectrum, of a broad-area diode laser with off-axis external-cavity feedback are presented. We show that the optical spectrum of the diode laser system is shifted to longer wavelengths due to the external-cavity feedback....... The intensity noise spectrum of the diode laser shows that the intensity noise is increased strongly by the external-cavity feedback. External-cavity modes are excited in the external cavity even in the off-axis configuration. The peak spacing of the intensity noise spectrum shows that single roundtrip external......-cavity modes are excited. We believe that the four-wave mixing process in the broad-area diode laser is responsible for the establishment of the external-cavity mode....

  7. Physical model for the incoherent writing/erasure of cavity solitons in semiconductor optical amplifiers.

    Science.gov (United States)

    Barbay, S; Kuszelewicz, R

    2007-09-17

    We present a physical mechanism that explains the recent observations of incoherent writing and erasure of Cavity Solitons in a semiconductor optical amplifier [S. Barbay et al, Opt. Lett. 31, 1504-1506 (2006)]. This mechanism allows to understand the main observations of the experiment. In particular it perfectly explains why writing and erasure are possible as a result of a local perturbation in the carrier density, and why a delay is observed along with the writing process. Numerical simulations in 1D are performed and show very good qualitative agreement with the experimental observations.

  8. Observation of modulation speed enhancement, frequency modulation suppression, and phase noise reduction by detuned loading in a coupled-cavity semiconductor laser

    OpenAIRE

    Vahala, Kerry; Paslaski, Joel; Yariv, Amnon

    1985-01-01

    Simultaneous direct modulation response enhancement, phase noise (linewidth) reduction, and frequency modulation suppression are produced in a coupled-cavity semiconductor laser by the detuned loading mechanism.

  9. Lead-chalcogenide mid-infrared vertical external cavity surface emitting lasers with improved threshold: Theory and experiment

    Science.gov (United States)

    Fill, Matthias; Debernardi, Pierluigi; Felder, Ferdinand; Zogg, Hans

    2013-11-01

    Mid-infrared Vertical External Cavity Surface Emitting Lasers (VECSEL) based on narrow gap lead-chalcogenide (IV-VI) semiconductors exhibit strongly reduced threshold powers if the active layers are structured laterally for improved optical confinement. This is predicted by 3-d optical calculations; they show that lateral optical confinement is needed to counteract the anti-guiding features of IV-VIs due to their negative temperature dependence of the refractive index. An experimental proof is performed with PbSe quantum well based VECSEL grown on a Si-substrate by molecular beam epitaxy and emitting around 3.3 μm. With proper mesa-etching, the threshold intensity is about 8-times reduced.

  10. Lead-chalcogenide mid-infrared vertical external cavity surface emitting lasers with improved threshold: Theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Fill, Matthias [ETH Zurich, Laser Spectroscopy and Sensing Lab, 8093 Zurich (Switzerland); Phocone AG, 8005 Zurich (Switzerland); Debernardi, Pierluigi [IEIIT-CNR, Torino 10129 (Italy); Felder, Ferdinand [Phocone AG, 8005 Zurich (Switzerland); Zogg, Hans [ETH Zurich (Switzerland)

    2013-11-11

    Mid-infrared Vertical External Cavity Surface Emitting Lasers (VECSEL) based on narrow gap lead-chalcogenide (IV-VI) semiconductors exhibit strongly reduced threshold powers if the active layers are structured laterally for improved optical confinement. This is predicted by 3-d optical calculations; they show that lateral optical confinement is needed to counteract the anti-guiding features of IV-VIs due to their negative temperature dependence of the refractive index. An experimental proof is performed with PbSe quantum well based VECSEL grown on a Si-substrate by molecular beam epitaxy and emitting around 3.3 μm. With proper mesa-etching, the threshold intensity is about 8-times reduced.

  11. Phase Locking of Laser Diode Array by Using an Off-Axis External Talbot Cavity

    International Nuclear Information System (INIS)

    Su Zhou-Ping; Zhu Zhuo-Wei; Que Li-Zhi; Zhu Yun; Ji Zhi-Cheng

    2012-01-01

    Phase locking of a laser diode array is demonstrated experimentally by using an off-axis external Talbot cavity with a feedback plane mirror. Due to good spatial mode discrimination, the cavity does not need a spatial filter. By employing the cavity, a clear and stable far-field interference pattern can be observed when the driver current is less than 14 A. In addition, the spectral line width can be reduced to 0.8 nm. The slope efficiency of the phase-locked laser diode array is about 0.62 W/A. (fundamental areas of phenomenology(including applications))

  12. Tunable high-power narrow-linewidth green external-cavity GaN diode laser

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system.......A tunable high-power green external-cavity diode laser is demonstrated. Up to 290 mW output power and a 9.2 nm tuning is achieve. This constitutes the highest output power from a tunable green diode laser system....

  13. Commercial mode-locked vertical external cavity surface emitting lasers

    Science.gov (United States)

    Head, C. Robin; Paboeuf, David; Ortega, Tiago; Lubeigt, Walter; Bialkowski, Bartlomiej; Lin, Jipeng; Hempler, Nils; Maker, Gareth T.; Malcolm, Graeme P. A.

    2018-02-01

    This paper presents the latest efforts in the development of commercial optically-pumped semiconductor disk lasers (SDLs) at M Squared Lasers. Two types of SDLs are currently being developed: an ultrafast system and a continuous wave single frequency system under the names of Dragonfly and Infinite, respectively. Both offer a compact, low-cost, easy-to-use and maintenance-free tool for a range of growing markets including nonlinear microscopy and quantum technology. To facilitate consumer uptake of the SDL technology, the performance specifications aim to closely match the currently employed systems. An extended Dragonfly system is being developed targeting the nonlinear microscopy market, which typically requires 1-W average power pulse trains with pulse durations below 200 fs. The pulse repetition frequency (PRF) of the commonly used laser systems, typically Titanium-sapphire lasers, is 80 MHz. This property is particularly challenging for mode-locked SDLs which tend to operate at GHz repetition rates, due to their short upper state carrier lifetime. Dragonfly has found a compromise at 200 MHz to balance mode-locking instabilities with a low PRF. In the ongoing development of Dragonfly, additional pulse compression and nonlinear spectral broadening stages are used to obtain pulse durations as short as 130 fs with an average power of 0.85 W, approaching the required performance. A variant of the Infinite system was adapted to provide a laser source suitable for the first stage of Sr atom cooling at 461 nm. Such a source requires average powers of approximately 1 W with a sub-MHz linewidth. As direct emission in the blue is not a viable approach at this stage, an SDL emitting at 922 nm followed by an M Squared Lasers SolTiS ECD-X doubler is currently under development. The SDL oscillator delivered >1 W of single frequency (RMS frequency noise <150kHz) light at 922 nm.

  14. Threshold for strong thermal dephasing in periodically poled KTP in external cavity frequency doubling

    DEFF Research Database (Denmark)

    Lundeman, Jesper Holm; Jensen, Ole Bjarlin; Andersen, Peter E.

    2009-01-01

    We present a measurement series of the efficiency of periodically poled KTP used for second-harmonic generation in an external phase-locked cavity. Due to the high absorption (0.01 cm^−1) in the PPKTP crystal at the pump wavelength a strong thermal dephasing of the periodically poled grating...

  15. Self-injection locking of the DFB laser through an external ring fiber cavity: Polarization behavior

    Directory of Open Access Journals (Sweden)

    J.L. Bueno Escobedo

    Full Text Available We study stability of self-injection locking realized with DFB laser coupled with an external fiber optic ring cavity. Polarization behavior of the radiation circulating in the feedback loop is reported. Two regimes of mode hopping have been observed; one of them is accompanied by polarization bistability involving two orthogonal polarization states. Keywords: Self-injection locking, Polarization, Optical fiber

  16. Continuously tunable monomode mid-infrared vertical external cavity surface emitting laser on Si

    Science.gov (United States)

    Khiar, A.; Rahim, M.; Fill, M.; Felder, F.; Hobrecker, F.; Zogg, H.

    2010-10-01

    A tunable PbTe based mid-infrared vertical external cavity surface emitting laser is described. The active part is a ˜1 μm thick PbTe layer grown epitaxially on a Bragg mirror on the Si-substrate. The cavity is terminated with a curved Si/SiO Bragg top mirror and pumped optically with a 1.55 μm laser. Cavity length is <100 μm in order that only one longitudinal mode is supported. By changing the cavity length, up to 5% wavelength continuous and mode-hop free tuning is achieved at fixed temperature. The total tuning extends from 5.6 to 4.7 μm at 100-170 K operation temperature.

  17. Dual-wavelength high-power diode laser system based on an external-cavity tapered amplifier with tunable frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2012-01-01

    knowledge, this is the broadest tuning range of the frequency difference from a dual-wavelength diode laser system. The spectrum, output power, and beam quality of the diode laser system are characterized. The power stability of each wavelength is measured, and the power fluctuations of the two wavelengths......A dual-wavelength high-power semiconductor laser system based on a tapered amplifier with double-Littrow external cavity is demonstrated around 800 nm. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 10.0 THz. To our...

  18. Linear induction accelerators made from pulse-line cavities with external pulse injection

    International Nuclear Information System (INIS)

    Smith, I.

    1979-01-01

    Two types of linear induction accelerator have been reported previously. In one, unidirectional voltage pulses are generated outside the accelerator and injected into the accelerator cavity modules, which contain ferromagnetic material to reduce energy losses in the form of currents induced, in parallel with the beam, in the cavity structure. In the other type, the accelerator cavity modules are themselves pulse-forming lines with energy storage and switches; parallel current losses are made zero by the use of circuits that generate bidirectional acceleration waveforms with a zero voltage-time integral. In a third type of design described here, the cavities are externally driven, and 100% efficient coupling of energy to the beam is obtained by designing the external pulse generators to produce bidirectional voltage waveforms with zero voltage-time integral. A design for such a pulse generator is described that is itself one hundred percent efficient and which is well suited to existing pulse power techniques. Two accelerator cavity designs are described that can couple the pulse from such a generator to the beam; one of these designs provides voltage doubling. Comparison is made between the accelerating gradients that can be obtained with this and the preceding types of induction accelerator

  19. Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

    Science.gov (United States)

    Hardman, Kyle S.; Bennetts, Shayne; Debs, John E.; Kuhn, Carlos C. N.; McDonald, Gordon D.; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  20. Construction and characterization of external cavity diode lasers for atomic physics.

    Science.gov (United States)

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-04-24

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

  1. Tunable single and dual mode operation of an external cavity quantum-dot injection laser

    International Nuclear Information System (INIS)

    Biebersdorf, A; Lingk, C; De Giorgi, M; Feldmann, J; Sacher, J; Arzberger, M; Ulbrich, C; Boehm, G; Amann, M-C; Abstreiter, G

    2003-01-01

    We investigate quantum-dot (QD) lasers in an external cavity using Littrow and Littman configurations. Here, we report on a continuously tunable QD laser with a broad tuning range from 1047 to 1130 nm with high stability and efficient side mode suppression. The full-width at half-maximum of the laser line is 0.85 nm determined mainly by the quality of the external grating. This laser can be operated in a dual-mode modus, where the mode-spacing can be tuned continuously between 1.1 and 34 nm. Simultaneous emission of the two laser modes is shown by sum frequency generation experiments

  2. IV-VI mid-IR tunable lasers and detectors with external resonant cavities

    Science.gov (United States)

    Zogg, H.; Rahim, M.; Khiar, A.; Fill, M.; Felder, F.; Quack, N.; Blunier, S.; Dual, J.

    2009-08-01

    Wavelength tunable emitters and detectors in the mid-IR wavelength region allow applications including thermal imaging and spectroscopy. Such devices may be realized using a resonant cavity. By mechanically changing the cavity length with MEMS mirror techniques, the wavelengths may be tuned over a considerable range. Vertical external cavity surface emitting lasers (VECSEL) may be applied for gas spectroscopy. Resonant cavity enhanced detectors (RCED) are sensitive at the cavity resonance only. They may be applied for low resolution spectroscopy, and, when arrays of such detectors are realized, as multicolor IR-FPA or IR-AFPA (IR-adaptive focal plane arrays). We review mid-infrared RCEDs and VECSELs using narrow gap IV-VI (lead chalcogenide) materials like PbTe and PbSe as the active medium. IV-VIs are fault tolerant and allow easy wavelength tuning. The VECSELs operate up to above room temperature and emit in the 4 - 5 μm range with a PbSe active layer. RCEDs with PbTe absorbing layers above 200 K operating temperature have higher sensitivities than the theoretical limit for a similar broad-band detector coupled with a passive tunable band-filter.

  3. Semiconductor

    International Nuclear Information System (INIS)

    2000-01-01

    This book deals with process and measurement of semiconductor. It contains 20 chapters, which goes as follows; semiconductor industry, introduction of semiconductor manufacturing, yield of semiconductor process, materials, crystal growth and a wafer forming, PN, control pollution, oxidation, photomasking photoresist chemistry, photomasking technologies, diffusion and ion injection, chemical vapor deposition, metallization, wafer test and way of evaluation, semiconductor elements, integrated circuit and semiconductor circuit technology.

  4. Optoelectronic integrated circuits utilising vertical-cavity surface-emitting semiconductor lasers

    International Nuclear Information System (INIS)

    Zakharov, S D; Fyodorov, V B; Tsvetkov, V V

    1999-01-01

    Optoelectronic integrated circuits with additional optical inputs/outputs, in which vertical-cavity surface-emitting (VCSE) lasers perform the data transfer functions, are considered. The mutual relationship and the 'affinity' between optical means for data transfer and processing, on the one hand, and the traditional electronic component base, on the other, are demonstrated in the case of implementation of three-dimensional interconnects with a high transmission capacity. Attention is drawn to the problems encountered when semiconductor injection lasers are used in communication lines. It is shown what role can be played by VCSE lasers in solving these problems. A detailed analysis is made of the topics relating to possible structural and technological solutions in the fabrication of single lasers and of their arrays, and also of the problems hindering integrating of lasers into emitter arrays. Considerable attention is given to integrated circuits with optoelectronic smart pixels. Various technological methods for vertical integration of GaAs VCSE lasers with the silicon substrate of a microcircuit (chip) are discussed. (review)

  5. Change in volume of lumpectomy cavity during external-beam irradiation of the intact breast

    International Nuclear Information System (INIS)

    Jacobson, Geraldine; Betts, Vicki; Smith, Brian

    2006-01-01

    Purpose: Definition of the lumpectomy cavity is an important component of irradiation of the breast. We use computed tomography (CT)-based planning and contour the lumpectomy volume on the planning CT. We obtained a second CT in the 4th or 5th week of treatment for boost planning and compared the volume change with the first planning-CT scan. Methods and Materials: This retrospective study reviewed the planning-CT data for 20 patients. In the first CT, images were obtained from the mandible to 2 cm below the breast in 3-mm slices. In the second CT, for the boost, images were obtained from the top to the bottom of the clinically defined breast, in 3-mm slices. Lumpectomy cavities were contoured on both CT scans and volumes compared. Results: Sixteen of the 20 patients (80%) had more than a 20% decrease from the first to the second volume, with a corresponding 95% confidence interval. The mean decrease was 16.13 cc, with a standard deviation of 14.05. The Spearman correlation coefficient of 0.18 did not show a significant correlation between the initial volume and the percent change. Conclusions: During external breast irradiation, many patients will have significant volume reduction in the lumpectomy cavity. Because CT-based definition of the lumpectomy cavity can influence the planning of a boost technique, further study appears warranted

  6. Dynamics of a green high-power tunable external-cavity broad-area GaN diode laser

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Hansen, Anders Kragh

    2018-01-01

    system based on a GaN BAL and Littrow external-cavity is investigated experimentally. The regular pulse package oscillation (PPO) is observed just above the threshold. The oscillating period of the pulse package decreases with the increasing injected current. As the current increases further, the pulse...... package oscillates irregularly, and finally changes to a chaotic state. The PPO is observed, for the first time to our knowledge, in a BAL with an external-cavity grating feedback....

  7. Ultrafast pulse amplification in mode-locked vertical external-cavity surface-emitting lasers

    Energy Technology Data Exchange (ETDEWEB)

    Böttge, C. N., E-mail: boettge@optics.arizona.edu; Hader, J.; Kilen, I.; Moloney, J. V. [College of Optical Sciences, The University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721 (United States); Koch, S. W. [College of Optical Sciences, The University of Arizona, 1630 E. University Blvd., Tucson, Arizona 85721 (United States); Department of Physics and Material Sciences Center, Philipps-Universität Marburg, Renthof 5, 35032 Marburg (Germany)

    2014-12-29

    A fully microscopic many-body Maxwell–semiconductor Bloch model is used to investigate the influence of the non-equilibrium carrier dynamics on the short-pulse amplification in mode-locked semiconductor microlaser systems. The numerical solution of the coupled equations allows for a self-consistent investigation of the light–matter coupling dynamics, the carrier kinetics in the saturable absorber and the multiple-quantum-well gain medium, as well as the modification of the light field through the pulse-induced optical polarization. The influence of the pulse-induced non-equilibrium modifications of the carrier distributions in the gain medium and the saturable absorber on the single-pulse amplification in the laser cavity is identified. It is shown that for the same structure, quantum wells, and gain bandwidth the non-equilibrium carrier dynamics lead to two preferred operation regimes: one with pulses in the (sub-)100 fs-regime and one with multi-picosecond pulses. The recovery time of the saturable absorber determines in which regime the device operates.

  8. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    DEFF Research Database (Denmark)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup Nielsen, Birgitte

    2010-01-01

    solution for preserving the beam quality of the bar in the range of that of a single emitter and at the same time, enabling the power scaling. We report spectral beam combining applied to a 12 emitter tapered laser bar at 980 nm. The external cavity has been designed for a wavelength separation of 4.0 nm......High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality...

  9. Passive mode locking in a multisegment laser diode with an external cavity

    International Nuclear Information System (INIS)

    Andreeva, E V; Magnitskiy, Sergey A; Koroteev, Nikolai I; Salik, E; Feinberg, J; Starodubov, D S; Shramenko, M V; Yakubovich, S D

    1999-01-01

    The structure and operating conditions of multisegment laser (GaAl)As diodes with passive locking of the modes of an external cavity (bulk and fibre) were optimised. Regular trains of optical single pulses of picosecond duration were generated in a spectral range 850 - 860 nm. The peak power of these pulses was several watts and the repetition rate was near 1 GHz. Under certain conditions these output pulses were linearly chirped, i.e. they were suitable for subpicosecond time compression. Laboratory prototypes were made of miniature light-emitting modules with these characteristics. (lasers)

  10. Progress in Rapidly-Tunable External Cavity Quantum Cascade Lasers with a Frequency-Shifted Feedback

    Directory of Open Access Journals (Sweden)

    Arkadiy Lyakh

    2016-04-01

    Full Text Available The recent demonstration of external cavity quantum cascade lasers with optical feedback, controlled by an acousto-optic modulator, paves the way to ruggedized infrared laser systems with the capability of tuning the emission wavelength on a microsecond scale. Such systems are of great importance for various critical applications requiring ultra-rapid wavelength tuning, including combustion and explosion diagnostics and standoff detection. In this paper, recent research results on these devices are summarized and the advantages of the new configuration are analyzed in the context of practical applications.

  11. A Digital Phase Lock Loop for an External Cavity Diode Laser

    Science.gov (United States)

    Wang, Xiao-Long; Tao, Tian-Jiong; Cheng, Bing; Wu, Bin; Xu, Yun-Fei; Wang, Zhao-Ying; Lin, Qiang

    2011-08-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems.

  12. Frequency and time domain analysis of an external cavity laser with strong filtered optical feedback

    DEFF Research Database (Denmark)

    Detoma, Enrico; Tromborg, Bjarne; Montrosset, Ivo

    The stability properties of an external cavity laser with strong grating-filtered optical feedback to an anti-reflection coated facet are studied with a general frequency domain model. The model takes into account non-linear effects like four wave mixing and gain compression. A small......-signal analysis in the frequency domain allows a calculation of the range of operation without mode hopping around the grating reflectivity peak. This region should be as large as possible for proper operation of the tunable laser source. The analysis shows this stabilizing effect of mode coupling and gain...

  13. Coherent addition of high power broad-area laser diodes with a compact VBG V-shaped external Talbot cavity

    Science.gov (United States)

    Liu, Bo; Braiman, Yehuda

    2018-05-01

    We introduced a compact V-shaped external Talbot cavity for phase locking of high power broad-area laser diodes. The length of compact cavity is ∼25 mm. Near diffraction-limit coherent addition of 10 broad-area laser diodes indicated that high quality phase locking was achieved. We measured the near-field emission mode of each individual broad-area laser diode with different feedback, such as a volume Bragg grating and a high reflection mirror. We found out that the best result of phase locking broad-area laser diodes was achieved by the compact V-shaped external Talbot cavity with volume Bragg grating feedback.

  14. Electron Raman scattering in semiconductor quantum wire in an external magnetic field

    International Nuclear Information System (INIS)

    Betancourt-Riera, Ri; Nieto Jalil, J M; Riera, R; Betancourt-Riera, Re; Rosas, R

    2008-01-01

    The differential cross-section for an electron Raman scattering process in a semiconductor quantum wire in the presence of an external magnetic field perpendicular to the plane of confinement is calculated. We assume a single parabolic conduction band. The emission spectra for different scattering configurations and the selection rules for the processes are studied. Singularities in the spectra are found and interpreted. The electron Raman scattering studied here can be used to provide direct information about the electron band and subband structure of these confinement systems. The magnetic field distribution is considered constant with value B 0 inside the wire and zero outside

  15. External-cavity high-power dual-wavelength tapered amplifier with tunable THz frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2012-01-01

    A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W is achie......A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W...... is achieved with a frequency difference of 0.86 THz, the output power is higher than 1.3 W in the 5.0 THz range of frequency difference, and the amplified spontaneous emission intensity is more than 20 dB suppressed in the range of frequency difference. The beam quality factor M2 is 1.22±0.15 at an output...

  16. A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

    Science.gov (United States)

    Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

    2015-10-01

    Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

  17. An external-cavity quantum cascade laser operating near 5.2 µm combined with cavity ring-down spectroscopy for multi-component chemical sensing

    Science.gov (United States)

    Dutta Banik, Gourab; Maity, Abhijit; Som, Suman; Pal, Mithun; Pradhan, Manik

    2018-04-01

    We report on the performance of a widely tunable continuous wave mode-hop-free external-cavity quantum cascade laser operating at λ ~ 5.2 µm combined with cavity ring-down spectroscopy (CRDS) technique for high-resolution molecular spectroscopy. The CRDS system has been utilized for simultaneous and molecule-specific detection of several environmentally and bio-medically important trace molecular species such as nitric oxide, nitrous oxide, carbonyl sulphide and acetylene (C2H2) at ultra-low concentrations by probing numerous rotationally resolved ro-vibrational transitions in the mid-IR spectral region within a relatively small spectral range of ~0.035 cm-1. This continuous wave external-cavity quantum cascade laser-based multi-component CRDS sensor with high sensitivity and molecular specificity promises applications in environmental sensing as well as non-invasive medical diagnosis through human breath analysis.

  18. Narrow-line external cavity diode laser micro-packaging in the NIR and MIR spectral range

    Science.gov (United States)

    Jiménez, A.; Milde, T.; Staacke, N.; Aßmann, C.; Carpintero, G.; Sacher, J.

    2017-07-01

    Narrow-linewidth tunable diode lasers are an important tool for spectroscopic instrumentation. Conventional external cavity diode lasers offer high output power and narrow linewidth. However, most external cavity diode lasers are designed as laboratory instrument and do not allow portability. In comparison, other commonly used lasers, like distributed feedback lasers (DFB) that are capable of driving a handheld device, are limited in power and show linewidths which are not sufficiently narrow for certain applications. We present new miniaturized types of tunable external cavity diode laser which overcome the drawbacks of conventional external cavity diode lasers and which preserve the advantages of this laser concept. Three different configurations are discussed in this article. The three types of miniaturized external cavity diode laser systems achieve power values of more than 50 mW within the 1.4 μm water vapor absorption band with excellent side-mode suppression and linewidth below 100 kHz. Typical features outstand with respect to other type of laser systems which are of extended use such as DFB laser diodes. The higher output power and the lower linewidth will enable a higher sensitivity and resolution for a wide range of applications.

  19. Generation of picosecond pulses and frequency combs in actively mode locked external ring cavity quantum cascade lasers

    International Nuclear Information System (INIS)

    Wójcik, Aleksander K.; Belyanin, Alexey; Malara, Pietro; Blanchard, Romain; Mansuripur, Tobias S.; Capasso, Federico

    2013-01-01

    We propose a robust and reliable method of active mode locking of mid-infrared quantum cascade lasers and develop its theoretical description. Its key element is the use of an external ring cavity, which circumvents fundamental issues undermining the stability of mode locking in quantum cascade lasers. We show that active mode locking can give rise to the generation of picosecond pulses and phase-locked frequency combs containing thousands of the ring cavity modes

  20. Note: Demonstration of an external-cavity diode laser system immune to current and temperature fluctuations.

    Science.gov (United States)

    Miao, Xinyu; Yin, Longfei; Zhuang, Wei; Luo, Bin; Dang, Anhong; Chen, Jingbiao; Guo, Hong

    2011-08-01

    We demonstrate an external-cavity laser system using an anti-reflection coated laser diode as gain medium with about 60 nm fluorescence spectrum, and a Rb Faraday anomalous dispersion optical filter (FADOF) as frequency-selecting element with a transmission bandwidth of 1.3 GHz. With 6.4% optical feedback, a single stable longitudinal mode is obtained with a linewidth of 69 kHz. The wavelength of this laser is operating within the center of the highest transmission peak of FADOF over a diode current range from 55 mA to 142 mA and a diode temperature range from 15 °C to 35 °C, thus it is immune to the fluctuations of current and temperature.

  1. A Digital Phase Lock Loop for an External Cavity Diode Laser

    International Nuclear Information System (INIS)

    Wang Xiao-Long; Tao Tian-Jiong; Cheng Bing; Wu Bin; Xu Yun-Fei; Wang Zhao-Ying; Lin Qiang

    2011-01-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad 2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems. (fundamental areas of phenomenology(including applications))

  2. Active mode locking of quantum cascade lasers in an external ring cavity.

    Science.gov (United States)

    Revin, D G; Hemingway, M; Wang, Y; Cockburn, J W; Belyanin, A

    2016-05-05

    Stable ultrashort light pulses and frequency combs generated by mode-locked lasers have many important applications including high-resolution spectroscopy, fast chemical detection and identification, studies of ultrafast processes, and laser metrology. While compact mode-locked lasers emitting in the visible and near infrared range have revolutionized photonic technologies, the systems operating in the mid-infrared range where most gases have their strong absorption lines, are bulky and expensive and rely on nonlinear frequency down-conversion. Quantum cascade lasers are the most powerful and versatile compact light sources in the mid-infrared range, yet achieving their mode-locked operation remains a challenge, despite dedicated effort. Here we report the demonstration of active mode locking of an external-cavity quantum cascade laser. The laser operates in the mode-locked regime at room temperature and over the full dynamic range of injection currents.

  3. Detection of protein-small molecule binding using a self-referencing external cavity laser biosensor.

    Science.gov (United States)

    Meng Zhang; Peh, Jessie; Hergenrother, Paul J; Cunningham, Brian T

    2014-01-01

    High throughput screening of protein-small molecule binding interactions using label-free optical biosensors is challenging, as the detected signals are often similar in magnitude to experimental noise. Here, we describe a novel self-referencing external cavity laser (ECL) biosensor approach that achieves high resolution and high sensitivity, while eliminating thermal noise with sub-picometer wavelength accuracy. Using the self-referencing ECL biosensor, we demonstrate detection of binding between small molecules and a variety of immobilized protein targets with binding affinities or inhibition constants in the sub-nanomolar to low micromolar range. The demonstrated ability to perform detection in the presence of several interfering compounds opens the potential for increasing the throughput of the approach. As an example application, we performed a "needle-in-the-haystack" screen for inhibitors against carbonic anhydrase isozyme II (CA II), in which known inhibitors are clearly differentiated from inactive molecules within a compound library.

  4. Broadband external cavity quantum cascade laser based sensor for gasoline detection

    Science.gov (United States)

    Ding, Junya; He, Tianbo; Zhou, Sheng; Li, Jinsong

    2018-02-01

    A new type of tunable diode spectroscopy sensor based on an external cavity quantum cascade laser (ECQCL) and a quartz crystal tuning fork (QCTF) were used for quantitative analysis of volatile organic compounds. In this work, the sensor system had been tested on different gasoline sample analysis. For signal processing, the self-established interpolation algorithm and multiple linear regression algorithm model were used for quantitative analysis of major volatile organic compounds in gasoline samples. The results were very consistent with that of the standard spectra taken from the Pacific Northwest National Laboratory (PNNL) database. In future, The ECQCL sensor will be used for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis, etc.

  5. Green high-power tunable external-cavity GaN diode laser at 515 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam...... incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode...... laser system....

  6. Study of evaluation methods for in-vessel corium retention through external vessel cooling and safety of reactor cavity

    Energy Technology Data Exchange (ETDEWEB)

    Huh, Hoon; Chang, Soon Heung; Kim, Soo Hyung; Kim, Kee Poong; Lee, Hyoung Wook; Jang, Kwang Keol; Jeong, Yong Hoon; Kim, Sang Jin; Lee, Seong Jin [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of); Park, Jae Hong [Korea Institute of Nuclear Safety, Taejon (Korea, Republic of)

    2001-03-15

    In this work, assessment system for methodology for reactor pressure vessel integrity is developed. Assessment system is make up of severe accident assessment code which can calculate the conditions of plant and structural analysis code which can assess the integrity of reactor vessel using given plant conditions. An assessment of cavity flooding using containment spray system has been done. As a result, by the containment spray, cavity can be flooded successfully and CCI can be reduced. The technical backgrounds for external vessel cooling and corium cooling on the cavity are summarized and provided in this report.

  7. Study of evaluation methods for in-vessel corium retention through external vessel cooling and safety of reactor cavity

    International Nuclear Information System (INIS)

    Huh, Hoon; Chang, Soon Heung; Kim, Soo Hyung; Kim, Kee Poong; Lee, Hyoung Wook; Jang, Kwang Keol; Jeong, Yong Hoon; Kim, Sang Jin; Lee, Seong Jin; Park, Jae Hong

    2001-03-01

    In this work, assessment system for methodology for reactor pressure vessel integrity is developed. Assessment system is make up of severe accident assessment code which can calculate the conditions of plant and structural analysis code which can assess the integrity of reactor vessel using given plant conditions. An assessment of cavity flooding using containment spray system has been done. As a result, by the containment spray, cavity can be flooded successfully and CCI can be reduced. The technical backgrounds for external vessel cooling and corium cooling on the cavity are summarized and provided in this report

  8. 5-μm vertical external-cavity surface-emitting laser (VECSEL) for spectroscopic applications

    Science.gov (United States)

    Rahim, M.; Khiar, A.; Felder, F.; Fill, M.; Zogg, H.; Sigrist, M. W.

    2010-08-01

    Mid-IR tunable VECSELs (Vertical External-Cavity Surface-Emitting Lasers) emitting at 4-7 μm wavelengths and suitable for spectroscopic sensing applications are described. They are realized with lead-chalcogenide (IV-VI) narrow band gap materials. The active part, a single 0.6-2-μm thick PbTe or PbSe gain layer, is grown onto an epitaxial Bragg mirror consisting of two or three Pb1- y Eu y Te/BaF2 quarter-wavelength layer pairs. All layers are deposited by MBE in a single run employing a BaF2 or Si substrate, no further processing is needed. The cavity is completed with an external curved top mirror, which is again realized with an epitaxial Bragg structure. Pumping is performed optically with a 1.5-μm laser. Maximum output power for pulsed operation is currently up to >1 Wp at -173°C and >10 mW at 10°C. In continuous wave (CW) operation, 18 mW at 100 K are reached. Still higher operating temperatures and/or powers are expected with better heat-removal structures and better designs employing QW (Quantum-Wells). Advantages of mid-IR VECSELs compared to edge-emitting lasers are their very good beam quality (circular beam with 15 μm are accessible with Pb1- y X y Z (X=Sr, Eu, Sn, Z=Se, Te) and/or including QW.

  9. Electron Raman scattering in semiconductor quantum wire in external magnetic field: Froehlich interaction

    International Nuclear Information System (INIS)

    Betancourt-Riera, Ri.; Nieto Jalil, J.M.; Betancourt-Riera, Re.; Riera, R.

    2009-01-01

    The differential cross-section for an electron Raman scattering process in a semiconductor quantum wire in the presence of an external magnetic field perpendicular to the plane of confinement regarding phonon-assisted transitions, is calculated. We assume single parabolic conduction band and present a description of the phonon modes of cylindrical structures embedded in another material using the Froehlich phonon interaction. To illustrate the theory we use a GaAs/Al 0.35 Ga 0.75 As system. The emission spectra are discussed for different scattering configurations and the selection rules for the processes are also studied. The magnetic field distribution is considered constant with value B 0 inside of the wire, and zero outside.

  10. Tuning range and output power optimization of an external-cavity GaN diode laser at 455 nm

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-01-01

    In this paper we discuss how different feedback gratings affect the tuning range and the output power of external feedback diode laser systems. A tunable high-power narrow-spectrum external-cavity diode laser system around 455 nm is investigated. The laser system is based on a high-power GaN diode...... laser in a Littrow external-cavity. Both a holographic diffraction grating and a ruled diffraction grating are used as feedback elements in the external cavity. The output power, spectral bandwidth, and tunable range of the external cavity diode laser system are measured and compared with the two...... gratings at different injected currents. When the holographic grating is used, the laser system can be tuned over a range of 1.4 nm with an output power around 530 mW. When the ruled grating is used, the laser system can be tuned over a range of 6.0 nm with an output power around 80 mW. The results can...

  11. Coherent coupling of two different semiconductor quantum dots via an optical cavity mode

    Energy Technology Data Exchange (ETDEWEB)

    Villas-Boas, Jose M. [Universidade Federal de Uberlandia (UFU), MG (Brazil). Inst. de Fisica; Laucht, Arne; Hauke, Norman; Hofbauer, Felix; Boehm, Gerhard; Kaniber, Michael; Finley, Jonathan J. [Technische Universitaet Muenchen, Garching (Germany). Walter Schottky Inst.

    2011-07-01

    Full text. We present a combined experimental and theoretical study of a strongly coupled system consisting of two spatially separated self-assembled InGaAs quantum dots and a single optical nano cavity mode. Due to their different size and strain profile, the two dots exhibit markedly different electric field dependences due to the quantum confined Stark effect. This allows us to tune them into resonance simply by changing the applied bias voltage and to independently tune them into the photonic crystal nano cavity mode. Photoluminescence measurements show a characteristic triple peak during the double anti crossing, which is a clear signature of a coherently coupled system of three quantum states. We fit the emission spectra of the coupled system to theory and are able to investigate the coupling between the two quantum dots directly via the cavity mode. Furthermore, we investigate the coupling between the two quantum dots when they are detuned from the cavity mode in a V-system where dephasing due to incoherent losses from the cavity mode can be reduced

  12. The Complex Way to Laser Diode Spectra: Example of an External Cavity Laser With Strong Optical Feedback

    DEFF Research Database (Denmark)

    Detoma, Enrico; Tromborg, Bjarne; Montrosset, Ivo

    2005-01-01

    An external cavity laser with strong grating-filtered feedback to an antireflection-coated facet is studied with a time-domain integral equation for the electric field, which reproduces the modes of the oscillation condition as steady-state solutions. For each mode, the stability and spectral...... to simulate the large signal time evolution after start from unstable modes....

  13. Volume Bragg grating external cavities for the passive phase locking of high-brightness diode laser arrays: theoretical and experimental study

    DEFF Research Database (Denmark)

    Paboeuf, David; Vijayakumar, Deepak; Jensen, Ole Bjarlin

    2011-01-01

    We describe the theoretical modeling of the external-cavity operation of a phase-locked array of diode lasers in two configurations, the self-imaging cavity based on the Talbot effect and the angular-filtering cavity. Complex filtering functions, such as the transmission or reflection of a volume...

  14. Optimal operating conditions for external cavity semiconductor laser optical chaos communication system

    International Nuclear Information System (INIS)

    Priyadarshi, S; Pierce, I; Hong, Y; Shore, K A

    2012-01-01

    In optical chaos communications a message is masked in the noise-like broadband output of a chaotic transmitter laser, and message recovery is enabled through the synchronization of the transmitter and the (chaotic) receiver laser. Key issues are to identify the laser operating conditions which provide the highest quality synchronization conditions and those which provide optimized message extraction. In general such operating conditions are not coincident. In this paper numerical simulations are performed with the aim of identifying a regime of operation where the highest quality synchronization and optimizing message extraction efficiency are achieved simultaneously. Use of such an operating regime will facilitate practical deployment of optical chaos communications systems without the need for re-adjustment of laser operating conditions in the field. (paper)

  15. Dual-wavelength external cavity laser device for fluorescence suppression in Raman spectroscopy

    Science.gov (United States)

    Zhang, Xuting; Cai, Zhijian; Wu, Jianhong

    2017-10-01

    Raman spectroscopy has been widely used in the detection of drugs, pesticides, explosives, food additives and environmental pollutants, for its characteristics of fast measurement, easy sample preparation, and molecular structure analyzing capability. However, fluorescence disturbance brings a big trouble to these applications, with strong fluorescence background covering up the weak Raman signals. Recently shifted excitation Raman difference spectroscopy (SERDS) not only can completely remove the fluorescence background, but also can be easily integrated into portable Raman spectrometers. Usually, SERDS uses two lasers with small wavelength gap to excite the sample, then acquires two spectra, and subtracts one to the other to get the difference spectrum, where the fluorescence background will be rejected. So, one key aspects of successfully applying SERDS method is to obtain a dual-wavelength laser source. In this paper, a dual-wavelength laser device design based on the principles of external cavity diode laser (ECDL) is proposed, which is low-cost and compact. In addition, it has good mechanical stability because of no moving parts. These features make it an ideal laser source for SERDS technique. The experiment results showed that the device can emit narrow-spectral-width lasers of two wavelengths, with the gap smaller than 2 nanometers. The laser power corresponding to each wavelength can be up to 100mW.

  16. Standoff detection of turbulent chemical mixture plumes using a swept external cavity quantum cascade laser

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Mark C. [Pacific Northwest National Laboratory, Richland, Washington; Brumfield, Brian E. [Pacific Northwest National Laboratory, Richland, Washington

    2017-08-21

    We demonstrate standoff detection of turbulent mixed-chemical plumes using a broadly-tunable external cavity quantum cascade laser (ECQCL). The ECQCL was directed through plumes of mixed methanol/ethanol vapor to a partially-reflective surface located 10 m away. The reflected power was measured as the ECQCL was swept over its tuning range of 930-1065 cm-1 (9.4-10.8 µm) at rates up to 200 Hz. Analysis of the transmission spectra though the plume was performed to determine chemical concentrations with time resolution of 0.005 s. Comparison of multiple spectral sweep rates of 2 Hz, 20 Hz, and 200 Hz shows that higher sweep rates reduce effects of atmospheric and source turbulence, resulting in lower detection noise and more accurate measurement of the rapidly-changing chemical concentrations. Detection sensitivities of 0.13 ppm*m for MeOH and 1.2 ppm*m for EtOH are demonstrated for a 200 Hz spectral sweep rate, normalized to 1 s detection time.

  17. General Method for Calculating the Response and Noise Spectra of Active Fabry-Perot Semiconductor Waveguides With External Optical Injection

    DEFF Research Database (Denmark)

    Blaaberg, Søren; Mørk, Jesper

    2009-01-01

    We present a theoretical method for calculating small-signal modulation responses and noise spectra of active Fabry-Perot semiconductor waveguides with external light injection. Small-signal responses due to either a modulation of the pump current or due to an optical amplitude or phase modulatio...... amplifiers and an injection-locked laser. We also demonstrate the applicability of the method to analyze slow and fast light effects in semiconductor waveguides. Finite reflectivities of the facets are found to influence the phase changes of the injected microwave-modulated light....

  18. External cavity diode laser-based detection of trace gases with NICE-OHMS using current modulation.

    Science.gov (United States)

    Centeno, R; Mandon, J; Cristescu, S M; Axner, O; Harren, F J M

    2015-03-09

    We combine an external cavity diode laser with noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) using current modulation. With a finesse of 1600, we demonstrate noise equivalent absorption sensitivities of 4.1 x 10(-10) cm(-1) Hz(-1/2), resulting in sub-ppbv detection limits for Doppler-broadened transitions of CH(4) at 6132.3 cm(-1), C(2)H(2) at 6578.5 cm(-1) and HCN at 6541.7 cm(-1). The system is used for hydrogen cyanide detection from sweet almonds.

  19. High-Speed Semiconductor Vertical-Cavity Surface-Emitting Lasers for Optical Data-Transmission Systems (Review)

    Science.gov (United States)

    Blokhin, S. A.; Maleev, N. A.; Bobrov, M. A.; Kuzmenkov, A. G.; Sakharov, A. V.; Ustinov, V. M.

    2018-01-01

    The main problems of providing a high-speed operation semiconductor lasers with a vertical microcavity (so-called "vertical-cavity surface-emitting lasers") under amplitude modulation and ways to solve them have been considered. The influence of the internal properties of the radiating active region and the electrical parasitic elements of the equivalent circuit of lasers are discussed. An overview of approaches that lead to an increase of the cutoff parasitic frequency, an increase of the differential gain of the active region, the possibility of the management of mode emission composition and the lifetime of photons in the optical microcavities, and reduction of the influence of thermal effects have been presented. The achieved level of modulation bandwidth of ˜30 GHz is close to the maximum achievable for the classical scheme of the direct-current modulation, which makes it necessary to use a multilevel modulation format to further increase the information capacity of optical channels constructed on the basis of vertical-cavity surface-emitting lasers.

  20. Coherent coupling of two different semiconductor quantum dots via an optical cavity mode

    Energy Technology Data Exchange (ETDEWEB)

    Laucht, Arne; Villas-Boas, Jose M.; Hauke, Norman; Hofbauer, Felix; Boehm, Gerhard; Kaniber, Michael; Finley, Jonathan J. [Walter Schottky Institut, Technische Universitaet Muenchen, Garching (Germany)

    2010-07-01

    We present a combined experimental and theoretical study of a strongly coupled system consisting of two spatially separated self-assembled InGaAs quantum dots and a single optical nanocavity mode. Due to their different size and strain profile, the two dots exhibit markedly different electric field dependences due to the quantum confined Stark effect. This allows us to tune them into resonance simply by changing the applied bias voltage and to independently tune them into the photonic crystal nanocavity mode. Photoluminescence measurements show a characteristic triple peak during the double anticrossing, which is a clear signature of a coherently coupled system of three quantum states. We fit the emission spectra of the coupled system to theory and are able to investigate the coupling between the two quantum dots directly via the cavity mode. Furthermore, we investigate the coupling between the two quantum dots when they are detuned from the cavity mode in a V-system where dephasing due to incoherent losses from the cavity mode can be reduced.

  1. Quantum Electrodynamics with Semiconductor Quantum Dots Coupled to Anderson‐localized Random Cavities

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren

    2011-01-01

    of the spontaneous emission decay rate by up to a factor 15 and an efficiency of channeling single photons into Anderson-localized modes reaching values as high as 94%. These results prove that disordered photonic media provide an efficient platform for quantum electrodynamics, offering a novel route to quantum......We demonstrate that the spontaneous emission decay rate of semiconductor quantum dots can be strongly modified by the coupling to disorder-induced Anderson-localized photonic modes. We experimentally measure, by means of time-resolved photoluminescence spectroscopy, the enhancement...

  2. The role of phonon scattering in the indistinguishability of photons emitted from semiconductor cavity QED systems

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Gregersen, Niels; Mørk, Jesper

    2013-01-01

    A solid-state single-photon source emitting indistinguishable photons on-demand is an essential component of linear optics quantum computing schemes. However, the emitter will inevitably interact with the solid-state environment causing decoherence and loss of indistinguishability. In this paper......, we present a comprehensive theoretical treatment of the influence of phonon scattering on the coherence properties of single photons emitted from semiconductor quantum dots. We model decoherence using a full microscopic theory and compare with standard Markovian approximations employing Lindblad...

  3. Self-Seeded RSOA-Fiber Cavity Lasers vs. ASE Spectrum-Sliced or Externally Seeded Transmitters—A Comparative Study

    Directory of Open Access Journals (Sweden)

    Simon A. Gebrewold

    2015-12-01

    Full Text Available Reflective semiconductor optical amplifier fiber cavity lasers (RSOA-FCLs are appealing, colorless, self-seeded, self-tuning and cost-efficient upstream transmitters. They are of interest for wavelength division multiplexed passive optical networks (WDM-PONs based links. In this paper, we compare RSOA-FCLs with alternative colorless sources, namely the amplified spontaneous emission (ASE spectrum-sliced and the externally seeded RSOAs. We compare the differences in output power, signal-to-noise ratio (SNR, relative intensity noise (RIN, frequency response and transmission characteristics of these three sources. It is shown that an RSOA-FCL offers a higher output power over an ASE spectrum-sliced source with SNR, RIN and frequency response characteristics halfway between an ASE spectrum-sliced and a more expensive externally seeded RSOA. The results show that the RSOA-FCL is a cost-efficient WDM-PON upstream source, borrowing simplicity and cost-efficiency from ASE spectrum slicing with characteristics that are, in many instances, good enough to perform short-haul transmission. To substantiate our statement and to quantitatively compare the potential of the three schemes, we perform data transmission experiments at 5 and 10 Gbit/s.

  4. The effect of an Er,Cr:YSGG laser on external adaptation of healthy and decayed cavities

    International Nuclear Information System (INIS)

    Kabbach, William; Tonetto, Mateus Rodrigues; Campos, Edson Alves; Andrade, Marcelo Ferrarezi; Frizzera, Fausto; Zezéll, Denise Maria; Bandéca, Matheus Coelho; Borges, Alvaro Henrique

    2014-01-01

    The aim of this study was to evaluate the influence of chlorhexidine and Er,Cr:YSGG laser irradiation on the bond strength and external adaptation in mixed healthy and caries-affected class V cavities before and after thermal cycling. Thirty-six cavity preparations were made in mixed class V buccal human molars, half of them being artificially caries-induced. Any remaining affected dentin was removed from the cavity with a round burr at low speed. The teeth were divided into six groups, according to cleaning agent for both healthy and caries-induced dentin: no treatment, chlorhexidine and erbium, chromium-doped: yttrium, scandium, gallium, garnet (Er,Cr:YSGG) laser irradiation. A Filtek P90 (3M ESPE, St Paul, MN, USA) silorane adhesive restorative system was used. The specimens were subjected to 5000 thermal cycles (5–55 °C 60 min). Epoxy replicas were obtained to characterize the external adaptation under scanning electron microscopy. The average percentages of non-continuous margins were 5.41% and 6.49% in enamel dentin before thermal cycling and 25% and 33.7% after thermal cycling, respectively. The caries-affected and laser irradiated cavities showed higher non-continuous margins. Thermal cycling was able to raise the percentage of non-continuous margin for all groups. Chlorhexidine did not affect the marginal adaptation results, and the Er,Cr: YSGG laser irradiation showed significantly worse results compared with the control group. (paper)

  5. The external Q factor of a dual-feed coupling for superconducting radio frequency cavities: Theoretical and experimental studies

    Science.gov (United States)

    Dai, J.; Belomestnykh, S.; Ben-Zvi, I.; Xu, Wencan

    2013-11-01

    We propose a theoretical model based on network analysis to study the external quality factor (Q factor) of dual-feed coupling for superconducting radio-frequency (SRF) cavities. Specifically, we apply our model to the dual-feed 704 MHz half-cell SRF gun for Brookhaven National Laboratory's prototype Energy Recovery Linac (ERL). The calculations show that the external Q factor of this dual-feed system is adjustable from 104 to 109 provided that the adjustment range of a phase shifter covers 0°-360°. With a period of 360°, the external Q factor of the coupling system changes periodically with the phase difference between the two coupling arms. When the RF phase of both coupling arms is adjusted simultaneously in the same direction, the external Q factor of the system also changes periodically, but with a period of 180°.

  6. High-power dual-wavelength external-Cavity diode laser based on tapered amplifier with tunable terahertz frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2011-01-01

    Tunable dual-wavelength operation of a diode laser system based on a tapered diode amplifier with double-Littrow external-cavity feedback is demonstrated around 800nm. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5:0 THz......, this is the highest output power from a dual-wavelength diode laser system operating with tunable terahertz frequency difference. © 2011 Optical Society of America....

  7. Ultrasensitive detection of cell lysing in an microfabricated semiconductor laser cavity

    Energy Technology Data Exchange (ETDEWEB)

    Gourley, P.L.; French, T.; McDonald, A.E.; Shields, E.A. [Sandia National Labs., Albuquerque, NM (United States); Gourley, M.F. [Washington Hospital Center, Washington, DC (United States)

    1998-01-01

    In this paper the authors report investigations of semiconductor laser microcavities for use in detecting changes of human blood cells during lysing. By studying the spectra before and during mixing of blood fluids with de-ionized water, they are able to quantify the cell shape and concentration of hemoglobin in real time during the dynamical process of lysing. The authors find that the spectra can detect subtle changes that are orders of magnitude smaller than can be observed by standard optical microscopy. Such sensitivity in observing cell structural changes has implications for measuring cell fragility, monitoring apoptotic events in real time, development of photosensitizers for photodynamic therapy, and in-vitro cell micromanipulation techniques.

  8. Tuning of External Q And Phase for The Cavities of A Superconducting Linear Accelerator

    CERN Document Server

    Katalev, V V

    2004-01-01

    The RF power required for a certain gradient of a superconducting cavity depends on the beam current and coupling between the cavity and waveguide. The coupling with the cavity may be changed by variation of Qext. Different devices can be used to adjust Qext or phase. In this paper three stub and E-H tuners are compared and their usability for the RF power distribution system for the superconducting accelerator of the European Xray laser and the TESLA linear collider is considered. The tuners were analyzed by using the scattering matrix. Advantages and limitations of the devices are presented.

  9. Continuous-wave dual-wavelength operation of a distributed feedback laser diode with an external cavity using a volume Bragg grating

    Science.gov (United States)

    Zheng, Yujin; Sekine, Takashi; Kurita, Takashi; Kato, Yoshinori; Kawashima, Toshiyuki

    2018-03-01

    We demonstrate continuous-wave dual-wavelength operation of a broad-area distributed feedback (DFB) laser diode with a single external-cavity configuration. This high-power DFB laser has a narrow bandwidth (current and temperature ranges.

  10. 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....

  11. Effect of beam arrangement on oral cavity dose in external beam radiotherapy of nasopharyngeal carcinoma

    International Nuclear Information System (INIS)

    Wu, Vincent W.C.; Yang Zhining; Zhang Wuzhe; Wu Lili; Lin Zhixiong

    2012-01-01

    This study compared the oral cavity dose between the routine 7-beam intensity-modulated radiotherapy (IMRT) beam arrangement and 2 other 7-beam IMRT with the conventional radiotherapy beam arrangements in the treatment of nasopharyngeal carcinoma (NPC). Ten NPC patients treated by the 7-beam routine IMRT technique (IMRT-7R) between April 2009 and June 2009 were recruited. Using the same computed tomography data, target information, and dose constraints for all the contoured structures, 2 IMRT plans with alternative beam arrangements (IMRT-7M and IMRT-7P) by avoiding the anterior facial beam and 1 conventional radiotherapy plan (CONRT) were computed using the Pinnacle treatment planning system. Dose-volume histograms were generated for the planning target volumes (PTVs) and oral cavity from which the dose parameters and the conformity index of the PTV were recorded for dosimetric comparisons among the plans with different beam arrangements. The dose distributions to the PTVs were similar among the 3 IMRT beam arrangements, whereas the differences were significant between IMRT-7R and CONRT plans. For the oral cavity dose, the 3 IMRT beam arrangements did not show significant difference. Compared with IMRT-7R, CONRT plan showed a significantly lower mean dose, V30 and V-40, whereas the V-60 was significantly higher. The 2 suggested alternative beam arrangements did not significantly reduce the oral cavity dose. The impact of varying the beam angles in IMRT of NPC did not give noticeable effect on the target and oral cavity. Compared with IMRT, the 2-D conventional radiotherapy irradiated a greater high-dose volume in the oral cavity.

  12. 1-W quasi-cw near-diffraction-limited semiconductor laser pumped optically by a fibre-coupled diode bar

    OpenAIRE

    Dhanjal, S.; Hoogland, S.; Roberts, J.S.; Hayward, R.A.; Clarkson, W.A.; Tropper, Anne

    2000-01-01

    We describe a diode-bar-pumped vertical-external-cavity surface-emitting semiconductor laser, which in quasi-cw operation emitted a peak power of >1 W at 1020 nm in a circular, near diffraction-limited beam.

  13. Detection of benzene and toluene gases using a midinfrared continuous-wave external cavity quantum cascade laser at atmospheric pressure.

    Science.gov (United States)

    Sydoryk, Ihor; Lim, Alan; Jäger, Wolfgang; Tulip, John; Parsons, Matthew T

    2010-02-20

    We demonstrate the application of a commercially available widely tunable continuous-wave external cavity quantum cascade laser as a spectroscopic source for the simultaneous detection of multiple gases. We measured broad absorption features of benzene and toluene between 1012 and 1063 cm(-1) (9.88 and 9.41 microm) at atmospheric pressure using an astigmatic Herriott multipass cell. Our results show experimental detection limits of 0.26 and 0.41 ppm for benzene and toluene, respectively, with a 100 m path length for these two gases.

  14. Simple, low-noise piezo driver with feed-forward for broad tuning of external cavity diode lasers.

    Science.gov (United States)

    Doret, S Charles

    2018-02-01

    We present an inexpensive, low-noise (piezo driver suitable for frequency tuning of external-cavity diode lasers. This simple driver improves upon many commercially available drivers by incorporating circuitry to produce a "feed-forward" signal appropriate for making simultaneous adjustments to the piezo voltage and laser current, enabling dramatic improvements in a mode-hop-free laser frequency tuning range. We present the theory behind our driver's operation, characterize its output noise, and demonstrate its use in absorption spectroscopy on the rubidium D 1 line.

  15. Highly Selective Volatile Organic Compounds Breath Analysis Using a Broadly-Tunable Vertical-External-Cavity Surface-Emitting Laser.

    Science.gov (United States)

    Tuzson, Béla; Jágerská, Jana; Looser, Herbert; Graf, Manuel; Felder, Ferdinand; Fill, Matthias; Tappy, Luc; Emmenegger, Lukas

    2017-06-20

    A broadly tunable mid-infrared vertical-external-cavity surface-emitting laser (VECSEL) is employed in a direct absorption laser spectroscopic setup to measure breath acetone. The large wavelength coverage of more than 30 cm -1 at 3.38 μm allows, in addition to acetone, the simultaneous measurement of isoprene, ethanol, methanol, methane, and water. Despite the severe spectral interferences from water and alcohols, an unambiguous determination of acetone is demonstrated with a precision of 13 ppbv that is achieved after 5 min averaging at typical breath mean acetone levels in synthetic gas samples mimicking human breath.

  16. 4.5 μm wavelength vertical external cavity surface emitting laser operating above room temperature

    Science.gov (United States)

    Rahim, M.; Khiar, A.; Felder, F.; Fill, M.; Zogg, H.

    2009-05-01

    A midinfrared vertical external cavity surface emitting laser with 4.5 μm emission wavelength and operating above room temperature has been realized. The active part consists of a single 850 nm thick epitaxial PbSe gain layer. It is followed by a 2 1/2 pair Pb1-yEuyTe/BaF2 Bragg mirror. No microstructural processing is needed. Excitation is done optically with a 1.5 μm wavelength laser. The device operates up to 45 °C with 100 ns pulses and delivers 6 mW output power at 27 °C heat-sink temperature.

  17. Efficient second harmonic generation of a diode-laser-pumped CW Nd:YAG laser using monolithic MgO:LiNbO3 external resonant cavities

    Science.gov (United States)

    Kozlovsky, William J.; Nabors, C. D.; Byer, Robert L.

    1988-01-01

    56-percent efficient external-cavity-resonant second-harmonic generation of a diode-laser pumped, CW single-axial-mode Nd:YAG laser is reported. A theory of external doubling with a resonant fundamental is presented and compared to experimental results for three monolithic cavities of nonlinear MgO:LiNbO3. The best conversion efficiency was obtained with a 12.5-mm-long monolithic ring cavity doubler, which produced 29.7 mW of CW, single-axial model 532-nm radiation from an input of 52.5 mW.

  18. Flow and heat transfer in gas turbine disk cavities subject to nonuniform external pressure field

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R.P.; Kim, Y.W.; Tong, T.W. [Arizona State Univ., Tempe, AZ (United States)

    1995-10-01

    Injestion of hot gas from the main-stream gas path into turbine disk cavities, particularly the first-stage disk cavity, has become a serious concern for the next-generation industrial gas turbines featuring high rotor inlet temperature. Fluid temperature in the cavities increases further due to windage generated by fluid drag at the rotating and stationary surfaces. The resulting problem of rotor disk heat-up is exacerbated by the high disk rim temperature due to adverse (relatively flat) temperature profile of the mainstream gas in the annular flow passage of the turbine. A designer is concerned about the level of stresses in the turbine rotor disk and its durability, both of which are affected significantly by the disk temperature distribution. This distribution also plays a major role in the radial position of the blade tip and thus, in establishing the clearance between the tip and the shroud. To counteract mainstream gas ingestion as well as to cool the rotor and the stator disks, it is necessary to inject cooling air (bled from the compressor discharge) into the wheel space. Since this bleeding of compressor air imposes a penalty on the engine cycle performance, the designers of disk cavity cooling and sealing systems need to accomplish these tasks with the minimum possible amount of bleed air without risking disk failure. This requires detailed knowledge of the flow characteristics and convective heat transfer in the cavity. The flow in the wheel space between the rotor and stator disks is quite complex. It is usually turbulent and contains recirculation regions. Instabilities such as vortices oscillating in space have been observed in the flow. It becomes necessary to obtain both a qualitative understanding of the general pattern of the fluid motion as well as a quantitative map of the velocity and pressure fields.

  19. THE DETERMINATION OF A CRITICAL VALUE FOR DYNAMIC STABILITY OF SEMICONDUCTOR LASER DIODE WITH EXTERNAL OPTICAL FEEDBACK

    Directory of Open Access Journals (Sweden)

    Remzi YILDIRIM

    1998-01-01

    Full Text Available In this study, dynamic stability analysis of semiconductor laser diodes with external optical feedback has been realized. In the analysis the frequency response of the transfer function of laser diode H jw( , the transfer m function of laser diode with external optical feedback TF jw( , and optical feedback transfer function m K jw( obtained from small signal equations has been m accomplished using Nyquist stability analysis in complex domain. The effect of optical feedback on the stability of the system has been introduced and to bring the laser diode to stable condition the working critical boundary range of dampig frequency and reflection power constant (R has been determined. In the study the reflection power has been taken as ( .

  20. Simultaneous monitoring of singlet and triplet exciton variations in solid organic semiconductors driven by an external static magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Baofu, E-mail: b.ding@ecu.edu.au; Alameh, Kamal, E-mail: k.alameh@ecu.edu.au [Electron Science Research Institute, Edith Cowan University, 270 Joondalup Drive, Joondalup, WA 6027 (Australia)

    2014-07-07

    The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.

  1. Simultaneous monitoring of singlet and triplet exciton variations in solid organic semiconductors driven by an external static magnetic field

    International Nuclear Information System (INIS)

    Ding, Baofu; Alameh, Kamal

    2014-01-01

    The research field of organic spintronics has remarkably and rapidly become a promising research area for delivering a range of high-performance devices, such as magnetic-field sensors, spin valves, and magnetically modulated organic light emitting devices (OLEDs). Plenty of microscopic physical and chemical models based on exciton or charge interactions have been proposed to explain organic magneto-optoelectronic phenomena. However, the simultaneous observation of singlet- and triplet-exciton variations in an external magnetic field is still unfeasible, preventing a thorough theoretical description of the spin dynamics in organic semiconductors. Here, we show that we can simultaneously observe variations of singlet excitons and triplet excitons in an external magnetic field, by designing an OLED structure employing a singlet-exciton filtering and detection layer in conjunction with a separate triplet-exciton detection layer. This OLED structure enables the observation of a Lorentzian and a non-Lorentzian line-shape magnetoresponse for singlet excitons and triplet excitons, respectively.

  2. Effects of Er, Cr:YSGG laser irradiation on external adaptation of restorations in caries-affected cavities

    International Nuclear Information System (INIS)

    Tonetto, Mateus Rodrigues; Saad, José Roberto Cury; Campos, Edson Alves de; Neto, Sizenando de Toledo Porto; De Andrade, Marcelo Ferrarezi; Bandéca, Matheus Coelho; Borges, Alvaro Henrique; Pinto, Shelon Cristina Souza

    2013-01-01

    This study evaluated the effect of Er,Cr:YSGG laser irradiation on the external adaptation of composite resin restorations in caries-affected cavities. Mixed class V cavity preparations were performed in 36 intact human third molars, in half of which caries was artificially induced. Both healthy and carious dentin were etched with 35% phosphoric acid (Ultradent Products Inc., South Jordan, Utah, USA), and the teeth were divided into three groups, i.e., (a) untreated etched dentin, (b) application of the Er, Cr:YSGG laser and (c) use of chlorhexidine as an adjunct in the bonding process. Restorations were fabricated with Z350 XT FiltekTM composite resin (3M ESPE) and subsequently the specimens were subjected to thermocycling to simulate artificial ageing. Quantitative analysis of external adaptation was performed by scanning electron microscopy in both healthy and affected dentin using epoxy resin replicas. It was concluded that the application of laser and chlorhexidine did not affect the percentages of marginal adaptation of class V restorations. Furthermore, thermocycling may influence adaptation values. (letter)

  3. First-principles study of anharmonic phonon effects in tetrahedral semiconductors via an external electric field

    Energy Technology Data Exchange (ETDEWEB)

    Dabiri, Zohreh, E-mail: z.dabiri@stu.yazd.ac.ir [Physics Department, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Kazempour, Ali [Department of Physics, Payame Noor University, P.O. BOX 119395-3697, Tehran (Iran, Islamic Republic of); Nano Structured Coatings Institute of Yazd Payame Noor University, P.O. Code 89431-74559, Yazd (Iran, Islamic Republic of); Sadeghzadeh, Mohammad Ali [Physics Department, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of)

    2016-11-15

    The strength of phonon anharmonicity is investigated in the framework of the Density Functional Perturbation Theory via an applied constant electric field. In contrast to routine approaches, we have employed the electric field as an effective probe to quest after the quasi-harmonic and anharmonic effects. Two typical tetrahedral semiconductors (diamond and silicon) have been selected to test the efficiency of this approach. In this scheme the applied field is responsible for establishing the perturbation and also inducing the anharmonicity in systems. The induced polarization is a result of changing the electronic density while ions are located at their ground state coordinates or at a specified strain. Employing this method, physical quantities of the semiconductors are calculated in presence of the electron–phonon interaction directly and, phonon–phonon interaction, indirectly. The present approach, which is in good agreement with previous theoretical and experimental studies, can be introduced as a benchmark to simply investigate the anharmonicity and pertinent consequences in materials.

  4. External and Internal Reconnection in Two Filament-Carrying Magnetic-Cavity Solar Eruptions

    Science.gov (United States)

    Sterling, Alphonse C.; Moore, Ronald L.

    2004-01-01

    We observe two near-limb solar filament eruptions, one of 2000 February 26 and the other of 2002 January 4. For both we use 195 A Fe XII images from the Extreme-Ultraviolet Imaging Telescope (EIT) and magnetograms from the Michelson Doppler Imager (MDI), both of which are on the Solar and Heliospheric Observatory (SOHO). For the earlier event we also use soft X-ray telescope (SXT), hard X-ray telescope (HXT), and Bragg Crystal Spectrometer (BCS) data from the Yohkoh satellite, and hard X-ray data from the BATSE experiment on the Compton Gamma Ra.v Observatory (CGRO). Both events occur in quadrupolar magnetic regions, and both have coronal features that we infer belong to the same magnetic cavity structures as the filaments. In both cases, the cavity and filament first rise slowly at approx.10 km/s prior to eruption and then accelerate to approx.100 km/s during the eruption, although the slow-rise movement for the higher altitude cavity elements is clearer in the later event. We estimate that both filaments and both cavities contain masses of approx.10(exp 14)-10(exp 15) and approx.10(exp 15)-10(exp 16) g, respectively. We consider whether two specific magnetic reconnection-based models for eruption onset, the "tether cutting" and the "breakout" models, are consistent with our observations. In the earlier event, soft X-rays from SXT show an intensity increase during the 12 minute interval over which fast eruption begins, which is consistent with tether- cutting-model predictions. Substantial hard X-rays, however, do not occur until after fast eruption is underway, and so this is a constraint the tether-cutting model must satisfy. During the same 12 minute interval over which fast eruption begins, there are brightenings and topological changes in the corona indicative of high-altitude reconnection early in the eruption, and this is consistent with breakout predictions. In both eruptions, the state of the overlying loops at the time of onset of the fast-rise phase of

  5. External and Internal Reconnection in Two Filament-Carrying Magnetic Cavity Solar Eruptions

    Science.gov (United States)

    Sterling, Alphonse C.; Moore, Ronald L.

    2004-01-01

    We observe two near-limb solar filament eruptions. one of 2000 February 26 and the other of 2002 January 4. For both we use 195 A Fe XII images from the Extreme-Ultraviolet Imaging Telescope (EIT) and magnetograms from the Michelson Doppler Imager (MDI). both of which are on the Solar and Heliospheric Observatory. (SOHO). For the earlier event we also use soft X-ray telescope (SXT). hard X-ray telescope (HXT). and Bragg Crystal Spectrometer (BCS) data from the Yohkoh satellite. and hard X-ray data from the BATSE experiment on the Compton Gamma Ray Observatory. (CGRO). Both events occur in quadrupolar magnetic regions. and both have coronal features that we infer belong to the same magnetic cavity structures as the filaments. In both cases. the cavity and filament first rise slowly at approx. 10 km/s prior to eruption and then accelerate to approx. 100 km/s during the eruption. although the slow-rise movement for the higher altitude cavity elements is clearer in the later event. We estimate that both filaments and both cavities contain masses of approx. 10(exp14) - 1 0(exp 15) and approx. l0(exp 15) - l0(exp 16) g. respectively. We consider whether two specific magnetic reconnection-based models for eruption onset. the "tether cutting" and the "breakout" models. are consistent with our observations. In the earlier event, soft X-rays from SXT show an intensity increase during the 12 minute interval over which fast eruption begins. which is consistent with tether- cutting-model predictions. Substantial hard X-ray. however. do not occur until after fast eruption is underway. and so this is a constraint the tether-cutting model must satisfy. During the same 12 minute interval over which fast eruption begins, there are brightenings and topological changes in the corona indicative of high-altitude reconnection early in the eruption. and this is consistent with breakout predictions. In both eruptions. the state of the overlying loops at the time of onset of the fast

  6. Wavelength-tunable prism-coupled external cavity passively mode-locked quantum-dot laser

    International Nuclear Information System (INIS)

    Wu Yan-Hua; Jian Wu; Jin Peng; Wang Fei-Fei; Hu Fa-Jie; Wei Heng; Wang Zhan-Guo

    2015-01-01

    A wavelength-tunable mode-locked quantum dot laser using an InAs/GaAs quantum-dot gain medium and a discrete semiconductor saturable absorber mirror is demonstrated. A dispersion prism, which has lower optical loss and less spectral narrowing than a blazed grating, is used for wavelength selection and tuning. A wavelength tuning range of 45.5 nm (from 1137.3 nm to 1182.8 nm) under 140-mA injection current in the passive mode-locked regime is achieved. The maximum average power of 19 mW is obtained at the 1170.3-nm wavelength, corresponding to the single pulse energy of 36.5 pJ. (paper)

  7. An ultra-long cavity passively mode-locked fiber laser based on nonlinear polarization rotation in a semiconductor optical amplifier

    International Nuclear Information System (INIS)

    Liu, Tonghui; Jia, Dongfang; Yang, Jingwen; Chen, Jiong; Wang, Zhaoying; Yang, Tianxin

    2013-01-01

    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)

  8. Probing different regimes of strong field light-matter interaction with semiconductor quantum dots and few cavity photons

    Science.gov (United States)

    Hargart, F.; Roy-Choudhury, K.; John, T.; Portalupi, S. L.; Schneider, C.; Höfling, S.; Kamp, M.; Hughes, S.; Michler, P.

    2016-12-01

    In this work we present an extensive experimental and theoretical investigation of different regimes of strong field light-matter interaction for cavity-driven quantum dot (QD) cavity systems. The electric field enhancement inside a high-Q micropillar cavity facilitates exceptionally strong interaction with few cavity photons, enabling the simultaneous investigation for a wide range of QD-laser detuning. In case of a resonant drive, the formation of dressed states and a Mollow triplet sideband splitting of up to 45 μeV is measured for a mean cavity photon number ≤slant 1. In the asymptotic limit of the linear AC Stark effect we systematically investigate the power and detuning dependence of more than 400 QDs. Some QD-cavity systems exhibit an unexpected anomalous Stark shift, which can be explained by an extended dressed 4-level QD model. We provide a detailed analysis of the QD-cavity systems properties enabling this novel effect. The experimental results are successfully reproduced using a polaron master equation approach for the QD-cavity system, which includes the driving laser field, exciton-cavity and exciton-phonon interactions.

  9. Fixed-wavelength H2O absorption spectroscopy system enhanced by an on-board external-cavity diode laser

    International Nuclear Information System (INIS)

    Brittelle, Mack S; Simms, Jean M; Sanders, Scott T; Gord, James R; Roy, Sukesh

    2016-01-01

    We describe a system designed to perform fixed-wavelength absorption spectroscopy of H 2 O vapor in practical combustion devices. The system includes seven wavelength-stabilized distributed feedback (WSDFB) lasers, each with a spectral accuracy of  ±1 MHz. An on-board external cavity diode laser (ECDL) that tunes 1320–1365 nm extends the capabilities of the system. Five system operation modes are described. In one mode, a sweep of the ECDL is used to monitor each WSDFB laser wavelength with an accuracy of  ±30 MHz. Demonstrations of fixed-wavelength thermometry at 10 kHz bandwidth in near-room-temperature gases are presented; one test reveals a temperature measurement error of ∼0.43%. (paper)

  10. Modular PbSrS/PbS mid-infrared vertical external cavity surface emitting laser on Si

    Science.gov (United States)

    Khiar, A.; Rahim, M.; Fill, M.; Felder, F.; Zogg, H.; Cao, D.; Kobayashi, S.; Yokoyama, T.; Ishida, A.

    2011-07-01

    A mid-infrared vertical external cavity surface emitting laser (VECSEL) based on undoped PbS is described herein. A 200 nm-thick PbS active layer embedded between PbSrS cladding layers forms a double heterostructure. The layers are grown on a lattice and thermal expansion mismatched Si-substrate. The substrate is placed onto a flat bottom Bragg mirror again grown on a Si substrate, and the VECSEL is completed with a curved top mirror. Pumping is done optically with a 1.55 μm laser diode. This leads to an extremely simple modular fabrication process. Lasing wavelengths range from 3-3.8 μm at 100-260 K heat sink temperature. The lowest threshold power is ˜210 mWp and highest output power is ˜250 mWp. The influence of the different recombination mechanism as well as free carrier absorption on the threshold power is modeled.

  11. PbSe quantum well mid-infrared vertical external cavity surface emitting laser on Si-substrates

    Science.gov (United States)

    Fill, M.; Khiar, A.; Rahim, M.; Felder, F.; Zogg, H.

    2011-05-01

    Mid-infrared vertical external cavity surface emitting lasers based on PbSe/PbSrSe multi-quantum-well structures on Si-substrates are realized. A modular design allows growing the active region and the bottom Bragg mirror on two different Si-substrates, thus facilitating comparison between different structures. Lasing is observed from 3.3 to 5.1 μm wavelength and up to 52 °C heat sink temperature with 1.55 μm optical pumping. Simulations show that threshold powers are limited by Shockley-Read recombination with lifetimes as short as 0.1 ns. At higher temperatures, an additional threshold power increase occurs probably due to limited carrier diffusion length and carrier leakage, caused by an unfavorable band alignment.

  12. Investigations of repetition rate stability of a mode-locked quantum dot semiconductor laser in an auxiliary optical fiber cavity

    DEFF Research Database (Denmark)

    Breuer, Stefan; Elsässer, Wolfgang; McInerney, J.G.

    2010-01-01

    We have investigated experimentally the pulse train (mode beating) stability of a monolithic mode-locked multi-section quantum-dot laser with an added passive auxiliary optical fiber cavity. Addition of the weakly coupled (¿ -24dB) cavity reduces the current-induced shift d¿/dI of the principal...

  13. Auger Processes Mediating the Nonresonant Optical Emission from a Semiconductor Quantum Dot Embedded Inside an Optical Cavity

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Nielsen, Per Kær; Lund, Anders Mølbjerg

    2013-01-01

    perform microscopic calculations of the effect treating the wetting layer as a non-Markovian reservoir interacting with the coupled quantum dot-cavity system through Coulomb interactions. Experimentally, cavity feeding has been observed in the asymmetric detuning range of -10 to +45 meV. We show...

  14. Single frequency semiconductor lasers

    CERN Document Server

    Fang, Zujie; Chen, Gaoting; Qu, Ronghui

    2017-01-01

    This book systematically introduces the single frequency semiconductor laser, which is widely used in many vital advanced technologies, such as the laser cooling of atoms and atomic clock, high-precision measurements and spectroscopy, coherent optical communications, and advanced optical sensors. It presents both the fundamentals and characteristics of semiconductor lasers, including basic F-P structure and monolithic integrated structures; interprets laser noises and their measurements; and explains mechanisms and technologies relating to the main aspects of single frequency lasers, including external cavity lasers, frequency stabilization technologies, frequency sweeping, optical phase locked loops, and so on. It paints a clear, physical picture of related technologies and reviews new developments in the field as well. It will be a useful reference to graduate students, researchers, and engineers in the field.

  15. Switching waves dynamics in optical bistable cavity-free system at femtosecond laser pulse propagation in semiconductor under light diffraction

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Egorenkov, Vladimir A.; Loginova, Maria M.

    2018-02-01

    We consider a propagation of laser pulse in a semiconductor under the conditions of an occurrence of optical bistability, which appears due to a nonlinear absorption of the semiconductor. As a result, the domains of high concentration of free charged particles (electrons and ionized donors) occur if an intensity of the incident optical pulse is greater than certain intensity. As it is well-known, that an optical beam must undergo a diffraction on (or reflection from) the domains boundaries. Usually, the beam diffraction along a coordinate of the optical pulse propagation does not take into account by using the slowly varying envelope approximation for the laser pulse interaction with optical bistable element. Therefore, a reflection of the beam from the domains with abrupt boundary does not take into account under computer simulation of the laser pulse propagation. However, the optical beams, reflected from nonhomogeneities caused by the domains of high concentration of free-charged particles, can essentially influence on a formation of switching waves in a semiconductor. We illustrate this statement by computer simulation results provided on the base of nonlinear Schrödinger equation and a set of PDEs, which describe an evolution of the semiconductor characteristics (concentrations of free-charged particles and potential of an electric field strength), and taking into account the longitudinal and transverse diffraction effects.

  16. Proposal for efficient mode converter based on cavity quantum electrodynamics dark mode in a semiconductor quantum dot coupled to a bimodal microcavity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiahua [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China); Key Laboratory of Fundamental Physical Quantities Measurement of Ministry of Education, Wuhan 430074 (China); Yu, Rong, E-mail: yurong321@126.com [School of Science, Hubei Province Key Laboratory of Intelligent Robot, Wuhan Institute of Technology, Wuhan 430073 (China); Ma, Jinyong; Wu, Ying, E-mail: yingwu2@163.com [School of Physics, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2014-10-28

    The ability to engineer and convert photons between different modes in a solid-state approach has extensive technological implications not only for classical communication systems but also for future quantum networks. In this paper, we put forward a scheme for coherent mode conversion of optical photons by utilizing the intermediate coupling between a single quantum dot and a bimodal photonic crystal microcavity via a waveguide. Here, one mode of the photonic crystal microcavity is coherently driven by an external single-frequency continuous-wave laser field and the two cavity modes are not coupled to each other due to their orthogonal polarizations. The undriven cavity mode is thus not directly coupled to the input driving laser and the only way it can get light is via the quantum dot. The influences of the system parameters on the photon-conversion efficiency are analyzed in detail in the limit of weak probe field and it is found that high photon-conversion efficiency can be achieved under appropriate conditions. It is shown that the cavity dark mode, which is a superposition of the two optical modes and is decoupled from the quantum dot, can appear in such a hybrid optical system. We discuss the properties of the dark mode and indicate that the formation of the dark mode enables the efficient transfer of optical fields between the two cavity modes.

  17. A photothermal Mach-Zehnder interferometer for measuring caffeine and proteins in aqueous solutions using external cavity quantum cascade lasers

    Science.gov (United States)

    Kristament, Christian; Schwaighofer, Andreas; Montemurro, Milagros; Lendl, Bernhard

    2018-02-01

    One of the advantages of mid-IR spectroscopy in biomedical research lies in its capability to provide direct information on the secondary structure of proteins in their natural, often aqueous, environment. One impediment of direct absorption measurements in the correspondent spectral region is the strong absorbance of the native solvent (H2O). In this regard, the advent of broadly-tunable external cavity quantum cascade lasers (EC-QCL) allowed to significantly increasing the optical path length employed in transmission measurements due to their high spectral power densities. Low measured S/N ratios were improved by elaborated data analysis protocols that corrected mechanical flaws in the tuning mechanism of ECQCLs and allow for S/N ratios comparable to research grade FTIR spectrometers. Recent development of new optical set-ups outpacing direct absorption measurements led to further advancements. We present a dedicated Mach-Zehnder interferometer for photothermal measurements in balanced detection mode. In this highly sensitive design, the interferometer is illuminated by a HeNe laser to detect the refractive index change induced by the heat insertion of the EC-QCL. Here, we present photothermal phase shift interferometry measurements of caffeine in ethanol as well as casein in water. Further, the dependency of the signal amplitude on varying modulation frequencies was investigated for different liquids.

  18. Rapid and Sensitive Quantification of Isotopic Mixtures Using a Rapidly-Swept External Cavity Quantum Cascade Laser

    Directory of Open Access Journals (Sweden)

    Brian E. Brumfield

    2016-05-01

    Full Text Available A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at a rate of 40 Hz (25-ms measurement time. The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of <1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ (NEC of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement time are determined for D2O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D2O and HDO, respectively. NECs <200 ppbv are also estimated for N2O, 1,1,1,2–tetrafluoroethane (F134A, CH4, acetone and SO2 for a 25-ms measurement time. The isotopic precision for measurement of the [D2O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.

  19. Wavelength modulation spectroscopy coupled with an external-cavity quantum cascade laser operating between 7.5 and 8 µm

    Science.gov (United States)

    Maity, Abhijit; Pal, Mithun; Maithani, Sanchi; Dutta Banik, Gourab; Pradhan, Manik

    2018-04-01

    We demonstrate a mid-infrared detection strategy with 1f-normalized 2f-wavelength modulation spectroscopy (WMS-2f/1f) using a continuous wave (CW) external-cavity quantum cascade laser (EC-QCL) operating between 7.5 and 8 µm. The detailed performance of the WMS-2f/1f detection method was evaluated by making rotationally resolved measurements in the (ν 4  +  ν 5) combination band of acetylene (C2H2) at 1311.7600 cm-1. A noise-limited detection limit of three parts per billion (ppb) with an integration time of 110 s was achieved for C2H2 detection. The present high-resolution CW-EC-QCL system coupled with the WMS-2f/1f strategy was further validated with an extended range of C2H2 concentration of 0.1-1000 ppm, which shows excellent promise for real-life practical sensing applications. Finally, we utilized the WMS-2f/1f technique to measure the C2H2 concentration in the exhaled breath of smokers.

  20. Resonance generation of photons from vacuum in cavities due to strong periodical changes of conductivity in a thin semiconductor boundary layer

    International Nuclear Information System (INIS)

    Dodonov, A V; Dodonov, V V

    2005-01-01

    We study a possibility of photon generation from vacuum in a cavity with an artificial effective time-dependent plasma mirror, which could be created by means of periodical short laser pulses, illuminating a thin semiconductor slab. We take into account two important circumstances: a big imaginary part of the complex time-dependent dielectric permeability inside the slab and a strong dependence of this imaginary part on the distance from the surface of the slab. We find the conditions under which the usual unitary quantization schemes in time-dependent media with real dielectric permeability can be applied to the problem concerned with relatively small (a few per cent) error. We show that, by using a slab with thickness of the order of 1 mm, it is possible to generate a large number of microwave (GHz) photons (up to 10 8 or more) after several thousand picosecond pulses with repetition frequency of the order of 1 GHz, provided that semiconductor materials with high mobility of carriers, high photoabsorption efficiency and small recombination time (less than 1 ns) can be found. We discuss the possible advantages of modes with TM polarization over TE ones, as well as some other important problems to be solved

  1. Size-controlled one-pot synthesis of fluorescent cadmium sulfide semiconductor nanoparticles in an apoferritin cavity

    International Nuclear Information System (INIS)

    Iwahori, K; Yamashita, I

    2008-01-01

    A simple size-controlled synthesis of cadmium sulfide (CdS) nanoparticle (NP) cores in the cavity of apoferritin from horse spleen (HsAFr) was performed by a slow chemical reaction synthesis and a two-step synthesis protocol. We found that the CdS NP core synthesis was slow and that premature CdS NP cores were formed in the apoferritin cavity when the concentration of ammonia water was low. It was proven that the control of the ammonia water concentration can govern the CdS NP core synthesis and successfully produce size-controlled CdS NP cores with diameters from 4.7 to 7.1 nm with narrow size dispersion. X-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS) analysis and high-resolution transmission electron microscopy (HR-TEM) observation characterized the CdS NP cores obtained as cubic polycrystalline NPs, which showed photoluminescence with red shifts depending on their diameters. From the research of CdS NP core synthesis in the recombinant apoferritins, the zeta potential of apoferritin is important for the biomineralization of CdS NP cores in the apoferritin cavity. These synthesized CdS NPs with different photoluminescence properties will be applicable in a wide variety of nano-applications.

  2. Mid-infrared PbTe vertical external cavity surface emitting laser on Si-substrate with above 1 W output power

    Science.gov (United States)

    Rahim, M.; Fill, M.; Felder, F.; Chappuis, D.; Corda, M.; Zogg, H.

    2009-12-01

    Mid-infrared vertical external cavity surface emitting lasers (VECSELs) emitting above 1 W output power in pulsed mode and up to 17 mW in continuous mode at -172 °C were realized. Emission wavelength changes from 5 μm at -172 °C to 3.6 μm at 20 °C heat sink temperature. The active medium is a one wavelength thick PbTe layer grown by molecular beam epitaxy on a Si-substrate. It is followed by a 2.5 pair Pb1-yEuyTe/EuTe epitaxial Bragg mirror. The cavity is completed with an external curved Pb1-yEuyTe/BaF2 mirror. The VECSEL is optically pumped with 1.55 μm wavelength laser and In-soldered to Cu heat sink. No microstructural processing is needed.

  3. Optically coupled cavities for wavelength switching

    Energy Technology Data Exchange (ETDEWEB)

    Costazo-Caso, Pablo A; Granieri, Sergio; Siahmakoun, Azad, E-mail: pcostanzo@ing.unlp.edu.ar, E-mail: granieri@rose-hulman.edu, E-mail: siahmako@rose-hulman.edu [Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN 47803 (United States)

    2011-01-01

    An optical bistable device which presents hysteresis behavior is proposed and experimentally demonstrated. The system finds applications in wavelength switching, pulse reshaping and optical bistability. It is based on two optically coupled cavities named master and slave. Each cavity includes a semiconductor optical amplifier (SOA), acting as the gain medium of the laser, and two pair of fiber Bragg gratings (FBG) which define the lasing wavelength (being different in each cavity). Finally, a variable optical coupler (VOC) is employed to couple both cavities. Experimental characterization of the system performance is made analyzing the effects of the coupling coefficient between the two cavities and the driving current in each SOA. The properties of the hysteretic bistable curve and switching can be controlled by adjusting these parameters and the loss in the cavities. By selecting the output wavelength ({lambda}{sub 1} or {lambda}{sub 2}) with an external filter it is possible to choose either the invert or non-invert switched signal. Experiments were developed employing both optical discrete components and a photonic integrated circuit. They show that for 8 m-long cavities the maximum switching frequency is about 500 KHz, and for 4 m-long cavities a minimum rise-time about 21 ns was measured. The switching time can be reduced by shortening the cavity lengths and using photonic integrated circuits.

  4. Self-injection locking of the DFB laser through an external ring fiber cavity: Application for phase sensitive OTDR acoustic sensor

    Directory of Open Access Journals (Sweden)

    J.L. Bueno Escobedo

    Full Text Available Self-injection locking of DFB laser implemented through the laser coupling with an external fiber optic ring cavity allows its direct employment as an interrogating light source for a phase sensitive OTDR acoustic sensor. Distributed detection and localization of dynamic perturbations of the optical fiber is experimentally demonstrated at the distance of 9270 m. Keywords: Self-injection locking, Optical fiber resonator, φ-OTDR

  5. An off Axis Cavity Enhanced Absorption Spectrometer and a Rapid Scan Spectrometer with a Room-Temperature External Cavity Quantum Cascade Laser

    Science.gov (United States)

    Liu, Xunchen; Kang, Cheolhwa; Xu, Yunjie

    2009-06-01

    Quantum cascade laser (QCL) is a new type of mid-infrared tunable diode lasers with superior output power and mode quality. Recent developments, such as room temperature operation, wide frequency tunability, and narrow line width, make QCLs an ideal light source for high resolution spectroscopy. Two slit jet infrared spectrometers, namely an off-axis cavity enhanced absorption (CEA) spectrometer and a rapid scan spectrometer with an astigmatic multi-pass cell assembly, have been coupled with a newly purchased room temperature tunable mod-hop-free QCL with a frequency coverage from 1592 cm^{-1} to 1698 cm^{-1} and a scan rate of 0.1 cm^{-1}/ms. Our aim is to utilize these two sensitive spectrometers, that are equipped with a molecular jet expansion, to investigate the chiral molecules-(water)_n clusters. To demonstrate the resolution and sensitivity achieved, the rovibrational transitions of the static N_2O gas and the bending rovibrational transitions of the Ar-water complex, a test system, at 1634 cm^{-1} have been measured. D. Hofstetter and J. Faist in High performance quantum cascade lasers and their applications, Vol.89 Springer-Verlag Berlin & Heidelberg, 2003, pp. 61-98. Y. Xu, X. Liu, Z. Su, R. M. Kulkarni, W. S. Tam, C. Kang, I. Leonov and L. D'Agostino, Proc. Spie, 2009, 722208 (1-11). M. J. Weida and D. J. Nesbitt, J. Chem. Phys. 1997, 106, 3078-3089.

  6. Photocathodes inside superconducting cavities. Studies on the feasibility of a superconducting photoelectron source of high brightness. External report

    International Nuclear Information System (INIS)

    Michalke, A.

    1992-01-01

    We have done studies and experiments to explore the feasibility of a photoemission RF gun with a superconducting accelerator cavity. This concept promises to provide an electron beam of high brightness in continuous operation. It is thus of strong interest for a free-electron-laser or a linear collider based on a superconducting accelerator. In a first step we studied possible technical solutions for its components, especially the material of the photocathode and the geometrical shape of the cavity. Based on these considerations, we developed the complete design for a prototype electron source. The cathode material was chosen to be alkali antimonide. In spite of its sensitivity, it seems to be the best choice for a gun with high average current due to its high quantum efficiency. The cavity shape was at first a reentrant-type single cell of 500 MHz. It is now replaced by a more regular two-and-half cell shape, an independent half cell added for emittance correction. Its beam dynamics properties are investigated by numerical simulations; we estimated a beam brightness of about 5x10 11 A/(m.rad) 2 . But the mutual interactions between alkali antimonide photocathode and superconducting cavity must be investigated experimentally, because they are completely unkown. (orig.)

  7. Efficient quasi-three-level Nd:YAG laser at 946 nm pumped by a tunable external cavity tapered diode laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter

    2010-01-01

    Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...... efficiency is obtained, the highest reported TEM00 power from any 946 nm Nd:YAG laser pumped by a single emitter diode laser pump source. A quantum efficiency of 0.85 has been estimated from experimental data using a simple quasi-three-level model. The reported value is in good agreement with published...

  8. Periodic dark pulse emission induced by delayed feedback in a quantum well semiconductor laser

    Directory of Open Access Journals (Sweden)

    L. Li

    2012-12-01

    Full Text Available We report the experimental observation of periodic dark pulse emission in a quantum-well semiconductor laser with delayed optical feedback. We found that under appropriate operation conditions the laser can also emit a stable train of dark pulses. The repetition frequency of the dark pulse is determined by the external cavity length. Splitting of the dark pulse was also observed. We speculate that the observed dark pulse is a kind of temporal cavity soliton formed in the laser.

  9. Development of the external cooling device of increase the productivity of neutron-transmutation-doped silicon semiconductor (NTD-Si) (Joint research)

    International Nuclear Information System (INIS)

    Hirose, Akira; Wada, Shigeru; Sasajima, Fumio; Kusunoki, Tsuyoshi; Kameyama, Iwao; Aizawa, Ryouji; Kikuchi, Naoyuki

    2007-01-01

    Neutron-Transmutation-Doped Silicon Semiconductor (hereinafter referred as 'NTD-Si') is the best semiconductor for the power device. The needs of NTD-Si increase recently in proportion to the popularization of hybrid-cars. A fission research reactor, which is a steady state neutron source, is being expected as the best device to meet the needs. So far, we have reconsidered the existing approach which is employed for NTD-Si production works at the research reactors JRR-3, JRR-4 and JMTR of JAEA so as to meet the needs. As one of the effective measures, we found out that the productivity can be increased by incorporating a new device to cool down radioactivity of irradiated silicon ingots at the place outside the main stream from the loading of silicon ingots to the withdrawal of irradiated ingots to the existing JRR-3 Uniformity Irradiation System. Consequently, we developed and installed the device (hereinafter referred as 'external cooling device'). After an ingot was irradiated once, it is turned over manually and irradiated again in order to irradiate the ingot uniformly. With the conventional system, it was necessary to wait the radioactivity of ingot decrease less than the permissible level with holding the ingot in the irradiation equipment. It was effective to shorten the waiting period by using an external cooling device for production increase of NTD-Si. It is expected that the productivity of NTD-Si will be increased by using the external cooling device. This report mentions the design of the external cooling device and verification between its design specifications and the performance of the device completed. (author)

  10. Qubit-qubit entanglement dynamics control via external classical pumping and Kerr nonlinearity mediated by a single detuned cavity field powered by two-photon processes

    Science.gov (United States)

    Ateto, M. S.

    2017-11-01

    The nonlinear time-dependent two-photon Hamiltonian of a couple of classically pumped independent qubits is analytically solved, and the corresponding time evolution unitary operator, in an exact form, is derived. Using the concurrence, entanglement dynamics between the qubits under the influence of a wide range of effective parameters are examined and, in detail, analyzed. Observations analysis is documented with aid of the field phase-space distribution Wigner function. A couple of initial qubit states is considered, namely similar excited states and a Bell-like pure state. It is demonstrated that an initial Bell-like pure state is as well typical initial qubits setting for robust, regular and a high degree of entanglement. Moreover, it is established that high-constant Kerr media represent an effective tool for generating periodical entanglement at fixed time cycles of maxima reach unity forever when qubits are initially in a Bell-like pure state. Further, it is showed that the medium strength of the classical pumping stimulates efficiently qubits entanglement, specially, when the interaction occurs off resonantly. However, the high-intensity pumping thermalizes the coherent distribution of photons, thus, the least photons number is used and, hence, the least minimum degree of qubits entanglement could be created. Furthermore, when the cavity field and external pumping are detuned, the external pumping acts like an auxiliary effective frequency for the cavity, as a result, the field Gaussian distribution acquires linear chirps, and consequently, more entanglement revivals appear in the same cycle during timescale.

  11. Study of evaluation methods for in-vessel corium retention through external vessel cooling and safety of reactor cavity

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Hong; Huh, Hoon; Chang, Soon Heung [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)] (and others)

    1999-03-15

    Cooling methodologies for the molten corium resulted from the severe accident of the Nuclear Power Plant is suggested as one of most important items for the safety of the NPP. In this regard, considerable experimental and analytical works have been devoted. In the second phase of this project, current status of research about corium-concrete interaction and corium coolability which can occur on the reactor cavity has been surveyed, and the researches about lower head failure mechanism have also been surveyed. And, severe accident analysis for Ulchin 3 and 4 has been conducted, and collapse load of lower head has been analyzed through structural analysis considering various heat transfer conditions. The results of accident analysis can be used as a basic input for structural analysis which will be conducted in 3rd phase of this study.

  12. Emergence of resonant mode-locking via delayed feedback in quantum dot semiconductor lasers.

    Science.gov (United States)

    Tykalewicz, B; Goulding, D; Hegarty, S P; Huyet, G; Erneux, T; Kelleher, B; Viktorov, E A

    2016-02-22

    With conventional semiconductor lasers undergoing external optical feedback, a chaotic output is typically observed even for moderate levels of the feedback strength. In this paper we examine single mode quantum dot lasers under strong optical feedback conditions and show that an entirely new dynamical regime is found consisting of spontaneous mode-locking via a resonance between the relaxation oscillation frequency and the external cavity repetition rate. Experimental observations are supported by detailed numerical simulations of rate equations appropriate for this laser type. The phenomenon constitutes an entirely new mode-locking mechanism in semiconductor lasers.

  13. Nonreciprocal propagation of light without external magnetic fields in a semiconductor waveguide isolator with a MnAs layer

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, T. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan) and Japan Science and Techonology Agency, SORST (Japan)]. E-mail: ametomo@hotaka.t.u-tokyo.ac.jp; Shimizu, H. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Japan Science and Techonology Agency, SORST (Japan); Hai, P.N. [Department of Electronic Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Japan Science and Techonology Agency, SORST (Japan); Tanaka, M. [Department of Electronic Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Japan Science and Techonology Agency, SORST (Japan); Nakano, Y. [Research Center for Advanced Science and Technology, University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904 (Japan); Japan Science and Techonology Agency, SORST (Japan)

    2007-03-15

    A 1.5-{mu}m, TM-mode waveguide optical isolator was developed for use in photonic integrated circuits. It consists of an InGaAlAs-based optical waveguide with a ferromagnetic MnAs layer and makes use of nonreciprocal propagation loss of light induced by the magnetized MnAs layer. With a large-remanence MnAs layer grown with the Mn-template epitaxy method, the isolator successfully showed an 8.7 dB/mm isolation ratio without external magnetic fields.

  14. Recent Advances and Applications of External Cavity-QCLs towards Hyperspectral Imaging for Standoff Detection and Real-Time Spectroscopic Sensing of Chemicals

    Directory of Open Access Journals (Sweden)

    Ralf Ostendorf

    2016-05-01

    Full Text Available External-cavity quantum cascade lasers (EC-QCL are now established as versatile wavelength-tunable light sources for analytical spectroscopy in the mid-infrared (MIR spectral range. We report on the realization of rapid broadband spectral tuning with kHz scan rates by combining a QCL chip with a broad gain spectrum and a resonantly driven micro-opto-electro-mechanical (MOEMS scanner with an integrated diffraction grating in Littrow configuration. The capability for real-time spectroscopic sensing based on MOEMS EC-QCLs is demonstrated by transmission measurements performed on polystyrene reference absorber sheets, as well as on hazardous substances, such as explosives. Furthermore, different applications for the EC-QCL technology in spectroscopic sensing are presented. These include the fields of process analysis with on- or even inline capability and imaging backscattering spectroscopy for contactless identification of solid and liquid contaminations on surfaces. Recent progress in trace detection of explosives and related precursors in relevant environments as well as advances in food quality monitoring by discriminating fresh and mold contaminated peanuts based on their MIR backscattering spectrum is shown.

  15. Simultaneous frequency stabilization and high-power dense wavelength division multiplexing (HP-DWDM) using an external cavity based on volume Bragg gratings (VBGs)

    Science.gov (United States)

    Hengesbach, Stefan; Klein, Sarah; Holly, Carlo; Witte, Ulrich; Traub, Martin; Hoffmann, Dieter

    2016-03-01

    Multiplexing technologies enable the development of high-brightness diode lasers for direct industrial applications. We present a High-Power Dense Wavelength Division Multiplexer (HP-DWDM) with an average channel spacing of 1.7 (1.5) nm and a subsequent external cavity mirror to provide feedback for frequency stabilization and multiplexing in one step. The "self-optimizing" multiplexing unit consists of four reflective Volume Bragg Gratings (VBGs) with 99% diffraction efficiency and seven dielectric mirrors to overlay the radiation of five input channels with an adjustable channel spacing of 1-2 nm. In detail, we focus on the analysis of the overall optical efficiency, the change of the beam parameter product and the spectral width. The performance is demonstrated using five 90 μm multimode 9xx single emitters with M2angular intensity distribution changes strongly and the beam parameter product decreases by a factor of 1.2 to 1.9. Thereby the angular intensity distribution is more affected than the width of the beam waist. The spectral width per emitter decreases to 3-200 pm (FWHM) depending on the injection current and the reflectance of the feedback mirror (0.75%, 1.5%, 4%, 6% or 8%). The overall optical multiplexing efficiency ranges between 77% and 86%. With some modifications (e.g. enhanced AR-coatings) we expect 90-95%.

  16. 2.5-Gb/s hybridly-integrated tunable external cavity laser using a superluminescent diode and a polymer Bragg reflector.

    Science.gov (United States)

    Yoon, Ki-Hong; Oh, Su Hwan; Kim, Ki Soo; Kwon, O-Kyun; Oh, Dae Kon; Noh, Young-Ouk; Lee, Hyung-Jong

    2010-03-15

    We presented a hybridly-integrated tunable external cavity laser with 0.8 nm mode spacing 16 channels operating in the direct modulation of 2.5-Gbps for a low-cost source of a WDM-PON system. The tunable laser was fabricated by using a superluminescent diode (SLD) and a polymer Bragg reflector. The maximum output power and the power slope efficiency of the tunable laser were 10.3 mW and 0.132 mW/mA, respectively, at the SLD current of 100 mA and the temperature of 25 degrees C. The directly-modulated tunable laser successfully provided 2.5-Gbps transmissions through 20-km standard single mode fiber. The power penalty of the tunable laser was less than 0.8 dB for 16 channels after a 20-km transmission. The power penalty variation was less than 1.4 dB during the blue-shifted wavelength tuning.

  17. Tunable high-power narrow-spectrum external-cavity diode laser at 675 nm as a pump source for UV generation

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Erbert, Gotz

    2011-01-01

    High-power narrow-spectrum diode laser systems based on tapered gain media in external cavity are demonstrated at 675 nm. Two 2-mm-long amplifiers are used, one with a 500-µm-long ridge-waveguide section (device A), the other with a 750-µm-long ridge-waveguide section (device B). The laser system...... of 1.0 W. The laser system B based on device B is tunable from 666 to 685 nm. As high as 1.05 W output power is obtained around 675.67 nm. The emission spectral bandwidth is less than 0.07 nm throughout the tuning range, and the beam quality factor M2 is 1.13 at an output power of 0.93 W. The laser...... system B is used as a pump source for the generation of 337.6 nm UV light by single-pass frequency doubling in a BIBO crystal. An output power of 109 µW UV light, corresponding to a conversion efficiency of 0.026%W-1 is attained....

  18. Nanocavity effects on misfit accommodation in semiconductors

    International Nuclear Information System (INIS)

    Myers, S.M.; Follstaedt, D.M.; Floro, J.A.; Lee, S.R.; Dawson, L.R.; Reno, J.L.

    1997-04-01

    The authors report an experimental and theoretical examination of the interaction of dislocations with microscopic cavities in semiconductors and the consequences for strain relaxation in heteroepitaxial structures. Dislocation-mediated relaxation and control of the resulting defect microstructure is central to the exploitation of such heterostructures in devices, and they demonstrate here that the introduction of nanometer-scale voids provides a means of strongly influencing this microstructural evolution. Methods for nanocavity formation using He ion implantation and annealing were developed for Si, SiGe on Si, GaAs, and InGaAs on GaAs. In detailed microstructural studies of SiGe on Si, cavities in the interfacial zone were shown to bind dislocations strongly. This effect reduced the excursion of dislocations into the nearby matrix, although threads into the SiGe overlayer were not eliminated. Interfacial cavities also increased the rate of stress relaxation by more than an order of magnitude as a result of enhanced nucleation of misfit dislocations. Further, in the presence of such cavities, the development of thickness variations in the overlayer during relaxation was suppressed. A theoretical model was developed to describe semiquantitatively the forces on dislocations arising from the combined influences of cavities, misfit strain, and the external surface. Predictions of this model are in accord with microstructural observations

  19. Generation of more than 300 mW diffraction-limited light at 405 nm by second-harmonic generation of a tapered diode laser with external cavity feedback

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Holm, J.; Sumpf, B.

    2007-01-01

    We have constructed a blue laser source consisting of a single-frequency tapered diode laser with external cavity feedback that is frequency doubled by a quasi-phase matched KTP (PPKTP) in a bowtie ring cavity and extract more than 360 mW of power at 405 nm. The conversion efficiency from...... fundamental laser power to second harmonic power is 35 %, while it is 64 % from coupled fundamental power to extracted blue light. Thermal effects and gray tracking set an upper limit on the amount of generated blue light....

  20. Semiconductor lasers stability, instability and chaos

    CERN Document Server

    Ohtsubo, Junji

    2017-01-01

    This book describes the fascinating recent advances made concerning the chaos, stability and instability of semiconductor lasers, and discusses their applications and future prospects in detail. It emphasizes the dynamics in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Applications of semiconductor laser chaos, control and noise, and semiconductor lasers are also demonstrated. Semiconductor lasers with new structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are intriguing and promising devices. Current topics include fast physical number generation using chaotic semiconductor lasers for secure communication, development of chaos, quantum-dot semiconductor lasers and quantum-cascade semiconductor lasers, and vertical-cavity surface-emitting lasers. This fourth edition has been significantly expanded to reflect the latest developments. The fundamental theory of laser chaos and the chaotic dynamics in se...

  1. Semiconductor lasers with a continuous tuning range above 100 nm in the nearest IR spectral region

    Energy Technology Data Exchange (ETDEWEB)

    Kostin, Yu O; Lobintsov, A A; Shramenko, M V [OOO ' Opton' , Moscow (Russian Federation); Ladugin, M A; Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Chamorovsky, A Yu [Superlum Ltd., Unit B3, Fota Point Enterprise Park, Carrigtwohill, Co Cork (Ireland); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

    2015-08-31

    We have developed two new types of lasers based on quantum-confined semiconductor optical amplifiers with an acousto-optic tunable filter in an external fibre ring cavity. The lasers offer continuous wavelength tuning ranges from 780 to 885 and from 880 to 1010 nm, 20 mW of cw output power, and a tuning rate up to 10{sup 4} nm s{sup -1} at an instantaneous spectral linewidth less than 0.1 nm. (lasers)

  2. Compact semiconductor lasers

    CERN Document Server

    Yu, Siyuan; Lourtioz, Jean-Michel

    2014-01-01

    This book brings together in a single volume a unique contribution by the top experts around the world in the field of compact semiconductor lasers to provide a comprehensive description and analysis of the current status as well as future directions in the field of micro- and nano-scale semiconductor lasers. It is organized according to the various forms of micro- or nano-laser cavity configurations with each chapter discussing key technical issues, including semiconductor carrier recombination processes and optical gain dynamics, photonic confinement behavior and output coupling mechanisms, carrier transport considerations relevant to the injection process, and emission mode control. Required reading for those working in and researching the area of semiconductors lasers and micro-electronics.

  3. Delay induced high order locking effects in semiconductor lasers

    Science.gov (United States)

    Kelleher, B.; Wishon, M. J.; Locquet, A.; Goulding, D.; Tykalewicz, B.; Huyet, G.; Viktorov, E. A.

    2017-11-01

    Multiple time scales appear in many nonlinear dynamical systems. Semiconductor lasers, in particular, provide a fertile testing ground for multiple time scale dynamics. For solitary semiconductor lasers, the two fundamental time scales are the cavity repetition rate and the relaxation oscillation frequency which is a characteristic of the field-matter interaction in the cavity. Typically, these two time scales are of very different orders, and mutual resonances do not occur. Optical feedback endows the system with a third time scale: the external cavity repetition rate. This is typically much longer than the device cavity repetition rate and suggests the possibility of resonances with the relaxation oscillations. We show that for lasers with highly damped relaxation oscillations, such resonances can be obtained and lead to spontaneous mode-locking. Two different laser types-—a quantum dot based device and a quantum well based device—are analysed experimentally yielding qualitatively identical dynamics. A rate equation model is also employed showing an excellent agreement with the experimental results.

  4. A Study of the interaction of radiation and semiconductor lasers: an analysis of transient and permanent effects induced on edge emitting and vertical cavity surface emitting laser diodes

    International Nuclear Information System (INIS)

    Pailharey, Eric

    2000-01-01

    The behavior of laser diodes under transient environment is presented in this work. The first section describes the basic phenomena of radiation interaction with matter. The radiative environments, the main characteristics of laser diodes and the research undertaken on the subject are presented and discussed. The tests on 1300 nm edge emitting laser diode are presented in the second section. The response to a transient ionizing excitation is explored using a 532 nm laser beam. The time of return to steady state after the perturbation is decomposed into several steps: decrease of the optical power during excitation, turn-on delay, relaxation oscillations and optical power offset. Their origins are analyzed using the device structure. To include all the phenomena in a numerical simulation of the device, an individual study of low conductivity materials used for the lateral confinement of the current density is undertaken. The effects of a single particle traversing the optical cavity and an analysis of permanent damages induced by neutrons are also determined. In the last section, 850 nm vertical cavity surface emitting laser diodes (VCSEL) are studied. The behavior of these devices which performances are in constant evolution, is investigated as a function of both temperature and polarization. Then VCSEL are submitted to transient ionizing irradiation and their responses are compared to those of edge emitting diodes. When proton implantation is used in the process, we observe the same behavior for both technologies. VCSEL were submitted to neutron fluence and we have studied the influence of the damages on threshold current, emission patterns and maximum of optical power. (author) [fr

  5. An ultra-wideband tunable multi-wavelength Brillouin fibre laser based on a semiconductor optical amplifier and dispersion compensating fibre in a linear cavity configuration

    International Nuclear Information System (INIS)

    Zulkifli, M Z; Ahmad, H; Hassan, N A; Jemangin, M H; Harun, S W

    2011-01-01

    A multi-wavelength Brillouin fibre laser (MBFL) with an ultra-wideband tuning range from 1420 nm to 1620 nm is demonstrated. The MBFL uses an ultra-wideband semiconductor optical amplifier (SOA) and a dispersion compensating fibre (DCF) as the linear gain medium and nonlinear gain medium, respectively. The proposed MBFL has a wide tuning range covering the short (S-), conventional (C-) and long (L-) bands with a wavelength spacing of 0.08 nm, making it highly suitable for DWDM system applications. The output power of the observed Brillouin Stokes ranges approximately from -5.94 dBm to -0.41 dBm for the S-band, from -4.34 dBm to 0.02 dBm for the C-band and from -2.19 dBm to 0.39 dBm for the L-band. The spacing between each adjacent wavelengths of all the three bands is about 0.08 nm, which is approximately 10.7 GHz for the frequency domain. (lasers)

  6. Guide for the implementation in external radiation therapy of quality insurance by in vivo measurements by thermoluminescent dosimeters and semi-conductors. S.F.P.M. report nr 18-2000

    International Nuclear Information System (INIS)

    Goyet, Dominique; Dusserre, Andree; Marcie, Serge; Telenczak, Pascale; Waultier, Serge; Costa, Andre; Lisbona, Albert; Noel, Alain

    2000-01-01

    This report aims at gathering all necessary information for the implementation of treatment quality insurance procedures by in vivo measurements in the case of external radiation therapy. It presents the different techniques, describes characteristics of TL meters, electro-meters, TL dosimeters, and semi-conductors currently available on the French market, and indicates all accessories required by these techniques. It also recalls principles of in vivo measurements, as well as calibration procedures. The last part proposes a description of acceptance and quality control procedures for these equipment

  7. Magnetic Resonance Image Guided Radiation Therapy for External Beam Accelerated Partial-Breast Irradiation: Evaluation of Delivered Dose and Intrafractional Cavity Motion

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Sahaja; Fischer-Valuck, Benjamin W.; Mazur, Thomas R.; Curcuru, Austen; Sona, Karl; Kashani, Rojano; Green, Olga; Ochoa, Laura; Mutic, Sasa; Zoberi, Imran; Li, H. Harold; Thomas, Maria A., E-mail: mthomas@radonc.wustl.edu

    2016-11-15

    Purpose: To use magnetic resonance image guided radiation therapy (MR-IGRT) for accelerated partial-breast irradiation (APBI) to (1) determine intrafractional motion of the breast surgical cavity; and (2) assess delivered dose versus planned dose. Methods and Materials: Thirty women with breast cancer (stages 0-I) who underwent breast-conserving surgery were enrolled in a prospective registry evaluating APBI using a 0.35-T MR-IGRT system. Clinical target volume was defined as the surgical cavity plus a 1-cm margin (excluding chest wall, pectoral muscles, and 5 mm from skin). No additional margin was added for the planning target volume (PTV). A volumetric MR image was acquired before each fraction, and patients were set up to the surgical cavity as visualized on MR imaging. To determine the delivered dose for each fraction, the electron density map and contours from the computed tomography simulation were transferred to the pretreatment MR image via rigid registration. Intrafractional motion of the surgical cavity was determined by applying a tracking algorithm to the cavity contour as visualized on cine MR. Results: Median PTV volume was reduced by 52% when using no PTV margin compared with a 1-cm PTV margin used conventionally. The mean (± standard deviation) difference between planned and delivered dose to the PTV (V95) was 0.6% ± 0.1%. The mean cavity displacement in the anterior–posterior and superior–inferior directions was 0.6 ± 0.4 mm and 0.6 ± 0.3 mm, respectively. The mean margin required for at least 90% of the cavity to be contained by the margin for 90% of the time was 0.7 mm (5th-95th percentile: 0-2.7 mm). Conclusion: Minimal intrafractional motion was observed, and the mean difference between planned and delivered dose was less than 1%. Assessment of efficacy and cosmesis of this MR-guided APBI approach is under way.

  8. 1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

    DEFF Research Database (Denmark)

    Hansen, Anders Kragh; Christensen, Mathias; Noordegraaf, Danny

    2017-01-01

    Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation......, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction...... power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination...

  9. Dental cavities

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001055.htm Dental cavities To use the sharing features on this page, please enable JavaScript. Dental cavities are holes (or structural damage) in the ...

  10. Mode-locking of an InAs Quantum Dot Based Vertical External Cavity Surface Emitting Laser Using Atomic Layer Graphene

    Science.gov (United States)

    2015-07-16

    catalyzed on either a copper foil or on nickel coated substrates. The graphene must be transferred off of these substrates and then on to the DBR/spacer to...properties of graphene in both the exfoliated single layer graphene (SLG) and few layer graphene (FLG) flakes . Sun et al. make use of bile salts to...semiconductors and dielectrics is the transfer of CVD graphene grown on copper foils. The graphene is grown on thin Cu-foils by CVD using methane and

  11. Loggerhead oral cavity morphometry study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Standard external morphometrics and internal oral cavity morphometrics data were collected on wild and captive reared loggerhead sea turtles in size classes ranging...

  12. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1987-01-01

    In-depth exploration of the implications of carrier populations and Fermi energies examines distribution of electrons in energy bands and impurity levels of semiconductors. Also: kinetics of semiconductors containing excess carriers, particularly in terms of trapping, excitation, and recombination.

  13. Semiconductor physics

    CERN Document Server

    Böer, Karl W

    2018-01-01

    This handbook gives a complete survey of the important topics and results in semiconductor physics. It addresses every fundamental principle and most research topics and areas of application in the field of semiconductor physics. Comprehensive information is provided on crystalline bulk and low-dimensional as well as amporphous semiconductors, including optical, transport, and dynamic properties.

  14. Strong Exciton-photon Coupling in Semiconductor Microcavities

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Borri, Paola; Hvam, Jørn Märcher

    1999-01-01

    The basic building block of vertical cavity surface emitting lasers (VCSELs) and high efficiency diodes, is a quantum well embedded in a semiconductor microcavity. The high finesse that may be achieved in such a cavity is utilised to get a low threshold current in the VCSELs and a high directiona......The basic building block of vertical cavity surface emitting lasers (VCSELs) and high efficiency diodes, is a quantum well embedded in a semiconductor microcavity. The high finesse that may be achieved in such a cavity is utilised to get a low threshold current in the VCSELs and a high......-optical switches based on semiconductor microcavities....

  15. Thermal conditions within tree cavities in ponderosa pine (Pinus ponderosa) forests: potential implications for cavity users

    Science.gov (United States)

    Vierling, Kerri T.; Lorenz, Teresa J.; Cunningham, Patrick; Potterf, Kelsi

    2017-11-01

    Tree cavities provide critical roosting and breeding sites for multiple species, and thermal environments in these cavities are important to understand. Our objectives were to (1) describe thermal characteristics in cavities between June 3 and August 9, 2014, and (2) investigate the environmental factors that influence cavity temperatures. We placed iButtons in 84 different cavities in ponderosa pine (Pinus ponderosa) forests in central Washington, and took hourly measurements for at least 8 days in each cavity. Temperatures above 40 °C are generally lethal to developing avian embryos, and 18% of the cavities had internal temperatures of ≥ 40 °C for at least 1 h of each day. We modeled daily maximum cavity temperature, the amplitude of daily cavity temperatures, and the difference between the mean internal cavity and mean ambient temperatures as a function of several environmental variables. These variables included canopy cover, tree diameter at cavity height, cavity volume, entrance area, the hardness of the cavity body, the hardness of the cavity sill (which is the wood below the cavity entrance which forms the barrier between the cavity and the external environment), and sill width. Ambient temperature had the largest effect size for maximum cavity temperature and amplitude. Larger trees with harder sills may provide more thermally stable cavity environments, and decayed sills were positively associated with maximum cavity temperatures. Summer temperatures are projected to increase in this region, and additional research is needed to determine how the thermal environments of cavities will influence species occupancy, breeding, and survival.

  16. Frequency modulation of semiconductor disk laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Zolotovskii, I O; Korobko, D A; Okhotnikov, O G [Ulyanovsk State University, Ulyanovsk (Russian Federation)

    2015-07-31

    A numerical model is constructed for a semiconductor disk laser mode-locked by a semiconductor saturable absorber mirror (SESAM), and the effect that the phase modulation caused by gain and absorption saturation in the semiconductor has on pulse generation is examined. The results demonstrate that, in a laser cavity with sufficient second-order dispersion, alternating-sign frequency modulation of pulses can be compensated for. We also examine a model for tuning the dispersion in the cavity of a disk laser using a Gires–Tournois interferometer with limited thirdorder dispersion. (control of radiation parameters)

  17. Photo-acoustic sensor based on an inexpensive piezoelectric film transducer and an amplitude-stabilized single-mode external cavity diode laser for in vitro measurements of glucose concentration

    Science.gov (United States)

    Bayrakli, Ismail; Erdogan, Yasar Kemal

    2018-06-01

    The present paper focuses on development of a compact photo-acoustic sensor using inexpensive components for glucose analysis. An amplitude-stabilized wavelength-tunable single-mode external cavity diode laser operating around 1050 nm was realized and characterized for the use of laser beam as an excitation light source. In the established setup, a fine tuning range of 9 GHz was achieved. The glucose solution was obtained by diluting D-glucose in sterile water. The acoustic signal generated by the optical excitation was detected via a chip piezoelectric film transducer. A detection limit of 50 mM (900 mg/dl) was achieved. The device may be of great interest for its applications in medicine and health monitoring. The sensor is promising for non-invasive in vivo glucose measurements from interstitial fluid.

  18. Semiconductor optical amplifier-based heterodyning detection for resolving optical terahertz beat-tone signals from passively mode-locked semiconductor lasers

    International Nuclear Information System (INIS)

    Latkowski, Sylwester; Maldonado-Basilio, Ramon; Carney, Kevin; Parra-Cetina, Josue; Philippe, Severine; Landais, Pascal

    2010-01-01

    An all-optical heterodyne approach based on a room-temperature controlled semiconductor optical amplifier (SOA) for measuring the frequency and linewidth of the terahertz beat-tone signal from a passively mode-locked laser is proposed. Under the injection of two external cavity lasers, the SOA acts as a local oscillator at their detuning frequency and also as an optical frequency mixer whose inputs are the self-modulated spectrum of the device under test and the two laser beams. Frequency and linewidth of the intermediate frequency signal (and therefore, the beat-tone signal) are resolved by using a photodiode and an electrical spectrum analyzer.

  19. Source of ultra-short laser pulses at 1,55μm in vertical-external-cavity for linear optical sampling applications

    International Nuclear Information System (INIS)

    Khadour, A.

    2009-12-01

    The objectives of this thesis were, in a first step, to develop and implement VECSEL structures containing an active zone formed by GaAlInAs/InP quantum wells located at the anti-nodes of the resonant electric field, positioned on a Bragg mirror, all this being bonded to a substrate of good thermal conductivity. For this, we have designed structures optimizing the evacuation of heat generated in the active zone. This has greatly improved the VECSEL performances, especially their output power. The VECSEL performances were evaluated in a simple cavity with two mirrors (plane-concave). The second point was to develop and implement SESAM structures which, owing to their nonlinear characteristics, would allow a passively mode-locked laser operation. The structures contained InGaAsN/GaAs quantum wells. The studied parameters were the number of quantum wells, and the resonant or anti-resonant behavior of the structure. The linear and nonlinear optical characterizations were used to optimize the SESAM structure and estimate their performances. Finally, the compatibility between the VECSEL and SESAM structures, in terms of modulation depth and resonance wavelength, made it possible to obtain the passive mode locking operation. The obtained pulses show two different behaviors depending on the dispersion properties of the structures. With low dispersion, we have made the first demonstration of a passively mode-locked VECSEL at 1550 nm, operating at room temperature. An all-optical sampling device implementing the linear optical sampling technique using short laser pulses has been realized and tested. This device will allow displaying eye diagrams and constellation diagrams with an expected sensitivity around -20 dBm of average power. Testing the device allowed to visualize the acquisition of very high repetition rate signals (40 Gb/s). (author)

  20. Quantum optics with semiconductor nanostructures

    CERN Document Server

    Jahnke, Frank

    2012-01-01

    A guide to the theory, application and potential of semiconductor nanostructures in the exploration of quantum optics. It offers an overview of resonance fluorescence emission.$bAn understanding of the interaction between light and matter on a quantum level is of fundamental interest and has many applications in optical technologies. The quantum nature of the interaction has recently attracted great attention for applications of semiconductor nanostructures in quantum information processing. Quantum optics with semiconductor nanostructures is a key guide to the theory, experimental realisation, and future potential of semiconductor nanostructures in the exploration of quantum optics. Part one provides a comprehensive overview of single quantum dot systems, beginning with a look at resonance fluorescence emission. Quantum optics with single quantum dots in photonic crystal and micro cavities are explored in detail, before part two goes on to review nanolasers with quantum dot emitters. Light-matter interaction...

  1. accelerating cavity

    CERN Multimedia

    On the inside of the cavity there is a layer of niobium. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment.

  2. Dissipative chaos in semiconductor superlattices

    Directory of Open Access Journals (Sweden)

    F. Moghadam

    2008-03-01

    Full Text Available In this paper the motion of electron in a miniband of a semiconductor superlattice (SSL under the influence of external electric and magnetic fields is investigated. The electric field is applied in a direction perpendicular to the layers of the semiconductor superlattice, and the magnetic field is applied in different direction Numerical calculations show conditions led to the possibility of chaotic behaviors.

  3. radiofrequency cavity

    CERN Multimedia

    1988-01-01

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  4. Experimental control of power dropouts by current modulation in a semiconductor laser with optical feedback

    International Nuclear Information System (INIS)

    Ticos, Catalin M; Andrei, Ionut R; Pascu, Mihail L; Bulinski, Mircea

    2011-01-01

    The injection current of an external-cavity semiconductor laser working in a regime of low-frequency fluctuations (LFFs) is modulated at several MHz. The rate of power dropouts in the laser emission is correlated with the amplitude and frequency of the modulating signal. The occurrence of dropouts becomes more regular when the laser is driven at 7 MHz, which is close to the dominant frequency of dropouts in the solitary laser. Driving the laser at 10 MHz also induces dropouts with a periodicity of 0.1 μs, resulting in LFFs with two dominant frequencies.

  5. Semiconductor Manufacturing equipment introduction

    International Nuclear Information System (INIS)

    Im, Jong Sun

    2001-02-01

    This book deals with semiconductor manufacturing equipment. It is comprised of nine chapters, which are manufacturing process of semiconductor device, history of semiconductor manufacturing equipment, kinds and role of semiconductor manufacturing equipment, construction and method of semiconductor manufacturing equipment, introduction of various semiconductor manufacturing equipment, spots of semiconductor manufacturing, technical elements of semiconductor manufacturing equipment, road map of technology of semiconductor manufacturing equipment and semiconductor manufacturing equipment in the 21st century.

  6. Optically pumped semiconductor lasers: Conception and characterization of a single mode source for Cesium atoms manipulation

    International Nuclear Information System (INIS)

    Cocquelin, B.

    2009-02-01

    Lasers currently used in atomic clocks or inertial sensors are suffering from a lack of power, narrow linewidth or compactness for future spatial missions. Optically pumped semiconductor lasers, which combine the approach of classical solid state lasers and the engineering of semiconductor laser, are considered here as a candidate to a metrological laser source dedicated to the manipulation of Cesium atoms in these instruments. These lasers have demonstrated high power laser emission in a circular single transverse mode, as well as single longitudinal mode emission, favoured by the semiconductor structure and the external cavity design. We study the definition and the characterization of a proper semiconductor structure for the cooling and the detection of Cesium atoms at 852 nm. A compact and robust prototype tunable on the Cesium D2 hyperfine structure is built. The laser frequency is locked to an atomic transition thanks to a saturated absorption setup. The emission spectral properties are investigated, with a particular attention to the laser frequency noise and the laser linewidth. Finally, we describe and model the thermal properties of the semiconductor structure, which enables the simulation of the laser power characteristic. The experimental parameters are optimised to obtain the maximum output power with our structure. Thanks to our analysis, we propose several ways to overcome these limitations, by reducing the structure heating. (authors)

  7. Semiconductor spintronics

    CERN Document Server

    Xia, Jianbai; Chang, Kai

    2012-01-01

    Semiconductor Spintronics, as an emerging research discipline and an important advanced field in physics, has developed quickly and obtained fruitful results in recent decades. This volume is the first monograph summarizing the physical foundation and the experimental results obtained in this field. With the culmination of the authors' extensive working experiences, this book presents the developing history of semiconductor spintronics, its basic concepts and theories, experimental results, and the prospected future development. This unique book intends to provide a systematic and modern foundation for semiconductor spintronics aimed at researchers, professors, post-doctorates, and graduate students, and to help them master the overall knowledge of spintronics.

  8. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Schlehahn, A.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T., E-mail: tobias.heindel@tu-berlin.de; Reitzenstein, S. [Institut für Festkörperphysik, Technische Universität Berlin, Berlin 10623 (Germany); Gaafar, M.; Vaupel, M.; Stolz, W.; Rahimi-Iman, A.; Koch, M. [Department of Physics and Materials Science Center, Philipps-Universität Marburg, 35032 Marburg (Germany)

    2015-07-27

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g{sup (2)}(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  9. Turbomachine Sealing and Secondary Flows - Part 3. Part 3; Review of Power-Stream Support, Unsteady Flow Systems, Seal and Disk Cavity Flows, Engine Externals, and Life and Reliability Issues

    Science.gov (United States)

    Hendricks, R. C.; Steinetz, B. M.; Zaretsky, E. V.; Athavale, M. M.; Przekwas, A. J.

    2004-01-01

    The issues and components supporting the engine power stream are reviewed. It is essential that companies pay close attention to engine sealing issues, particularly on the high-pressure spool or high-pressure pumps. Small changes in these systems are reflected throughout the entire engine. Although cavity, platform, and tip sealing are complex and have a significant effect on component and engine performance, computational tools (e.g., NASA-developed INDSEAL, SCISEAL, and ADPAC) are available to help guide the designer and the experimenter. Gas turbine engine and rocket engine externals must all function efficiently with a high degree of reliability in order for the engine to run but often receive little attention until they malfunction. Within the open literature statistically significant data for critical engine components are virtually nonexistent; the classic approach is deterministic. Studies show that variations with loading can have a significant effect on component performance and life. Without validation data they are just studies. These variations and deficits in statistical databases require immediate attention.

  10. Reduction in the interface-states density of metal-oxide-semiconductor field-effect transistors fabricated on high-index Si (114) surfaces by using an external magnetic field

    International Nuclear Information System (INIS)

    Molina, J.; De La Hidalga, J.; Gutierrez, E.

    2014-01-01

    After fabrication of Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) devices on high-index silicon (114) surfaces, their threshold voltage (Vth) and interface-states density (Dit) characteristics were measured under the influence of an externally applied magnetic field of B = 6 μT at room temperature. The electron flow of the MOSFET's channel presents high anisotropy on Si (114), and this effect is enhanced by using an external magnetic field B, applied parallel to the Si (114) surface but perpendicular to the electron flow direction. This special configuration results in the channel electrons experiencing a Lorentzian force which pushes the electrons closer to the Si (114)-SiO 2 interface and therefore to the special morphology of the Si (114) surface. Interestingly, Dit evaluation of n-type MOSFETs fabricated on Si (114) surfaces shows that the Si (114)-SiO 2 interface is of high quality so that Dit as low as ∼10 10  cm −2 ·eV −1 are obtained for MOSFETs with channels aligned at specific orientations. Additionally, using both a small positive Vds ≤ 100 mV and B = 6 μT, the former Dit is reduced by 35% in MOSFETs whose channels are aligned parallel to row-like nanostructures formed atop Si (114) surfaces (channels having a 90° rotation), whereas Dit is increased by 25% in MOSFETs whose channels are aligned perpendicular to these nanostructures (channels having a 0° rotation). From these results, the special morphology of a high-index Si (114) plane having nanochannels on its surface opens the possibility to reduce the electron-trapping characteristics of MOSFET devices having deep-submicron features and operating at very high frequencies

  11. Effect of gain nonlinearity in semiconductor lasers

    DEFF Research Database (Denmark)

    Jensen, Niels H.; Christiansen, Peter Leth; Skovgaard, Ove

    1988-01-01

    Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2+1)-dimensi......Semiconductor lasers are modeled by single-mode rate equations with Langevin noise terms and the influence of nonlinear gain is investigated. For cw operation the probability distribution for the carrier number and the photon number in the laser cavity is obtained. The corresponding (2...

  12. Semiconductor spintronics

    International Nuclear Information System (INIS)

    Fabian, J.; Abiague, A.M.; Ertler, Ch.; Stano, P.; Zutic, I.

    2007-01-01

    Spintronics refers commonly to phenomena in which the spin of electrons in a solid state environment plays the determining role. In a more narrow sense spintronics is an emerging research field of electronics: spintronics devices are based on a spin control of electronics, or on an electrical and optical control of spin of magnetism. While metal spintronics has already found its niche in the computer industry - giant magnetoresistance systems are used as hard disk read heads - semiconductor spintronics is vet demonstrate its full potential. This review presents selected themes of semiconductor spintronics, introducing important concepts in spin transport, spin transport, spin injection. Silsbee-Johnson spin-charge coupling, and spin-dependent tunneling, as well as spin relaxation and spin dynamics. The most fundamental spin-dependent interaction in nonmagnetic semiconductors is spin-orbit coupling. Depending on the crystal symmetries of the material, as well as on the structural properties of semiconductor based heterostructures, the spin-orbit coupling takes on different functional forms, giving a nice playground of effective spin-orbit Hamiltonians. The effective Hamiltonians for the most relevant classes of materials and heterostructures are derived here from realistic electronic band structure descriptions. Most semiconductor device systems are still theoretical concepts, waiting for experimental demonstrations. A review of selected proposed, and a few demonstrated devices is presented, with detailed description of two important classes: magnetic resonant tunnel structures and bipolar magnetic diodes and transistors. In view of the importance of ferromagnetic semiconductor material, a brief discussion of diluted magnetic semiconductors is included. In most cases the presentation is of tutorial style, introducing the essential theoretical formalism at an accessible level, with case-study-like illustrations of actual experimental results, as well as with brief

  13. Oxide semiconductors

    CERN Document Server

    Svensson, Bengt G; Jagadish, Chennupati

    2013-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scient

  14. Semiconductor statistics

    CERN Document Server

    Blakemore, J S

    1962-01-01

    Semiconductor Statistics presents statistics aimed at complementing existing books on the relationships between carrier densities and transport effects. The book is divided into two parts. Part I provides introductory material on the electron theory of solids, and then discusses carrier statistics for semiconductors in thermal equilibrium. Of course a solid cannot be in true thermodynamic equilibrium if any electrical current is passed; but when currents are reasonably small the distribution function is but little perturbed, and the carrier distribution for such a """"quasi-equilibrium"""" co

  15. Semiconductor Lasers Stability, Instability and Chaos

    CERN Document Server

    Ohtsubo, Junji

    2013-01-01

    This third edition of “Semiconductor Lasers, Stability, Instability and Chaos” was significantly extended.  In the previous edition, the dynamics and characteristics of chaos in semiconductor lasers after the introduction of the fundamental theory of laser chaos and chaotic dynamics induced by self-optical feedback and optical injection was discussed. Semiconductor lasers with new device structures, such as vertical-cavity surface-emitting lasers and broad-area semiconductor lasers, are interesting devices from the viewpoint of chaotic dynamics since they essentially involve chaotic dynamics even in their free-running oscillations. These topics are also treated with respect to the new developments in the current edition. Also the control of such instabilities and chaos control are critical issues for applications. Another interesting and important issue of semiconductor laser chaos in this third edition is chaos synchronization between two lasers and the application to optical secure communication. One o...

  16. Semiconductor Detectors

    International Nuclear Information System (INIS)

    Cortina, E.

    2007-01-01

    Particle detectors based on semiconductor materials are among the few devices used for particle detection that are available to the public at large. In fact we are surrounded by them in our daily lives: they are used in photoelectric cells for opening doors, in digital photographic and video camera, and in bar code readers at supermarket cash registers. (Author)

  17. All-optical packet envelope detection using a slow semiconductor saturable absorber gate and a semiconductor optical amplifier

    NARCIS (Netherlands)

    Porzi, C.; Fresi, F.; Poti, L.; Bogoni, A.; Guina, M.; Orsila, L.; Okhotnikov, O.; Calabretta, N.

    2008-01-01

    Abstract—We propose a simple and effective scheme for alloptical packet envelope detection (AO-PED), exploiting a slow saturable absorber-based vertical cavity semiconductor gate and a semiconductor optical amplifier. A high extinction ratio of 15 dB was measured for the recovered envelope signal.

  18. Ultranarrow polaritons in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Jensen, Jacob Riis; Borri, Paola; Langbein, Wolfgang

    2000-01-01

    We have achieved a record high ratio (19) of the Rabi splitting (3.6 meV) to the polariton linewidth (190 mu eV), in a semiconductor lambda microcavity with a single 25 nm GaAs quantum well at the antinode. The narrow polariton lines are obtained with a special cavity design which reduces...

  19. Numerical and Experimental Study of the Q Factor of High-Q Micropillar Cavities

    DEFF Research Database (Denmark)

    Gregersen, Niels; Reitzenstein, S.; Kistner, C.

    2010-01-01

    Micropillar cavities are potential candidates for high-efficiency single-photon sources and are testbeds for cavity quantum electrodynamics experiments. In both applications a high quality (Q) factor is desired. It was recently shown that the Q of high-Q semiconductor micropillar cavities exhibit...

  20. Wavelength switching dynamics of two-colour semiconductor lasers with optical injection and feedback

    International Nuclear Information System (INIS)

    Osborne, S; Heinricht, P; Brandonisio, N; Amann, A; O’Brien, S

    2012-01-01

    The wavelength switching dynamics of two-colour semiconductor lasers with optical injection and feedback are presented. These devices incorporate slotted regions etched into the laser ridge waveguide for tailoring the output spectrum. Experimental measurements are presented demonstrating that optical injection in one or both modes of these devices can induce wavelength bistability. Measured switching dynamics with modulated optical injection are shown to be in excellent agreement with numerical simulations based on a simple rate equation model. We also demonstrate experimentally that time-delayed optical feedback can induce wavelength bistability for short external cavity lengths. Numerical simulations indicate that this two-colour optical feedback system can provide fast optical memory functionality based on injected optical pulses without the need for an external holding beam. (paper)

  1. Semiconductor sensors

    International Nuclear Information System (INIS)

    Hartmann, Frank

    2011-01-01

    Semiconductor sensors have been around since the 1950s and today, every high energy physics experiment has one in its repertoire. In Lepton as well as Hadron colliders, silicon vertex and tracking detectors led to the most amazing physics and will continue doing so in the future. This contribution tries to depict the history of these devices exemplarily without being able to honor all important developments and installations. The current understanding of radiation damage mechanisms and recent R and D topics demonstrating the future challenges and possible technical solutions for the SLHC detectors are presented. Consequently semiconductor sensor candidates for an LHC upgrade and a future linear collider are also briefly introduced. The work presented here is a collage of the work of many individual silicon experts spread over several collaborations across the world.

  2. Semiconductor Optics

    CERN Document Server

    Klingshirn, Claus F

    2012-01-01

    This updated and enlarged new edition of Semiconductor Optics provides an introduction to and an overview of semiconductor optics from the IR through the visible to the UV, including linear and nonlinear optical properties, dynamics, magneto and electrooptics, high-excitation effects and laser processes, some applications, experimental techniques and group theory. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered extend from physics to materials science and optoelectronics. Significantly updated chapters add coverage of current topics such as electron hole plasma, Bose condensation of excitons and meta materials. Over 120 problems, chapter introductions and a detailed index make it the key textbook for graduate students in physics. The mathematics is kept as elementary as possible, sufficient for an intuitive understanding of the experimental results and techniques treated. The subjects covered ...

  3. Semiconductor annealing

    International Nuclear Information System (INIS)

    Young, J.M.; Scovell, P.D.

    1982-01-01

    A process for annealing crystal damage in ion implanted semiconductor devices in which the device is rapidly heated to a temperature between 450 and 900 0 C and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device may be heated on a graphite element mounted between electrodes in an inert atmosphere in a chamber. (author)

  4. [Comparison of ability to humidification of inspired air through the nose and oral cavity using dew point hygrometer].

    Science.gov (United States)

    Paczesny, Daniel; Rapiejko, Piotr; Weremczuk, Jerzy; Jachowicz, Ryszard; Jurkiewicz, Dariusz

    2007-01-01

    Aim of this study was to check at the hospital the dew point hygrometer for fast measurement of air humidity in upper airways. The nose ability to humidification of inspired air and partially recover moisture from expired air was evaluated. Measurements from respiration through the nose and oral cavity were compared. The study was carried out in a group of 30 people (8 female and 22 male), age group 18 to 70 (mean age: 37 years old). In 22 of the participants there were no deviation from normal state in laryngologic examination, while in 4 participants nasal septum deviation without imaired nasal; oatency was found, in other 3--nasal vonchae hyperthrophy and in 1--nasal polips (grade I). The measurements of air humidity in upper air ways was done using specially designed and constructed measurement system. The air inspired through the nose and oral cavity is humidified. For typical external conditions (T = 22 degrees C i RH = 50%) the nose humidifies inspired air two times better then oral cavity (short time range of measurement approximately 1 min). Moisture from expired air through the nose is partially recovered (for patients with regular patency is 25% of the value of humidifying of inspired air). The oral cavity does not have ability to partially recovery moisture form expired air. The paper presented fast dew point hygrometer based on semiconductor microsystems for measurement humidity in inspired and expired air through the nose and oral cavity. Presented system can be a proper instrument for evaluation of nasal functions.

  5. Anomalous normal mode oscillations in semiconductor microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H. [Univ. of Oregon, Eugene, OR (United States). Dept. of Physics; Hou, H.Q.; Hammons, B.E. [Sandia National Labs., Albuquerque, NM (United States)

    1997-04-01

    Semiconductor microcavities as a composite exciton-cavity system can be characterized by two normal modes. Under an impulsive excitation by a short laser pulse, optical polarizations associated with the two normal modes have a {pi} phase difference. The total induced optical polarization is then expected to exhibit a sin{sup 2}({Omega}t)-like oscillation where 2{Omega} is the normal mode splitting, reflecting a coherent energy exchange between the exciton and cavity. In this paper the authors present experimental studies of normal mode oscillations using three-pulse transient four wave mixing (FWM). The result reveals surprisingly that when the cavity is tuned far below the exciton resonance, normal mode oscillation in the polarization is cos{sup 2}({Omega}t)-like, in contrast to what is expected form the simple normal mode model. This anomalous normal mode oscillation reflects the important role of virtual excitation of electronic states in semiconductor microcavities.

  6. Analysis of mechanical fabrication experience with CEBAF's production SRF cavities

    International Nuclear Information System (INIS)

    Mammosser, J.; Kneisel, P.; Benesch, J.

    1993-06-01

    CEBAF has received a total of 360 five-cell niobium cavities, the largest group of industrially fabricated superconducting cavities so far. An extensive data base exists on the fabrication, surface treatment, assembly and cavity performance parameters. Analysis of the mechanical features of the cavities includes the following: the spread in fabrication tolerances of the cells derived from field profiles of the ''as fabricated'' cavities and the ''as fabricated'' external Q-values of the fundamental power coupler compared to dimensional deviations. A comparison is made of the pressure sensitivity of cavities made of materials from different manufacturers between 760 torr (4.2 K) and 23 torr (2 K)

  7. Semiconductor annealing

    International Nuclear Information System (INIS)

    Young, J.M.; Scovell, P.D.

    1981-01-01

    A process for annealing crystal damage in ion implanted semiconductor devices is described in which the device is rapidly heated to a temperature between 450 and 600 0 C and allowed to cool. It has been found that such heating of the device to these relatively low temperatures results in rapid annealing. In one application the device may be heated on a graphite element mounted between electrodes in an inert atmosphere in a chamber. The process may be enhanced by the application of optical radiation from a Xenon lamp. (author)

  8. Magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bihler, Christoph

    2009-04-15

    In this thesis we investigated in detail the properties of Ga{sub 1-x}Mn{sub x}As, Ga{sub 1-x}Mn{sub x}P, and Ga{sub 1-x}Mn{sub x}N dilute magnetic semiconductor thin films with a focus on the magnetic anisotropy and the changes of their properties upon hydrogenation. We applied two complementary spectroscopic techniques to address the position of H in magnetic semiconductors: (i) Electron paramagnetic resonance, which provides direct information on the symmetry of the crystal field of the Mn{sup 2+} atoms and (ii) x-ray absorption fine structure analysis which allows to probe the local crystallographic neighborhood of the absorbing Mn atom via analysing the fine structure at the Mn K absorption edge. Finally, we discussed the obstacles that have to be overcome to achieve Curie temperatures above the current maximum in Ga{sub 1-x}Mn{sub x}As of 185 K. Here, we outlined in detail the generic problem of the formation of precipitates at the example of Ge:MN. (orig.)

  9. Regional Externalities

    NARCIS (Netherlands)

    Heijman, W.J.M.

    2007-01-01

    The book offers practical and theoretical insights in regional externalities. Regional externalities are a specific subset of externalities that can be defined as externalities where space plays a dominant role. This class of externalities can be divided into three categories: (1) externalities

  10. Manipulating semiconductor colloidal stability through doping.

    Science.gov (United States)

    Fleharty, Mark E; van Swol, Frank; Petsev, Dimiter N

    2014-10-10

    The interface between a doped semiconductor material and electrolyte solution is of considerable fundamental interest, and is relevant to systems of practical importance. Both adjacent domains contain mobile charges, which respond to potential variations. This is exploited to design electronic and optoelectronic sensors, and other enabling semiconductor colloidal materials. We show that the charge mobility in both phases leads to a new type of interaction between semiconductor colloids suspended in aqueous electrolyte solutions. This interaction is due to the electrostatic response of the semiconductor interior to disturbances in the external field upon the approach of two particles. The electrostatic repulsion between two charged colloids is reduced from the one governed by the charged groups present at the particles surfaces. This type of interaction is unique to semiconductor particles and may have a substantial effect on the suspension dynamics and stability.

  11. Semiconductor Laser Measurements Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Semiconductor Laser Measurements Laboratory is equipped to investigate and characterize the lasing properties of semiconductor diode lasers. Lasing features such...

  12. Radiation-pressure-mediated control of an optomechanical cavity

    Science.gov (United States)

    Cripe, Jonathan; Aggarwal, Nancy; Singh, Robinjeet; Lanza, Robert; Libson, Adam; Yap, Min Jet; Cole, Garrett D.; McClelland, David E.; Mavalvala, Nergis; Corbitt, Thomas

    2018-01-01

    We describe and demonstrate a method to control a detuned movable-mirror Fabry-Pérot cavity using radiation pressure in the presence of a strong optical spring. At frequencies below the optical spring resonance, self-locking of the cavity is achieved intrinsically by the optomechanical (OM) interaction between the cavity field and the movable end mirror. The OM interaction results in a high rigidity and reduced susceptibility of the mirror to external forces. However, due to a finite delay time in the cavity, this enhanced rigidity is accompanied by an antidamping force, which destabilizes the cavity. The cavity is stabilized by applying external feedback in a frequency band around the optical spring resonance. The error signal is sensed in the amplitude quadrature of the transmitted beam with a photodetector. An amplitude modulator in the input path to the cavity modulates the light intensity to provide the stabilizing radiation pressure force.

  13. Singly-resonant sum frequency generation of visible light in a semiconductor disk laser

    DEFF Research Database (Denmark)

    Andersen, Martin Thalbitzer; Schlosser, P.J.; Hastie, J.E.

    2009-01-01

    In this paper a generic approach for visible light generation is presented. It is based on sum frequency generation between a semiconductor disk laser and a solid-state laser, where the frequency mixing is achieved within the cavity of the semiconductor disk laser using a singlepass of the solid......-state laser light. This exploits the good beam quality and high intra-cavity power present in the semiconductor disk laser to achieve high conversion efficiency. Combining sum frequency mixing and semiconductor disk lasers in this manner allows in principle for generation of any wavelength within the visible...

  14. Cellular automata in photonic cavity arrays.

    Science.gov (United States)

    Li, Jing; Liew, T C H

    2016-10-31

    We propose theoretically a photonic Turing machine based on cellular automata in arrays of nonlinear cavities coupled with artificial gauge fields. The state of the system is recorded making use of the bistability of driven cavities, in which losses are fully compensated by an external continuous drive. The sequential update of the automaton layers is achieved automatically, by the local switching of bistable states, without requiring any additional synchronization or temporal control.

  15. Statistics of magnetoconductance in ballistic cavities

    International Nuclear Information System (INIS)

    Yang, X.; Ishio, H.; Burgdoerfer, J.

    1995-01-01

    The statistical properties of magnetoconductance in ballistic microcavities are investigated numerically. The distribution of conductance for chaotic cavities is found to follow the renormalized Porter-Thomas distribution suggested by random-matrix theory for the Gaussian ensemble while the conductance distribution of regular cavities in magnetic fields is nonuniversal and shifted towards the maximum value for a given number of open channels. The renormalized Porter-Thomas distribution implies a universal dependence of fluctuation amplitude on the mean conductance for chaotic cavities in the absence of time-reversal symmetry. The fluctuation amplitude for regular cavities is found to be larger than the saturation value of the fluctuation amplitude of chaotic cavities predicted by random-matrix theory. The change of the mean conductance as a function of the external magnetic field is consistent with semiclassical predictions

  16. Semiconductor laser shearing interferometer

    International Nuclear Information System (INIS)

    Ming Hai; Li Ming; Chen Nong; Xie Jiaping

    1988-03-01

    The application of semiconductor laser on grating shearing interferometry is studied experimentally in the present paper. The method measuring the coherence of semiconductor laser beam by ion etching double frequency grating is proposed. The experimental result of lens aberration with semiconductor laser shearing interferometer is given. Talbot shearing interferometry of semiconductor laser is also described. (author). 2 refs, 9 figs

  17. Segmented trapped vortex cavity

    Science.gov (United States)

    Grammel, Jr., Leonard Paul (Inventor); Pennekamp, David Lance (Inventor); Winslow, Jr., Ralph Henry (Inventor)

    2010-01-01

    An annular trapped vortex cavity assembly segment comprising includes a cavity forward wall, a cavity aft wall, and a cavity radially outer wall there between defining a cavity segment therein. A cavity opening extends between the forward and aft walls at a radially inner end of the assembly segment. Radially spaced apart pluralities of air injection first and second holes extend through the forward and aft walls respectively. The segment may include first and second expansion joint features at distal first and second ends respectively of the segment. The segment may include a forward subcomponent including the cavity forward wall attached to an aft subcomponent including the cavity aft wall. The forward and aft subcomponents include forward and aft portions of the cavity radially outer wall respectively. A ring of the segments may be circumferentially disposed about an axis to form an annular segmented vortex cavity assembly.

  18. Dynamically controlling the emission of single excitons in photonic crystal cavities

    NARCIS (Netherlands)

    Pagliano, F.; Cho, Y.; Xia, T.; Otten, van F.W.M.; Johne, R.; Fiore, A.

    2014-01-01

    Single excitons in semiconductor microcavities represent a solid state and scalable platform for cavity quantum electrodynamics, potentially enabling an interface between flying (photon) and static (exciton) quantum bits in future quantum networks. While both singlephoton emission and the strong

  19. Reflectivity and transmissivity of a cavity coupled to a nanoparticle

    Science.gov (United States)

    Khan, M. A.; Farooq, K.; Hou, S. C.; Niaz, Shanawer; Yi, X. X.

    2014-07-01

    Any dielectric nanoparticle moving inside an optical cavity generates an optomechanical interaction. In this paper, we theoretically analyze the light scattering of an optomechanical cavity which strongly interacts with a dielectric nanoparticle. The cavity is driven by an external laser field. This interaction gives rise to different dynamics that can be used to cool, trap and levitate nanoparticle. We analytically calculate reflection and transmission rate of the cavity field, and study the time evolution of the intracavity field, momentum and position of the nanoparticle. We find the nanoparticle occupies a discrete position inside the cavity. This effect can be exploited to separate nanoparticle and couplings between classical particles and quantized fields.

  20. Endoscopic versus external approach dacryocystorhinostomy: A ...

    African Journals Online (AJOL)

    Endoscopic versus external approach dacryocystorhinostomy: A comparative analysis. Rinki Saha, Anuradha Sinha, Jyoti Prakash Phukan. Abstract. Background: Dacryocystorhinostomy (DCR) consists of creating a lacrimal drainage pathway to the nasal cavity to restore permanent drainage of previously obstructed ...

  1. Semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Marstein Erik Stensrud

    2003-07-01

    This thesis presents a study of two material systems containing semiconductor nanocrystals, namely porous silicon (PSi) films and germanium (Ge) nanocrystals embedded in silicon dioxide (SiO2) films. The PSi films were made by anodic etching of silicon (Si) substrates in an electrolyte containing hydrofluoric acid. The PSi films were doped with erbium (Er) using two different doping methods. electrochemical doping and doping by immersing the PSi films in a solution containing Er. The resulting Er concentration profiles were investigated using scanning electron microscopy (SEN1) combined with energy dispersive X-ray analysis (EDS). The main subject of the work on PSi presented in this thesis was investigating and comparing these two doping methods. Ge nanocrystals were made by implanting Ge ions into Si02 films that were subsequently annealed. However. nanocrystal formation occurred only for certain sets of processing parameters. The dependence of the microstructure of the Ge implanted Si02 films on the processing parameters were therefore investigated. A range of methods were employed for these investigations, including transmission electron microscopy (TEM) combined with EDS, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The observed structures, ranging from Ge nanocrystals to voids with diameters of several tens of nanometers and Ge rich Si02 films without any nanocrystals is described. A model explaining the void formation is also presented. For certain sets of processing parameters. An accumulation of Ge at the Si-Si02 interface was observed. The effect of this accumulation on the electrical properties of MOS structures made from Ge implanted SiO2 films was investigated using CV-measurements. (Author)

  2. Comparative study of the performance of semiconductor laser based coherent Doppler lidars

    DEFF Research Database (Denmark)

    Rodrigo, Peter John; Pedersen, Christian

    2012-01-01

    Coherent Doppler Lidars (CDLs), operating at an eye-safe 1.5-micron wavelength, have found promising applications in the optimization of wind-power production. To meet the wind-energy sector's impending demand for more cost-efficient industrial sensors, we have focused on the development of conti......Coherent Doppler Lidars (CDLs), operating at an eye-safe 1.5-micron wavelength, have found promising applications in the optimization of wind-power production. To meet the wind-energy sector's impending demand for more cost-efficient industrial sensors, we have focused on the development...... of continuous-wave CDL systems using compact, inexpensive semiconductor laser (SL) sources. In this work, we compare the performance of two candidate emitters for an allsemiconductor CDL system: (1) a monolithic master-oscillator-power-amplifier (MOPA) SL and (2) an external-cavity tapered diode laser (ECTDL)....

  3. Phase locking of a semiconductor double-quantum-dot single-atom maser

    Science.gov (United States)

    Liu, Y.-Y.; Hartke, T. R.; Stehlik, J.; Petta, J. R.

    2017-11-01

    We experimentally study the phase stabilization of a semiconductor double-quantum-dot (DQD) single-atom maser by injection locking. A voltage-biased DQD serves as an electrically tunable microwave frequency gain medium. The statistics of the maser output field demonstrate that the maser can be phase locked to an external cavity drive, with a resulting phase noise L =-99 dBc/Hz at a frequency offset of 1.3 MHz. The injection locking range, and the phase of the maser output relative to the injection locking input tone are in good agreement with Adler's theory. Furthermore, the electrically tunable DQD energy level structure allows us to rapidly switch the gain medium on and off, resulting in an emission spectrum that resembles a frequency comb. The free running frequency comb linewidth is ≈8 kHz and can be improved to less than 1 Hz by operating the comb in the injection locked regime.

  4. Fundamentals of semiconductor devices

    CERN Document Server

    Lindmayer, Joseph

    1965-01-01

    Semiconductor properties ; semiconductor junctions or diodes ; transistor fundamentals ; inhomogeneous impurity distributions, drift or graded-base transistors ; high-frequency properties of transistors ; band structure of semiconductors ; high current densities and mechanisms of carrier transport ; transistor transient response and recombination processes ; surfaces, field-effect transistors, and composite junctions ; additional semiconductor characteristics ; additional semiconductor devices and microcircuits ; more metal, insulator, and semiconductor combinations for devices ; four-pole parameters and configuration rotation ; four-poles of combined networks and devices ; equivalent circuits ; the error function and its properties ; Fermi-Dirac statistics ; useful physical constants.

  5. Construction of an optical semiconductor amplifier starting from a Fabry-Perot semiconductor laser

    International Nuclear Information System (INIS)

    Garcia, E.; Soto, H.; Marquez, H.; Valles V, N.

    2000-01-01

    A methodology to convert a semiconductor laser Fabry-Perot (SL-FP) in a semiconductor optical amplifier (SOA) is presented. In order to suppress the cavity resonant an optical thin film coating was deposited on the facets of the SL-FP. The experiment was carried out putting on service a new monitoring technique that consist in the observation of the laser power spectrum during the antireflection coatings deposition. This allows to determine the moment were the facets reflectivity is minimum. The SOA obtained was characterized for different polarization currents. (Author)

  6. Improved reactor cavity

    International Nuclear Information System (INIS)

    Katz, L.R.; Demarchais, W.E.

    1984-01-01

    A reactor pressure vessel disposed in a cavity has coolant inlet or outlet pipes extending through passages in the cavity walls and welded to pressure nozzles. The cavity wall has means for directing fluid away from a break at a weld away from the pressure vessel, and means for inhibiting flow of fluid toward the vessel. (author)

  7. Squeezing in an injection-locked semiconductor laser

    Science.gov (United States)

    Inoue, S.; Machida, S.; Yamamoto, Y.; Ohzu, H.

    1993-09-01

    The intensity-noise properties of an injection-locked semiconductor laser were studied experimentally. The constant-current-driven semiconductor laser producing the amplitude-squeezed state whose intensity noise was reduced below the standard quantum limit (SQL) by 0.72 dB was injection-locked by an external master laser. The measured intensity-noise level of the injection-locked semiconductor laser was 0.91 dB below the SQL. This experimental result indicates that a phase-coherent amplitude-squeezed state or squeezed vacuum state together with a reference local oscillator wave can be generated directly by semiconductor laser systems.

  8. Solid spectroscopy: semiconductors

    International Nuclear Information System (INIS)

    Silva, C.E.T.G. da

    1983-01-01

    Photoemission as technique of study of the semiconductor electronic structure is shortly discussed. Homogeneous and heterogeneous semiconductors, where volume and surface electronic structure, core levels and O and H chemisorption in GaAs, Schottky barrier are treated, respectively. Amorphous semiconductors are also discussed. (L.C.) [pt

  9. Research and development of an ultra clean surface for RF cavities

    International Nuclear Information System (INIS)

    Miwa, Hajime; Ikeda, Tokumi; Suzuki, Takafusa; Kurosawa, Kiyosi; Kako, Eiji; Noguchi, Shuichi; Saito, Kenji; Kneisel, P.

    1993-01-01

    Suppression of field emission is essentially important in order to attain higher accelerating gradients. Therefore, elimination of residual dust particles on the inner surface of RF cavities is necessary. Surface of a niobium cavity was simulated in silicon wafers, and analysis of dust particles was performed by a particle counter used for semiconductor industries. Experimental results in various surface treatments and applications to niobium cavities are described in this paper. (author)

  10. Optical properties of semiconductors quantum microcavity structures

    International Nuclear Information System (INIS)

    Afshar, A.M.

    1996-12-01

    The principal phenomenon investigated in this thesis is vacuum Rabi coupling in semiconductor microcavity structures. In these structures quantum well excitons are embedded in a Fabry - Perot like cavity, defined by two semiconductor dielectric mirrors. In such a system the coupled exciton and cavity photon mode form a mixed - mode polariton, where on - resonance there are two branches, each having 50% exciton and 50% photon character. The separation between the upper and lower branches is a measure of the coupling strength where the strength is dependent on the exciton oscillator strength. This interaction is known as vacuum Rabi coupling, and clear anticrossing is seen when the exciton is tuned through the cavity. In our reflectivity experiments we demonstrate control of the coupling between the cavity mode and the exciton by varying temperature, applied electric or magnetic field. Modelling of the reflectivity spectra and the tuning was done using a Transfer Matrix Reflectivity (TMR) model or a linear dispersion model, where in both cases the excitons are treated as Lorentz oscillators. Temperature tuning is achieved because exciton energy decreases with temperature at a much faster rate than the cavity mode. We have demonstrated vacuum Rabi coupling of the cavity mode with both the heavy - hole and light - hole excitons. Electric field tuning is achieved via the quantum confined Stark effect which decreases the exciton energy with increasing field, whilst at the same time the cavity mode energy remains constant. A study of how the electric field reduction of exciton oscillator strength reduces the vacuum Rabi coupling strength is performed. We report the first observation in a semiconductor structure of motional narrowing, seen in both electric field and in temperature tuning experiments at high magnetic field. In magnetic field studies we show how magnetic field induced increase in exciton oscillator strength affects the vacuum Rabi coupling. We also show by

  11. External and internal anatomy of mandibular molars.

    Science.gov (United States)

    Rocha, L F; Sousa Neto, M D; Fidel, S R; da Costa, W F; Pécora, J D

    1996-01-01

    The external and internal anatomy of 628 extracted, mandibular first and second molars was studied. The external anatomy was studied by measuring each tooth and by observing the direction of the root curvatures from the facial surface. The internal anatomy of the pulp cavity was studied by a method of making the teeth translucent.

  12. Alfvenic resonant cavities in the solar atmosphere

    International Nuclear Information System (INIS)

    Hollweg, J.V.

    1984-01-01

    We investigate the propagation of Alfven waves in a simple medium consisting of three uniform layers; each layer is characterized by a different value for the Alfven speed, νsub(A). We show how the central layer can act as a resonant cavity under quite general conditions. If the cavity is driven externally, by an incident wave in one of the outer layers, there result resonant transmission peaks, which allow large energy fluxes to enter the cavity from outside. The transmission peaks result from the destructive interference between a wave which leaks out of the cavity, and a directly reflected wave. We show that there are two types of resonances. The first type occurs when the cavity has the largest (or smallest) of the three Alfven speeds; this situation occurs on coronal loops. The second type occurs when the cavity Alfven speed is intermediate between the other two values of νsub(A); this situation may occur on solar spicules. Significant heating of the cavity can occur if the waves are damped. We show that if the energy lost to heat greatly exceeds the energy lost by leakage out of the cavity, then the cavity heating can be independent of the damping rate. This conclusion is shown to apply to coronal resonances and to the spicule resonances. This conclusion agrees with a point made by Ionson in connection with the coronal resonances. Except for a numerical factor of order unity, we recover Ionson's expression for the coronal heating rate. However, Ionson's qualities are much too large. For solar parameters, the maximum quality is of the order of 100, but the heating is independent of the damping rate only when dissipation reduces the quality to less than about 10. (WB)

  13. The LHC superconducting cavities

    CERN Document Server

    Boussard, Daniel; Häbel, E; Kindermann, H P; Losito, R; Marque, S; Rödel, V; Stirbet, M

    1999-01-01

    The LHC RF system, which must handle high intensity (0.5 A d.c.) beams, makes use of superconducting single-cell cavities, best suited to minimizing the effects of periodic transient beam loading. There will be eight cavities per beam, each capable of delivering 2 MV (5 MV/m accelerating field) at 400 MHz. The cavities themselves are now being manufactured by industry, using niobium-on-copper technology which gives full satisfaction at LEP. A cavity unit includes a helium tank (4.5 K operating temperature) built around a cavity cell, RF and HOM couplers and a mechanical tuner, all housed in a modular cryostat. Four-unit modules are ultimately foreseen for the LHC (two per beam), while at present a prototype version with two complete units is being extensively tested. In addition to a detailed description of the cavity and its ancillary equipment, the first test results of the prototype will be reported.

  14. Towards the generation of random bits at terahertz rates based on a chaotic semiconductor laser

    International Nuclear Information System (INIS)

    Kanter, Ido; Aviad, Yaara; Reidler, Igor; Cohen, Elad; Rosenbluh, Michael

    2010-01-01

    Random bit generators (RBGs) are important in many aspects of statistical physics and crucial in Monte-Carlo simulations, stochastic modeling and quantum cryptography. The quality of a RBG is measured by the unpredictability of the bit string it produces and the speed at which the truly random bits can be generated. Deterministic algorithms generate pseudo-random numbers at high data rates as they are only limited by electronic hardware speed, but their unpredictability is limited by the very nature of their deterministic origin. It is widely accepted that the core of any true RBG must be an intrinsically non-deterministic physical process, e.g. measuring thermal noise from a resistor. Owing to low signal levels, such systems are highly susceptible to bias, introduced by amplification, and to small nonrandom external perturbations resulting in a limited generation rate, typically less than 100M bit/s. We present a physical random bit generator, based on a chaotic semiconductor laser, having delayed optical feedback, which operates reliably at rates up to 300Gbit/s. The method uses a high derivative of the digitized chaotic laser intensity and generates the random sequence by retaining a number of the least significant bits of the high derivative value. The method is insensitive to laser operational parameters and eliminates the necessity for all external constraints such as incommensurate sampling rates and laser external cavity round trip time. The randomness of long bit strings is verified by standard statistical tests.

  15. Towards the generation of random bits at terahertz rates based on a chaotic semiconductor laser

    Science.gov (United States)

    Kanter, Ido; Aviad, Yaara; Reidler, Igor; Cohen, Elad; Rosenbluh, Michael

    2010-06-01

    Random bit generators (RBGs) are important in many aspects of statistical physics and crucial in Monte-Carlo simulations, stochastic modeling and quantum cryptography. The quality of a RBG is measured by the unpredictability of the bit string it produces and the speed at which the truly random bits can be generated. Deterministic algorithms generate pseudo-random numbers at high data rates as they are only limited by electronic hardware speed, but their unpredictability is limited by the very nature of their deterministic origin. It is widely accepted that the core of any true RBG must be an intrinsically non-deterministic physical process, e.g. measuring thermal noise from a resistor. Owing to low signal levels, such systems are highly susceptible to bias, introduced by amplification, and to small nonrandom external perturbations resulting in a limited generation rate, typically less than 100M bit/s. We present a physical random bit generator, based on a chaotic semiconductor laser, having delayed optical feedback, which operates reliably at rates up to 300Gbit/s. The method uses a high derivative of the digitized chaotic laser intensity and generates the random sequence by retaining a number of the least significant bits of the high derivative value. The method is insensitive to laser operational parameters and eliminates the necessity for all external constraints such as incommensurate sampling rates and laser external cavity round trip time. The randomness of long bit strings is verified by standard statistical tests.

  16. Compound Semiconductor Radiation Detector

    International Nuclear Information System (INIS)

    Kim, Y. K.; Park, S. H.; Lee, W. G.; Ha, J. H.

    2005-01-01

    In 1945, Van Heerden measured α, β and γ radiations with the cooled AgCl crystal. It was the first radiation measurement using the compound semiconductor detector. Since then the compound semiconductor has been extensively studied as radiation detector. Generally the radiation detector can be divided into the gas detector, the scintillator and the semiconductor detector. The semiconductor detector has good points comparing to other radiation detectors. Since the density of the semiconductor detector is higher than that of the gas detector, the semiconductor detector can be made with the compact size to measure the high energy radiation. In the scintillator, the radiation is measured with the two-step process. That is, the radiation is converted into the photons, which are changed into electrons by a photo-detector, inside the scintillator. However in the semiconductor radiation detector, the radiation is measured only with the one-step process. The electron-hole pairs are generated from the radiation interaction inside the semiconductor detector, and these electrons and charged ions are directly collected to get the signal. The energy resolution of the semiconductor detector is generally better than that of the scintillator. At present, the commonly used semiconductors as the radiation detector are Si and Ge. However, these semiconductor detectors have weak points. That is, one needs thick material to measure the high energy radiation because of the relatively low atomic number of the composite material. In Ge case, the dark current of the detector is large at room temperature because of the small band-gap energy. Recently the compound semiconductor detectors have been extensively studied to overcome these problems. In this paper, we will briefly summarize the recent research topics about the compound semiconductor detector. We will introduce the research activities of our group, too

  17. Q0 Degradation of LANL 700-MHZ β = 0.64 Elliptical Cavities and ANL 340 MHZ Spoke Cavities

    International Nuclear Information System (INIS)

    Tajima, Tsuyoshi; Chan, Kwok-Chi D.; Edwards, Randall L.; Gentzlinger, Robert C.; Kelley, John Patrick; Krawczyk, Frank L.; Madrid, Michael A.; Montoya, Debbie I.; Schrage, Dale L.; Shapiro, Alan H.

    2002-01-01

    The quality factor (Q 0 ) of most of the six LANL β = 0.64 700-MHz 5-cell elliptical cavities starts to drop at E acc = 8-10 MV/m, which may be related to multipacting. Residual resistances of these cavities were measured to be 5.0-7.6 n(Omega). The sensitivity of surface resistance to the external magnetic field was measured to be 0.22 n(Omega)/mG. Q disease tests have shown no significant Q 0 degradation for both elliptical cavities and a spoke cavity with our 100 (micro)m BCP.

  18. LEP copper accelerating cavities

    CERN Multimedia

    Laurent Guiraud

    1999-01-01

    These copper cavities were used to generate the radio frequency electric field that was used to accelerate electrons and positrons around the 27-km Large Electron-Positron (LEP) collider at CERN, which ran from 1989 to 2000. The copper cavities were gradually replaced from 1996 with new superconducting cavities allowing the collision energy to rise from 90 GeV to 200 GeV by mid-1999.

  19. Semiconductor apparatus and method of fabrication for a semiconductor apparatus

    NARCIS (Netherlands)

    2010-01-01

    The invention relates to a semiconductor apparatus (1) and a method of fabrication for a semiconductor apparatus (1), wherein the semiconductor apparatus (1) comprises a semiconductor layer (2) and a passivation layer (3), arranged on a surface of the semiconductor layer (2), for passivating the

  20. Comparative study of the displacement of the selected clips in the cavity measured by orthogonal kilovoltage X-ray film in conditions of free breath and active breathing control for patients treated by external-beam partial breast irradiation

    International Nuclear Information System (INIS)

    Li Jianbin; Han Lei; Zhang Yingjie; Xu Min; Fan Tingyong; Shao Qing; Gong Guanzhong

    2010-01-01

    Objective: To compare the displacements of the clips in the cavity measured with orthogonal kilovoltage (KV) X-my plain film in conditions of moderate deep inspiration breathing hold (mDIBH) and free breath (FB), and compare the margins from clinical target volume (CTV) to planning target volume (PTV) based on the displacements. Methods: Before radiotherapy, 2 and 5 sets of orthogonal KV plain film were respectively collected in mDIBH and FB group, then the automatic registration of the reconstructed KV plain film and DRR derived from the planning CT images was finished. In conditions of mDIBH and FB, the displacements of the selected clip at the same location in the different directions and of the different selected clips in the same direction were compared. The margins in three dimensional directions were calculated and compared in conditions of mDIBH and FB. Results: In FB hold group, the difference of displacement in left-right (LR), cranial-caudal (CC) and anterior-posterior (AP) directions were statistically significant between the clips at the cranial and caudal border of the cavity (9.7 mm and 10.6 nun (Z = -2.12, P =0.037) ,7.3 mm and 8.3 mm (Z = -2.31 ,P=0.041) ,15.5 mm and 16.1 nun (Z = -2.32,P = 0.041)), but not statistically significant for the clips at the bottom and lateral P=0.814),15.7 mm and 16.5 mm (Z=-0.26, P=0.856)). The corresponding differences in the different directions were statistically significant (5.0 mm and 7.8 mm(Z = -2.31, P =0.036), 5.0 mm and 9. 3 nun (Z= -2.21, P=0.021), 7.8 mm and 9.3 mm (Z= -2.11, P=0.041)). In FB group, the differences of the displacements of the four selected clips were statistically significant in CC and AP directions (7.3 mm and 8.4 mm (Z= -2.45, P=0.021), 15.5 mm and 16.5 mm (Z= -2.41, P= 0.043)), but not in LF direction (10.6 nun and 10.6 mm (Z= -0.24, P=0.815)). In mDIBH group, the displacements in LF direction were statistically significant (4.4 mm and 5.4 mm (Z = -2.31, P = O. 031)), but not in CC and

  1. Semiconductor Physical Electronics

    CERN Document Server

    Li, Sheng

    2006-01-01

    Semiconductor Physical Electronics, Second Edition, provides comprehensive coverage of fundamental semiconductor physics that is essential to an understanding of the physical and operational principles of a wide variety of semiconductor electronic and optoelectronic devices. This text presents a unified and balanced treatment of the physics, characterization, and applications of semiconductor materials and devices for physicists and material scientists who need further exposure to semiconductor and photonic devices, and for device engineers who need additional background on the underlying physical principles. This updated and revised second edition reflects advances in semicondutor technologies over the past decade, including many new semiconductor devices that have emerged and entered into the marketplace. It is suitable for graduate students in electrical engineering, materials science, physics, and chemical engineering, and as a general reference for processing and device engineers working in the semicondi...

  2. Multiphoton microscopy in every lab: the promise of ultrafast semiconductor disk lasers

    Science.gov (United States)

    Emaury, Florian; Voigt, Fabian F.; Bethge, Philipp; Waldburger, Dominik; Link, Sandro M.; Carta, Stefano; van der Bourg, Alexander; Helmchen, Fritjof; Keller, Ursula

    2017-07-01

    We use an ultrafast diode-pumped semiconductor disk laser (SDL) to demonstrate several applications in multiphoton microscopy. The ultrafast SDL is based on an optically pumped Vertical External Cavity Surface Emitting Laser (VECSEL) passively mode-locked with a semiconductor saturable absorber mirror (SESAM) and generates 170-fs pulses at a center wavelength of 1027 nm with a repetition rate of 1.63 GHz. We demonstrate the suitability of this laser for structural and functional multiphoton in vivo imaging in both Drosophila larvae and mice for a variety of fluorophores (including mKate2, tdTomato, Texas Red, OGB-1, and R-CaMP1.07) and for endogenous second-harmonic generation in muscle cell sarcomeres. We can demonstrate equivalent signal levels compared to a standard 80-MHz Ti:Sapphire laser when we increase the average power by a factor of 4.5 as predicted by theory. In addition, we compare the bleaching properties of both laser systems in fixed Drosophila larvae and find similar bleaching kinetics despite the large difference in pulse repetition rates. Our results highlight the great potential of ultrafast diode-pumped SDLs for creating a cost-efficient and compact alternative light source compared to standard Ti:Sapphire lasers for multiphoton imaging.

  3. Theoretical modeling of the dynamics of a semiconductor laser subject to double-reflector optical feedback

    Energy Technology Data Exchange (ETDEWEB)

    Bakry, A. [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia); Abdulrhmann, S. [Jazan University, 114, Department of Physics, Faculty of Sciences (Saudi Arabia); Ahmed, M., E-mail: mostafa.farghal@mu.edu.eg [King Abdulaziz University, 80203, Department of Physics, Faculty of Science (Saudi Arabia)

    2016-06-15

    We theoretically model the dynamics of semiconductor lasers subject to the double-reflector feedback. The proposed model is a new modification of the time-delay rate equations of semiconductor lasers under the optical feedback to account for this type of the double-reflector feedback. We examine the influence of adding the second reflector to dynamical states induced by the single-reflector feedback: periodic oscillations, period doubling, and chaos. Regimes of both short and long external cavities are considered. The present analyses are done using the bifurcation diagram, temporal trajectory, phase portrait, and fast Fourier transform of the laser intensity. We show that adding the second reflector attracts the periodic and perioddoubling oscillations, and chaos induced by the first reflector to a route-to-continuous-wave operation. During this operation, the periodic-oscillation frequency increases with strengthening the optical feedback. We show that the chaos induced by the double-reflector feedback is more irregular than that induced by the single-reflector feedback. The power spectrum of this chaos state does not reflect information on the geometry of the optical system, which then has potential for use in chaotic (secure) optical data encryption.

  4. The theoretical and numerical models of the novel and fast tunable semiconductor ring laser

    Science.gov (United States)

    Zhu, Jiangbo; Zhang, Junwen; Chi, Nan; Yu, Siyuan

    2011-01-01

    Fast wavelength-tunable semiconductor lasers will be the key components in future optical packet switching networks. Especially, they are of great importance in the optical network nodes: transmitters, optical wavelength-routers, etc. In this paper, a new scheme of a next-generation fast tunable ring laser was given. Tunable lasers in this design have better wavelength tunability compared with others, for they are switched faster in wavelength and simpler to control with the injecting light from an external distributed Bragg-reflector(DBR). Then some discussion of the waveguide material system and coupler design of the ring laser were given. And we also derived the multimode rate equations corresponding to this scheme by analyzing some characteristics of the semiconductor ring cavity, directionality, nonlinear mode competition, optical injection locking, etc. We did MatLab simulation based on the new rate equations to research the process of mode competition and wavelength switching in the laser, and achieved the basic functions of a tunable laser. Finally some discussion of the impact of several key parameters was given.

  5. Contacts to semiconductors

    International Nuclear Information System (INIS)

    Tove, P.A.

    1975-08-01

    Contacts to semiconductors play an important role in most semiconductor devices. These devices range from microelectronics to power components, from high-sensitivity light or radiation detectors to light-emitting of microwave-generating components. Silicon is the dominating material but compound semiconductors are increasing in importance. The following survey is an attempt to classify contact properties and the physical mechanisms involved, as well as fabrication methods and methods of investigation. The main interest is in metal-semiconductor type contacts where a few basic concepts are dealt with in some detail. (Auth.)

  6. Semiconductor Electrical Measurements Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The Semiconductor Electrical Measurements Laboratory is a research laboratory which complements the Optical Measurements Laboratory. The laboratory provides for Hall...

  7. RF BREAKDOWN STUDIES USING PRESSURIZED CAVITIES

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Rolland

    2014-09-21

    Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Part of the problem is that RF breakdown in an evacuated cavity involves a complex mixture of effects, which include the geometry, metallurgy, and surface preparation of the accelerating structures and the make-up and pressure of the residual gas in which plasmas form. Studies showed that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas, as needed for muon cooling channels, without the need for long conditioning times, even in the presence of strong external magnetic fields. This positive result was expected because the dense gas can practically eliminate dark currents and multipacting. In this project we used this high pressure technique to suppress effects of residual vacuum and geometry that are found in evacuated cavities in order to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of magnetic field, frequency, and surface preparation. One of the interesting and useful outcomes of this project was the unanticipated collaborations with LANL and Fermilab that led to new insights as to the operation of evacuated normal-conducting RF cavities in high external magnetic fields. Other accomplishments included: (1) RF breakdown experiments to test the effects of SF6 dopant in H2 and He gases with Sn, Al, and Cu electrodes were carried out in an 805 MHz cavity and compared to calculations and computer simulations. The heavy corrosion caused by the SF6 components led to the suggestion that a small admixture of oxygen, instead of SF6, to the hydrogen would allow the same advantages without the corrosion in a practical muon beam line. (2) A

  8. Cavity design programs

    International Nuclear Information System (INIS)

    Nelson, E.M.

    1996-01-01

    Numerous computer programs are available to help accelerator physicists and engineers model and design accelerator cavities and other microwave components. This article discusses the problems these programs solve and the principles upon which these programs are based. Some examples of how these programs are used in the design of accelerator cavities are also given

  9. Cavity quantum electrodynamics

    International Nuclear Information System (INIS)

    Walther, Herbert; Varcoe, Benjamin T H; Englert, Berthold-Georg; Becker, Thomas

    2006-01-01

    This paper reviews the work on cavity quantum electrodynamics of free atoms. In recent years, cavity experiments have also been conducted on a variety of solid-state systems resulting in many interesting applications, of which microlasers, photon bandgap structures and quantum dot structures in cavities are outstanding examples. Although these phenomena and systems are very interesting, discussion is limited here to free atoms and mostly single atoms because these systems exhibit clean quantum phenomena and are not disturbed by a variety of other effects. At the centre of our review is the work on the one-atom maser, but we also give a survey of the entire field, using free atoms in order to show the large variety of problems dealt with. The cavity interaction can be separated into two main regimes: the weak coupling in cavity or cavity-like structures with low quality factors Q and the strong coupling when high-Q cavities are involved. The weak coupling leads to modification of spontaneous transitions and level shifts, whereas the strong coupling enables one to observe a periodic exchange of photons between atoms and the radiation field. In this case, atoms and photons are entangled, this being the basis for a variety of phenomena observed, some of them leading to interesting applications in quantum information processing. The cavity experiments with free atoms reached a new domain with the advent of experiments in the visible spectral region. A review on recent achievements in this area is also given

  10. Formation of coronal cavities

    International Nuclear Information System (INIS)

    An, C.H.; Suess, S.T.; Tandberg-Hanssen, E.; Steinolfson, R.S.

    1986-01-01

    A theoretical study of the formation of a coronal cavity and its relation to a quiescent prominence is presented. It is argued that the formation of a cavity is initiated by the condensation of plasma which is trapped by the coronal magnetic field in a closed streamer and which then flows down to the chromosphere along the field lines due to lack of stable magnetic support against gravity. The existence of a coronal cavity depends on the coronal magnetic field strength; with low strength, the plasma density is not high enough for condensation to occur. Furthermore, we suggest that prominence and cavity material is supplied from the chromospheric level. Whether a coronal cavity and a prominence coexist depends on the magnetic field configuration; a prominence requires stable magnetic support

  11. RF Power Requirements for PEFP SRF Cavity Test

    International Nuclear Information System (INIS)

    Kim, Han Sung; Seol, Kyung Tae; Kwon, Hyeok Jung; Cho, Yong Sub

    2011-01-01

    For the future extension of the PEFP (Proton Engineering Frontier Project) Proton linac, preliminary study on the SRF (superconducting radio-frequency) cavity is going on including a five-cell prototype cavity development to confirm the design and fabrication procedures and to check the RF and mechanical properties of a low-beta elliptical cavity. The main parameters of the cavity are like followings. - Frequency: 700 MHz - Operating mode: TM010 pi mode - Cavity type: Elliptical - Geometrical beta: 0.42 - Number of cells: 5 - Accelerating gradient: 8 MV/m - Epeak/Eacc: 3.71 - Bpeak/Eacc: 7.47 mT/(MV/m) - R/Q: 102.3 ohm - Epeak: 29.68 MV/m (1.21 Kilp.) - Geometrical factor: 121.68 ohm - Cavity wall thickness: 4.3 mm - Stiffening structure: Double ring - Effective length: 0.45 m For the test of the cavity at low temperature of 4.2 K, many subsystems are required such as a cryogenic system, RF system, vacuum system and radiation shielding. RF power required to generate accelerating field inside cavity depends on the RF coupling parameters of the power coupler and quality factor of the SRF cavity and the quality factor itself is affected by several factors such as operating temperature, external magnetic field level and surface condition. Therefore, these factors should be considered to estimate the required RF power for the SRF cavity test

  12. Cavity parameters identification for TESLA control system development

    Energy Technology Data Exchange (ETDEWEB)

    Czarski, T.; Pozniak, K.T.; Romaniuk, R.S. [Warsaw Univ. of Technology (Poland). ELHEP Lab., ISE; Simrock, S. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2005-07-01

    The control system modeling for the TESLA - TeV-Energy Superconducting Linear Accelerator project has been developed for the efficient stabilization of the pulsed, accelerating EM field of the resonator. The cavity parameters identification is an essential task for the comprehensive control algorithm. The TESLA cavity simulator has been successfully implemented by applying very high speed FPGA - Field Programmable Gate Array technology. The electromechanical model of the cavity resonator includes the basic features - Lorentz force detuning and beam loading. The parameters identification bases on the electrical model of the cavity. The model is represented by the state space equation for the envelope of the cavity voltage driven by the current generator and the beam loading. For a given model structure, the over-determined matrix equation is created covering the long enough measurement range with the solution according to the least squares method. A low degree polynomial approximation is applied to estimate the time-varying cavity detuning during the pulse. The measurement channel distortion is considered, leading to the external cavity model seen by the controller. The comprehensive algorithm of the cavity parameters identification has been implemented in the Matlab system with different modes of the operation. Some experimental results have been presented for different cavity operational conditions. The following considerations have lead to the synthesis of the efficient algorithm for the cavity control system predicted for the potential FPGA technology implementation. (orig.)

  13. Cavity parameters identification for TESLA control system development

    International Nuclear Information System (INIS)

    Czarski, T.; Pozniak, K.T.; Romaniuk, R.S.

    2005-01-01

    The control system modeling for the TESLA - TeV-Energy Superconducting Linear Accelerator project has been developed for the efficient stabilization of the pulsed, accelerating EM field of the resonator. The cavity parameters identification is an essential task for the comprehensive control algorithm. The TESLA cavity simulator has been successfully implemented by applying very high speed FPGA - Field Programmable Gate Array technology. The electromechanical model of the cavity resonator includes the basic features - Lorentz force detuning and beam loading. The parameters identification bases on the electrical model of the cavity. The model is represented by the state space equation for the envelope of the cavity voltage driven by the current generator and the beam loading. For a given model structure, the over-determined matrix equation is created covering the long enough measurement range with the solution according to the least squares method. A low degree polynomial approximation is applied to estimate the time-varying cavity detuning during the pulse. The measurement channel distortion is considered, leading to the external cavity model seen by the controller. The comprehensive algorithm of the cavity parameters identification has been implemented in the Matlab system with different modes of the operation. Some experimental results have been presented for different cavity operational conditions. The following considerations have lead to the synthesis of the efficient algorithm for the cavity control system predicted for the potential FPGA technology implementation. (orig.)

  14. Minimum wakefield achievable by waveguide damped cavity

    International Nuclear Information System (INIS)

    Lin, X.E.; Kroll, N.M.

    1995-01-01

    The authors use an equivalent circuit to model a waveguide damped cavity. Both exponentially damped and persistent (decay t -3/2 ) components of the wakefield are derived from this model. The result shows that for a cavity with resonant frequency a fixed interval above waveguide cutoff, the persistent wakefield amplitude is inversely proportional to the external Q value of the damped mode. The competition of the two terms results in an optimal Q value, which gives a minimum wakefield as a function of the distance behind the source particle. The minimum wakefield increases when the resonant frequency approaches the waveguide cutoff. The results agree very well with computer simulation on a real cavity-waveguide system

  15. New Icosahedral Boron Carbide Semiconductors

    Science.gov (United States)

    Echeverria Mora, Elena Maria

    Novel semiconductor boron carbide films and boron carbide films doped with aromatic compounds have been investigated and characterized. Most of these semiconductors were formed by plasma enhanced chemical vapor deposition. The aromatic compound additives used, in this thesis, were pyridine (Py), aniline, and diaminobenzene (DAB). As one of the key parameters for semiconducting device functionality is the metal contact and, therefore, the chemical interactions or band bending that may occur at the metal/semiconductor interface, X-ray photoemission spectroscopy has been used to investigate the interaction of gold (Au) with these novel boron carbide-based semiconductors. Both n- and p-type films have been tested and pure boron carbide devices are compared to those containing aromatic compounds. The results show that boron carbide seems to behave differently from other semiconductors, opening a way for new analysis and approaches in device's functionality. By studying the electrical and optical properties of these films, it has been found that samples containing the aromatic compound exhibit an improvement in the electron-hole separation and charge extraction, as well as a decrease in the band gap. The hole carrier lifetimes for each sample were extracted from the capacitance-voltage, C(V), and current-voltage, I(V), curves. Additionally, devices, with boron carbide with the addition of pyridine, exhibited better collection of neutron capture generated pulses at ZERO applied bias, compared to the pure boron carbide samples. This is consistent with the longer carrier lifetimes estimated for these films. The I-V curves, as a function of external magnetic field, of the pure boron carbide films and films containing DAB demonstrate that significant room temperature negative magneto-resistance (> 100% for pure samples, and > 50% for samples containing DAB) is possible in the resulting dielectric thin films. Inclusion of DAB is not essential for significant negative magneto

  16. Semiconductors data handbook

    CERN Document Server

    Madelung, Otfried

    2004-01-01

    This volume Semiconductors: Data Handbook contains frequently used data from the corresponding larger Landolt-Börnstein handbooks in a low price book for the individual scientist working in the laboratory. The Handbook contain important information about a large number of semiconductors

  17. Semiconductor radiation detection systems

    CERN Document Server

    2010-01-01

    Covers research in semiconductor detector and integrated circuit design in the context of medical imaging using ionizing radiation. This book explores other applications of semiconductor radiation detection systems in security applications such as luggage scanning, dirty bomb detection and border control.

  18. Spin physics in semiconductors

    CERN Document Server

    Dyakonov, Mikhail I

    2008-01-01

    This book describes beautiful optical and transport phenomena related to the electron and nuclear spins in semiconductors with emphasis on a clear presentation of the physics involved. Recent results on quantum wells and quantum dots are reviewed. The book is intended for students and researchers in the fields of semiconductor physics and nanoelectronics.

  19. High-Q AlAs/GaAs adiabatic micropillar cavities with submicron diameters for cQED experiments

    DEFF Research Database (Denmark)

    Lermer, M.; Gregersen, Niels; Dunzer, F.

    Quantum dot (QD) micropillar cavities represent an interesting class of microresonator systems aiming at the observation and application of cavity quantum electrodynamics (cQED) on a semiconductor platform. They combine valuable properties i.e. a highly directional and approximately Gaussian shaped...

  20. A semiconductor nanowire Josephson junction microwave laser

    Science.gov (United States)

    Cassidy, Maja; Uilhoorn, Willemijn; Kroll, James; de Jong, Damaz; van Woerkom, David; Nygard, Jesper; Krogstrup, Peter; Kouwenhoven, Leo

    We present measurements of microwave lasing from a single Al/InAs/Al nanowire Josephson junction strongly coupled to a high quality factor superconducting cavity. Application of a DC bias voltage to the Josephson junction results in photon emission into the cavity when the bias voltage is equal to a multiple of the cavity frequency. At large voltage biases, the strong non-linearity of the circuit allows for efficient down conversion of high frequency microwave photons down to multiple photons at the fundamental frequency of the cavity. In this regime, the emission linewidth narrows significantly below the bare cavity linewidth to 50%. The junction-cavity coupling and laser emission can be tuned rapidly via an external gate, making it suitable to be integrated into a scalable qubit architecture as a versatile source of coherent microwave radiation. This work has been supported by the Netherlands Organisation for Scientific Research (NWO/OCW), Foundation for Fundamental Research on Matter (FOM), European Research Council (ERC), and Microsoft Corporation Station Q.

  1. SPS RF Accelerating Cavity

    CERN Multimedia

    1979-01-01

    This picture shows one of the 2 new cavities installed in 1978-1979. 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

  2. Compound Semiconductor Radiation Detectors

    CERN Document Server

    Owens, Alan

    2012-01-01

    Although elemental semiconductors such as silicon and germanium are standard for energy dispersive spectroscopy in the laboratory, their use for an increasing range of applications is becoming marginalized by their physical limitations, namely the need for ancillary cooling, their modest stopping powers, and radiation intolerance. Compound semiconductors, on the other hand, encompass such a wide range of physical and electronic properties that they have become viable competitors in a number of applications. Compound Semiconductor Radiation Detectors is a consolidated source of information on all aspects of the use of compound semiconductors for radiation detection and measurement. Serious Competitors to Germanium and Silicon Radiation Detectors Wide-gap compound semiconductors offer the ability to operate in a range of hostile thermal and radiation environments while still maintaining sub-keV spectral resolution at X-ray wavelengths. Narrow-gap materials offer the potential of exceeding the spectral resolutio...

  3. Terahertz semiconductor nonlinear optics

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias

    2013-01-01

    In this proceedings we describe our recent results on semiconductor nonlinear optics, investigated using single-cycle THz pulses. We demonstrate the nonlinear absorption and self-phase modulation of strong-field THz pulses in doped semiconductors, using n-GaAs as a model system. The THz...... nonlinearity in doped semiconductors originates from the near-instantaneous heating of free electrons in the ponderomotive potential created by electric field of the THz pulse, leading to ultrafast increase of electron effective mass by intervalley scattering. Modification of effective mass in turn leads...... to a decrease of plasma frequency in semiconductor and produces a substantial modification of THz-range material dielectric function, described by the Drude model. As a result, the nonlinearity of both absorption coefficient and refractive index of the semiconductor is observed. In particular we demonstrate...

  4. Organic semiconductor crystals.

    Science.gov (United States)

    Wang, Chengliang; Dong, Huanli; Jiang, Lang; Hu, Wenping

    2018-01-22

    Organic semiconductors have attracted a lot of attention since the discovery of highly doped conductive polymers, due to the potential application in field-effect transistors (OFETs), light-emitting diodes (OLEDs) and photovoltaic cells (OPVs). Single crystals of organic semiconductors are particularly intriguing because they are free of grain boundaries and have long-range periodic order as well as minimal traps and defects. Hence, organic semiconductor crystals provide a powerful tool for revealing the intrinsic properties, examining the structure-property relationships, demonstrating the important factors for high performance devices and uncovering fundamental physics in organic semiconductors. This review provides a comprehensive overview of the molecular packing, morphology and charge transport features of organic semiconductor crystals, the control of crystallization for achieving high quality crystals and the device physics in the three main applications. We hope that this comprehensive summary can give a clear picture of the state-of-art status and guide future work in this area.

  5. Superconducting TESLA cavities

    Directory of Open Access Journals (Sweden)

    B. Aune

    2000-09-01

    Full Text Available The conceptional design of the proposed linear electron-positron collider TESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with an accelerating gradient of E_{acc}≥25 MV/m at a quality factor Q_{0}≥5×10^{9}. The design goal for the cavities of the TESLA Test Facility (TTF linac was set to the more moderate value of E_{acc}≥15 MV/m. In a first series of 27 industrially produced TTF cavities the average gradient at Q_{0}=5×10^{9} was measured to be 20.1±6.2 MV/m, excluding a few cavities suffering from serious fabrication or material defects. In the second production of 24 TTF cavities, additional quality control measures were introduced, in particular, an eddy-current scan to eliminate niobium sheets with foreign material inclusions and stringent prescriptions for carrying out the electron-beam welds. The average gradient of these cavities at Q_{0}=5×10^{9} amounts to 25.0±3.2 MV/m with the exception of one cavity suffering from a weld defect. Hence only a moderate improvement in production and preparation techniques will be needed to meet the ambitious TESLA goal with an adequate safety margin. In this paper we present a detailed description of the design, fabrication, and preparation of the TESLA Test Facility cavities and their associated components and report on cavity performance in test cryostats and with electron beam in the TTF linac. The ongoing research and development towards higher gradients is briefly addressed.

  6. Cavity-enhanced spectroscopies

    CERN Document Server

    van Zee, Roger

    2003-01-01

    ""Cavity-Enhanced Spectroscopy"" discusses the use of optical resonators and lasers to make sensitive spectroscopic measurements. This volume is written by the researcchers who pioneered these methods. The book reviews both the theory and practice behind these spectroscopic tools and discusses the scientific discoveries uncovered by these techniques. It begins with a chapter on the use of optical resonators for frequency stabilization of lasers, which is followed by in-depth chapters discussing cavity ring-down spectroscopy, frequency-modulated, cavity-enhanced spectroscopy, intracavity spectr

  7. Tuned optical cavity magnetometer

    Science.gov (United States)

    Okandan, Murat; Schwindt, Peter

    2010-11-02

    An atomic magnetometer is disclosed which utilizes an optical cavity formed from a grating and a mirror, with a vapor cell containing an alkali metal vapor located inside the optical cavity. Lasers are used to magnetically polarize the alkali metal vapor and to probe the vapor and generate a diffracted laser beam which can be used to sense a magnetic field. Electrostatic actuators can be used in the magnetometer for positioning of the mirror, or for modulation thereof. Another optical cavity can also be formed from the mirror and a second grating for sensing, adjusting, or stabilizing the position of the mirror.

  8. Hydroforming of elliptical cavities

    Science.gov (United States)

    Singer, W.; Singer, X.; Jelezov, I.; Kneisel, P.

    2015-02-01

    Activities of the past several years in developing the technique of forming seamless (weldless) cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients Eacc up to 35 MV /m after buffered chemical polishing (BCP) and up to 42 MV /m after electropolishing (EP). More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients Eacc of 30 - 35 MV /m were measured after BCP and Eacc up to 40 MV /m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of Eacc=30 - 35 MV /m . One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and double-cell cavities of the TESLA shape have been

  9. Hydroforming of elliptical cavities

    Directory of Open Access Journals (Sweden)

    W. Singer

    2015-02-01

    Full Text Available Activities of the past several years in developing the technique of forming seamless (weldless cavity cells by hydroforming are summarized. An overview of the technique developed at DESY for the fabrication of single cells and multicells of the TESLA cavity shape is given and the major rf results are presented. The forming is performed by expanding a seamless tube with internal water pressure while simultaneously swaging it axially. Prior to the expansion the tube is necked at the iris area and at the ends. Tube radii and axial displacements are computer controlled during the forming process in accordance with results of finite element method simulations for necking and expansion using the experimentally obtained strain-stress relationship of tube material. In cooperation with industry different methods of niobium seamless tube production have been explored. The most appropriate and successful method is a combination of spinning or deep drawing with flow forming. Several single-cell niobium cavities of the 1.3 GHz TESLA shape were produced by hydroforming. They reached accelerating gradients E_{acc} up to 35  MV/m after buffered chemical polishing (BCP and up to 42  MV/m after electropolishing (EP. More recent work concentrated on fabrication and testing of multicell and nine-cell cavities. Several seamless two- and three-cell units were explored. Accelerating gradients E_{acc} of 30–35  MV/m were measured after BCP and E_{acc} up to 40  MV/m were reached after EP. Nine-cell niobium cavities combining three three-cell units were completed at the company E. Zanon. These cavities reached accelerating gradients of E_{acc}=30–35  MV/m. One cavity is successfully integrated in an XFEL cryomodule and is used in the operation of the FLASH linear accelerator at DESY. Additionally the fabrication of bimetallic single-cell and multicell NbCu cavities by hydroforming was successfully developed. Several NbCu clad single-cell and

  10. Quantum gate for Q switching in monolithic photonic-band-gap cavities containing two-level atoms

    International Nuclear Information System (INIS)

    Greentree, Andrew D.; Prawer, Steven; Hollenberg, Lloyd C. L.; Salzman, J.

    2006-01-01

    Photonic-band-gap cavities are prime solid-state systems to investigate light-matter interactions in the strong coupling regime. However, as the cavity is defined by the geometry of the periodic dielectric pattern, cavity control in a monolithic structure can be problematic. Thus, either the state coherence is limited by the read-out channel, or in a high-Q cavity, it is nearly decoupled from the external world, making measurement of the state extremely challenging. We present here a method for ameliorating these difficulties by using a coupled cavity arrangement, where one cavity acts as a switch for the other cavity, tuned by control of the atomic transition

  11. 1.9 W yellow, CW, high-brightness light from a high efficiency semiconductor laser-based system

    Science.gov (United States)

    Hansen, A. K.; Christensen, M.; Noordegraaf, D.; Heist, P.; Papastathopoulos, E.; Loyo-Maldonado, V.; Jensen, O. B.; Stock, M. L.; Skovgaard, P. M. W.

    2017-02-01

    Semiconductor lasers are ideal sources for efficient electrical-to-optical power conversion and for many applications where their small size and potential for low cost are required to meet market demands. Yellow lasers find use in a variety of bio-related applications, such as photocoagulation, imaging, flow cytometry, and cancer treatment. However, direct generation of yellow light from semiconductors with sufficient beam quality and power has so far eluded researchers. Meanwhile, tapered semiconductor lasers at near-infrared wavelengths have recently become able to provide neardiffraction- limited, single frequency operation with output powers up to 8 W near 1120 nm. We present a 1.9 W single frequency laser system at 562 nm, based on single pass cascaded frequency doubling of such a tapered laser diode. The laser diode is a monolithic device consisting of two sections: a ridge waveguide with a distributed Bragg reflector, and a tapered amplifier. Using single-pass cascaded frequency doubling in two periodically poled lithium niobate crystals, 1.93 W of diffraction-limited light at 562 nm is generated from 5.8 W continuous-wave infrared light. When turned on from cold, the laser system reaches full power in just 60 seconds. An advantage of using a single pass configuration, rather than an external cavity configuration, is increased stability towards external perturbations. For example, stability to fluctuating case temperature over a 30 K temperature span has been demonstrated. The combination of high stability, compactness and watt-level power range means this technology is of great interest for a wide range of biological and biomedical applications.

  12. SPS accelerating cavity

    CERN Multimedia

    CERN PhotoLab

    1976-01-01

    The SPS started up with 2 accelerating cavities (each consisting of 5 tank sections) in LSS3. They have a 200 MHz travelling wave structure (see 7411032 and 7802190) and 750 kW of power is fed to each of the cavities from a 1 MW tetrode power amplifier, located in a surface building above, via a coaxial transmission line. Clemens Zettler, builder of the SPS RF system, is standing at the side of one of the cavities. In 1978 and 1979 another 2 cavities were added and entered service in 1980. These were part of the intensity improvement programme and served well for the new role of the SPS as proton-antiproton collider. See also 7411032, 8011289, 8104138, 8302397.

  13. Dental Sealants Prevent Cavities

    Science.gov (United States)

    ... Digital Press Kit Read the MMWR Science Clips Dental Sealants Prevent Cavities Effective protection for children Language: ... more use of sealants and reimbursement of services. Dental care providers can Apply sealants to children at ...

  14. Statistical electromagnetics: Complex cavities

    NARCIS (Netherlands)

    Naus, H.W.L.

    2008-01-01

    A selection of the literature on the statistical description of electromagnetic fields and complex cavities is concisely reviewed. Some essential concepts, for example, the application of the central limit theorem and the maximum entropy principle, are scrutinized. Implicit assumptions, biased

  15. accelerating cavity from LEP

    CERN Multimedia

    This is an accelerating cavity from LEP, with a layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities are now used in LEP to double the energy of the particle beams.

  16. Preparation and handling of surfaces for superconducting radio frequency cavities

    International Nuclear Information System (INIS)

    Bloess, D.

    1988-01-01

    Fortunately, surface treatment for s.c. cavities knows only one simple rule. If one observes this rule strictly one will be successful, if not, one will fail! The rule is CLEANLINESS. This means: clean material (high purity niobium without inclusions), clean (analytical grade) polishing chemicals and solvents, ultraclean (semiconductor grade) rinsing water, ultraclean (class 100) assembly environment. In general, if one applies the same working practice as the semiconductor industry, one will produce surfaces that are less clean than silicon wafers, due to the shape of the cavity (an inner surface is much more difficult to clean than a flat wafer); due to its size and due to the material (niobium is hydrophilic which makes the water with all the dirt in it stick to the surface). 9 references

  17. Hybrid vertical cavity laser

    DEFF Research Database (Denmark)

    Chung, Il-Sug; Mørk, Jesper

    2010-01-01

    A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide.......A new hybrid vertical cavity laser structure for silicon photonics is suggested and numerically investigated. It incorporates a silicon subwavelength grating as a mirror and a lateral output coupler to a silicon ridge waveguide....

  18. Construction of an optical semiconductor amplifier starting from a Fabry-Perot semiconductor laser; Construccion de un amplificador optico de semiconductor a partir de un laser de semiconductor Fabry-Perot

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, E.; Soto, H.; Marquez, H.; Valles V, N. [Departamento de Electronica y Telecomunicaciones, Centro de Investigacion Cientifica y de Educacion Superior de Ensenada. Km. 107, Carretera Tijuana-Ensenada, 22860 Ensenada, Baja California (Mexico)

    2000-07-01

    A methodology to convert a semiconductor laser Fabry-Perot (SL-FP) in a semiconductor optical amplifier (SOA) is presented. In order to suppress the cavity resonant an optical thin film coating was deposited on the facets of the SL-FP. The experiment was carried out putting on service a new monitoring technique that consist in the observation of the laser power spectrum during the antireflection coatings deposition. This allows to determine the moment were the facets reflectivity is minimum. The SOA obtained was characterized for different polarization currents. (Author)

  19. The Superconducting TESLA Cavities

    CERN Document Server

    Aune, B.; Bloess, D.; Bonin, B.; Bosotti, A.; Champion, M.; Crawford, C.; Deppe, G.; Dwersteg, B.; Edwards, D.A.; Edwards, H.T.; Ferrario, M.; Fouaidy, M.; Gall, P-D.; Gamp, A.; Gössel, A.; Graber, J.; Hubert, D.; Hüning, M.; Juillard, M.; Junquera, T.; Kaiser, H.; Kreps, G.; Kuchnir, M.; Lange, R.; Leenen, M.; Liepe, M.; Lilje, L.; Matheisen, A.; Möller, W-D.; Mosnier, A.; Padamsee, H.; Pagani, C.; Pekeler, M.; Peters, H-B.; Peters, O.; Proch, D.; Rehlich, K.; Reschke, D.; Safa, H.; Schilcher, T.; Schmüser, P.; Sekutowicz, J.; Simrock, S.; Singer, W.; Tigner, M.; Trines, D.; Twarowski, K.; Weichert, G.; Weisend, J.; Wojtkiewicz, J.; Wolff, S.; Zapfe, K.

    2000-01-01

    The conceptional design of the proposed linear electron-positron colliderTESLA is based on 9-cell 1.3 GHz superconducting niobium cavities with anaccelerating gradient of Eacc >= 25 MV/m at a quality factor Q0 > 5E+9. Thedesign goal for the cavities of the TESLA Test Facility (TTF) linac was set tothe more moderate value of Eacc >= 15 MV/m. In a first series of 27industrially produced TTF cavities the average gradient at Q0 = 5E+9 wasmeasured to be 20.1 +- 6.2 MV/m, excluding a few cavities suffering fromserious fabrication or material defects. In the second production of 24 TTFcavities additional quality control measures were introduced, in particular aneddy-current scan to eliminate niobium sheets with foreign material inclusionsand stringent prescriptions for carrying out the electron-beam welds. Theaverage gradient of these cavities at Q0 = 5E+9 amounts to 25.0 +- 3.2 MV/mwith the exception of one cavity suffering from a weld defect. Hence only amoderate improvement in production and preparation technique...

  20. Reconfigurable engineered motile semiconductor microparticles.

    Science.gov (United States)

    Ohiri, Ugonna; Shields, C Wyatt; Han, Koohee; Tyler, Talmage; Velev, Orlin D; Jokerst, Nan

    2018-05-03

    Locally energized particles form the basis for emerging classes of active matter. The design of active particles has led to their controlled locomotion and assembly. The next generation of particles should demonstrate robust control over their active assembly, disassembly, and reconfiguration. Here we introduce a class of semiconductor microparticles that can be comprehensively designed (in size, shape, electric polarizability, and patterned coatings) using standard microfabrication tools. These custom silicon particles draw energy from external electric fields to actively propel, while interacting hydrodynamically, and sequentially assemble and disassemble on demand. We show that a number of electrokinetic effects, such as dielectrophoresis, induced charge electrophoresis, and diode propulsion, can selectively power the microparticle motions and interactions. The ability to achieve on-demand locomotion, tractable fluid flows, synchronized motility, and reversible assembly using engineered silicon microparticles may enable advanced applications that include remotely powered microsensors, artificial muscles, reconfigurable neural networks and computational systems.

  1. Photodiodes based on fullerene semiconductor

    International Nuclear Information System (INIS)

    Voz, C.; Puigdollers, J.; Cheylan, S.; Fonrodona, M.; Stella, M.; Andreu, J.; Alcubilla, R.

    2007-01-01

    Fullerene thin films have been deposited by thermal evaporation on glass substrates at room temperature. A comprehensive optical characterization was performed, including low-level optical absorption measured by photothermal deflection spectroscopy. The optical absorption spectrum reveals a direct bandgap of 2.3 eV and absorption bands at 2.8 and 3.6 eV, which are related to the creation of charge-transfer excitons. Various photodiodes on indium-tin-oxide coated glass substrates were also fabricated, using different metallic contacts in order to compare their respective electrical characteristics. The influence of a poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) buffer layer between the indium-tin-oxide electrode and the fullerene semiconductor is also demonstrated. These results are discussed in terms of the workfunction for each electrode. Finally, the behaviour of the external quantum efficiency is analyzed for the whole wavelength spectrum

  2. Defects in semiconductors

    International Nuclear Information System (INIS)

    Pimentel, C.A.F.

    1983-01-01

    Some problems openned in the study of defects in semiconductors are presented. In particular, a review is made of the more important problems in Si monocrystals of basic and technological interest: microdefects and the presence of oxigen and carbon. The techniques usually utilized in the semiconductor material characterization are emphatized according its potentialities. Some applications of x-ray techniques in the epitaxial shell characterization in heterostructures, importants in electronic optics, are shown. The increase in the efficiency of these defect analysis methods in semiconductor materials with the use of synchrotron x-ray sources is shown. (L.C.) [pt

  3. Introduction to Semiconductor Devices

    Science.gov (United States)

    Brennan, Kevin F.

    2005-03-01

    This volume offers a solid foundation for understanding the most important devices used in the hottest areas of electronic engineering today, from semiconductor fundamentals to state-of-the-art semiconductor devices in the telecommunications and computing industries. Kevin Brennan describes future approaches to computing hardware and RF power amplifiers, and explains how emerging trends and system demands of computing and telecommunications systems influence the choice, design and operation of semiconductor devices. In addition, he covers MODFETs and MOSFETs, short channel effects, and the challenges faced by continuing miniaturization. His book is both an excellent senior/graduate text and a valuable reference for practicing engineers and researchers.

  4. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  5. Physics of semiconductor lasers

    CERN Document Server

    Mroziewicz, B; Nakwaski, W

    2013-01-01

    Written for readers who have some background in solid state physics but do not necessarily possess any knowledge of semiconductor lasers, this book provides a comprehensive and concise account of fundamental semiconductor laser physics, technology and properties. The principles of operation of these lasers are therefore discussed in detail with the interrelations between their design and optical, electrical and thermal properties. The relative merits of a large number of laser structures and their parameters are described to acquaint the reader with the various aspects of the semiconductor l

  6. Semiconductors bonds and bands

    CERN Document Server

    Ferry, David K

    2013-01-01

    As we settle into this second decade of the twenty-first century, it is evident that the advances in micro-electronics have truly revolutionized our day-to-day lifestyle. The technology is built upon semiconductors, materials in which the band gap has been engineered for special values suitable to the particular application. This book, written specifically for a one semester course for graduate students, provides a thorough understanding of the key solid state physics of semiconductors. It describes how quantum mechanics gives semiconductors unique properties that enabled the micro-electronics revolution, and sustain the ever-growing importance of this revolution.

  7. Defects in semiconductors

    CERN Document Server

    Romano, Lucia; Jagadish, Chennupati

    2015-01-01

    This volume, number 91 in the Semiconductor and Semimetals series, focuses on defects in semiconductors. Defects in semiconductors help to explain several phenomena, from diffusion to getter, and to draw theories on materials' behavior in response to electrical or mechanical fields. The volume includes chapters focusing specifically on electron and proton irradiation of silicon, point defects in zinc oxide and gallium nitride, ion implantation defects and shallow junctions in silicon and germanium, and much more. It will help support students and scientists in their experimental and theoret

  8. Dynamics in terahertz semiconductor microcavity: quantum noise spectra

    Science.gov (United States)

    Jabri, H.; Eleuch, H.

    2018-05-01

    We investigate the physics of an optical semiconductor microcavity containing a coupled double quantum well interacting with cavity photons. The photon statistics of the transmitted light by the cavity is explored. We show that the nonlinear interactions in the direct and indirect excitonic modes generate an important squeezing despite the weak nonlinearities. When the strong coupling regime is achieved, the noise spectra of the system is dominated by the indirect exciton distribution. At the opposite, in the weak regime, direct excitons contribute much larger in the noise spectra.

  9. Avaliação quantitativa das dimensões óculo-palpebrais em portadores de cavidade anoftálmica em uso de prótese ocular externa Quantitative eyelid evaluation of anophthalmic cavity carriers with external ocular prosthesis

    Directory of Open Access Journals (Sweden)

    Rodrigo Ueno Takahagi

    2005-08-01

    alteration. The superior eyelid sulcus distance had shorter values with the prosthesis and higher values were seen analyzing the other parameters when the external prosthesis was in place. CONCLUSION: All patients had some abnormalities, which show us how difficult it is to provide a normal aspect for anophthalmic cavity carriers. The image processing allowed objective evaluations of the measures contributing to the follow-up of the patients.

  10. Biggest semiconductor installed

    CERN Multimedia

    2008-01-01

    Scientists and technicians at the European Laboratory for Particle Physics, commonly known by its French acronym CERN (Centre Europen pour la Recherche Nuclaire), have completed the installation of the largest semiconductor silicon detector.

  11. High Power Diode Lasers with External Feedback: Overview and Prospects

    DEFF Research Database (Denmark)

    Chi, Mingjun; Petersen, Paul Michael

    2012-01-01

    In summary, different external-cavity feedback techniques to improve the spatial beam quality and narrow the linewidth of the output beam from both BALs and TDLs are presented. Broad-area diode laser system with external-cavity feedback around 800 nm can produce several Watts of output power...... with a good beam quality. Tapered diode laser systems with external-cavity feedback around 800 and 1060 nm can deliver more than 2 W output power with diffraction-limited beam quality and can be operated in single-longitudinal mode. These high-brightness, narrow linewidth, and tunable external-cavity diode...... lasers emerge as the next generation of compact lasers that have the potential of replacing conventional high power laser systems in many existing applications....

  12. Radiation effects in semiconductors

    CERN Document Server

    2011-01-01

    There is a need to understand and combat potential radiation damage problems in semiconductor devices and circuits. Written by international experts, this book explains the effects of radiation on semiconductor devices, radiation detectors, and electronic devices and components. These contributors explore emerging applications, detector technologies, circuit design techniques, new materials, and innovative system approaches. The text focuses on how the technology is being used rather than the mathematical foundations behind it. It covers CMOS radiation-tolerant circuit implementations, CMOS pr

  13. Market survey of semiconductors

    International Nuclear Information System (INIS)

    Mackintosh, I.M.; Diegel, D.; Brown, A.; Brinker, C.S. den

    1977-06-01

    Examination of technology and product trends over the range of current and future products in integrated circuits and optoelectronic displays. Analysis and forecast of major economic influences that affect the production costs of integrated circuits and optoelectronic displays. Forecast of the applications and markets for integrated circuits up to 1985 in West Europe, the USA and Japan. Historic development of the semiconductor industry and the prevailing tendencies - factors which influence success in the semiconductor industry. (orig.) [de

  14. Electronic properties of semiconductor heterostructures

    International Nuclear Information System (INIS)

    Einevoll, G.T.

    1991-02-01

    Ten papers on the electronic properties of semiconductors and semiconductor heterostructures constitute the backbone of this thesis. Four papers address the form and validity of the single-band effective mass approximation for semiconductor heterostructures. In four other papers properties of acceptor states in bulk semiconductors and semiconductor heterostructures are studied using the novel effective bond-orbital model. The last two papers deal with localized excitions. 122 refs

  15. Microscopic theory of indistinguishable single-photon emission from a quantum dot coupled to a cavity: The role of non-Markovian phonon-induced decoherence

    DEFF Research Database (Denmark)

    Nielsen, Per Kær; Lodahl, Peter; Jauho, Antti-Pekka

    2013-01-01

    We study the fundamental limit on single-photon indistinguishability imposed by decoherence due to phonon interactions in semiconductor quantum dot-cavity quantum electrodynamics systems. Employing an exact diagonalization approach we find large differences compared to standard methods...

  16. Radiotherapy for Oral Cavity Cancer

    International Nuclear Information System (INIS)

    Shim, Jae Won

    1993-01-01

    Eighty five patients of oral cavity cancer, treated with radiation at the Department of Therapeutic Radiology, Korea Cancer Center Hospital, during the period from March 1985 to September 1990 were analyzed retrospectively. Among 85 patients, 37 patients were treated with radiation only and 48 patients were treated with radiation following surgery And 70 patients received external irradiation only by 60 Co with or without electron, the others were 7 patients for external irradiation plus interstitial implantation and 8 patients for external irradiation plus oral cone electron therapy. Primary sites were mobile tongue for 40 patients, mouth floor for 17 patients, palate for 12 patients, gingiva including retromolar trigone for 10 patients, buccal mucosa for 5 patients, and lip for 1 patient. According to pathologic classification, squamous cell carcinoma was the most common (77 patients). According to AJC TNM stage, stage I + II were 28 patients and stage III + IV were 57 patients. Acturial overall survival rate at 3 years was 43.9%, 3 year survival rates were 60.9% for stage I + II, and 23.1% for stage III + IV, respectively. As a prognostic factor, primary T stage was a significant factor (p<0.01). The others, age, location, lymph node metastasis, surgery, radiation dose, and cell differentiation were not statistically significant. Among those factors, radiation plus surgery was more effective than radiation only in T3 + T4 or in any N stage although it was not statistically sufficient(p<0.1). From those results, it was conclusive that definitive radiotherapy was more effective than surgery especially in the view of pertaining of anatomical integrity and function in early stage, and radiation plus surgery was considered to be better therapeutic tool in advanced stage

  17. Video Toroid Cavity Imager

    Energy Technology Data Exchange (ETDEWEB)

    Gerald, Rex E. II; Sanchez, Jairo; Rathke, Jerome W.

    2004-08-10

    A video toroid cavity imager for in situ measurement of electrochemical properties of an electrolytic material sample includes a cylindrical toroid cavity resonator containing the sample and employs NMR and video imaging for providing high-resolution spectral and visual information of molecular characteristics of the sample on a real-time basis. A large magnetic field is applied to the sample under controlled temperature and pressure conditions to simultaneously provide NMR spectroscopy and video imaging capabilities for investigating electrochemical transformations of materials or the evolution of long-range molecular aggregation during cooling of hydrocarbon melts. The video toroid cavity imager includes a miniature commercial video camera with an adjustable lens, a modified compression coin cell imager with a fiat circular principal detector element, and a sample mounted on a transparent circular glass disk, and provides NMR information as well as a video image of a sample, such as a polymer film, with micrometer resolution.

  18. Earth-ionosphere cavity

    International Nuclear Information System (INIS)

    Tran, A.; Polk, C.

    1976-01-01

    To analyze ELF wave propagation in the earth-ionosphere cavity, a flat earth approximation may be derived from the exact equations, which are applicable to the spherical cavity, by introducing a second-order or Debye approximation for the spherical Hankel functions. In the frequency range 3 to 30 Hz, however, the assumed conditions for the Debye approximation are not satisfied. For this reason an exact evaluation of the spherical Hankel functions is used to study the effects of the flat earth approximation on various propagation and resonance parameters. By comparing the resonance equation for a spherical cavity with its flat earth counterpart and by assuming that the surface impedance Z/sub i/ at the upper cavity boundary is known, the relation between the eigenvalue ν and S/sub v/, the sine of the complex angle of incidence at the lower ionosphere boundary, is established as ν(ν + 1) = (kaS/sub v/) 2 . It is also shown that the approximation ν(ν + 1) approximately equals (ν + 1/2) 2 which was used by some authors is not adequate below 30 Hz. Numerical results for both spherical and planar stratification show that (1) planar stratification is adequate for the computation of the lowest three ELF resonance frequencies to within 0.1 Hz; (2) planar stratification will lead to errors in cavity Q and wave attenuation which increase with frequency; (3) computation of resonance frequencies to within 0.1 Hz requires the extension of the lower boundary of the ionosphere to a height where the ratio of conduction current to displacement current, (sigma/ωepsilon 0 ), is less than 0.3; (4) atmospheric conductivity should be considered down to ground level in computing cavity Q and wave attenuation

  19. Materials for superconducting cavities

    International Nuclear Information System (INIS)

    Bonin, B.

    1996-01-01

    The ideal material for superconducting cavities should exhibit a high critical temperature, a high critical field, and, above all, a low surface resistance. Unfortunately, these requirements can be conflicting and a compromise has to be found. To date, most superconducting cavities for accelerators are made of niobium. The reasons for this choice are discussed. Thin films of other materials such as NbN, Nb 3 Sn, or even YBCO compounds can also be envisaged and are presently investigated in various laboratories. It is shown that their success will depend critically on the crystalline perfection of these films. (author)

  20. Experimental investigation of cavity flows

    Energy Technology Data Exchange (ETDEWEB)

    Loeland, Tore

    1999-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  1. Experimental investigation of cavity flows

    Energy Technology Data Exchange (ETDEWEB)

    Loeland, Tore

    1998-12-31

    This thesis uses LDV (Laser Doppler Velocimetry), PIV (Particle Image Velocimetry) and Laser Sheet flow Visualisation to study flow inside three different cavity configurations. For sloping cavities, the vortex structure inside the cavities is found to depend upon the flow direction past the cavity. The shape of the downstream corner is a key factor in destroying the boundary layer flow entering the cavity. The experimental results agree well with numerical simulations of the same geometrical configurations. The results of the investigations are used to find the influence of the cavity flow on the accuracy of the ultrasonic flowmeter. A method to compensate for the cavity velocities is suggested. It is found that the relative deviation caused by the cavity velocities depend linearly on the pipe flow. It appears that the flow inside the cavities should not be neglected as done in the draft for the ISO technical report on ultrasonic flowmeters. 58 refs., 147 figs., 2 tabs.

  2. Pressurized rf cavities in ionizing beams

    Directory of Open Access Journals (Sweden)

    B. Freemire

    2016-06-01

    Full Text Available A muon collider or Higgs factory requires significant reduction of the six dimensional emittance of the beam prior to acceleration. One method to accomplish this involves building a cooling channel using high pressure gas filled radio frequency cavities. The performance of such a cavity when subjected to an intense particle beam must be investigated before this technology can be validated. To this end, a high pressure gas filled radio frequency (rf test cell was built and placed in a 400 MeV beam line from the Fermilab linac to study the plasma evolution and its effect on the cavity. Hydrogen, deuterium, helium and nitrogen gases were studied. Additionally, sulfur hexafluoride and dry air were used as dopants to aid in the removal of plasma electrons. Measurements were made using a variety of beam intensities, gas pressures, dopant concentrations, and cavity rf electric fields, both with and without a 3 T external solenoidal magnetic field. Energy dissipation per electron-ion pair, electron-ion recombination rates, ion-ion recombination rates, and electron attachment times to SF_{6} and O_{2} were measured.

  3. Heat loss investigation from spherical cavity receiver of solar concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Shewale, V. C. [Dept. of Mechanical Engineering, NDMVPS KBT College of Engineering, Nashik (India); Dongarwar, P. R. [Dept. of Mechanical Engineering, College of Military Engineering, Pune (India); Gawande, R. P. [Dept. of Mechanical Engineering, B.D.C.O.E. Wardha, Nagpur University, NagpurI (India)

    2016-11-15

    The heat losses are mainly affects on the performance of cavity receiver of solar concentrator. In this paper, the experimental and numerical study is carried out for different heat losses from spherical cavity receiver of 0.385 m cavity diameter and 0.154 m opening diameter. The total and convection losses are studied experimentally to no wind and wind conditions for the temperature range of 150 °C to 300 °C at 0°, 30°, 45°, 60° and 90° inclination angle of cavity receiver. The experimental set up mainly consists of copper tube material cavity receiver wrapped with nichrome heating coil to heat the cavity and insulated with glasswool insulation. The numerical analysis was carried out with Fluent Computational fluid dynamics (CFD) software, to study connective heat losses for no wind condition only. The numerical results are compared with experimental results and found good agreement with maximum deviation of 12 %. The effect of inclination angle of cavity receiver on total losses and convection losses shows that as the inclination angle increases from 0o to 90o, both losses decreased due to decreased in convective zone into the cavity receiver. The effect of operating temperature of cavity shows that as the temperature of cavity receiver increases, the total and convective losses goes on increasing. The effect of external wind at 2 m/s and 4 m/s in two directions (side-on wind and head-on wind) is also studied experimentally for total and convective heat losses. The result shows that the heat losses are higher for head-on wind condition compared to side-on wind and no wind condition at all inclination angle of cavity receiver. The present results are also compared to the convective losses obtained from the correlations of Stine and Mcdonald and M. Prakash. The convective loss from these correlations shows nearest prediction to both experimental and numerical results.

  4. Heat loss investigation from spherical cavity receiver of solar concentrator

    International Nuclear Information System (INIS)

    Shewale, V. C.; Dongarwar, P. R.; Gawande, R. P.

    2016-01-01

    The heat losses are mainly affects on the performance of cavity receiver of solar concentrator. In this paper, the experimental and numerical study is carried out for different heat losses from spherical cavity receiver of 0.385 m cavity diameter and 0.154 m opening diameter. The total and convection losses are studied experimentally to no wind and wind conditions for the temperature range of 150 °C to 300 °C at 0°, 30°, 45°, 60° and 90° inclination angle of cavity receiver. The experimental set up mainly consists of copper tube material cavity receiver wrapped with nichrome heating coil to heat the cavity and insulated with glasswool insulation. The numerical analysis was carried out with Fluent Computational fluid dynamics (CFD) software, to study connective heat losses for no wind condition only. The numerical results are compared with experimental results and found good agreement with maximum deviation of 12 %. The effect of inclination angle of cavity receiver on total losses and convection losses shows that as the inclination angle increases from 0o to 90o, both losses decreased due to decreased in convective zone into the cavity receiver. The effect of operating temperature of cavity shows that as the temperature of cavity receiver increases, the total and convective losses goes on increasing. The effect of external wind at 2 m/s and 4 m/s in two directions (side-on wind and head-on wind) is also studied experimentally for total and convective heat losses. The result shows that the heat losses are higher for head-on wind condition compared to side-on wind and no wind condition at all inclination angle of cavity receiver. The present results are also compared to the convective losses obtained from the correlations of Stine and Mcdonald and M. Prakash. The convective loss from these correlations shows nearest prediction to both experimental and numerical results

  5. Ultrafast dynamics and laser action of organic semiconductors

    CERN Document Server

    Vardeny, Zeev Valy

    2009-01-01

    Spurred on by extensive research in recent years, organic semiconductors are now used in an array of areas, such as organic light emitting diodes (OLEDs), photovoltaics, and other optoelectronics. In all of these novel applications, the photoexcitations in organic semiconductors play a vital role. Exploring the early stages of photoexcitations that follow photon absorption, Ultrafast Dynamics and Laser Action of Organic Semiconductors presents the latest research investigations on photoexcitation ultrafast dynamics and laser action in pi-conjugated polymer films, solutions, and microcavities.In the first few chapters, the book examines the interplay of charge (polarons) and neutral (excitons) photoexcitations in pi-conjugated polymers, oligomers, and molecular crystals in the time domain of 100 fs-2 ns. Summarizing the state of the art in lasing, the final chapters introduce the phenomenon of laser action in organics and cover the latest optoelectronic applications that use lasing based on a variety of caviti...

  6. Method of doping a semiconductor

    International Nuclear Information System (INIS)

    Yang, C.Y.; Rapp, R.A.

    1983-01-01

    A method is disclosed for doping semiconductor material. An interface is established between a solid electrolyte and a semiconductor to be doped. The electrolyte is chosen to be an ionic conductor of the selected impurity and the semiconductor material and electrolyte are jointly chosen so that any compound formed from the impurity and the semiconductor will have a free energy no lower than the electrolyte. A potential is then established across the interface so as to allow the impurity ions to diffuse into the semiconductor. In one embodiment the semiconductor and electrolyte may be heated so as to increase the diffusion coefficient

  7. Polariton solitons and nonlinear localized states in a one-dimensional semiconductor microcavity

    Science.gov (United States)

    Chen, Ting-Wei; Cheng, Szu-Cheng

    2018-01-01

    This paper presents numerical studies of cavity polariton solitons (CPSs) in a resonantly pumped semiconductor microcavity with an imbedded spatial defect. In the bistable regime of the well-known homogeneous polariton condensate, with proper incident wave vector and pump strength, bright and/or dark cavity solitons can be found in the presence of a spatially confined potential. The minimum pump strength required to observe the CPSs or nonlinear localized states in this parametric pump scheme is therefore reported.

  8. Semiconductor quantum optics with tailored photonic nanostructures

    International Nuclear Information System (INIS)

    Laucht, Arne

    2011-01-01

    This thesis describes detailed investigations of the effects of photonic nanostructures on the light emission properties of self-assembled InGaAs quantum dots. Nanoscale optical cavities and waveguides are employed to enhance the interaction between light and matter, i.e. photons and excitons, up to the point where optical non-linearities appear at the quantum (single photon) level. Such non-linearities are an essential component for the realization of hardware for photon based quantum computing since they can be used for the creation and detection of non-classical states of light and may open the way to new genres of quantum optoelectronic devices such as optical modulators and optical transistors. For single semiconductor quantum dots in photonic crystal nanocavities we investigate the coupling between excitonic transitions and the highly localized mode of the optical cavity. We explore the non-resonant coupling mechanisms which allow excitons to couple to the cavity mode, even when they are not spectrally in resonance. This effect is not observed for atomic cavity quantum electrodynamics experiments and its origin is traced to phonon-assisted scattering for small detunings (ΔE ∝5 meV). For quantum dots in high-Q cavities we observe the coherent coupling between exciton and cavity mode in the strong coupling regime of light-matter interaction, probe the influence of pure dephasing on the coherent interaction at high excitation levels and high lattice temperatures, and examine the coupling of two spatially separated quantum dots via the exchange of real and virtual photons mediated by the cavity mode. Furthermore, we study the spontaneous emission properties of quantum dots in photonic crystal waveguide structures, estimate the fraction of all photons emitted into the propagating waveguide mode, and demonstrate the on-chip generation of single photon emission into the waveguide. The results obtained during the course of this thesis contribute significantly to

  9. Semiconductor quantum optics with tailored photonic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Laucht, Arne

    2011-06-15

    This thesis describes detailed investigations of the effects of photonic nanostructures on the light emission properties of self-assembled InGaAs quantum dots. Nanoscale optical cavities and waveguides are employed to enhance the interaction between light and matter, i.e. photons and excitons, up to the point where optical non-linearities appear at the quantum (single photon) level. Such non-linearities are an essential component for the realization of hardware for photon based quantum computing since they can be used for the creation and detection of non-classical states of light and may open the way to new genres of quantum optoelectronic devices such as optical modulators and optical transistors. For single semiconductor quantum dots in photonic crystal nanocavities we investigate the coupling between excitonic transitions and the highly localized mode of the optical cavity. We explore the non-resonant coupling mechanisms which allow excitons to couple to the cavity mode, even when they are not spectrally in resonance. This effect is not observed for atomic cavity quantum electrodynamics experiments and its origin is traced to phonon-assisted scattering for small detunings ({delta}E<{proportional_to}5 meV) and a multi-exciton-based, Auger-like process for larger detunings ({delta}E >{proportional_to}5 meV). For quantum dots in high-Q cavities we observe the coherent coupling between exciton and cavity mode in the strong coupling regime of light-matter interaction, probe the influence of pure dephasing on the coherent interaction at high excitation levels and high lattice temperatures, and examine the coupling of two spatially separated quantum dots via the exchange of real and virtual photons mediated by the cavity mode. Furthermore, we study the spontaneous emission properties of quantum dots in photonic crystal waveguide structures, estimate the fraction of all photons emitted into the propagating waveguide mode, and demonstrate the on-chip generation of

  10. Multipactors in klystron cavities

    International Nuclear Information System (INIS)

    Hayashi, Kazutaka; Iyeki, Hiroshi; Kikunaga, Toshiyuki.

    1993-01-01

    A multipactor phenomenon in a klystron causes gain shortage or instability problem. Some tests using a prototype klystron input cavity revealed the microwave discharges in vacuum with magnetic field. The test results and the methods to avoid multipactors are discussed in this paper. (author)

  11. What's a Cavity?

    Science.gov (United States)

    ... and deeper over time. Cavities are also called dental caries (say: KARE-eez), and if you have a ... made up mostly of the germs that cause tooth decay. The bacteria in your mouth make acids and when plaque clings to your teeth, the acids can eat away at the outermost ...

  12. Vertical cavity laser

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention provides a vertical cavity laser comprising a grating layer comprising an in-plane grating, the grating layer having a first side and having a second side opposite the first side and comprising a contiguous core grating region having a grating structure, wherein an index...

  13. Oral cavity and jaw

    International Nuclear Information System (INIS)

    Solntsev, A.M.; Koval', G.Yu.

    1984-01-01

    Radioanatome of oral cavity and jaw is described. Diseases of the teeth, jaw, large salivary glands, temporo-mandibular articulation are considered. Roentgenograms of oral cacity and jaw of healthy people are presented and analyzed as well as roentgenograms in the above-mentioned diseases

  14. Niobium superconducting cavity

    CERN Multimedia

    CERN PhotoLab

    1980-01-01

    This 5-cell superconducting cavity, made from bulk-Nb, stems from the period of general studies, not all directed towards direct use at LEP. This one is dimensioned for 1.5 GHz, the frequency used at CEBAF and also studied at Saclay (LEP RF was 352.2 MHz). See also 7908227, 8007354, 8209255, 8210054, 8312339.

  15. Superconducting elliptical cavities

    CERN Document Server

    Sekutowicz, J K

    2011-01-01

    We give a brief overview of the history, state of the art, and future for elliptical superconducting cavities. Principles of the cell shape optimization, criteria for multi-cell structures design, HOM damping schemes and other features are discussed along with examples of superconducting structures for various applications.

  16. Additive Manufactured Superconducting Cavities

    Science.gov (United States)

    Holland, Eric; Rosen, Yaniv; Woolleet, Nathan; Materise, Nicholas; Voisin, Thomas; Wang, Morris; Mireles, Jorge; Carosi, Gianpaolo; Dubois, Jonathan

    Superconducting radio frequency cavities provide an ultra-low dissipative environment, which has enabled fundamental investigations in quantum mechanics, materials properties, and the search for new particles in and beyond the standard model. However, resonator designs are constrained by limitations in conventional machining techniques. For example, current through a seam is a limiting factor in performance for many waveguide cavities. Development of highly reproducible methods for metallic parts through additive manufacturing, referred to colloquially as 3D printing\\x9D, opens the possibility for novel cavity designs which cannot be implemented through conventional methods. We present preliminary investigations of superconducting cavities made through a selective laser melting process, which compacts a granular powder via a high-power laser according to a digitally defined geometry. Initial work suggests that assuming a loss model and numerically optimizing a geometry to minimize dissipation results in modest improvements in device performance. Furthermore, a subset of titanium alloys, particularly, a titanium, aluminum, vanadium alloy (Ti - 6Al - 4V) exhibits properties indicative of a high kinetic inductance material. This work is supported by LDRD 16-SI-004.

  17. Cavity Nesting Birds

    Science.gov (United States)

    Virgil E. Scott; Keith E. Evans; David R. Patton; Charles P. Stone

    1977-01-01

    Many species of cavity-nesting birds have declined because of habitat reduction. In the eastern United States, where primeval forests are gone, purple martins depend almost entirely on man-made nesting structures (Allen and Nice 1952). The hole-nesting population of peregrine falcons disappeared with the felling of the giant trees upon which they depended (Hickey and...

  18. LEP superconducting cavity

    CERN Multimedia

    1995-01-01

    Engineers work in a clean room on one of the superconducting cavities for the upgrade to the LEP accelerator, known as LEP-2. The use of superconductors allow higher electric fields to be produced so that higher beam energies can be reached.

  19. Open microwave cavities

    Czech Academy of Sciences Publication Activity Database

    Šeba, Petr; Rotter, I.; Mueller, M.; Persson, C.; Pichugin, Konstantin N.

    2001-01-01

    Roč. 9, - (2001), s. 484-487 ISSN 1386-9477 Institutional research plan: CEZ:A02/98:Z1-010-914 Keywords : microwave cavity * resonances Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.009, year: 2001

  20. Filling a Conical Cavity

    Science.gov (United States)

    Nye, Kyle; Eslam-Panah, Azar

    2016-11-01

    Root canal treatment involves the removal of infected tissue inside the tooth's canal system and filling the space with a dense sealing agent to prevent further infection. A good root canal treatment happens when the canals are filled homogeneously and tightly down to the root apex. Such a tooth is able to provide valuable service for an entire lifetime. However, there are some examples of poorly performed root canals where the anterior and posterior routes are not filled completely. Small packets of air can be trapped in narrow access cavities when restoring with resin composites. Such teeth can cause trouble even after many years and lead the conditions like acute bone infection or abscesses. In this study, the filling of dead-end conical cavities with various liquids is reported. The first case studies included conical cavity models with different angles and lengths to visualize the filling process. In this investigation, the rate and completeness at which a variety of liquids fill the cavity were observed to find ideal conditions for the process. Then, a 3D printed model of the scaled representation of a molar with prepared post spaces was used to simulate the root canal treatment. The results of this study can be used to gain a better understanding of the restoration for endodontically treated teeth.

  1. Megavolt nanosecond generator with semiconductor current breaker

    CERN Document Server

    Bushlyakov, A I; Rukin, S N; Slovikovskij, B G; Timoshenkov, S P

    2002-01-01

    The heavy-current nanosecond generator with the pulse capacity up to 1.6 GW and output voltage of 0.5-1 MW is described. The generator contains four capacity storages, one induction storage and six solid body commutators: one thyristor, four magnetic commutators and a semiconductor current breaker on the SOS-diodes. The results of studies on the energy change-over efficiency through a semiconductor breaker by various external resistance loads as well as the results of the thermal and frequency tests are presented. It is established that selection of the optimal cooling system provides for the generator continuous mode of operation with the pulse sequence frequency from 300 Hz up to 850 Hz

  2. Fundamentals of semiconductor lasers

    CERN Document Server

    Numai, Takahiro

    2015-01-01

    This book explains physics under the operating principles of semiconductor lasers in detail based on the experience of the author, dealing with the first manufacturing of phase-shifted DFB-LDs and recent research on transverse modes.   The book also bridges a wide gap between journal papers and textbooks, requiring only an undergraduate-level knowledge of electromagnetism and quantum mechanics, and helps readers to understand journal papers where definitions of some technical terms vary, depending on the paper. Two definitions of the photon density in the rate equations and two definitions of the phase-shift in the phase-shifted DFB-LD are explained, and differences in the calculated results are indicated, depending on the definitions.    Readers can understand the physics of semiconductor lasers and analytical tools for Fabry-Perot LDs, DFB-LDs, and VCSELs and will be stimulated to develop semiconductor lasers themselves.

  3. Coherent dynamics in semiconductors

    DEFF Research Database (Denmark)

    Hvam, Jørn Märcher

    1998-01-01

    enhanced in quantum confined lower-dimensional systems, where exciton and biexciton effects dominate the spectra even at room temperature. The coherent dynamics of excitons are at modest densities well described by the optical Bloch equations and a number of the dynamical effects known from atomic......Ultrafast nonlinear optical spectroscopy is used to study the coherent dynamics of optically excited electron-hole pairs in semiconductors. Coulomb interaction implies that the optical inter-band transitions are dominated, at least at low temperatures, by excitonic effects. They are further...... and molecular systems are found and studied in the exciton-biexciton system of semiconductors. At densities where strong exciton interactions, or many-body effects, become dominant, the semiconductor Bloch equations present a more rigorous treatment of the phenomena Ultrafast degenerate four-wave mixing is used...

  4. Hydrogen in semiconductors II

    CERN Document Server

    Nickel, Norbert H; Weber, Eicke R; Nickel, Norbert H

    1999-01-01

    Since its inception in 1966, the series of numbered volumes known as Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. The "Willardson and Beer" Series, as it is widely known, has succeeded in publishing numerous landmark volumes and chapters. Not only did many of these volumes make an impact at the time of their publication, but they continue to be well-cited years after their original release. Recently, Professor Eicke R. Weber of the University of California at Berkeley joined as a co-editor of the series. Professor Weber, a well-known expert in the field of semiconductor materials, will further contribute to continuing the series' tradition of publishing timely, highly relevant, and long-impacting volumes. Some of the recent volumes, such as Hydrogen in Semiconductors, Imperfections in III/V Materials, Epitaxial Microstructures, High-Speed Heterostructure Devices, Oxygen in Silicon, and others promise that this tradition ...

  5. Photoelectronic properties of semiconductors

    CERN Document Server

    Bube, Richard H

    1992-01-01

    The interaction between light and electrons in semiconductors forms the basis for many interesting and practically significant properties. This book examines the fundamental physics underlying this rich complexity of photoelectronic properties of semiconductors, and will familiarise the reader with the relatively simple models that are useful in describing these fundamentals. The basic physics is also illustrated with typical recent examples of experimental data and observations. Following introductory material on the basic concepts, the book moves on to consider a wide range of phenomena, including photoconductivity, recombination effects, photoelectronic methods of defect analysis, photoeffects at grain boundaries, amorphous semiconductors, photovoltaic effects and photoeffects in quantum wells and superlattices. The author is Professor of Materials Science and Electrical Engineering at Stanford University, and has taught this material for many years. He is an experienced author, his earlier books having fo...

  6. Implosion of the small cavity and large cavity cannonball targets

    International Nuclear Information System (INIS)

    Nishihara, Katsunobu; Yamanaka, Chiyoe.

    1984-01-01

    Recent results of cannonball target implosion research are briefly reviewed with theoretical predictions for GEKKO XII experiments. The cannonball targets are classified into two types according to the cavity size ; small cavity and large cavity. The compression mechanisms of the two types are discussed. (author)

  7. Advances in semiconductor lasers

    CERN Document Server

    Coleman, James J; Jagadish, Chennupati

    2012-01-01

    Semiconductors and Semimetals has distinguished itself through the careful selection of well-known authors, editors, and contributors. Originally widely known as the ""Willardson and Beer"" Series, it has succeeded in publishing numerous landmark volumes and chapters. The series publishes timely, highly relevant volumes intended for long-term impact and reflecting the truly interdisciplinary nature of the field. The volumes in Semiconductors and Semimetals have been and will continue to be of great interest to physicists, chemists, materials scientists, and device engineers in academia, scien

  8. Superconductivity in doped semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bustarret, E., E-mail: Etienne.bustarret@neel.cnrs.fr

    2015-07-15

    A historical survey of the main normal and superconducting state properties of several semiconductors doped into superconductivity is proposed. This class of materials includes selenides, tellurides, oxides and column-IV semiconductors. Most of the experimental data point to a weak coupling pairing mechanism, probably phonon-mediated in the case of diamond, but probably not in the case of strontium titanate, these being the most intensively studied materials over the last decade. Despite promising theoretical predictions based on a conventional mechanism, the occurrence of critical temperatures significantly higher than 10 K has not been yet verified. However, the class provides an enticing playground for testing theories and devices alike.

  9. Semiconductor opto-electronics

    CERN Document Server

    Moss, TS; Ellis, B

    1972-01-01

    Semiconductor Opto-Electronics focuses on opto-electronics, covering the basic physical phenomena and device behavior that arise from the interaction between electromagnetic radiation and electrons in a solid. The first nine chapters of this book are devoted to theoretical topics, discussing the interaction of electromagnetic waves with solids, dispersion theory and absorption processes, magneto-optical effects, and non-linear phenomena. Theories of photo-effects and photo-detectors are treated in detail, including the theories of radiation generation and the behavior of semiconductor lasers a

  10. Ternary chalcopyrite semiconductors

    CERN Document Server

    Shay, J L; Pamplin, B R

    2013-01-01

    Ternary Chalcopyrite Semiconductors: Growth, Electronic Properties, and Applications covers the developments of work in the I-III-VI2 and II-IV-V2 ternary chalcopyrite compounds. This book is composed of eight chapters that focus on the crystal growth, characterization, and applications of these compounds to optical communications systems. After briefly dealing with the status of ternary chalcopyrite compounds, this book goes on describing the crystal growth of II-IV-V2 and I-III-VI2 single crystals. Chapters 3 and 4 examine the energy band structure of these semiconductor compounds, illustrat

  11. Compound semiconductor device physics

    CERN Document Server

    Tiwari, Sandip

    2013-01-01

    This book provides one of the most rigorous treatments of compound semiconductor device physics yet published. A complete understanding of modern devices requires a working knowledge of low-dimensional physics, the use of statistical methods, and the use of one-, two-, and three-dimensional analytical and numerical analysis techniques. With its systematic and detailed**discussion of these topics, this book is ideal for both the researcher and the student. Although the emphasis of this text is on compound semiconductor devices, many of the principles discussed will also be useful to those inter

  12. Introductory semiconductor device physics

    CERN Document Server

    Parker, Greg

    2004-01-01

    ATOMS AND BONDINGThe Periodic TableIonic BondingCovalent BondingMetallic bondingvan der Waals BondingStart a DatabaseENERGY BANDS AND EFFECTIVE MASSSemiconductors, Insulators and MetalsSemiconductorsInsulatorsMetalsThe Concept of Effective MassCARRIER CONCENTRATIONS IN SEMICONDUCTORSDonors and AcceptorsFermi-LevelCarrier Concentration EquationsDonors and Acceptors Both PresentCONDUCTION IN SEMICONDUCTORSCarrier DriftCarrier MobilitySaturated Drift VelocityMobility Variation with TemperatureA Derivation of Ohm's LawDrift Current EquationsSemiconductor Band Diagrams with an Electric Field Presen

  13. Resin bleed improvement on surface mount semiconductor device

    Science.gov (United States)

    Rajoo, Indra Kumar; Tahir, Suraya Mohd; Aziz, Faieza Abdul; Shamsul Anuar, Mohd

    2018-04-01

    Resin bleed is a transparent layer of epoxy compound which occurs during molding process but is difficult to be detected after the molding process. Resin bleed on the lead on the unit from the focused package, SOD123, can cause solderability failure at end customer. This failed unit from the customer will be considered as a customer complaint. Generally, the semiconductor company has to perform visual inspection after the plating process to detect resin bleed. Mold chase with excess hole, split cavity & stepped design ejector pin hole have been found to be the major root cause of resin bleed in this company. The modifications of the mold chase, changing of split cavity to solid cavity and re-design of the ejector pin proposed were derived after a detailed study & analysis conducted to arrive at these solutions. The solutions proposed have yield good results during the pilot run with zero (0) occurrence of resin bleed for 3 consecutive months.

  14. Tunable radiation emitting semiconductor device

    NARCIS (Netherlands)

    2009-01-01

    A tunable radiation emitting semiconductor device includes at least one elongated structure at least partially fabricated from one or more semiconductor materials exhibiting a bandgap characteristic including one or more energy transitions whose energies correspond to photon energies of light

  15. Loggerhead sea turtle oral cavity morphometrics and size class from 2001 to 2004 (NCEI Accession 0164321)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains standard external morphometrics and internal oral cavity morphometrics from wild and captive reared loggerhead sea turtles in size classes...

  16. Physical principles of semiconductor detectors

    International Nuclear Information System (INIS)

    Micek, S.L.

    1979-01-01

    The general properties of semiconductors with respect to the possibilities of their use as the ionization radiation detectors are discussed. Some chosen types of semiconductor junctions and their characteristics are briefly presented. There are also discussed the physical phenomena connected with the formation of barriers in various types of semiconductor counters. Finally, the basic properties of three main types of semiconductor detectors are given. (author)

  17. Metal semiconductor contacts and devices

    CERN Document Server

    Cohen, Simon S; Einspruch, Norman G

    1986-01-01

    VLSI Electronics Microstructure Science, Volume 13: Metal-Semiconductor Contacts and Devices presents the physics, technology, and applications of metal-semiconductor barriers in digital integrated circuits. The emphasis is placed on the interplay among the theory, processing, and characterization techniques in the development of practical metal-semiconductor contacts and devices.This volume contains chapters that are devoted to the discussion of the physics of metal-semiconductor interfaces and its basic phenomena; fabrication procedures; and interface characterization techniques, particularl

  18. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah

    2011-01-01

    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  19. Operational characteristics of dual gain single cavity Nd:YVO 4 laser

    Indian Academy of Sciences (India)

    Operational characteristics of a dual gain single cavity Nd:YVO4 laser have been investigated. With semiconductor diode laser pump power of 2 W, 800 mW output was obtained with a slope efficiency of 49%. Further, by changing the relative orientation of the two crystals the polarization characteristics of the output could be ...

  20. Hollow waveguide cavity ringdown spectroscopy

    Science.gov (United States)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  1. Optimization of photonic crystal cavities

    DEFF Research Database (Denmark)

    Wang, Fengwen; Sigmund, Ole

    2017-01-01

    We present optimization of photonic crystal cavities. The optimization problem is formulated to maximize the Purcell factor of a photonic crystal cavity. Both topology optimization and air-hole-based shape optimization are utilized for the design process. Numerical results demonstrate...... that the Purcell factor of the photonic crystal cavity can be significantly improved through optimization....

  2. Nuclear reactor cavity streaming shield

    International Nuclear Information System (INIS)

    Klotz, R.J.; Stephen, D.W.

    1978-01-01

    The upper portion of a nuclear reactor vessel supported in a concrete reactor cavity has a structure mounted below the top of the vessel between the outer vessel wall and the reactor cavity wall which contains hydrogenous material which will attenuate radiation streaming upward between vessel and the reactor cavity wall while preventing pressure buildup during a loss of coolant accident

  3. Intra-cavity metamorphosis of a Gaussian beam to flat-top distribution

    CSIR Research Space (South Africa)

    Naidoo, Darryl

    2014-02-01

    Full Text Available We explore an intra-cavity beam shaping approach to generate a Gaussian distribution by the metamorphosis of a Gaussian beam into a flat-top distribution on opposing mirrors. The concept is tested external to the cavity through the use of two...

  4. Negative differential resistance in Josephson junctions coupled to a cavity

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Filatrella, G.; Pierro, V.

    2014-01-01

    or external – is often used. A cavity may also induce a negative differential resistance region at the lower side of the resonance frequency. We investigate the dynamics of Josephson junctions with a negative differential resistance in the quasi particle tunnel current, i.e. in the McCumber curve. We find...

  5. Depletion field focusing in semiconductors

    NARCIS (Netherlands)

    Prins, M.W.J.; Gelder, Van A.P.

    1996-01-01

    We calculate the three-dimensional depletion field profile in a semiconductor, for a planar semiconductor material with a spatially varying potential upon the surface, and for a tip-shaped semiconductor with a constant surface potential. The nonuniform electric field gives rise to focusing or

  6. Nonlinear Elasticity of Doped Semiconductors

    Science.gov (United States)

    2017-02-01

    AFRL-RY-WP-TR-2016-0206 NONLINEAR ELASTICITY OF DOPED SEMICONDUCTORS Mark Dykman and Kirill Moskovtsev Michigan State University...2016 4. TITLE AND SUBTITLE NONLINEAR ELASTICITY OF DOPED SEMICONDUCTORS 5a. CONTRACT NUMBER FA8650-16-1-7600 5b. GRANT NUMBER 5c. PROGRAM...vibration amplitude. 15. SUBJECT TERMS semiconductors , microresonators, microelectromechanical 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

  7. Magnetic field mapping for HIE-ISOLDE cavities

    CERN Document Server

    Bianchi, Antonio

    2015-01-01

    In this report the importance of a magnetic field mapping (B-mapping) around the HIE-ISOLDE superconducting cavities is described. In fact the cavities are not always above the HIE-ISOLDE specification, so it is important to understand the reason of their bad performances and improve them. For doing the B-mapping, the supports for three fluxgate sensors are designed and manufactured. The material of the supports is PEEK: a proper thermoplastic for the extreme operation conditions of the cavities. According to simulation of behavior of external magnetic field, an initial configuration of the sensors is proposed for the first measurements, in order to get the extent of Meissner effect around the superconducting cavities.

  8. Semi-conductor rectifiers

    International Nuclear Information System (INIS)

    1981-01-01

    A method is described for treating a semiconductor rectifier, comprising: heating the rectifier to a temperature in the range of 100 0 C to 500 0 C, irradiating the rectifier while maintaining its temperature within the said range, and then annealing the rectifier at a temperature of between 280 0 C and 350 0 C for between two and ten hours. (author)

  9. Semiconductor detector physics

    International Nuclear Information System (INIS)

    Equer, B.

    1987-01-01

    Comprehension of semiconductor detectors follows comprehension of some elements of solid state physics. They are recalled here, limited to the necessary physical principles, that is to say the conductivity. P-n and MIS junctions are discussed in view of their use in detection. Material and structure (MOS, p-n, multilayer, ..) are also reviewed [fr

  10. Colloquium: cavity optomechanics

    CERN Multimedia

    2011-01-01

    Monday 14 November 2011, 17:00 Ecole de Physique, Auditoire Stueckelberg Université de Genève Cavity optomechanics: controlling micro mechanical oscillators with laser light Prof. Tobias Kippenberg EPFL, Lausanne Laser light can be used to cool and to control trapped ions, atoms and molecules at the quantum level. This has lead to spectacular advances such as the most precise atomic clocks. An outstanding frontier is the control with lasers of nano- and micro-mechancial systems. Recent advances in cavity optomechanics have allowed such elementary control for the first time, enabling mechanical systems to be ground state cooled leading to readout with quantum limited sensitivity and permitting to explore new device concepts resulting from radiation pressure.  

  11. Cavity-photon-switched coherent transient transport in a double quantum waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, Nzar Rauf, E-mail: nra1@hi.is; Gudmundsson, Vidar, E-mail: vidar@raunvis.hi.is [Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik (Iceland); Tang, Chi-Shung [Department of Mechanical Engineering, National United University, 1, Lienda, 36003 Miaoli, Taiwan (China); Manolescu, Andrei [School of Science and Engineering, Reykjavik University, Menntavegur 1, IS-101 Reykjavik (Iceland)

    2014-12-21

    We study a cavity-photon-switched coherent electron transport in a symmetric double quantum waveguide. The waveguide system is weakly connected to two electron reservoirs, but strongly coupled to a single quantized photon cavity mode. A coupling window is placed between the waveguides to allow electron interference or inter-waveguide transport. The transient electron transport in the system is investigated using a quantum master equation. We present a cavity-photon tunable semiconductor quantum waveguide implementation of an inverter quantum gate, in which the output of the waveguide system may be selected via the selection of an appropriate photon number or “photon frequency” of the cavity. In addition, the importance of the photon polarization in the cavity, that is, either parallel or perpendicular to the direction of electron propagation in the waveguide system is demonstrated.

  12. Glial heterotopia of the oral cavity

    Directory of Open Access Journals (Sweden)

    Radhames E. Lizardo

    2015-07-01

    Full Text Available We report an unusual case of a glial heterotopia arising from the oral cavity of an African neonate. The patient presented with an external pedunculated oral mass which was connected to the anterior hard palate by a firm, rubbery stalk of mucosal tissue. While the mass appeared painless, it interfered with the infant's feeding and was disturbing to the parents. After a computed tomography scan excluded an intracranial connection, the mass was excised at its base and sent for biopsy. Histopathology examination confirmed glial heterotopia. Glial heterotopias should be included in the differential diagnosis of congenital masses in the oral region.

  13. Leaching materials from cavities

    International Nuclear Information System (INIS)

    Hodgson, T.D.; Jordan, T.W.J.

    1980-01-01

    A material is leached from a cavity by contacting the material with a liquid and subjecting the liquid to a number of pressure cycles, each pressure cycle involving a decrease in pressure to cause boiling of the liquid, followed by a rise in pressure to inhibit the boiling. The method may include the step of heating the liquid to a temperature near to its boiling point. The material may be nuclear fuel pellets or calcium carbonate pellets. (author)

  14. Superconducting cavities for HERA

    International Nuclear Information System (INIS)

    Dwersteg, B.; Ebeling, W.; Moeller, W.D.; Renken, D.; Proch, D.; Sekutowicz, J.; Susta, J.; Tong, D.

    1988-01-01

    Superconducting 500 MHz cavities are developed to demonstrate the feasibility of upgrading the e-beam energy of the HERA storage ring. A prototype module with 2 x 4 cell resonators and appropriate fundamental and higher mode couplers has been designed at DESY and is being built by industrial firms. The design and results of RF and cryogenic measurements are reported in detail. 17 references, 10 figures, 2 tables

  15. Thermal modeling of a pressurized air cavity receiver for solar dish Stirling system

    Science.gov (United States)

    Zou, Chongzhe; Zhang, Yanping; Falcoz, Quentin; Neveu, Pierre; Li, Jianlan; Zhang, Cheng

    2017-06-01

    A solar cavity receiver model for the dish collector system is designed in response to growing demand of renewable energy. In the present research field, no investigations into the geometric parameters of a cavity receiver have been performed. The cylindrical receiver in this study is composed of an enclosed bottom at the back, an aperture at the front, a helical pipe inside the cavity and an insulation layer on the external surface of the cavity. The influence of several critical receiver parameters on the thermal efficiency is analyzed in this paper: cavity inner diameter and cavity length. The thermal model in this paper is solved considering the cavity dimensions as variables. Implementing the model into EES, each parameter influence is separately investigated, and a preliminary optimization method is proposed.

  16. Crab cavities for linear colliders

    CERN Document Server

    Burt, G; Carter, R; Dexter, A; Tahir, I; Beard, C; Dykes, M; Goudket, P; Kalinin, A; Ma, L; McIntosh, P; Shulte, D; Jones, Roger M; Bellantoni, L; Chase, B; Church, M; Khabouline, T; Latina, A; Adolphsen, C; Li, Z; Seryi, Andrei; Xiao, L

    2008-01-01

    Crab cavities have been proposed for a wide number of accelerators and interest in crab cavities has recently increased after the successful operation of a pair of crab cavities in KEK-B. In particular crab cavities are required for both the ILC and CLIC linear colliders for bunch alignment. Consideration of bunch structure and size constraints favour a 3.9 GHz superconducting, multi-cell cavity as the solution for ILC, whilst bunch structure and beam-loading considerations suggest an X-band copper travelling wave structure for CLIC. These two cavity solutions are very different in design but share complex design issues. Phase stabilisation, beam loading, wakefields and mode damping are fundamental issues for these crab cavities. Requirements and potential design solutions will be discussed for both colliders.

  17. Dephasing of optically generated electron spins in semiconductors

    International Nuclear Information System (INIS)

    Idrish Miah, M.

    2010-01-01

    Dephasing of optically generated electron spins in the presence of the external magnetic field and electric bias in semiconductor nano-structures has been studied by time- and polarization-resolved spectrometry. The obtained experimental data are presented in dependence of the strength of the magnetic field. The optically generated electron-spin precession frequency and dephasing time and rate are estimated. It is found that both the spin precession frequency and dephasing rate increase linearly with the external magnetic field up to about 9 T. However, the spin dephasing time is within sub-μs and is found to decrease exponentially with the strength of the external magnetic field. The results are discussed by exploring possible mechanisms of spin dephasing in low-dimensional semiconductor structures, where the quantum-confinement persists within the nano-range.

  18. Dephasing of optically generated electron spins in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M., E-mail: m.miah@griffith.edu.a [Department of Physics, University of Chittagong, Chittagong, Chittagong - 4331 (Bangladesh)

    2010-09-13

    Dephasing of optically generated electron spins in the presence of the external magnetic field and electric bias in semiconductor nano-structures has been studied by time- and polarization-resolved spectrometry. The obtained experimental data are presented in dependence of the strength of the magnetic field. The optically generated electron-spin precession frequency and dephasing time and rate are estimated. It is found that both the spin precession frequency and dephasing rate increase linearly with the external magnetic field up to about 9 T. However, the spin dephasing time is within sub-{mu}s and is found to decrease exponentially with the strength of the external magnetic field. The results are discussed by exploring possible mechanisms of spin dephasing in low-dimensional semiconductor structures, where the quantum-confinement persists within the nano-range.

  19. Gain-assisted broadband ring cavity enhanced spectroscopy

    Science.gov (United States)

    Selim, Mahmoud A.; Adib, George A.; Sabry, Yasser M.; Khalil, Diaa

    2017-02-01

    Incoherent broadband cavity enhanced spectroscopy can significantly increase the effective path length of light-matter interaction to detect weak absorption lines over broad spectral range, for instance to detect gases in confined environments. Broadband cavity enhancement can be based on the decay time or the intensity drop technique. Decay time measurement is based on using tunable laser source that is expensive and suffers from long scan time. Intensity dependent measurement is usually reported based on broadband source using Fabry-Perot cavity, enabling short measurement time but suffers from the alignment tolerance of the cavity and the cavity insertion loss. In this work we overcome these challenges by using an alignment-free ring cavity made of an optical fiber loop and a directional coupler, while having a gain medium pumped below the lasing threshold to improve the finesse and reduce the insertion loss. Acetylene (C2H2) gas absorption is measured around 1535 nm wavelength using a semiconductor optical amplifier (SOA) gain medium. The system is analyzed for different ring resonator forward coupling coefficient and loses, including the 3-cm long gas cell insertion loss and fiber connector losses used in the experimental verification. The experimental results are obtained for a coupler ratio of 90/10 and a fiber length of 4 m. The broadband source is the amplified spontaneous emission of another SOA and the output is measured using a 70pm-resolution optical spectrum analyzer. The absorption depth and the effective interaction length are improved about an order of magnitude compared to the direct absorption of the gas cell. The presented technique provides an engineering method to improve the finesse and, consequently the effective length, while relaxing the technological constraints on the high reflectivity mirrors and free-space cavity alignment.

  20. Semirelativity in semiconductors: a review.

    Science.gov (United States)

    Zawadzki, Wlodek

    2017-09-20

    An analogy between behavior of electrons in narrow-gap semiconductors (NGS) and relativistic electrons in vacuum is reviewed. Energy band structures [Formula: see text] are considered for various NGS materials and their correspondence to the energy-momentum relation in special relativity is emphasized. It is indicated that special relativity for vacuum is analogous to a two-band [Formula: see text] description for NGS. The maximum electron velocity in NGS is [Formula: see text], which corresponds to the light velocity in vacuum. An effective mass of charge carriers in semiconductors is introduced, relating their velocity to quasimomentum and it is shown that this mass depends on electron energy (or velocity) in a way similar to the mass of free relativistic electrons. In [Formula: see text] alloys one can reach vanishing energy gap at which electrons and light holes become three-dimensional massless Dirac fermions. A wavelength [Formula: see text] is defined for NGS, in analogy to the Compton wavelength in relativistic quantum mechanics. It is estimated that [Formula: see text] is on the order of tens of Angstroms in typical semiconducting materials which is experimentally confirmed in tunneling experiments on energy dispersion in the forbidden gap. Statistical properties of the electron gas in NGS are calculated and their similarity is demonstrated to those of the Juttner gas of relativistic particles. Interband electron tunneling in NGS is described and shown to be in close analogy to the predicted but unobserved tunneling between negative and positive energies resulting from the Dirac equation for free electrons. It is demonstrated that the relativistic analogy holds for orbital and spin properties of electrons in the presence of an external magnetic field. In particular, it is shown that the spin magnetic moment of both NGS electrons and relativistic electrons approaches zero with increasing energy. This conclusion is confirmed experimentally for NGS. Electrons

  1. Semirelativity in semiconductors: a review

    Science.gov (United States)

    Zawadzki, Wlodek

    2017-09-01

    An analogy between behavior of electrons in narrow-gap semiconductors (NGS) and relativistic electrons in vacuum is reviewed. Energy band structures \\varepsilon ≤ft(\\mathbf{k}\\right) are considered for various NGS materials and their correspondence to the energy-momentum relation in special relativity is emphasized. It is indicated that special relativity for vacuum is analogous to a two-band \\mathbf{k}\\centerdot \\mathbf{p} description for NGS. The maximum electron velocity in NGS is u≃ 1× {{10}8}~\\text{cm}~{{\\text{s}}-1} , which corresponds to the light velocity in vacuum. An effective mass of charge carriers in semiconductors is introduced, relating their velocity to quasimomentum and it is shown that this mass depends on electron energy (or velocity) in a way similar to the mass of free relativistic electrons. In \\text{H}{{\\text{g}}1-x}\\text{C}{{\\text{d}}x}\\text{Te} alloys one can reach vanishing energy gap at which electrons and light holes become three-dimensional massless Dirac fermions. A wavelength {λz} is defined for NGS, in analogy to the Compton wavelength in relativistic quantum mechanics. It is estimated that {λz} is on the order of tens of Angstroms in typical semiconducting materials which is experimentally confirmed in tunneling experiments on energy dispersion in the forbidden gap. Statistical properties of the electron gas in NGS are calculated and their similarity is demonstrated to those of the Juttner gas of relativistic particles. Interband electron tunneling in NGS is described and shown to be in close analogy to the predicted but unobserved tunneling between negative and positive energies resulting from the Dirac equation for free electrons. It is demonstrated that the relativistic analogy holds for orbital and spin properties of electrons in the presence of an external magnetic field. In particular, it is shown that the spin magnetic moment of both NGS electrons and relativistic electrons approaches zero with increasing

  2. Optical feedback in dfb quantum cascade laser for mid-infrared cavity ring-down spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Terabayashi, Ryohei, E-mail: terabayashi.ryouhei@h.mbox.nagoya-u.ac.jp; Sonnenschein, Volker, E-mail: volker@nagoya-u.jp; Tomita, Hideki, E-mail: tomita@nagoya-u.jp; Hayashi, Noriyoshi, E-mail: hayashi.noriyoshi@h.mbox.nagoya-u.ac.jp; Kato, Shusuke, E-mail: katou.shuusuke@f.mbox.nagoya-u.ac.jp; Jin, Lei, E-mail: kin@nuee.nagoya-u.ac.jp; Yamanaka, Masahito, E-mail: yamanaka@nuee.nagoya-u.ac.jp; Nishizawa, Norihiko, E-mail: nishizawa@nuee.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan); Sato, Atsushi, E-mail: atsushi.sato@sekisui.com; Nozawa, Kohei, E-mail: kohei.nozawa@sekisui.com; Hashizume, Kenta, E-mail: kenta.hashizume@sekisui.com; Oh-hara, Toshinari, E-mail: toshinari.ohara@sekisui.com [Sekisui Medical Co., Ltd., Drug Development Solutions Center (Japan); Iguchi, Tetsuo, E-mail: t-iguchi@nucl.nagoya-u.ac.jp [Nagoya University, Department of Quantum Engineering, Graduate School of Engineering (Japan)

    2017-11-15

    A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

  3. Optical re-injection in cavity-enhanced absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Leen, J. Brian, E-mail: b.leen@lgrinc.com; O’Keefe, Anthony [Los Gatos Research, 67 E. Evelyn Avenue, Suite 3, Mountain View, California 94041 (United States)

    2014-09-15

    Non-mode-matched cavity-enhanced absorption spectrometry (e.g., cavity ringdown spectroscopy and integrated cavity output spectroscopy) is commonly used for the ultrasensitive detection of trace gases. These techniques are attractive for their simplicity and robustness, but their performance may be limited by the reflection of light from the front mirror and the resulting low optical transmission. Although this low transmitted power can sometimes be overcome with higher power lasers and lower noise detectors (e.g., in the near-infrared), many regimes exist where the available light intensity or photodetector sensitivity limits instrument performance (e.g., in the mid-infrared). In this article, we describe a method of repeatedly re-injecting light reflected off the front mirror of the optical cavity to boost the cavity's circulating power and deliver more light to the photodetector and thus increase the signal-to-noise ratio of the absorption measurement. We model and experimentally demonstrate the method's performance using off-axis cavity ringdown spectroscopy (OA-CRDS) with a broadly tunable external cavity quantum cascade laser. The power coupled through the cavity to the detector is increased by a factor of 22.5. The cavity loss is measured with a precision of 2 × 10{sup −10} cm{sup −1}/√(Hz;) an increase of 12 times over the standard off-axis configuration without reinjection and comparable to the best reported sensitivities in the mid-infrared. Finally, the re-injected CRDS system is used to measure the spectrum of several volatile organic compounds, demonstrating the improved ability to resolve weakly absorbing spectroscopic features.

  4. Basic semiconductor physics

    CERN Document Server

    Hamaguchi, Chihiro

    2017-01-01

    This book presents a detailed description of basic semiconductor physics. The text covers a wide range of important phenomena in semiconductors, from the simple to the advanced. Four different methods of energy band calculations in the full band region are explained: local empirical pseudopotential, non-local pseudopotential, KP perturbation and tight-binding methods. The effective mass approximation and electron motion in a periodic potential, Boltzmann transport equation and deformation potentials used for analysis of transport properties are discussed. Further, the book examines experiments and theoretical analyses of cyclotron resonance in detail. Optical and transport properties, magneto-transport, two-dimensional electron gas transport (HEMT and MOSFET) and quantum transport are reviewed, while optical transition, electron-phonon interaction and electron mobility are also addressed. Energy and electronic structure of a quantum dot (artificial atom) are explained with the help of Slater determinants. The...

  5. Semiconductor physics an introduction

    CERN Document Server

    Seeger, Karlheinz

    1999-01-01

    Semiconductor Physics - An Introduction - is suitable for the senior undergraduate or new graduate student majoring in electrical engineering or physics. It will also be useful to solid-state scientists and device engineers involved in semiconductor design and technology. The text provides a lucid account of charge transport, energy transport and optical processes, and a detailed description of many devices. It includes sections on superlattices and quantum well structures, the effects of deep-level impurities on transport, the quantum Hall effect and the calculation of the influence of a magnetic field on the carrier distribution function. This 6th edition has been revised and corrected, and new sections have been added to different chapters.

  6. Three dimensional strained semiconductors

    Science.gov (United States)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  7. Compound semiconductor device modelling

    CERN Document Server

    Miles, Robert

    1993-01-01

    Compound semiconductor devices form the foundation of solid-state microwave and optoelectronic technologies used in many modern communication systems. In common with their low frequency counterparts, these devices are often represented using equivalent circuit models, but it is often necessary to resort to physical models in order to gain insight into the detailed operation of compound semiconductor devices. Many of the earliest physical models were indeed developed to understand the 'unusual' phenomena which occur at high frequencies. Such was the case with the Gunn and IMPATI diodes, which led to an increased interest in using numerical simulation methods. Contemporary devices often have feature sizes so small that they no longer operate within the familiar traditional framework, and hot electron or even quantum­ mechanical models are required. The need for accurate and efficient models suitable for computer aided design has increased with the demand for a wider range of integrated devices for operation at...

  8. Optically coupled semiconductor device

    Energy Technology Data Exchange (ETDEWEB)

    Kumagaya, Naoki

    1988-11-18

    This invention concerns an optically coupled semiconductor device using the light as input signal and a MOS transistor for the output side in order to control on-off of the output side by the input signal which is insulated from the output. Concerning this sort of element, when a MOS transistor and a load resistance are planned to be accumulated on the same chip, a resistor and control of impurity concentration of the channel, etc. become necessary despite that the only formation of a simple P-N junction is enough, for a solar cell, hence cost reduction thereof cannot be done. In order to remove this defect, this invention offers an optically coupled semiconductor device featuring that two solar cells are connected in reverse parallel between the gate sources of the output MOS transistors and an operational light emitting element is individually set facing a respective solar cell. 4 figs.

  9. Non-linear spin transport in magnetic semiconductor superlattices

    International Nuclear Information System (INIS)

    Bejar, Manuel; Sanchez, David; Platero, Gloria; MacDonald, A.H.

    2004-01-01

    The electronic spin dynamics in DC-biased n-doped II-VI semiconductor multiquantum wells doped with magnetic impurities is presented. Under certain range of electronic doping, conventional semiconductor superlattices present self-sustained oscillations. Magnetically doped wells (Mn) present large spin splittings due to the exchange interaction. The interplay between non-linear interwell transport, the electron-electron interaction and the exchange between electrons and the magnetic impurities produces interesting time-dependent features in the spin polarization current tuned by an external magnetic field

  10. ISR RF cavities

    CERN Multimedia

    1983-01-01

    In each ISR ring the radiofrequency cavities were installed in one 9 m long straight section. The RF system of the ISR had the main purpose to stack buckets of particles (most of the time protons)coming from the CPS and also to accelerate the stacked beam. The installed RF power per ring was 18 kW giving a peak accelerating voltage of 20 kV. The system had a very fine regulation feature allowing to lower the voltage down to 75 V in a smooth and well controlled fashion.

  11. Doping of organic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Luessem, B.; Riede, M.; Leo, K. [Institut fuer Angewandte Photophysik, TU Dresden (Germany)

    2013-01-15

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Images through semiconductors

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Improved image processing techniques are constantly being developed for television and for scanners using X-rays or other radiation for industrial or medical applications, etc. As Erik Heijne of CERN explains here, particle physics too has its own special requirements for image processing. The increasing use of semiconductor techniques for handling measurements down to the level of a few microns provides another example of the close interplay between scientific research and technological development. (orig.).

  13. Muonium states in semiconductors

    International Nuclear Information System (INIS)

    Patterson, B.D.

    1987-01-01

    There is a brief summary of what is known about the muonium states isotropic, anisotropic and diamagnetic in diamond and zincblende semiconductors. The report deals with muonium spectroscopy, including the formation probabilities, hyperfine parameters and electronic g-factors of the states. The dynamics of the states is treated including a discussion of the transition from isotropic Mu to anisotropic Mu in diamond, temperature-dependent linewidthes in silicon and germanium and effects of daping and radiation damage

  14. Nonradiative recombination in semiconductors

    CERN Document Server

    Abakumov, VN; Yassievich, IN

    1991-01-01

    In recent years, great progress has been made in the understandingof recombination processes controlling the number of excessfree carriers in semiconductors under nonequilibrium conditions. As a result, it is now possible to give a comprehensivetheoretical description of these processes. The authors haveselected a number of experimental results which elucidate theunderlying physical problems and enable a test of theoreticalmodels. The following topics are dealt with: phenomenological theory ofrecombination, theoretical models of shallow and deep localizedstates, cascade model of carrier captu

  15. Doping of organic semiconductors

    International Nuclear Information System (INIS)

    Luessem, B.; Riede, M.; Leo, K.

    2013-01-01

    The understanding and applications of organic semiconductors have shown remarkable progress in recent years. This material class has been developed from being a lab curiosity to the basis of first successful products as small organic LED (OLED) displays; other areas of application such as OLED lighting and organic photovoltaics are on the verge of broad commercialization. Organic semiconductors are superior to inorganic ones for low-cost and large-area optoelectronics due to their flexibility, easy deposition, and broad variety, making tailor-made materials possible. However, electrical doping of organic semiconductors, i.e. the controlled adjustment of Fermi level that has been extremely important to the success of inorganic semiconductors, is still in its infancy. This review will discuss recent work on both fundamental principles and applications of doping, focused primarily to doping of evaporated organic layers with molecular dopants. Recently, both p- and n-type molecular dopants have been developed that lead to efficient and stable doping of organic thin films. Due to doping, the conductivity of the doped layers increases several orders of magnitude and allows for quasi-Ohmic contacts between organic layers and metal electrodes. Besides reducing voltage losses, doping thus also gives design freedom in terms of transport layer thickness and electrode choice. The use of doping in applications like OLEDs and organic solar cells is highlighted in this review. Overall, controlled molecular doping can be considered as key enabling technology for many different organic device types that can lead to significant improvements in efficiencies and lifetimes. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  16. Isotopically controlled semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Haller, Eugene E.

    2006-06-19

    The following article is an edited transcript based on the Turnbull Lecture given by Eugene E. Haller at the 2005 Materials Research Society Fall Meeting in Boston on November 29, 2005. The David Turnbull Lectureship is awarded to recognize the career of a scientist who has made outstanding contributions to understanding materials phenomena and properties through research, writing, and lecturing, as exemplified by the life work of David Turnbull. Haller was named the 2005 David Turnbull Lecturer for his 'pioneering achievements and leadership in establishing the field of isotopically engineered semiconductors; for outstanding contributions to materials growth, doping and diffusion; and for excellence in lecturing, writing, and fostering international collaborations'. The scientific interest, increased availability, and technological promise of highly enriched isotopes have led to a sharp rise in the number of experimental and theoretical studies with isotopically controlled semiconductor crystals. This article reviews results obtained with isotopically controlled semiconductor bulk and thin-film heterostructures. Isotopic composition affects several properties such as phonon energies, band structure, and lattice constant in subtle, but, for their physical understanding, significant ways. Large isotope-related effects are observed for thermal conductivity in local vibrational modes of impurities and after neutron transmutation doping. Spectacularly sharp photoluminescence lines have been observed in ultrapure, isotopically enriched silicon crystals. Isotope multilayer structures are especially well suited for simultaneous self- and dopant-diffusion studies. The absence of any chemical, mechanical, or electrical driving forces makes possible the study of an ideal random-walk problem. Isotopically controlled semiconductors may find applications in quantum computing, nanoscience, and spintronics.

  17. Survey of semiconductor physics

    CERN Document Server

    Böer, Karl W

    1992-01-01

    Any book that covers a large variety of subjects and is written by one author lacks by necessity the depth provided by an expert in his or her own field of specialization. This book is no exception. It has been written with the encouragement of my students and colleagues, who felt that an extensive card file I had accumulated over the years of teaching solid state and semiconductor physics would be helpful to more than just a few of us. This file, updated from time to time, contained lecture notes and other entries that were useful in my research and permitted me to give to my students a broader spectrum of information than is available in typical textbooks. When assembling this material into a book, I divided the top­ ics into material dealing with the homogeneous semiconductor, the subject of the previously published Volume 1, and the inhomoge­ neous semiconductor, the subject of this Volume 2. In order to keep the book to a manageable size, sections of tutorial character which can be used as text for a g...

  18. Semiconductor Ion Implanters

    International Nuclear Information System (INIS)

    MacKinnon, Barry A.; Ruffell, John P.

    2011-01-01

    In 1953 the Raytheon CK722 transistor was priced at $7.60. Based upon this, an Intel Xeon Quad Core processor containing 820,000,000 transistors should list at $6.2 billion! Particle accelerator technology plays an important part in the remarkable story of why that Intel product can be purchased today for a few hundred dollars. Most people of the mid twentieth century would be astonished at the ubiquity of semiconductors in the products we now buy and use every day. Though relatively expensive in the nineteen fifties they now exist in a wide range of items from high-end multicore microprocessors like the Intel product to disposable items containing 'only' hundreds or thousands like RFID chips and talking greeting cards. This historical development has been fueled by continuous advancement of the several individual technologies involved in the production of semiconductor devices including Ion Implantation and the charged particle beamlines at the heart of implant machines. In the course of its 40 year development, the worldwide implanter industry has reached annual sales levels around $2B, installed thousands of dedicated machines and directly employs thousands of workers. It represents in all these measures, as much and possibly more than any other industrial application of particle accelerator technology. This presentation discusses the history of implanter development. It touches on some of the people involved and on some of the developmental changes and challenges imposed as the requirements of the semiconductor industry evolved.

  19. The Physics of Semiconductors

    Science.gov (United States)

    Brennan, Kevin F.

    1999-02-01

    Modern fabrication techniques have made it possible to produce semiconductor devices whose dimensions are so small that quantum mechanical effects dominate their behavior. This book describes the key elements of quantum mechanics, statistical mechanics, and solid-state physics that are necessary in understanding these modern semiconductor devices. The author begins with a review of elementary quantum mechanics, and then describes more advanced topics, such as multiple quantum wells. He then disusses equilibrium and nonequilibrium statistical mechanics. Following this introduction, he provides a thorough treatment of solid-state physics, covering electron motion in periodic potentials, electron-phonon interaction, and recombination processes. The final four chapters deal exclusively with real devices, such as semiconductor lasers, photodiodes, flat panel displays, and MOSFETs. The book contains many homework exercises and is suitable as a textbook for electrical engineering, materials science, or physics students taking courses in solid-state device physics. It will also be a valuable reference for practicing engineers in optoelectronics and related areas.

  20. Computer Aided Modeling of Human Mastoid Cavity Biomechanics Using Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Chou Yuan-Fang

    2010-01-01

    Full Text Available The aim of the present study was to analyze the human mastoid cavity on sound transmission using finite element method. Pressure distributions in the external ear canal and middle ear cavity at different frequencies were demonstrated. Our results showed that, first, blocking the aditus improves middle ear sound transmission in the 1500- to 2500-Hz range and decreases displacement in frequencies below 1000 Hz when compared with the normal ear. Second, at frequencies lower than 1000 Hz, the acoustic pressures were almost uniformly distributed in the external ear canal and middle ear cavity. At high frequencies, higher than 1000 Hz, the pressure distribution varied along the external ear canal and middle ear cavity. Third, opening the aditus, the pressures difference in dB between the middle ear cavity and external ear canal were larger than those of the closed mastoid cavity in low frequency (<1000 Hz. Finally, there was no significant difference in the acoustic pressure between the oval window and round window is noted and increased by 5 dB by blocking the aditus. These results suggest that our complete FE model including the mastoid cavity is potentially useful and can provide more information in the study of middle ear biomechanics.

  1. Time-resolved photoluminescence spectroscopy of semiconductors for optical applications beyond the visible spectral range

    Energy Technology Data Exchange (ETDEWEB)

    Chernikov, Alexey A.

    2011-07-01

    the impact of Coulomb-correlations on the carrier-phonon scattering. The experiments presented in chapter 5 deal with the characterization of recently synthesizedmaterial systems: ZnO/(ZnMg)O heterostructures, GaN quantum wires (QWires), as well as (GaAs)Bi quantum wells (QWs). TRPL spectroscopy is applied to gain insight as well as a better understanding of the respective carrier relaxation and recombination processes crucial for the device operation. The aim of the studies is the systematic investigation of carrier dynamics influenced by disorder. The measurements are supported by kinetic Monte- Carlo simulations, providing a quantitative analysis of carrier localization effects. In chapter 6, optimization and characterization studies of semiconductor lasers, based on the well-studied (GaIn)As material system designed for NIR applications, are performed. The device under investigation is the so-called vertical-external-cavity surface emitting laser (VECSEL). The experiments focus on the study of the thermal properties of a high-power VECSEL. The distribution and removal of the excess heat as well as the optimization of the laser for increased performance are addressed applying different heat-spreading and heat-transfer approaches. Based on these investigations, the possibility for power-scaling is evaluated and the underlying restrictions are analyzed. The latter investigations are performed applying spatially-resolved PL spectroscopy. An experimental setup is designed for monitoring the spatial distribution of heat in the semiconductor structure during laser operation.

  2. Oral cavity eumycetoma

    Directory of Open Access Journals (Sweden)

    Gisele Alborghetti Nai

    2011-06-01

    Full Text Available Mycetoma is a pathological process in which eumycotic (fungal or actinomycotic causative agents from exogenous source produce grains. It is a localized chronic and deforming infectious disease of subcutaneous tissue, skin and bones. We report the first case of eumycetoma of the oral cavity in world literature. CASE REPORT: A 43-year-old male patient, complaining of swelling and fistula in the hard palate. On examination, swelling of the anterior and middle hard palate, with fistula draining a dark liquid was observed. The panoramic radiograph showed extensive radiolucent area involving the region of teeth 21-26 and the computerized tomography showed communication with the nasal cavity, suggesting the diagnosis of periapical cyst. Surgery was performed to remove the lesion. Histopathological examination revealed purulent material with characteristic grain. Gram staining for bacteria was negative and Grocott-Gomori staining for the detection of fungi was positive, concluding the diagnosis of eumycetoma. The patient was treated with ketoconazole for nine months, and was considered cured at the end of treatment. CONCLUSION: Histopathological examination, using histochemical staining, and direct microscopic grains examination can provide the distinction between eumycetoma and actinomycetoma accurately.

  3. Resonant cavity light-emitting diodes based on dielectric passive cavity structures

    Science.gov (United States)

    Ledentsov, N.; Shchukin, V. A.; Kropp, J.-R.; Zschiedrich, L.; Schmidt, F.; Ledentsov, N. N.

    2017-02-01

    A novel design for high brightness planar technology light-emitting diodes (LEDs) and LED on-wafer arrays on absorbing substrates is proposed. The design integrates features of passive dielectric cavity deposited on top of an oxide- semiconductor distributed Bragg reflector (DBR), the p-n junction with a light emitting region is introduced into the top semiconductor λ/4 DBR period. A multilayer dielectric structure containing a cavity layer and dielectric DBRs is further processed by etching into a micrometer-scale pattern. An oxide-confined aperture is further amended for current and light confinement. We study the impact of the placement of the active region into the maximum or minimum of the optical field intensity and study an impact of the active region positioning on light extraction efficiency. We also study an etching profile composed of symmetric rings in the etched passive cavity over the light emitting area. The bottom semiconductor is an AlGaAs-AlAs multilayer DBR selectively oxidized with the conversion of the AlAs layers into AlOx to increase the stopband width preventing the light from entering the semiconductor substrate. The approach allows to achieve very high light extraction efficiency in a narrow vertical angle keeping the reasonable thermal and current conductivity properties. As an example, a micro-LED structure has been modeled with AlGaAs-AlAs or AlGaAs-AlOx DBRs and an active region based on InGaAlP quantum well(s) emitting in the orange spectral range at 610 nm. A passive dielectric SiO2 cavity is confined by dielectric Ta2O5/SiO2 and AlGaAs-AlOx DBRs. Cylindrically-symmetric structures with multiple ring patterns are modeled. It is demonstrated that the extraction coefficient of light to the air can be increased from 1.3% up to above 90% in a narrow vertical angle (full width at half maximum (FWHM) below 20°). For very small oxide-confined apertures 100nm the narrowing of the FWHM for light extraction can be reduced down to 5

  4. Cryostat for TRISTAN superconducting cavity

    International Nuclear Information System (INIS)

    Mitsunobu, S.; Furuya, T.; Hara, K.

    1990-01-01

    Superconducting cavities generate rather high heat load of hundreds watts in one cryostat and have high sensitivity for pressure. We adopted usual pool-boiling type cooling for its stable pressure operation. Two 5-cell Nb cavities were installed in one flange type cryostat. Tuning mechanics actuated by a pulse-motor and a Piezo-electric element are set at outside of vacuum end flange. The design and performance of the cryostat for TRISTAN superconducting cavities are described. (author)

  5. Superconducting Radio-Frequency Cavities

    Science.gov (United States)

    Padamsee, Hasan S.

    2014-10-01

    Superconducting cavities have been operating routinely in a variety of accelerators with a range of demanding applications. With the success of completed projects, niobium cavities have become an enabling technology, offering upgrade paths for existing facilities and pushing frontier accelerators for nuclear physics, high-energy physics, materials science, and the life sciences. With continued progress in basic understanding of radio-frequency superconductivity, the performance of cavities has steadily improved to approach theoretical capabilities.

  6. Electronic structure of defects in semiconductor heterojunctions

    International Nuclear Information System (INIS)

    Haussy, Bernard; Ganghoffer, Jean Francois

    2002-01-01

    Full text.heterojunctions and semiconductors and superlattices are well known and well used by people interested in optoelectronics communications. Components based on the use of heterojunctions are interesting for confinement of light and increase of quantum efficiency. An heterojunction is the contact zone between two different semiconductors, for example GaAs and Ga 1-x Al x As. Superlattices are a succession of heterojunctions (up to 10 or 20). These systems have been the subjects of many experiments ao analyse the contact between semiconductors. They also have been theoretically studied by different types of approach. The main result of those studies is the prediciton of band discontinuities. Defects in heterojunctions are real traps for charge carriers; they can affect the efficiency of the component decreasing the currents and the fluxes in it. the knowledge of their electronic structure is important, a great density of defects deeply modifies the electronic structure of the whole material creating real new bands of energy in the band structure of the component. in the first part of this work, we will describe the heterostructure and the defect in terms of quantum wells and discrete levels. This approach allows us to show the role of the width of the quantum well describing the structure but induces specific behaviours due to the one dimensional modelling. Then a perturbative treatment is proposed using the Green's functions formalism. We build atomic chains with different types of atoms featuring the heterostructure and the defect. Densities of states of a structure with a defect and levels associated to the defect are obtained. Results are comparable with the free electrons work, but the modelling do not induce problems due to a one dimensional approach. To extend our modelling, a three dimensions approach, based on a cavity model, is investigated. The influence of the defect, - of hydrogenoid type - introduced in the structure, is described by a cavity

  7. Emerging applications for vertical cavity surface emitting lasers

    International Nuclear Information System (INIS)

    Harris, J S; O'sullivan, T; Sarmiento, T; Lee, M M; Vo, S

    2011-01-01

    Vertical cavity surface emitting lasers (VCSELs) emitting at 850 nm have experienced explosive growth in the past decade because of their many attractive optical features and incredibly low-cost manufacturability. This review reviews the foundations for GaAs-based VCSEL technology as well as the materials and device challenges to extend the operating wavelength to both shorter and longer wavelengths. We discuss some of the applications that are enabled by the integration of VCSELs with both active and passive semiconductor elements for telecommunications, both in vivo and in vitro biosensing, high-density optical storage and imaging at wavelengths much less than the diffraction limit of light

  8. RF Characterization of Niobium Films for Superconducting Cavities

    CERN Document Server

    Aull† , S; Doebert, S; Junginger, T; Ehiasarian, AP; Knobloch, J; Terenziani, G

    2013-01-01

    The surface resistance RS of superconductors shows a complex dependence on the external parameters such as temperature, frequency or radio-frequency (RF) field. The Quadrupole Resonator modes of 400, 800 and 1200 MHz allow measurements at actual operating frequencies of superconducting cavities. Niobium films on copper substrates have several advantages over bulk niobium cavities. HIPIMS (High-power impulse magnetron sputtering) is a promising technique to increase the quality and therefore the performance of niobium films. This contribution will introduce CERNs recently developed HIPIMS coating apparatus. Moreover, first results of niobium coated copper samples will be presented, revealing the dominant loss mechanisms.

  9. CEBAF: Accelerating cavities look good

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1990-09-15

    The first assembled pairs of superconducting accelerating cavities from German supplier Interatom for the Continuous Electron Beam Accelerator Facility, Newport News, Virginia, have exceeded performance specifications.

  10. CEBAF: Accelerating cavities look good

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    The first assembled pairs of superconducting accelerating cavities from German supplier Interatom for the Continuous Electron Beam Accelerator Facility, Newport News, Virginia, have exceeded performance specifications

  11. Cavity quantum electrodynamics with Anderson-localized modes

    DEFF Research Database (Denmark)

    Sapienza, Luca; Nielsen, Henri Thyrrestrup; Stobbe, Søren

    2010-01-01

    by a factor of 15 on resonance with the Anderson-localized mode, and 94% of the emitted single photons coupled to the mode. Disordered photonic media thus provide an efficient platform for quantum electrodynamics, offering an approach to inherently disorder-robust quantum information devices.......A major challenge in quantum optics and quantum information technology is to enhance the interaction between single photons and single quantum emitters. This requires highly engineered optical cavities that are inherently sensitive to fabrication imperfections. We have demonstrated a fundamentally...... different approach in which disorder is used as a resource rather than a nuisance. We generated strongly confined Anderson-localized cavity modes by deliberately adding disorder to photonic crystal waveguides. The emission rate of a semiconductor quantum dot embedded in the waveguide was enhanced...

  12. Solid-state cavity quantum electrodynamics using quantum dots

    International Nuclear Information System (INIS)

    Gerard, J.M.; Gayral, B.; Moreau, E.; Robert, I.; Abram, I.

    2001-01-01

    We review the recent development of solid-state cavity quantum electrodynamics using single self-assembled InAs quantum dots and three-dimensional semiconductor microcavities. We discuss first prospects for observing a strong coupling regime for single quantum dots. We then demonstrate that the strong Purcell effect observed for single quantum dots in the weak coupling regime allows us to prepare emitted photons in a given state (the same spatial mode, the same polarization). We present finally the first single-mode solid-state source of single photons, based on an isolated quantum dot in a pillar microcavity. This optoelectronic device, the first ever to rely on a cavity quantum electrodynamics effect, exploits both Coulomb interaction between trapped carriers in a single quantum dot and single mode photon tunneling in the microcavity. (author)

  13. Electrodes for Semiconductor Gas Sensors

    Science.gov (United States)

    Lee, Sung Pil

    2017-01-01

    The electrodes of semiconductor gas sensors are important in characterizing sensors based on their sensitivity, selectivity, reversibility, response time, and long-term stability. The types and materials of electrodes used for semiconductor gas sensors are analyzed. In addition, the effect of interfacial zones and surface states of electrode–semiconductor interfaces on their characteristics is studied. This study describes that the gas interaction mechanism of the electrode–semiconductor interfaces should take into account the interfacial zone, surface states, image force, and tunneling effect. PMID:28346349

  14. 1/f Fluctuations in ion implanted metal semiconductor contacts

    International Nuclear Information System (INIS)

    Stojanovic, M.; Marjanovic, N.; Radojevic, B.

    1998-01-01

    Ion implanted Metal-Semiconductor contacts is the most widely used structures in electrical devices. Weather complete devices or some parts are of interest, properties of metal-semiconductor junction strongly influence the quality and external characteristic of electronic devices. That is the reason why special attention is paid to the investigation of factor (noise for example) that could influence given junction. Low frequency 1/f fluctuations (noise) are constantly present in metal-semiconductor junction, so measurement of their level as well as the dependence on factors such as temperature must be taken into account in detailed analysis of electrical characteristics of devices such as contact, nuclear detector with surface barrier etc. In this paper we present the results of low frequency noise level measurements on TiN-Ti-Si structures produced by As + ion implantation. (author)

  15. Key techniques for space-based solar pumped semiconductor lasers

    Science.gov (United States)

    He, Yang; Xiong, Sheng-jun; Liu, Xiao-long; Han, Wei-hua

    2014-12-01

    In space, the absence of atmospheric turbulence, absorption, dispersion and aerosol factors on laser transmission. Therefore, space-based laser has important values in satellite communication, satellite attitude controlling, space debris clearing, and long distance energy transmission, etc. On the other hand, solar energy is a kind of clean and renewable resources, the average intensity of solar irradiation on the earth is 1353W/m2, and it is even higher in space. Therefore, the space-based solar pumped lasers has attracted much research in recent years, most research focuses on solar pumped solid state lasers and solar pumped fiber lasers. The two lasing principle is based on stimulated emission of the rare earth ions such as Nd, Yb, Cr. The rare earth ions absorb light only in narrow bands. This leads to inefficient absorption of the broad-band solar spectrum, and increases the system heating load, which make the system solar to laser power conversion efficiency very low. As a solar pumped semiconductor lasers could absorb all photons with energy greater than the bandgap. Thus, solar pumped semiconductor lasers could have considerably higher efficiencies than other solar pumped lasers. Besides, solar pumped semiconductor lasers has smaller volume chip, simpler structure and better heat dissipation, it can be mounted on a small satellite platform, can compose satellite array, which can greatly improve the output power of the system, and have flexible character. This paper summarizes the research progress of space-based solar pumped semiconductor lasers, analyses of the key technologies based on several application areas, including the processing of semiconductor chip, the design of small and efficient solar condenser, and the cooling system of lasers, etc. We conclude that the solar pumped vertical cavity surface-emitting semiconductor lasers will have a wide application prospects in the space.

  16. Laser of optical fiber composed by two coupled cavities: application as optical fiber sensor

    International Nuclear Information System (INIS)

    Vazquez S, R.A.; Kuzin, E.A.; Ibarra E, B.; May A, M.; Shlyagin, M.; Marquez B, I.

    2004-01-01

    We show an optical fiber laser sensor which consist of two cavities coupled and three fiber Bragg gratings. We used one Bragg grating (called reference) and two Bragg gratings (called sensors), which have the lower reflection wavelength. The reference grating with the two sensors grating make two cavities: first one is the internal cavity which has 4230 m of length and the another one is the external cavity which has 4277 m of length. Measuring the laser beating frequency for a resonance cavity and moving the frequency peaks when the another cavity is put in resonance, we prove that the arrangement can be used as a two points sensor for determining the difference of temperature or stress between these two points. (Author)

  17. Intra-Cavity Total Reflection For High Sensitivity Measurement Of Optical Properties

    Science.gov (United States)

    Pipino, Andrew Charles Rule

    1999-11-16

    An optical cavity resonator device is provided for conducting sensitive murement of optical absorption by matter in any state with diffraction-limited spatial resolution through utilization of total internal reflection within a high-Q (high quality, low loss) optical cavity. Intracavity total reflection generates an evanescent wave that decays exponentially in space at a point external to the cavity, thereby providing a localized region where absorbing materials can be sensitively probed through alteration of the Q-factor of the otherwise isolated cavity. When a laser pulse is injected into the cavity and passes through the evanescent state, an amplitude loss resulting from absorption is incurred that reduces the lifetime of the pulse in the cavity. By monitoring the decay of the injected pulse, the absorption coefficient of manner within the evanescent wave region is accurately obtained from the decay time measurement.

  18. Development of semiconductor electronics

    International Nuclear Information System (INIS)

    Bardeen, John.

    1977-01-01

    In 1931, Wilson applied Block's theory about the energy bands for the motion of electrons in a crystal lattice to semiconductors and showed that conduction can take place in two different ways, by electrons and by holes. Not long afterwards Frenkel showed that these carriers can flow by diffusion in a concentration gradient as well as under the influence of an electric field and wrote down equations for the current flow. The third major contribution, in the late 1930's was the explanation of rectification at a metalsemiconductor contact by Mott and more completely by Schottky. In late 1947 the first transistor of the point contact type was invented by Brattin, Shockley and Bardeen. Then after single crystals of Ge were grown, the junction transistor was developed by the same group. The first silicon transistors appeared in 1954. Then an important step was discovery of the planar transistor by Hoenri in 1960 which led to development of integrated circuits by 1962. Many transistors are produced by batch processing on a slice of silicon. Then in 1965 Mos (Metal-Oxide Semiconductor) transistor and in 1968 LSI (Large Scale Intergration circuits) were developed. Aside from electronic circuits, there are many other applications of semiconductors, including junction power rectifiers, junction luminescence (including lasers), solar batteries, radiation detectors, microwave oscillators and charged-coupled devices for computer memories and devices. One of the latest developments is a microprocessor with thousands of transistors and associated circuitry on a single small chip of silicon. It can be programmed to provide a variety of circuit functions, thus it is not necessary to go through the great expense of LSI's for each desired function, but to use standard microprocessors and program to do the job

  19. Layered semiconductor neutron detectors

    Science.gov (United States)

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  20. Basic properties of semiconductors

    CERN Document Server

    Landsberg, PT

    2013-01-01

    Since Volume 1 was published in 1982, the centres of interest in the basic physics of semiconductors have shifted. Volume 1 was called Band Theory and Transport Properties in the first edition, but the subject has broadened to such an extent that Basic Properties is now a more suitable title. Seven chapters have been rewritten by the original authors. However, twelve chapters are essentially new, with the bulk of this work being devoted to important current topics which give this volume an almost encyclopaedic form. The first three chapters discuss various aspects of modern band theory and the

  1. Electrowetting on semiconductors

    Science.gov (United States)

    Palma, Cesar; Deegan, Robert

    2015-01-01

    Applying a voltage difference between a conductor and a sessile droplet sitting on a thin dielectric film separating it from the conductor will cause the drop to spread. When the conductor is a good metal, the change of the drop's contact angle due to the voltage is given by the Young-Lippmann (YL) equation. Here, we report experiments with lightly doped, single crystal silicon as the conductive electrode. We derive a modified YL equation that includes effects due to the semiconductor and contact line pinning. We show that light induces a non-reversible wetting transition, and that our model agrees well with our experimental results.

  2. Semiconductor ionizino. radiation detectors

    International Nuclear Information System (INIS)

    1982-01-01

    Spectrometric semiconductor detectors of ionizing radiation with the electron-hole junction, based on silicon and germanium are presented. The following parameters are given for the individual types of germanium detectors: energy range of detected radiation, energy resolution given as full width at half maximum (FWHM) and full width at one tenth of maximum (FWTM) for 57 Co and 60 Co, detection sensitivity, optimal voltage, and electric capacitance at optimal voltage. For silicon detectors the value of FWHM for 239 Pu is given, the sensitive area and the depth of the sensitive area. (E.S.)

  3. Band structure of semiconductors

    CERN Document Server

    Tsidilkovski, I M

    2013-01-01

    Band Structure of Semiconductors provides a review of the theoretical and experimental methods of investigating band structure and an analysis of the results of the developments in this field. The book presents the problems, methods, and applications in the study of band structure. Topics on the computational methods of band structure; band structures of important semiconducting materials; behavior of an electron in a perturbed periodic field; effective masses and g-factors for the most commonly encountered band structures; and the treatment of cyclotron resonance, Shubnikov-de Haas oscillatio

  4. Few emitters in a cavity: from cooperative emission to individualization

    International Nuclear Information System (INIS)

    Auffeves, A; Portolan, S; Gerace, D; Drezet, A; Franca Santos, M

    2011-01-01

    We study the temporal correlations of the field emitted by an electromagnetic resonator coupled to a mesoscopic number of two-level emitters that are incoherently pumped by a weak external drive. We solve the master equation of the system for increasing number of emitters and as a function of the cavity quality factor, and we identify three main regimes characterized by well-distinguished statistical properties of the emitted radiation. For small cavity decay rates, the emission events are uncorrelated and the number of photons in the emitted field becomes larger than one, resembling the build-up of a laser field inside the cavity. At intermediate decay rates (as compared with the emitter-cavity coupling) and for a few emitters, the statistics of the emitted radiation is bunched and strikingly dependent on the parity of the number of emitters. The latter property is related to the cooperativity of the emitters mediated by their coupling to the cavity mode, and its connection with steady-state subradiance is discussed. Finally, in the bad cavity regime the typical situation of emission from a collection of individual emitters is recovered. We also analyze how the cooperative behavior evolves as a function of pure dephasing, which allows us to recover the case of a classical source made of an ensemble of independent emitters, similar to what is obtained for a very leaky cavity. State-of-the-art techniques of Q-switch of resonant cavities, allied with the recent capability of tuning single emitters in and out of resonance, suggest this system to be a versatile source of different quantum states of light.

  5. Few emitters in a cavity: from cooperative emission to individualization

    Energy Technology Data Exchange (ETDEWEB)

    Auffeves, A; Portolan, S [CEA/CNRS/UJF Joint Team ' Nanophysics and Semiconductors' , Institut Neel-CNRS, BP 166, 25 Rue des Martyrs, 38042 Grenoble Cedex 9 (France); Gerace, D [Dipartimento di Fisica ' Alessandro Volta' and UdR CNISM, Universita di Pavia, via Bassi 6, 27100 Pavia (Italy); Drezet, A [Institut Neel-CNRS, BP 166, 25 Rue des Martyrs, 38042 Grenoble Cedex 9 (France); Franca Santos, M, E-mail: msantos@fisica.ufmg.br [Departamento de Fisica, Universidade Federal de Minas Gerais, Belo Horizonte, CP 702, 30123-970 (Brazil)

    2011-09-15

    We study the temporal correlations of the field emitted by an electromagnetic resonator coupled to a mesoscopic number of two-level emitters that are incoherently pumped by a weak external drive. We solve the master equation of the system for increasing number of emitters and as a function of the cavity quality factor, and we identify three main regimes characterized by well-distinguished statistical properties of the emitted radiation. For small cavity decay rates, the emission events are uncorrelated and the number of photons in the emitted field becomes larger than one, resembling the build-up of a laser field inside the cavity. At intermediate decay rates (as compared with the emitter-cavity coupling) and for a few emitters, the statistics of the emitted radiation is bunched and strikingly dependent on the parity of the number of emitters. The latter property is related to the cooperativity of the emitters mediated by their coupling to the cavity mode, and its connection with steady-state subradiance is discussed. Finally, in the bad cavity regime the typical situation of emission from a collection of individual emitters is recovered. We also analyze how the cooperative behavior evolves as a function of pure dephasing, which allows us to recover the case of a classical source made of an ensemble of independent emitters, similar to what is obtained for a very leaky cavity. State-of-the-art techniques of Q-switch of resonant cavities, allied with the recent capability of tuning single emitters in and out of resonance, suggest this system to be a versatile source of different quantum states of light.

  6. Electrically pumped edge-emitting photonic bandgap semiconductor laser

    Science.gov (United States)

    Lin, Shawn-Yu; Zubrzycki, Walter J.

    2004-01-06

    A highly efficient, electrically pumped edge-emitting semiconductor laser based on a one- or two-dimensional photonic bandgap (PBG) structure is described. The laser optical cavity is formed using a pair of PBG mirrors operating in the photonic band gap regime. Transverse confinement is achieved by surrounding an active semiconductor layer of high refractive index with lower-index cladding layers. The cladding layers can be electrically insulating in the passive PBG mirror and waveguide regions with a small conducting aperture for efficient channeling of the injection pump current into the active region. The active layer can comprise a quantum well structure. The quantum well structure can be relaxed in the passive regions to provide efficient extraction of laser light from the active region.

  7. Excitons in atomically thin 2D semiconductors and their applications

    Science.gov (United States)

    Xiao, Jun; Zhao, Mervin; Wang, Yuan; Zhang, Xiang

    2017-06-01

    The research on emerging layered two-dimensional (2D) semiconductors, such as molybdenum disulfide (MoS2), reveals unique optical properties generating significant interest. Experimentally, these materials were observed to host extremely strong light-matter interactions as a result of the enhanced excitonic effect in two dimensions. Thus, understanding and manipulating the excitons are crucial to unlocking the potential of 2D materials for future photonic and optoelectronic devices. In this review, we unravel the physical origin of the strong excitonic effect and unique optical selection rules in 2D semiconductors. In addition, control of these excitons by optical, electrical, as well as mechanical means is examined. Finally, the resultant devices such as excitonic light emitting diodes, lasers, optical modulators, and coupling in an optical cavity are overviewed, demonstrating how excitons can shape future 2D optoelectronics.

  8. Single and Coupled Nanobeam Cavities

    DEFF Research Database (Denmark)

    Ivinskaya, Aliaksandra; Lavrinenko, Andrei; Shyroki, Dzmitry M.

    2013-01-01

    for analysis and design of photonic crystal devices, such as 2D ring resonators for filters, single and coupled nanobeam cavities, birefringence in photonic crystal cavities, threshold analysis in photonic crystal lasers, gap solitons in photonic crystals, novel photonic atolls, dynamic characteristics...

  9. Technical tasks in superconducting cavities

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Kenji [High Energy Accelerator Research Organization, Tsukuba, Ibaraki (Japan)

    1997-11-01

    The feature of superconducting rf cavities is an extremely small surface resistance on the wall. It brings a large energy saving in the operation, even those are cooled with liquid helium. That also makes possible to operate themselves in a higher field gradient comparing to normal conducting cavities, and brings to make accelerators compact. These merits are very important for the future accelerator engineering which is planed at JAERI for the neutron material science and nuclear waste transmutation. This machine is a high intensity proton linac and uses sc cavities in the medium and high {beta} sections. In this paper, starting R and D of proton superconducting cavities, several important technical points which come from the small surface resistance of sc cavities, are present to succeed it and also differences between the medium and high - {beta} structures are discussed. (author)

  10. Pacer processing: cavity inventory relationships

    International Nuclear Information System (INIS)

    Dietz, R.J.; Gritzo, L.A.

    1975-09-01

    The pacer cavity and its associated primary power loop comprise a recirculating system in which materials are introduced by a series of thermonuclear explosions while debris is continuously removed by radioactive decay, sorption phenomena, and deliberate processing. Safe, reliable, and economical realization of the Pacer concept depends on the removal and control of both noxious and valuable by-products of the fusion reaction. Mathematical relationships are developed that describe the quantities of materials that are introduced into the Pacer cavity by a series of discrete events and are removed continuously by processing and decay. An iterative computer program based on these relationships is developed that allows both the total cavity inventory and the amounts of important individual species to be determined at any time during the lifetime of the cavity in order to establish the effects of the thermonuclear event, the cavity, the flow, and various processing parameters on Pacer design requirements

  11. Single filament semiconductor laser

    International Nuclear Information System (INIS)

    Botez, D.

    1980-01-01

    A semiconductor laser comprising: a body of semiconductor material including a substrate having a surface and a pair of spaced, substantially parallel dove-tailed shaped grooves in said surface, said body having a pair of end surfaces between which said grooves extend, said end surfaces being reflective to light with at least one of said end surfaces being partially transparent to light a first epitaxial layer over said surface of the substrate and the surfaces of the grooves, said first epitaxial layer having a flat surface portion over the portion of the substrate surface between the grooves, a thin second epitaxial layer over said first epitaxial layer, a third epitaxial layer over said second epitaxial layer, said first and third epitaxial layers being of opposite conductivity types and the second epitaxial layer being the active recombination region of the laser with the light being generated therein in the vicinity of the portion which is over the flat surface portion of the first epitaxial layer, and a pair of contacts on said body with one contact being over said third epitaxial body and the other being on said substrate

  12. New approach for measuring the microwave Hall mobility of semiconductors

    International Nuclear Information System (INIS)

    Murthy, D. V. B.; Subramanian, V.; Murthy, V. R. K.

    2006-01-01

    Measurement of Hall mobility in semiconductor samples using bimodal cavity method gives distinct advantages due to noncontact nature as well as the provision to measure anisotropic mobility. But the measurement approaches followed till now have a disadvantage of having high error values primarily due to the problem in evaluating the calibration constant of the whole experimental arrangement. This article brings out a new approach that removes such disadvantage and presents the calibration constant with 1% accuracy. The overall error in the carrier mobility values is within 5%

  13. II-VI semiconductor compounds

    CERN Document Server

    1993-01-01

    For condensed matter physicists and electronic engineers, this volume deals with aspects of II-VI semiconductor compounds. Areas covered include devices and applications of II-VI compounds; Co-based II-IV semi-magnetic semiconductors; and electronic structure of strained II-VI superlattices.

  14. Electronic structure of semiconductor interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Herman, F

    1983-02-01

    The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered.

  15. Quantum transport in semiconductor nanowires

    NARCIS (Netherlands)

    Van Dam, J.

    2006-01-01

    This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS)

  16. Semiconductor photocatalysis principles and applications

    CERN Document Server

    Kisch, Horst

    2014-01-01

    Focusing on the basic principles of semiconductor photocatalysis, this book also gives a brief introduction to photochemistry, photoelectrochemistry, and homogeneous photocatalysis. In addition, the author - one of the leading authorities in the field - presents important environmental and practical aspects. A valuable, one-stop source for all chemists, material scientists, and physicists working in this area, as well as novice researchers entering semiconductor photocatalysis.

  17. Progress in semiconductor drift detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Walton, J.; Gatti, E.

    1985-01-01

    Progress in testing semiconductor drift detectors is reported. Generally better position and energy resolutions were obtained than resolutions published previously. The improvement is mostly due to new electronics better matched to different detectors. It is shown that semiconductor drift detectors are becoming versatile and reliable detectors for position and energy measurements

  18. Semiconductor materials and their properties

    NARCIS (Netherlands)

    Reinders, Angelina H.M.E.; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre; Reinders, Angele; Verlinden, Pierre; van Sark, Wilfried; Freundlich, Alexandre

    2017-01-01

    Semiconductor materials are the basic materials which are used in photovoltaic (PV) devices. This chapter introduces solid-state physics and semiconductor properties that are relevant to photovoltaics without spending too much time on unnecessary information. Usually atoms in the group of

  19. Optical coherent control in semiconductors

    DEFF Research Database (Denmark)

    Østergaard, John Erland; Vadim, Lyssenko; Hvam, Jørn Märcher

    2001-01-01

    of quantum control including the recent applications to semiconductors and nanostructures. We study the influence of inhomogeneous broadening in semiconductors on CC results. Photoluminescence (PL) and the coherent emission in four-wave mixing (FWM) is recorded after resonant excitation with phase...

  20. Terahertz Nonlinear Optics in Semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2013-01-01

    We demonstrate the nonlinear optical effects – selfphase modulation and saturable absorption of a single-cycle THz pulse in a semiconductor. Resulting from THz-induced modulation of Drude plasma, these nonlinear optical effects, in particular, lead to self-shortening and nonlinear spectral...... breathing of a single-cycle THz pulse in a semiconductor....

  1. Electronic structure of semiconductor interfaces

    International Nuclear Information System (INIS)

    Herman, F.

    1983-01-01

    The study of semiconductor interfaces is one of the most active and exciting areas of current semiconductor research. Because interfaces play a vital role in modern semiconductor technology (integrated circuits, heterojunction lasers, solar cells, infrared detectors, etc.), there is a strong incentive to understand interface properties at a fundamental level and advance existing technology thereby. At the same time, technological advances such as molecular beam epitaxy have paved the way for the fabrication of semiconductor heterojunctions and superlattices of novel design which exhibit unusual electronic, optical, and magnetic properties and offer unique opportunities for fundamental scientific research. A general perspective on this subject is offered treating such topics as the atomic and electronic structure of semiconductor surfaces and interfaces; oxidation and oxide layers; semiconductor heterojunctions and superlattices; rectifying metal-semiconductor contacts; and interface reactions. Recent progress is emphasized and some future directions are indicated. In addition, the role that large-scale scientific computation has played in furthering our theoretical understanding of semiconductor surfaces and interfaces is discussed. Finally, the nature of theoretical models, and the role they play in describing the physical world is considered. (Author) [pt

  2. Injection Locking of a Semiconductor Double Quantum Dot Micromaser.

    Science.gov (United States)

    Liu, Y-Y; Stehlik, J; Gullans, M J; Taylor, J M; Petta, J R

    2015-11-01

    Emission linewidth is an important figure of merit for masers and lasers. We recently demonstrated a semiconductor double quantum dot (DQD) micromaser where photons are generated through single electron tunneling events. Charge noise directly couples to the DQD energy levels, resulting in a maser linewidth that is more than 100 times larger than the Schawlow-Townes prediction. Here we demonstrate a linewidth narrowing of more than a factor 10 by locking the DQD emission to a coherent tone that is injected to the input port of the cavity. We measure the injection locking range as a function of cavity input power and show that it is in agreement with the Adler equation. The position and amplitude of distortion sidebands that appear outside of the injection locking range are quantitatively examined. Our results show that this unconventional maser, which is impacted by strong charge noise and electron-phonon coupling, is well described by standard laser models.

  3. Design and analysis of magnetic shield for 650 MHz SCRF cavity

    International Nuclear Information System (INIS)

    Thakur, Vanshree; Jain, Vikas; Das, S.; Shinde, R.S.; Joshi, S.C.

    2015-01-01

    Five-cell, 650 MHz Superconducting RF (SCRF) cavity is being developed at RRCAT for the Injector Linac of proposed ISNS project. The SCRF cavity needs to be shielded effectively from earth magnetic field. The external magnetic field can cause magnetic field trapping that limits the performance of SCRF cavity. The allowable limit of earth magnetic field in the cavity surface is < 10 mG. The magnetic shielding analysis carried out for 650 MHz dressed SCRF cavity is presented in this paper. For axial magnetic field shielding analysis, 2-D code PANDIRA has been used. A 2-D axisymmetric geometry (cylinder of Cryoperm10 sheet with 460 mm diameter of various thickness and 1100 mm length) has been modelled and analyzed in the presence of 240 mG external axial magnetic field. The influence of partial opening of 120 mm diameter at both ends of the cylinder on magnetic field pattern inside the shielded region has been evaluated. The transverse magnetic shielding analysis in the presence of 500 mG transverse external field has been carried out using OPERA 3D code. The flux leakage through the major openings for cavity supports, ports on the shield is investigated and accordingly the openings are designed to minimize the leakage. Inference of material thickness on the magnetic shielding for reducing magnetic field below specified limit has been investigated. Details of design and analysis of magnetic shield for SCRF cavity will be discussed in this paper. (author)

  4. Organic semiconductors in a spin

    CERN Document Server

    Samuel, I

    2002-01-01

    A little palladium can go a long way in polymer-based light-emitting diodes. Inorganic semiconductors such as silicon and gallium arsenide are essential for countless applications in everyday life, ranging from PCs to CD players. However, while they offer unrivalled computational speed, inorganic semiconductors are also rigid and brittle, which means that they are less suited to applications such as displays and flexible electronics. A completely different class of materials - organic semiconductors - are being developed for these applications. Organic semiconductors have many attractive features: they are easy to make, they can emit visible light, and there is tremendous scope for tailoring their properties to specific applications by changing their chemical structure. Research groups and companies around the world have developed a wide range of organic-semiconductor devices, including transistors, light-emitting diodes (LEDs), solar cells and lasers. (U.K.)

  5. Frequency-feedback cavity enhanced spectrometer

    Science.gov (United States)

    Hovde, David Christian; Gomez, Anthony

    2015-08-18

    A spectrometer comprising an optical cavity, a light source capable of producing light at one or more wavelengths transmitted by the cavity and with the light directed at the cavity, a detector and optics positioned to collect light transmitted by the cavity, feedback electronics causing oscillation of amplitude of the optical signal on the detector at a frequency that depends on cavity losses, and a sensor measuring the oscillation frequency to determine the cavity losses.

  6. Ion implantation for semiconductors

    International Nuclear Information System (INIS)

    Grey-Morgan, T.

    1995-01-01

    Full text: Over the past two decades, thousands of particle accelerators have been used to implant foreign atoms like boron, phosphorus and arsenic into silicon crystal wafers to produce special embedded layers for manufacturing semiconductor devices. Depending on the device required, the atomic species, the depth of implant and doping levels are the main parameters for the implantation process; the selection and parameter control is totally automated. The depth of the implant, usually less than 1 micron, is determined by the ion energy, which can be varied between 2 and 600 keV. The ion beam is extracted from a Freeman or Bernas type ion source and accelerated to 60 keV before mass analysis. For higher beam energies postacceleration is applied up to 200 keV and even higher energies can be achieved by mass selecting multiplycharged ions, but with a corresponding reduction in beam output. Depending on the device to be manufactured, doping levels can range from 10 10 to 10 15 atoms/cm 2 and are controlled by implanter beam currents in the range up to 30mA; continuous process monitoring ensures uniformity across the wafer of better than 1 % . As semiconductor devices get smaller, additional sophistication is required in the design of the implanter. The silicon wafers charge electrically during implantation and this charge must be dissipated continuously to reduce the electrical stress in the device and avoid destructive electrical breakdown. Electron flood guns produce low energy electrons (below 10 electronvolts) to neutralize positive charge buildup and implanter design must ensure minimum contamination by other isotopic species and ensure low internal sputter rates. The pace of technology in the semiconductor industry is such that implanters are being built now for 256 Megabit circuits but which are only likely to be widely available five years from now. Several specialist companies manufacture implanter systems, each costing around US$5 million, depending on the

  7. Nonlocal Intracranial Cavity Extraction

    Science.gov (United States)

    Manjón, José V.; Eskildsen, Simon F.; Coupé, Pierrick; Romero, José E.; Collins, D. Louis; Robles, Montserrat

    2014-01-01

    Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV) is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden. PMID:25328511

  8. Nonlocal Intracranial Cavity Extraction

    Directory of Open Access Journals (Sweden)

    José V. Manjón

    2014-01-01

    Full Text Available Automatic and accurate methods to estimate normalized regional brain volumes from MRI data are valuable tools which may help to obtain an objective diagnosis and followup of many neurological diseases. To estimate such regional brain volumes, the intracranial cavity volume (ICV is often used for normalization. However, the high variability of brain shape and size due to normal intersubject variability, normal changes occurring over the lifespan, and abnormal changes due to disease makes the ICV estimation problem challenging. In this paper, we present a new approach to perform ICV extraction based on the use of a library of prelabeled brain images to capture the large variability of brain shapes. To this end, an improved nonlocal label fusion scheme based on BEaST technique is proposed to increase the accuracy of the ICV estimation. The proposed method is compared with recent state-of-the-art methods and the results demonstrate an improved performance both in terms of accuracy and reproducibility while maintaining a reduced computational burden.

  9. Bloch-wave engineered submicron-diameter quantum-dot micropillars for cavity QED experiments

    DEFF Research Database (Denmark)

    Gregersen, Niels; Lermer, Matthias; Reitzenstein, Stephan

    2013-01-01

    The semiconductor micropillar is attractive for cavity QED experiments. For strong coupling, the figure of merit is proportional to Q/√V, and a design combining a high Q and a low mode volume V is thus desired. However, for the standard submicron diameter design, poor mode matching between the ca...... the cavity and the DBR Bloch mode limits the Q. We present a novel adiabatic design where Bloch-wave engineering is employed to improve the mode matching, allowing the demonstration of a record-high vacuum Rabi splitting of 85 μeV and a Q of 13600 for a 850 nm diameter micropillar....

  10. Photons in a spherical cavity

    International Nuclear Information System (INIS)

    Ionescu-Pallas, N.; Vlad, V.I.

    1999-01-01

    The spectrum of black body radiation at the absolute temperature T, in an ideal spherical cavity of radius R, is studied. The departures from the classical predictions of Planck's theory, due to the discrete energies of the radiation quanta confined inside the cavity, depend on the adiabatic invariant RT and are significant for RT≤ 1 cm K. Special attention was paid to evidence sudden changes in the spectrum intensities, forbidden bands of frequency, as well as major modifications of the total energy for RT≤ 1 cm K. Similar effects were present in case of a cubic cavity too. (authors)

  11. Semiconductor radiation detector

    Science.gov (United States)

    Bell, Zane W.; Burger, Arnold

    2010-03-30

    A semiconductor detector for ionizing electromagnetic radiation, neutrons, and energetic charged particles. The detecting element is comprised of a compound having the composition I-III-VI.sub.2 or II-IV-V.sub.2 where the "I" component is from column 1A or 1B of the periodic table, the "II" component is from column 2B, the "III" component is from column 3A, the "IV" component is from column 4A, the "V" component is from column 5A, and the "VI" component is from column 6A. The detecting element detects ionizing radiation by generating a signal proportional to the energy deposited in the element, and detects neutrons by virtue of the ionizing radiation emitted by one or more of the constituent materials subsequent to capture. The detector may contain more than one neutron-sensitive component.

  12. Semiconductor testing method

    International Nuclear Information System (INIS)

    Brown, Stephen.

    1992-01-01

    In a method of avoiding use of nuclear radiation, eg gamma rays, X-rays, electron beams, for testing semiconductor components for resistance to hard radiation, which hard radiation causes data corruption in some memory devices and 'latch-up' in others, similar fault effects can be achieved using a xenon or other 'light' flash gun even though the penetration of light is significantly less than that of gamma rays. The method involves treating a device with gamma radiation, measuring a particular fault current at the onset of a fault event, repeating the test with light to confirm the occurrence of the fault event at the same measured fault current, and using the fault current value as a reference for future tests using light on similar devices. (author)

  13. Radial semiconductor drift chambers

    International Nuclear Information System (INIS)

    Rawlings, K.J.

    1987-01-01

    The conditions under which the energy resolution of a radial semiconductor drift chamber based detector system becomes dominated by the step noise from the detector dark current have been investigated. To minimise the drift chamber dark current attention should be paid to carrier generation at Si/SiO 2 interfaces. This consideration conflicts with the desire to reduce the signal risetime: a higher drift field for shorter signal pulses requires a larger area of SiO 2 . Calculations for the single shaping and pseudo Gaussian passive filters indicate that for the same degree of signal risetime sensitivity in a system dominated by the step noise from the detector dark current, the pseudo Gaussian filter gives only a 3% improvement in signal/noise and 12% improvement in rate capability compared with the single shaper performance. (orig.)

  14. Energy distribution in semiconductors

    International Nuclear Information System (INIS)

    Ance, C.

    1979-01-01

    For various semiconductors the dispersive energy Esub(d) defined in the Wemple-Didomenico model is connected with the covalent and ionic energies Esub(h) and C. A continuous curve of ionicity against the ratio of the two energies Esub(A) and Esub(B), connected to Esub(h) and C is reported. Afromowitz's model is applied to the ternary compounds Gasub(1-x)Alsub(x)Sb using optical decomposition. From these results the average energy gap Esub(g) is given by Esub(g) = D 0 M 0 sup((IB))/(epsilon 1 (0)-1) where M 0 sup((IB)) is the interband transition contribution to the optical moment M 0 . (author)

  15. Organic Semiconductor Photovoltaics

    Science.gov (United States)

    Sariciftci, Niyazi Serdar

    2005-03-01

    Recent developments on organic photovoltaic elements are reviewed. Semiconducting conjugated polymers and molecules as well as nanocrystalline inorganic semiconductors are used in composite thin films. The photophysics of such photoactive devices is based on the photoinduced charge transfer from donor type semiconducting molecules onto acceptor type molecules such as Buckminsterfullerene, C60 and/or nanoparticles. Similar to the first steps in natural photosynthesis, this photoinduced electron transfer leads to a number of potentially interesting applications which include sensitization of the photoconductivity and photovoltaic phenomena. Examples of photovoltaic architectures are discussed with their potential in terrestrial solar energy conversion. Several materials are introduced and discussed for their photovoltaic activities. Furthermore, nanomorphology has been investigated with AFM, SEM and TEM. The morphology/property relationship for a given photoactive system is found to be a major effect.

  16. Improved-Delayed-Detached-Eddy Simulation of cavity-induced transition in hypersonic boundary layer

    International Nuclear Information System (INIS)

    Xiao, Lianghua; Xiao, Zhixiang; Duan, Zhiwei; Fu, Song

    2015-01-01

    Highlights: • This work is about hypersonic cavity-induced transition with IDDES approach. • The length-to-width-to-depth ratio of the cavity is 19.9:3.57:1 at AoA −10° and −15°. • Flow remains laminar at −10°, transition occurs at −15° and cavity changed from open to close type. • Streamwise vortices, impingement shock, traveling shocks and exit shock are observed. • Breakdown of these vortices triggering rapid flow transition. - Abstract: Hypersonic flow transition from laminar to turbulent due to the surface irregularities, like local cavities, can greatly affect the surface heating and skin friction. In this work, the hypersonic flows over a three-dimensional rectangular cavity with length-to-width-to-depth ratio, L:W:D, of 19.9:3.57:1 at two angles of attack (AoA) were numerically studied with Improved-Delayed-Detached-Eddy Simulation (IDDES) method to highlight the mechanism of transition triggered by the cavity. The present approach was firstly applied to the transonic flow over M219 rectangular cavity. The results, including the fluctuating pressure and frequency, agreed with experiment well. In the hypersonic case at Mach number about 9.6 the cavity is seen as “open” at AoA of −10° but “closed” at AoA of −15° unconventional to the two-dimensional cavity case where the flow always exhibits closed cavity feature when the length-to-depth ratio L/D is larger than 14. For the open cavity flow, the shear layer is basically steady and the flow maintains laminar. For the closed cavity case, the external flow goes into the cavity and impinges on the bottom floor. High intensity streamwise vortices, impingement shock and exit shock are observed causing breakdown of these vortices triggering rapid flow transition

  17. A study of the cavity polariton under strong excitation:dynamics and nonlinearities in II-VI micro-cavities

    International Nuclear Information System (INIS)

    Muller, Markus

    2000-01-01

    This work contains an experimental study of the photoluminescence dynamics of cavity polaritons in strong coupling micro-cavities based on II-VI semiconductor compounds. The small exciton size and the strong exciton binding energy in these materials allowed us to study the strong coupling regime between photon and exciton up to high excitation densities, exploring the linear and non-linear emission regimes. Our main experimental techniques are picosecond time-resolved and angular photoluminescence spectroscopy. In the linear regime and for a negative photon-exciton detuning, we observe a suppression of the polariton relaxation by the emission of acoustic phonons leading to a non-equilibrium polariton distribution on the lower branch. This 'bottleneck' effect, which has already been described for polaritons in bulk semiconductors, results from the pronounced photon like character of the polaritons near k(parallel) = 0 in this configuration. At high excitation densities, non-linear relaxation processes, namely final state stimulation of the relaxation and polariton-polariton scattering, bypass this bottleneck giving rise to a very rapid relaxation down to the bottom of the band. We show that this dramatic change in the relaxation dynamics is finally responsible of the super-linear increase of the polariton emission from these states. (author) [fr

  18. Cavity Microwave Searches for Cosmological Axions

    CERN Multimedia

    CERN. Geneva

    2005-01-01

    The lecture will cover the searches for dark matter axions based on the microwave cavity experiment of Sikivie. The topics will begin with a brief overview of halo dark matter, and the axion as a candidate. The principle of resonant conversion of axions in an external magnetic field will be described, and practical considerations in optimizing the experiment as a signal-to-noise problem. A major focus of the lecture will be the two complementary strategies for ultra-low noise detection of the microwave photons - the "photon-as-wave" approach (i.e. conventional heterojunction amplifiers and soon quantum-limited SQUID devices), and "photon-as-particle" (i.e. Rydberg-atom single-quantum detection). Experimental results will be presented; these experiments have already reached well into the range of sensitivity to exclude plausible axion models, for limited ranges of mass. The lecture will conclude with a discussion of future plans and challenges for the microwave ca...

  19. Physics design of APT linac with normal conducting rf cavities

    International Nuclear Information System (INIS)

    Nath, S.; Billen, J.H.; Stovall, J.E.; Takeda, Harunori; Young, L.M.

    1996-01-01

    The accelerator based production of tritium calls for a high-power, cw proton linac. Previous designs for such a linac use a radiofrequency quadrupole (RFQ), followed by a drift-tube linac (DTL) to an intermediate energy and a coupled-cavity linc (CCL) to the final energy. The Los Alamos design uses a high-energy (6.7 MeV) RFQ followed by the newly developed coupled-cavity drift-tube linac (CCDTL) and a CCL. This design accommodates external electromagnetic quadrupole lenses which provide a strong uniform focusing lattice from the end of the RFQ to the end of the CCL. The cell lengths in linacs of traditional design are typically graded as a function of particle velocity. By making groups of cells symmetric in both the CCDTL and CCL, the cavity design as well as mechanical design and fabrication is simplified without compromising the performance. At higher energies, there are some advantages of using superconducting rf cavities. Currently, such schemes are under vigorous study. This paper describes the linac design based on normal conducting cavities and presents simulation results

  20. Cavity and goaf control

    Energy Technology Data Exchange (ETDEWEB)

    Stassen, P

    1978-01-01

    A summary of stowing, including a definition, calculation of stowing material requirements and settling of packs is given. A) Stowing using dirt found locally - the dirt bands in the seam - the use of ripping dirt brought down by the scraper loader and used for packing purposes and the construction of dummy roads. B) Control of cavities by leaving short, thick props and timber chocks in place. C) Stowing methods involving imported firt: packing by hand, use of scraper loaders, slinger stowing and control led-gravity stowing. D) Pneumatic stowing: describes the various types of machine and their scope; pipelines, their installation and cost price; pneumatic stowing in conjunc tion with powered supports; the use of crusher-stowers for stowing ripping dirt; construction of anhydrite packs by means of a pneumatic stower. E) Hydraulic stowing: how it works, the materials involved, utilization conditions, the surface storage post, pipes, stoppings with stowed material, water removal, rates of hydraulic stowing, results of theoretical studies, and the use of hydraulic stowing in the metal-mines. F) Pumped packs: how they work, how the packs are installed, the strength of the packs and their various uses. G) Caving: describes the principle of caving, support patterns, caving with packs and makes a comparison between caving and stowing. H) Comparison between the various methods of stowing compares pneumatic with hydraulic stowing methods; compares packing by hand and mechanical stowing compares surface subsidence in terms of the method of goaf used underground. An appendix gives details of equipment used. (15 refs.) (In French)

  1. Photo-electret effects in homogenous semiconductors

    International Nuclear Information System (INIS)

    Nabiev, G.A.

    2004-01-01

    In the given work is shown the opportunity and created the theory of photo-electret condition in semiconductors with Dember mechanism of photo-voltage generation. Photo-electret of such type can be created, instead of traditional and without an external field as a result of only one illumination. Polar factor, in this case, is the distinction of electrons and holes mobility. Considered the multilayered structure with homogeneous photoactive micro areas shared by the layers, which are interfering to alignment of carriers concentration. We consider, that the homogeneous photoactive areas contain deep levels of stick. Because of addition of elementary photo voltage in separate micro photo cells it is formed the abnormal-large photo voltage (APV-effect). Let's notice, that Dember photo-voltage in a separate micro photo-cell ≤kT/q. From the received expressions, in practically important, special case, when quasi- balance between valent zone and stick levels established in much more smaller time, than free hole lifetime, and we received, that photo-voltage is relaxing. Comparing of the received expressions with the laws of photo voltage attenuation in p-n- junction structures shows their identity; the difference is only in absolute meanings of photo voltage. During the illumination in the semiconductor are created the superfluous concentration of charge carriers and part from them stays at deep levels. At de-energizing light there is a gradual generation of carriers located at these levels

  2. Semiconductor Quantum Dots with Photoresponsive Ligands.

    Science.gov (United States)

    Sansalone, Lorenzo; Tang, Sicheng; Zhang, Yang; Thapaliya, Ek Raj; Raymo, Françisco M; Garcia-Amorós, Jaume

    2016-10-01

    Photochromic or photocaged ligands can be anchored to the outer shell of semiconductor quantum dots in order to control the photophysical properties of these inorganic nanocrystals with optical stimulations. One of the two interconvertible states of the photoresponsive ligands can be designed to accept either an electron or energy from the excited quantum dots and quench their luminescence. Under these conditions, the reversible transformations of photochromic ligands or the irreversible cleavage of photocaged counterparts translates into the possibility to switch luminescence with external control. As an alternative to regulating the photophysics of a quantum dot via the photochemistry of its ligands, the photochemistry of the latter can be controlled by relying on the photophysics of the former. The transfer of excitation energy from a quantum dot to a photocaged ligand populates the excited state of the species adsorbed on the nanocrystal to induce a photochemical reaction. This mechanism, in conjunction with the large two-photon absorption cross section of quantum dots, can be exploited to release nitric oxide or to generate singlet oxygen under near-infrared irradiation. Thus, the combination of semiconductor quantum dots and photoresponsive ligands offers the opportunity to assemble nanostructured constructs with specific functions on the basis of electron or energy transfer processes. The photoswitchable luminescence and ability to photoinduce the release of reactive chemicals, associated with the resulting systems, can be particularly valuable in biomedical research and can, ultimately, lead to the realization of imaging probes for diagnostic applications as well as to therapeutic agents for the treatment of cancer.

  3. Niobium LEP 2 accelerating cavities

    CERN Multimedia

    An accelerating cavity from LEP. This could be cut open to show the layer of niobium on the inside. Operating at 4.2 degrees above absolute zero, the niobium is superconducting and carries an accelerating field of 6 million volts per metre with negligible losses. Each cavity has a surface of 6 m2. The niobium layer is only 1.2 microns thick, ten times thinner than a hair. Such a large area had never been coated to such a high accuracy. A speck of dust could ruin the performance of the whole cavity so the work had to be done in an extremely clean environment. These challenging requirements pushed European industry to new achievements. 256 of these cavities were used in an upgrade of the LEP accelerator to double the energy of the particle beams.

  4. Bistability of Cavity Magnon Polaritons

    Science.gov (United States)

    Wang, Yi-Pu; Zhang, Guo-Qiang; Zhang, Dengke; Li, Tie-Fu; Hu, C.-M.; You, J. Q.

    2018-01-01

    We report the first observation of the magnon-polariton bistability in a cavity magnonics system consisting of cavity photons strongly interacting with the magnons in a small yttrium iron garnet (YIG) sphere. The bistable behaviors emerged as sharp frequency switchings of the cavity magnon polaritons (CMPs) and related to the transition between states with large and small numbers of polaritons. In our experiment, we align, respectively, the [100] and [110] crystallographic axes of the YIG sphere parallel to the static magnetic field and find very different bistable behaviors (e.g., clockwise and counter-clockwise hysteresis loops) in these two cases. The experimental results are well fitted and explained as being due to the Kerr nonlinearity with either a positive or negative coefficient. Moreover, when the magnetic field is tuned away from the anticrossing point of CMPs, we observe simultaneous bistability of both magnons and cavity photons by applying a drive field on the lower branch.

  5. Design of rf conditioner cavities

    International Nuclear Information System (INIS)

    Govil, R.; Rimmer, R.A.; Sessler, A.; Kirk, H.G.

    1992-06-01

    Theoretical studies are made of radio frequency structures which can be used to condition electron beams so as to greatly reduce the stringent emittance requirements for successful lasing in a free-electron laser. The basic strategy of conditioning calls for modulating an electron beam in the transverse dimension, by a periodic focusing channel, while it traverses a series of rf cavities, each operating in a TM 210 mode. In this paper, we analyze the cavities both analytically and numerically (using MAFIA simulations). We find that when cylindrical symmetry is broken the coupling impedance can be greatly enhanced. We present results showing various performance characteristics as a function of cavity parameters, as well as possible designs for conditioning cavities

  6. SRF Cavity Fabrication and Materials

    CERN Document Server

    Singer, W

    2014-07-17

    The technological and metallurgical requirements of material for highgradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10μg/g. The hydrogen content should be kept below 2μg/g to prevent degradation of the Q-value under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Defects may be detected by quality control methods such as eddy current scanning and identified by a number of special methods. Conventional and alternative cavity fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and Electron-Beam Welding (EBW). The welding of half-cells is a delicate...

  7. Generation of single-frequency tunable green light in a coupled ring tapered diode laser cavity

    DEFF Research Database (Denmark)

    Jensen, Ole Bjarlin; Petersen, Paul Michael

    2013-01-01

    in the broad wavelength range from 1049 nm to 1093 nm and the beam propagation factor is improved from M2 = 2.8 to below 1.1. The laser frequency is automatically locked to the cavity resonance frequency using optical feedback. Furthermore, we show that this adaptive external cavity approach leads to efficient......We report the realization of a tapered diode laser operated in a coupled ring cavity that significantly improves the coherence properties of the tapered laser and efficiently generates tunable light at the second harmonic frequency. The tapered diode laser is tunable with single-frequency output...... frequency doubling. More than 500 mW green output power is obtained by placing a periodically poled LiNbO3 crystal in the external cavity. The single frequency green output from the laser system is tunable in the 530 nm to 533 nm range limited by the LiNbO3 crystal. The optical to optical conversion...

  8. Magnetic excitations in ferromagnetic semiconductors

    International Nuclear Information System (INIS)

    Furdyna, J.K.; Liu, X.; Zhou, Y.Y.

    2009-01-01

    Magnetic excitations in a series of GaMnAs ferromagnetic semiconductor films were studied by ferromagnetic resonance (FMR). Using the FMR approach, multi-mode spin wave resonance spectra have been observed, whose analysis provides information on magnetic anisotropy (including surface anisotropy), distribution of magnetization precession within the GaMnAs film, dynamic surface spin pinning (derived from surface anisotropy), and the value of exchange stiffness constant D. These studies illustrate a combination of magnetism and semiconductor physics that is unique to magnetic semiconductors

  9. Semiconductor Nanocrystals for Biological Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Aihua; Gu, Weiwei; Larabell, Carolyn; Alivisatos, A. Paul

    2005-06-28

    Conventional organic fluorophores suffer from poor photo stability, narrow absorption spectra and broad emission feature. Semiconductor nanocrystals, on the other hand, are highly photo-stable with broad absorption spectra and narrow size-tunable emission spectra. Recent advances in the synthesis of these materials have resulted in bright, sensitive, extremely photo-stable and biocompatible semiconductor fluorophores. Commercial availability facilitates their application in a variety of unprecedented biological experiments, including multiplexed cellular imaging, long-term in vitro and in vivo labeling, deep tissue structure mapping and single particle investigation of dynamic cellular processes. Semiconductor nanocrystals are one of the first examples of nanotechnology enabling a new class of biomedical applications.

  10. LEP Radio Frequency Copper Cavity

    CERN Multimedia

    The pulse of a particle accelerator. 128 of these radio frequency cavities were positioned around CERN's 27-kilometre LEP ring to accelerate electrons and positrons. The acceleration was produced by microwave electric oscillations at 352 MHz. The electrons and positrons were grouped into bunches, like beads on a string, and the copper sphere at the top stored the microwave energy between the passage of individual bunches. This made for valuable energy savings as it reduced the heat generated in the cavity.

  11. The dynamics of coupled atom and field assisted by continuous external pumping

    International Nuclear Information System (INIS)

    Burlak, G.; Hernandez, J.A.; Starostenko, O.

    2006-01-01

    The dynamics of a coupled system comprising a two-level atom and cavity field assisted by a continuous external classical field (driving Jaynes-Cummings model) is studied. When the initial field is prepared in a coherent state, the dynamics strongly depends on the algebraic sum of both fields. If this sum is zero (the compensative case) in the system, only the vacuum Rabi oscillations occur. The results with dissipation and external field detuning from the cavity field are also discussed. (Author)

  12. The dynamics of coupled atom and field assisted by continuous external pumping

    Energy Technology Data Exchange (ETDEWEB)

    Burlak, G.; Hernandez, J.A. [Centro de Investigacion en Ingenieria y Ciencias Aplicadas, Universidad Autonoma de Morelos, Cuernavaca, Morelos (Mexico); Starostenko, O. [Departamento de Fisica, Electronica, Sistemas y Mecatronica, Universidad de las Americas, 72820 Puebla (Mexico)

    2006-07-01

    The dynamics of a coupled system comprising a two-level atom and cavity field assisted by a continuous external classical field (driving Jaynes-Cummings model) is studied. When the initial field is prepared in a coherent state, the dynamics strongly depends on the algebraic sum of both fields. If this sum is zero (the compensative case) in the system, only the vacuum Rabi oscillations occur. The results with dissipation and external field detuning from the cavity field are also discussed. (Author)

  13. Degradation of Side-Mode Suppression Ratio in a DFB Laser Integrated With a Semiconductor Optical Amplifier

    DEFF Research Database (Denmark)

    Champagne, A.; Lestrade, Michel; Camel, Jérôme

    2004-01-01

    The degradation of the side-mode suppression ratio (SMSR) in a monolithically integrated distributed feedback laser and semiconductor optical amplifier (SOA) cavity is investigated. An expression is derived that gives the degradation of the SMSR in the case of a perfectly antireflection-coated SO...

  14. TESLA superconducting RF cavity development

    International Nuclear Information System (INIS)

    Koepke, K.

    1995-01-01

    The TESLA collaboration has made steady progress since its first official meeting at Cornell in 1990. The infrastructure necessary to assemble and test superconducting rf cavities has been installed at the TESLA Test Facility (TTF) at DESY. 5-cell, 1.3 GHz cavities have been fabricated and have reached accelerating fields of 25 MV/m. Full sized 9-cell copper cavities of TESLA geometry have been measured to verify the higher order modes present and to evaluate HOM coupling designs. The design of the TESLA 9-cell cavity has been finalized and industry has started delivery. Two prototype 9-cell niobium cavities in their first tests have reached accelerating fields of 10 MV/m and 15 MV/m in a vertical dewar after high peak power (HPP) conditioning. The first 12 m TESLA cryomodule that will house 8 9-cell cavities is scheduled to be delivered in Spring 1995. A design report for the TTF is in progress. The TTF test linac is scheduled to be commissioned in 1996/1997. (orig.)

  15. State of the art in semiconductor detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1990-01-01

    The state of the art in semiconductor detectors for elementary particle physics and X-ray astronomy is briefly reviewed. Semiconductor detectors are divided into two groups; i) classical semiconductor diode detectors and ii) semiconductor memory detectors. Principles of signal formation for both groups of detectors are described and their performance is compared. New developments of silicon detectors are reported here. (orig.)

  16. State of the art in semiconductor detectors

    International Nuclear Information System (INIS)

    Rehak, P.; Gatti, E.

    1989-01-01

    The state of the art in semiconductor detectors for elementary particle physics and x-ray astronomy is briefly reviewed. Semiconductor detectors are divided into two groups; classical semiconductor diode detectors; and semiconductor memory detectors. Principles of signal formation for both groups of detectors are described and their performance is compared. New developments of silicon detectors are reported here. 13 refs., 8 figs

  17. Semiconductor device comprising a pn-heterojunction

    NARCIS (Netherlands)

    2007-01-01

    An electric device is disclosed comprising a pn-heterojunction ( 4 ) formed by a nanowire ( 3 ) of 111 -V semiconductor material and a semiconductor body ( 1 ) comprising a group IV semiconductor material. The nanowire ( 3 ) is positioned in direct contact with the surface ( 2 ) of the semiconductor

  18. Toward designing semiconductor-semiconductor heterojunctions for photocatalytic applications

    Science.gov (United States)

    Zhang, Liping; Jaroniec, Mietek

    2018-02-01

    Semiconductor photocatalysts show a great potential for environmental and energy-related applications, however one of the major disadvantages is their relatively low photocatalytic performance due to the recombination of electron-hole pairs. Therefore, intensive research is being conducted toward design of heterojunctions, which have been shown to be effective for improving the charge-transfer properties and efficiency of photocatalysts. According to the type of band alignment and direction of internal electric field, heterojunctions are categorized into five different types, each of which is associated with its own charge transfer characteristics. Since the design of heterojunctions requires the knowledge of band edge positions of component semiconductors, the commonly used techniques for the assessment of band edge positions are reviewed. Among them the electronegativity-based calculation method is applied for a large number of popular visible-light-active semiconductors, including some widely investigated bismuth-containing semiconductors. On basis of the calculated band edge positions and the type of component semiconductors reported, heterojunctions composed of the selected bismuth-containing semiconductors are proposed. Finally, the most popular synthetic techniques for the fabrication of heterojunctions are briefly discussed.

  19. Bistable laser device with multiple coupled active vertical-cavity resonators

    Science.gov (United States)

    Fischer, Arthur J.; Choquette, Kent D.; Chow, Weng W.

    2003-08-19

    A new class of bistable coupled-resonator vertical-cavity semiconductor laser devices has been developed. These bistable laser devices can be switched, either electrically or optically, between lasing and non-lasing states. A switching signal with a power of a fraction of a milliwatt can change the laser output of such a device by a factor of a hundred, thereby enabling a range of optical switching and data encoding applications.

  20. Time delay signature elimination of chaos in a semiconductor laser by dispersive feedback from a chirped FBG.

    Science.gov (United States)

    Wang, Daming; Wang, Longsheng; Zhao, Tong; Gao, Hua; Wang, Yuncai; Chen, Xianfeng; Wang, Anbang

    2017-05-15

    Time delay signature (TDS) of a semiconductor laser subject to dispersive optical feedback from a chirped fibre Bragg grating (CFBG) is investigated experimentally and numerically. Different from mirror, CFBG provides additional frequency-dependent delay caused by dispersion, and thus induces external-cavity modes with irregular mode separation rather than a fixed separation induced by mirror feedback. Compared with mirror feedback, the CFBG feedback can greatly depress and even eliminate the TDS, although it leads to a similar quasi-period route to chaos with increases of feedback. In experiments, by using a CFBG with dispersion of 2000ps/nm, the TDS is decreased by 90% to about 0.04 compared with mirror feedback. Furthermore, both numerical and experimental results show that the TDS evolution is quite different: the TDS decreases more quickly down to a lower plateau (even background noise level of autocorrelation function) and never rises again. This evolution tendency is also different from that of FBG feedback, of which the TDS first decreases to a minimal value and then increases again as feedback strength increases. In addition, the CFBG feedback has no filtering effects and does not require amplification for feedback light.

  1. Method of manufacturing a semiconductor device and semiconductor device obtained with such a method

    NARCIS (Netherlands)

    2008-01-01

    The invention relates to a method of manufacturing a semiconductor device (10) with a semiconductor body (1) which is provided with at least one semiconductor element, wherein on the surface of the semiconductor body (1) a mesa- shaped semiconductor region (2) is formed, a masking layer (3) is

  2. Selective, electrochemical etching of a semiconductor

    Science.gov (United States)

    Dahal, Rajendra P.; Bhat, Ishwara B.; Chow, Tat-Sing

    2018-03-20

    Methods for facilitating fabricating semiconductor structures are provided which include: providing a multilayer structure including a semiconductor layer, the semiconductor layer including a dopant and having an increased conductivity; selectively increasing, using electrochemical processing, porosity of the semiconductor layer, at least in part, the selectively increasing porosity utilizing the increased conductivity of the semiconductor layer; and removing, at least in part, the semiconductor layer with the selectively increased porosity from the multilayer structure. By way of example, the selectively increasing porosity may include selectively, anodically oxidizing, at least in part, the semiconductor layer of the multilayer structure.

  3. Mid-Infrared Tunable Resonant Cavity Enhanced Detectors

    Directory of Open Access Journals (Sweden)

    Hans Zogg

    2008-09-01

    Full Text Available Mid-infrared detectors that are sensitive only in a tunable narrow spectral band are presented. They are based on the Resonant Cavity Enhanced Detector (RCED principle and employing a thin active region using IV-VI narrow gap semiconductor layers. A Fabry-Pérot cavity is formed by two mirrors. The active layer is grown onto one mirror, while the second mirror can be displaced. This changes the cavity length thus shifting the resonances where the detector is sensitive. Using electrostatically actuated MEMS micromirrors, a very compact tunable detector system has been fabricated. Mirror movements of more than 3 μm at 30V are obtained. With these mirrors, detectors with a wavelength tuning range of about 0.7 μm have been realized. Single detectors can be used in mid-infrared micro spectrometers, while a detector arrangement in an array makes it possible to realize Adaptive Focal Plane Arrays (AFPA.

  4. Metal-insulator-semiconductor photodetectors.

    Science.gov (United States)

    Lin, Chu-Hsuan; Liu, Chee Wee

    2010-01-01

    The major radiation of the sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  5. Metal-Insulator-Semiconductor Photodetectors

    Directory of Open Access Journals (Sweden)

    Chu-Hsuan Lin

    2010-09-01

    Full Text Available The major radiation of the Sun can be roughly divided into three regions: ultraviolet, visible, and infrared light. Detection in these three regions is important to human beings. The metal-insulator-semiconductor photodetector, with a simpler process than the pn-junction photodetector and a lower dark current than the MSM photodetector, has been developed for light detection in these three regions. Ideal UV photodetectors with high UV-to-visible rejection ratio could be demonstrated with III-V metal-insulator-semiconductor UV photodetectors. The visible-light detection and near-infrared optical communications have been implemented with Si and Ge metal-insulator-semiconductor photodetectors. For mid- and long-wavelength infrared detection, metal-insulator-semiconductor SiGe/Si quantum dot infrared photodetectors have been developed, and the detection spectrum covers atmospheric transmission windows.

  6. Atomic layer deposition for semiconductors

    CERN Document Server

    Hwang, Cheol Seong

    2014-01-01

    This edited volume discusses atomic layer deposition (ALD) for all modern semiconductor devices, moving from the basic chemistry of ALD and modeling of ALD processes to sections on ALD for memories, logic devices, and machines.

  7. Semiconductor technology program. Progress briefs

    Science.gov (United States)

    Bullis, W. M.

    1980-01-01

    Measurement technology for semiconductor materials, process control, and devices is reviewed. Activities include: optical linewidth and thermal resistance measurements; device modeling; dopant density profiles; resonance ionization spectroscopy; and deep level measurements. Standardized oxide charge terminology is also described.

  8. Semiconductor radiation detectors. Device physics

    International Nuclear Information System (INIS)

    Lutz, G.

    2007-01-01

    Starting from basic principles, the author, whose own contributions to these developments have been significant, describes the rapidly growing field of modern semiconductor detectors used for energy and position measurement radiation. This development was stimulated by requirements in elementary particle physics where it has led to important scientific discoveries. It has now spread to many other fields of science and technology. The book is written in a didactic way and includes an introduction to semiconductor physics. The working principles of semiconductor radiation detectors are explained in an intuitive way, followed by formal quantitative analysis. Broad coverage is also given to electronic signal readout and to the subject of radiation damage. The book is the first to comprehensively cover the semiconductor radiation detectors currently in use. It is useful as a teaching guide and as a reference work for research and applications. (orig.)

  9. Self-assembling peptide semiconductors

    Science.gov (United States)

    Tao, Kai; Makam, Pandeeswar; Aizen, Ruth; Gazit, Ehud

    2017-01-01

    Semiconductors are central to the modern electronics and optics industries. Conventional semiconductive materials bear inherent limitations, especially in emerging fields such as interfacing with biological systems and bottom-up fabrication. A promising candidate for bioinspired and durable nanoscale semiconductors is the family of self-assembled nanostructures comprising short peptides. The highly ordered and directional intermolecular π-π interactions and hydrogen-bonding network allow the formation of quantum confined structures within the peptide self-assemblies, thus decreasing the band gaps of the superstructures into semiconductor regions. As a result of the diverse architectures and ease of modification of peptide self-assemblies, their semiconductivity can be readily tuned, doped, and functionalized. Therefore, this family of electroactive supramolecular materials may bridge the gap between the inorganic semiconductor world and biological systems. PMID:29146781

  10. Temperature controller of semiconductor laser

    Czech Academy of Sciences Publication Activity Database

    Matoušek, Vít; Číp, Ondřej

    2003-01-01

    Roč. 73, č. 3 (2003), s. 10 - 12 ISSN 0928-5008 Institutional research plan: CEZ:AV0Z2065902 Keywords : temperature controller * semiconductor laser * laser diode Subject RIV: BH - Optics, Masers, Lasers

  11. Vertical Cavity Surface Emitting Laser for Operation at 1.5 µm with Integral AlGaInAs/InP Bragg mirrors

    OpenAIRE

    Linnik, M.; Christou, A.

    2001-01-01

    The design and performance of a low threshold selectively oxidized Vertical Cavity Surface Emitting Laser (VCSEL) fabricated for operation at a wavelength of 1.55 µm is based on III-V quaternary semiconductor alloys and is grown by Molecular Beam Epitaxy technique. The theoretical investigation of the optical properties of the compound semiconductor alloys allows one to select the optimum materials for highly reflective Bragg mirrors. The simulation of the designed VCSEL performance has been ...

  12. Observation of Stable Low Surface Resistance in Large-Grain Niobium SRF Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Rongli [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Huang, Shichun [Institute of Modern Physics (IMP)/Chinese Academy of Sciences (CAS), Lanzhou (China)

    2016-05-01

    Low surface resistance, or high unloaded quality factor (Q0), superconducting radio frequency (SRF) cavities are being pursued actively nowadays as their application in large-scale CW SRF accelerators can save capital and operational cost in cryogenics. There are different options in realization of such cavities. One of them is the large-grain (LG) niobium cavity. In this contribution, we present new experimental results in evaluation of LG niobium cavities cooled down in the presence of an external magnetic field. High Q0 values are achieved even with an ambient magnetic field of up to 100 mG. More over, it is observed that these high Q0 values are super-robust against repeated quench, literally not affected at all after the cavity being deliberately quenched for hundreds of times in the presence of an ambient magnetic field of up to 200 mG.

  13. Photon-Induced Spin-Orbit Coupling in Ultracold Atoms inside Optical Cavity

    Directory of Open Access Journals (Sweden)

    Lin Dong

    2015-05-01

    Full Text Available We consider an atom inside a ring cavity, where a plane-wave cavity field together with an external coherent laser beam induces a two-photon Raman transition between two hyperfine ground states of the atom. This cavity-assisted Raman transition induces effective coupling between atom’s internal degrees of freedom and its center-of-mass motion. In the meantime, atomic dynamics exerts a back-action to cavity photons. We investigate the properties of this system by adopting a mean-field and a full quantum approach, and show that the interplay between the atomic dynamics and the cavity field gives rise to intriguing nonlinear phenomena.

  14. Studies of HOMs in chains of SRF cavities using state-space concatenation scheme

    Energy Technology Data Exchange (ETDEWEB)

    Galek, Tomasz; Heller, Johann; Flisgen, Thomas; Brackebusch, Korinna; Rienen, Ursula van [Institut fuer Allgemeine Elektrotechnik, Universitaet Rostock (Germany)

    2016-07-01

    The design of modern superconducting radio frequency cavities for acceleration of charged particle bunches requires intensive numerical simulations, as they typically arise as modules of several multi-cell cavities. A wide variety of parameters vital to the proper operation of accelerating cavities must be optimized and studied. One of the most important issues concerning the SRF cavities is the influence of the higher order modes on the beam quality, in this contribution. For TESLA-like structures with 1.3 GHz accelerating mode, higher order modes are calculated up to 4 GHz, the external quality factor and the shunt/geometrical impedance spectra are analyzed. To compute properties of complete RF modules the state-space concatenation scheme is used. The aspects of the concatenation scheme and its application to the bERLinPro's chain of cavities is discussed.

  15. Mid infrared resonant cavity detectors and lasers with epitaxial lead-chalcogenides

    Science.gov (United States)

    Zogg, H.; Rahim, M.; Khiar, A.; Fill, M.; Felder, F.; Quack, N.

    2010-09-01

    Wavelength tunable emitters and detectors in the mid-IR wavelength region allow applications including thermal imaging and gas spectroscopy. One way to realize such tunable devices is by using a resonant cavity. By mechanically changing the cavity length with MEMS mirror techniques, the wavelengths may be tuned over a considerable range. Resonant cavity enhanced detectors (RCED) are sensitive at the cavity resonance only. They may be applied for low resolution spectroscopy, and, when arrays of such detectors are realized, as multicolour IR-FPA or "IR-AFPA", adaptive focal plane arrays. We report the first room temperature mid-IR VECSEL (vertical external cavity surface emitting laser) with a wavelength above 3 μm. The active region is just 850 nm PbSe, followed by a 2.5 pair Bragg mirror. Output power is > 10 mW at RT.

  16. 21 CFR 872.3260 - Cavity varnish.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cavity varnish. 872.3260 Section 872.3260 Food and... DENTAL DEVICES Prosthetic Devices § 872.3260 Cavity varnish. (a) Identification. Cavity varnish is a device that consists of a compound intended to coat a prepared cavity of a tooth before insertion of...

  17. Wake fields in semiconductor plasmas

    International Nuclear Information System (INIS)

    Berezhiani, V.I.; Mahajan, S.M.

    1994-05-01

    It is shown that an intense short laser pulse propagating through a semiconductor plasma will generated longitudinal Langmuir waves in its wake. The measurable wake field can be used as a diagnostic to study nonlinear optical phenomena. For narrow gap semiconductors (for examples InSb) with Kane-type dispersion relation, the system can simulate, at currently available laser powers, the physics underlying wake-field accelerators. (author). 9 refs, 1 fig

  18. Semiconductor research with reactor neutrons

    International Nuclear Information System (INIS)

    Kimura, Itsuro

    1992-01-01

    Reactor neutrons play an important role for characterization of semiconductor materials as same as other advanced materials. On the other hand reactor neutrons bring about not only malignant irradiation effects called radiation damage, but also useful effects such as neutron transmutation doping and defect formation for opto-electronics. Research works on semiconductor materials with the reactor neutrons of the Kyoto University Reactor (KUR) are briefly reviewed. In this review, a stress is laid on the present author's works. (author)

  19. Semiconductor crystal high resolution imager

    Science.gov (United States)

    Levin, Craig S. (Inventor); Matteson, James (Inventor)

    2011-01-01

    A radiation imaging device (10). The radiation image device (10) comprises a subject radiation station (12) producing photon emissions (14), and at least one semiconductor crystal detector (16) arranged in an edge-on orientation with respect to the emitted photons (14) to directly receive the emitted photons (14) and produce a signal. The semiconductor crystal detector (16) comprises at least one anode and at least one cathode that produces the signal in response to the emitted photons (14).

  20. Reducing leakage current in semiconductor devices

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Bin; Matioli, Elison de Nazareth; Palacios, Tomas Apostol

    2018-03-06

    A semiconductor device includes a first region having a first semiconductor material and a second region having a second semiconductor material. The second region is formed over the first region. The semiconductor device also includes a current blocking structure formed in the first region between first and second terminals of the semiconductor device. The current blocking structure is configured to reduce current flow in the first region between the first and second terminals.

  1. Optical orientation in ferromagnet/semiconductor hybrids

    International Nuclear Information System (INIS)

    Korenev, V L

    2008-01-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin–spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism

  2. Optical orientation in ferromagnet/semiconductor hybrids

    Science.gov (United States)

    Korenev, V. L.

    2008-11-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin-spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism.

  3. Optical Orientation in Ferromagnet/Semiconductor Hybrids

    OpenAIRE

    Korenev, V. L.

    2008-01-01

    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  4. TEM observations of crack tip: cavity interactions

    International Nuclear Information System (INIS)

    Horton, J.A.; Ohr, S.M.; Jesser, W.A.

    1981-01-01

    Crack tip-cavity interactions have been studied by performing room temperature deformation experiments in a transmission electron microscope on ion-irradiated type 316 stainless steel with small helium containing cavities. Slip dislocations emitted from a crack tip cut, sheared, and thereby elongated cavities without a volume enlargement. As the crack tip approached, a cavity volume enlargement occurred. Instead of the cavities continuing to enlarge until they touch, the walls between the cavities fractured. Fracture surface dimples do not correlate in size or density with these enlarged cavities

  5. Semiconductors for plasmonics and metamaterials

    DEFF Research Database (Denmark)

    Naik, G.V.; Boltasseva, Alexandra

    2010-01-01

    Plasmonics has conventionally been in the realm of metal-optics. However, conventional metals as plasmonic elements in the near-infrared (NIR) and visible spectral ranges suffer from problems such as large losses and incompatibility with semiconductor technology. Replacing metals with semiconduct......Plasmonics has conventionally been in the realm of metal-optics. However, conventional metals as plasmonic elements in the near-infrared (NIR) and visible spectral ranges suffer from problems such as large losses and incompatibility with semiconductor technology. Replacing metals...... with semiconductors can alleviate these problems if only semiconductors could exhibit negative real permittivity. Aluminum doped zinc oxide (AZO) is a low loss semiconductor that can show negative real permittivity in the NIR. A comparative assessment of AZO-based plasmonic devices such as superlens and hyperlens...... with their metal-based counterparts shows that AZO-based devices significantly outperform at a wavelength of 1.55 µm. This provides a strong stimulus in turning to semiconductor plasmonics at the telecommunication wavelengths. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)....

  6. Fabrication of elliptical SRF cavities

    Science.gov (United States)

    Singer, W.

    2017-03-01

    The technological and metallurgical requirements of material for high-gradient superconducting cavities are described. High-purity niobium, as the preferred metal for the fabrication of superconducting accelerating cavities, should meet exact specifications. The content of interstitial impurities such as oxygen, nitrogen, and carbon must be below 10 μg g-1. The hydrogen content should be kept below 2 μg g-1 to prevent degradation of the quality factor (Q-value) under certain cool-down conditions. The material should be free of flaws (foreign material inclusions or cracks and laminations) that can initiate a thermal breakdown. Traditional and alternative cavity mechanical fabrication methods are reviewed. Conventionally, niobium cavities are fabricated from sheet niobium by the formation of half-cells by deep drawing, followed by trim machining and electron beam welding. The welding of half-cells is a delicate procedure, requiring intermediate cleaning steps and a careful choice of weld parameters to achieve full penetration of the joints. A challenge for a welded construction is the tight mechanical and electrical tolerances. These can be maintained by a combination of mechanical and radio-frequency measurements on half-cells and by careful tracking of weld shrinkage. The main aspects of quality assurance and quality management are mentioned. The experiences of 800 cavities produced for the European XFEL are presented. Another cavity fabrication approach is slicing discs from the ingot and producing cavities by deep drawing and electron beam welding. Accelerating gradients at the level of 35-45 MV m-1 can be achieved by applying electrochemical polishing treatment. The single-crystal option (grain boundary free) is discussed. It seems that in this case, high performance can be achieved by a simplified treatment procedure. Fabrication of the elliptical resonators from a seamless pipe as an alternative is briefly described. This technology has yielded good

  7. Hydroforming of superconducting TESLA cavities

    International Nuclear Information System (INIS)

    Singer, W.; Kaiser, H.; Singer, X.

    2003-01-01

    Seamless fabrication of single-cell and multi-cell TESLA shape cavities by hydroforming has been developed at DESY. The forming takes place by expanding the seamless tube with internal water pressure while simultaneously swaging it axially. Tube radius and axial displacement are being computer controlled in accordance with results of FEM simulations and the experimentally obtained strain-stress curve of tube material. Several Nb single cell cavities have been produced. A first bulk Nb double cell cavity has been fabricated. The Nb seamless tubes have been produced by spinning and deep drawing. Surface treatment such as buffered chemical polishing, (BCP), electropolishing (EP), high pressure ultra pure water rinsing (HPR), annealing at 800degC and baking at ca. 150degC have been applied. The best single cell bulk Nb cavity has reached an accelerating gradient of Eacc > 42 MV/m after ca. 250 μm BCP and 100 μm EP. Several bimetallic NbCu single cell cavities of TESLA shape have been fabricated. The seamless tubes have been produced by explosive bonding and subsequent flow forming. The thicknesses of Nb and Cu layers in the tube wall are about 1 mm and 3 mm respectively. The RF performance of NbCu clad cavities is similar to that of bulk Nb cavities. The highest accelerating gradient achieved was 40 MV/m after ca. 180 μm BCP, annealing at 800degC and baking at 140degC for 30 hours. The degradation of the quality factor Qo after repeated quenching is moderate, after ca. 150 quenches it reaches the saturation point of Qo=1.4x10 10 at low field. This indicates that on the basis of RF performance and material costs the combination of hydroforming with tube cladding is a very promising option. (author)

  8. Adiabatic transfer of energy fluctuations between membranes inside an optical cavity

    Science.gov (United States)

    Garg, Devender; Chauhan, Anil K.; Biswas, Asoka

    2017-08-01

    A scheme is presented for the adiabatic transfer of average fluctuations in the phonon number between two membranes in an optical cavity. We show that by driving the cavity modes with external time-delayed pulses, one can obtain an effect analogous to stimulated Raman adiabatic passage in the atomic systems. The adiabatic transfer of fluctuations from one membrane to the other is attained through a "dark" mode, which is robust against decay of the mediating cavity mode. The results are supported with analytical and numerical calculations with experimentally feasible parameters.

  9. Recent status of FCI: PIC simulation of coupled-cavity structure

    International Nuclear Information System (INIS)

    Shintake, Tsumoru

    1996-01-01

    New version of FCI (Field Charge Interaction)-code simulates beam dynamics of an electron beam running in a coupled-cavity structure, such as a multi-cell output structure in a klystron amplifier, a coupled cavity TWT amplifier, a bunching structure in an electron injector and also an rf-gun with multi-cell accelerating cavity. The particle-in-cell simulation takes into account the space charge field, the beam loading effect and energy exchange with an external circuit in a self-consistent manner. (author)

  10. Ripening of Semiconductor Nanoplatelets.

    Science.gov (United States)

    Ott, Florian D; Riedinger, Andreas; Ochsenbein, David R; Knüsel, Philippe N; Erwin, Steven C; Mazzotti, Marco; Norris, David J

    2017-11-08

    Ostwald ripening describes how the size distribution of colloidal particles evolves with time due to thermodynamic driving forces. Typically, small particles shrink and provide material to larger particles, which leads to size defocusing. Semiconductor nanoplatelets, thin quasi-two-dimensional (2D) particles with thicknesses of only a few atomic layers but larger lateral dimensions, offer a unique system to investigate this phenomenon. Experiments show that the distribution of nanoplatelet thicknesses does not defocus during ripening, but instead jumps sequentially from m to (m + 1) monolayers, allowing precise thickness control. We investigate how this counterintuitive process occurs in CdSe nanoplatelets. We develop a microscopic model that treats the kinetics and thermodynamics of attachment and detachment of monomers as a function of their concentration. We then simulate the growth process from nucleation through ripening. For a given thickness, we observe Ostwald ripening in the lateral direction, but none perpendicular. Thicker populations arise instead from nuclei that capture material from thinner nanoplatelets as they dissolve laterally. Optical experiments that attempt to track the thickness and lateral extent of nanoplatelets during ripening appear consistent with these conclusions. Understanding such effects can lead to better synthetic control, enabling further exploration of quasi-2D nanomaterials.

  11. A semiconductor laser device

    Energy Technology Data Exchange (ETDEWEB)

    Takaro, K.; Naoki, T.; Satosi, K.; Yasutosi, K.

    1984-03-17

    A device is proposed which makes it possible to obtain single vertical mode emission in the absence of noise. Noise suppression is achieved by a method which determines the relationship between the donor densities in the second and third layers of an n type semiconductor laser, and the total output optical emission of layers with respect to the emission from the entire laser. The device consists of a photoresist film with a window applied to a 100 GaAs n type conductivity substrate using a standard method. Chemical etching through this window in the substrate is used to generate a slot approximately 1 micrometer in size. After the photoresist film is removed, the following layers are deposited from the liquid phase onto the substrate in the sequence indicated: a telurium doped protective layer of n type AlxGa(1-x) As; 2) an undoped active p type AlyGa(1-6) As layer and a tellurium doped upper protective n type conductivity GaAs layer.

  12. Semiconductor integrated circuits

    International Nuclear Information System (INIS)

    Michel, A.E.; Schwenker, R.O.; Ziegler, J.F.

    1979-01-01

    An improved method involving ion implantation to form non-epitaxial semiconductor integrated circuits. These are made by forming a silicon substrate of one conductivity type with a recessed silicon dioxide region extending into the substrate and enclosing a portion of the silicon substrate. A beam of ions of opposite conductivity type impurity is directed at the substrate at an energy and dosage level sufficient to form a first region of opposite conductivity within the silicon dioxide region. This impurity having a concentration peak below the surface of the substrate forms a region of the one conductivity type which extends from the substrate surface into the first opposite type region to a depth between the concentration peak and the surface and forms a second region of opposite conductivity type. The method, materials and ion beam conditions are detailed. Vertical bipolar integrated circuits can be made this way when the first opposite type conductivity region will function as a collector. Also circuits with inverted bipolar devices when this first region functions as a 'buried'' emitter region. (U.K.)

  13. Impurity gettering in semiconductors

    Science.gov (United States)

    Sopori, Bhushan L.

    1995-01-01

    A process for impurity gettering in a semiconductor substrate or device such as a silicon substrate or device. The process comprises hydrogenating the substrate or device at the back side thereof with sufficient intensity and for a time period sufficient to produce a damaged back side. Thereafter, the substrate or device is illuminated with electromagnetic radiation at an intensity and for a time period sufficient to cause the impurities to diffuse to the back side and alloy with a metal there present to form a contact and capture the impurities. The impurity gettering process also can function to simultaneously passivate defects within the substrate or device, with the defects likewise diffusing to the back side for simultaneous passivation. Simultaneously, substantially all hydrogen-induced damage on the back side of the substrate or device is likewise annihilated. Also taught is an alternate process comprising thermal treatment after hydrogenation of the substrate or device at a temperature of from about 500.degree. C. to about 700.degree. C. for a time period sufficient to cause the impurities to diffuse to the damaged back side thereof for subsequent capture by an alloying metal.

  14. Semiconductor acceleration sensor

    Science.gov (United States)

    Ueyanagi, Katsumichi; Kobayashi, Mitsuo; Goto, Tomoaki

    1996-09-01

    This paper reports a practical semiconductor acceleration sensor especially suited for automotive air bag systems. The acceleration sensor includes four beams arranged in a swastika structure. Two piezoresistors are formed on each beam. These eight piezoresistors constitute a Wheatstone bridge. The swastika structure of the sensing elements, an upper glass plate and a lower glass plate exhibit the squeeze film effect which enhances air dumping, by which the constituent silicon is prevented from breakdown. The present acceleration sensor has the following features. The acceleration force component perpendicular to the sensing direction can be cancelled. The cross-axis sensitivity is less than 3 percent. And, the erroneous offset caused by the differences between the thermal expansion coefficients of the constituent materials can be canceled. The high aspect ratio configuration realized by plasma etching facilitates reducing the dimensions and improving the sensitivity of the acceleration sensor. The present acceleration sensor is 3.9 mm by 3.9 mm in area and 1.2 mm in thickness. The present acceleration sensor can measure from -50 to +50 G with sensitivity of 0.275 mV/G and with non-linearity of less than 1 percent. The acceleration sensor withstands shock of 3000 G.

  15. Partial Cavity Flows at High Reynolds Numbers

    Science.gov (United States)

    Makiharju, Simo; Elbing, Brian; Wiggins, Andrew; Dowling, David; Perlin, Marc; Ceccio, Steven

    2009-11-01

    Partial cavity flows created for friction drag reduction were examined on a large-scale. Partial cavities were investigated at Reynolds numbers up to 120 million, and stable cavities with frictional drag reduction of more than 95% were attained at optimal conditions. The model used was a 3 m wide and 12 m long flat plate with a plenum on the bottom. To create the partial cavity, air was injected at the base of an 18 cm backwards-facing step 2.1 m from the leading edge. The geometry at the cavity closure was varied for different flow speeds to optimize the closure of the cavity. Cavity gas flux, thickness, frictional loads, and cavity pressures were measured over a range of flow speeds and air injection fluxes. High-speed video was used extensively to investigate the unsteady three dimensional cavity closure, the overall cavity shape and oscillations.

  16. Regulating multiple externalities

    DEFF Research Database (Denmark)

    Waldo, Staffan; Jensen, Frank; Nielsen, Max

    2016-01-01

    Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory instrume......Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory...

  17. Purcell effect in an organic-inorganic halide perovskite semiconductor microcavity system

    International Nuclear Information System (INIS)

    Wang, Jun; Wang, Yafeng; Hu, Tao; Wu, Lin; Shen, Xuechu; Chen, Zhanghai; Cao, Runan; Xu, Fei; Da, Peimei; Zheng, Gengfeng; Lu, Jian

    2016-01-01

    Organic-inorganic halide perovskite semiconductors with the attractive physics properties, including strong photoluminescence (PL), huge oscillator strengths, and low nonradiative recombination losses, are ideal candidates for studying the light-matter interaction in nanostructures. Here, we demonstrate the coupling of the exciton state and the cavity mode in the lead halide perovskite microcavity system at room temperature. The Purcell effect in the coupling system is clearly observed by using angle-resolved photoluminescence spectra. Kinetic analysis based on time-resolved PL reveals that the spontaneous emission rate of the halide perovskite semiconductor is significantly enhanced at resonance of the exciton energy and the cavity mode. Our results provide the way for developing electrically driven organic polariton lasers, optical devices, and on-chip coherent quantum light sources

  18. Quantum Computation by Optically Coupled Steady Atoms/Quantum-Dots Inside a Quantum Cavity

    Science.gov (United States)

    Pradhan, P.; Wang, K. L.; Roychowdhury, V. P.; Anantram, M. P.; Mor, T.; Saini, Subhash (Technical Monitor)

    1999-01-01

    We present a model for quantum computation using $n$ steady 3-level atoms kept inside a quantum cavity, or using $n$ quantum-dots (QDs) kept inside a quantum cavity. In this model one external laser is pointed towards all the atoms/QDs, and $n$ pairs of electrodes are addressing the atoms/QDs, so that each atom is addressed by one pair. The energy levels of each atom/QD are controlled by an external Stark field given to the atom/QD by its external pair of electrodes. Transition between two energy levels of an individual atom/ QD are controlled by the voltage on its electrodes, and by the external laser. Interactions between two atoms/ QDs are performed with the additional help of the cavity mode (using on-resonance condition). Laser frequency, cavity frequency, and energy levels are far off-resonance most of the time, and they are brought to the resonance (using the Stark effect) only at the time of operations. Steps for a controlled-NOT gate between any two atoms/QDs have been described for this model. Our model demands some challenging technological efforts, such as manufacturing single-electron QDs inside a cavity. However, it promises big advantages over other existing models which are currently implemented, and might enable a much easier scale-up, to compute with many more qubits.

  19. A reciprocity formulation for the EM scattering by an obstacle within a large open cavity

    Science.gov (United States)

    Pathak, Prabhakar H.; Burkholder, Robert J.

    1993-01-01

    A formulation based on a generalized reciprocity theorem is developed for analyzing the external high frequency EM scattering by a complex obstacle inside a relatively arbitrary open-ended waveguide cavity when it is illuminated by an external source. This formulation is also extended to include EM fields whose time dependence may be nonperiodic. A significant advantage of this formulation is that it allows one to break up the analysis into two independent parts; one deals with the waveguide cavity shape alone and the other with the obstacle alone. The external scattered field produced by the obstacle (in the presence of the waveguide cavity structure) is given in terms of a generalized reciprocity integral over a surface S(T) corresponding to the interior waveguide cavity cross section located conveniently but sufficiently close to the obstacle. Furthermore, the fields coupled into the cavity from the source in the exterior region generally need to propagate only one-way via the open front end (which is directly illuminated) to the interior surface S(T) in this approach, and not back, in order to find the external field scattered by the obstacle.

  20. Normal Conducting RF Cavity for MICE

    International Nuclear Information System (INIS)

    Li, D.; DeMello, A.; Virostek, S.; Zisman, M.; Summers, D.

    2010-01-01

    Normal conducting RF cavities must be used for the cooling section of the international Muon Ionization Cooling Experiment (MICE), currently under construction at Rutherford Appleton Laboratory (RAL) in the UK. Eight 201-MHz cavities are needed for the MICE cooling section; fabrication of the first five cavities is complete. We report the cavity fabrication status including cavity design, fabrication techniques and preliminary low power RF measurements.