Optical characterization of semiconductors infrared, Raman, and photoluminescence spectroscopy

CERN Document Server

Perkowitz, Sidney

1993-01-01

This is the first book to explain, illustrate, and compare the most widely used methods in optics: photoluminescence, infrared spectroscopy, and Raman scattering. Written with non-experts in mind, the book develops the background needed to understand the why and how of each technique, but does not require special knowledge of semiconductors or optics. Each method is illustrated with numerous case studies. Practical information drawn from the authors experience is given to help establish optical facilities, including commercial sources for equipment, and experimental details. For industrial sci

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...

Optical Regeneration and Noise in Semiconductor Devices

DEFF Research Database (Denmark)

Öhman, Filip

2005-01-01

In this report all-optical 2R-regeneration in optical communication systems is investigated. A simple regenerator device based on concatenated semiconductor optical amplifiers (SOAs) and electro absorbers (EAs) is introduced and examined. Experiments show that the monolithic SOA-EA 2R-regenerator......In this report all-optical 2R-regeneration in optical communication systems is investigated. A simple regenerator device based on concatenated semiconductor optical amplifiers (SOAs) and electro absorbers (EAs) is introduced and examined. Experiments show that the monolithic SOA-EA 2R...

Optically pumped semiconductor lasers for atomic and molecular physics

Science.gov (United States)

Burd, S.; Leibfried, D.; Wilson, A. C.; Wineland, D. J.

2015-03-01

Experiments in atomic, molecular and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power and intensity stability. Optically pumped semiconductor lasers (OPSLs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. We are developing a source for laser cooling and spectroscopy of Mg+ ions at 280 nm, based on a frequency quadrupled OPSL with the gain chip fabricated at the ORC at Tampere Univ. of Technology, Finland. This OPSL system could serve as a prototype for many other sources used in atomic and molecular physics.

Quantum theory of the optical and electronic properties of semiconductors

CERN Document Server

Haug, Hartmut

2009-01-01

This invaluable textbook presents the basic elements needed to understand and research into semiconductor physics. It deals with elementary excitations in bulk and low-dimensional semiconductors, including quantum wells, quantum wires and quantum dots. The basic principles underlying optical nonlinearities are developed, including excitonic and many-body plasma effects. Fundamentals of optical bistability, semiconductor lasers, femtosecond excitation, the optical Stark effect, the semiconductor photon echo, magneto-optic effects, as well as bulk and quantum-confined Franz-Keldysh effects, are covered. The material is presented in sufficient detail for graduate students and researchers with a general background in quantum mechanics.This fifth edition includes an additional chapter on 'Quantum Optical Effects' where the theory of quantum optical effects in semiconductors is detailed. Besides deriving the 'semiconductor luminescence equations' and the expression for the stationary luminescence spectrum, the resu...

Compound semiconductor optical waveguide switch

Science.gov (United States)

Spahn, Olga B.; Sullivan, Charles T.; Garcia, Ernest J.

2003-06-10

An optical waveguide switch is disclosed which is formed from III-V compound semiconductors and which has a moveable optical waveguide with a cantilevered portion that can be bent laterally by an integral electrostatic actuator to route an optical signal (i.e. light) between the moveable optical waveguide and one of a plurality of fixed optical waveguides. A plurality of optical waveguide switches can be formed on a common substrate and interconnected to form an optical switching network.

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.

The Dynamics of Semiconductor Optical Amplifiers – Modeling and Applications

DEFF Research Database (Denmark)

Mørk, Jesper; Nielsen, Mads Lønstrup; Berg, Tommy Winther

2003-01-01

The importance of semiconductor optical amplifiers is discussed. A semiconductor optical amplifier (SOA) is a semiconductor laser with anti-reflection coated facets that amplifies an injected light signal by means of stimulated emission. SOAs have a number of unique properties that open up...

Semiconductor light sources fabricated by vapor phase epitaxial regrowth

International Nuclear Information System (INIS)

Powazinik, W.; Olshansky, R.; Meland, E.; Lauer, R.B.

1986-01-01

An extremely versatile technique for the fabrication of semiconductor light sources is described. The technique which is based on the halide vapor phase regrowth (VPR) of InP on channeled and selectively etched InGaAsP/InP double heterostructure material, results in a buried heterostructure (BH) index-guided VPR-BH diode laser structure which can be optimized for a number of different types of semiconductor light sources. The conditions and parameters associated with the halide VPR process are given, and the properties of the regrown InP are reported. The processing and characterization of high-frequency lasers with 18-GHz bandwidths and high-power lasers with cw single-spatial-mode powers of 60 mW are described. Additionally, the fabrication and characterization of superluminescent LEDs based on the this basic VPR-BH structure are described. These LEDs are capable of coupling more than 80 μW of optical power into a single-mode fiber at 100 mA, and can couple as much as 8 μW of optical power into a single-mode fiber at drive currents as low as 20 mA

All optical regeneration using semiconductor devices

DEFF Research Database (Denmark)

Mørk, Jesper; Öhman, Filip; Tromborg, Bjarne

All-optical regeneration is a key functionality for implementing all-optical networks. We present a simple theory for the bit-error-rate in links employing all-optical regenerators, which elucidates the interplay between the noise and and nonlinearity of the regenerator. A novel device structure ...... is analyzed, emphasizing general aspects of active semiconductor waveguides....

Semiconductor devices for all-optical regeneration

DEFF Research Database (Denmark)

Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne

2003-01-01

We review different implementations of semiconductor devices for all-optical regeneration. A general model will be presented for all-optical regeneration in fiber links, taking into consideration the trade-off between non-linearity and noise. Furthermore we discuss a novel regenerator type, based...

Quantum Dot Semiconductor Optical Amplifiers - Physics and Applications

DEFF Research Database (Denmark)

Berg, Tommy Winther

2004-01-01

This thesis describes the physics and applications of quantum dot semiconductor optical amplifiers based on numerical simulations. These devices possess a number of unique properties compared with other types of semiconductor amplifiers, which should allow enhanced performance of semiconductor...... respects is comparable to those of fiber amplifiers. The possibility of inverting the optically active states to a large degree is essential in order to achieve this performance. Optical signal processing through cross gain modulation and four wave mixing is modeled and described. For both approaches...... and QW devices and to experiments on quantum dot amplifiers. These comparisons outline the qualitative differences between the different types of amplifiers. In all cases focus is put on the physical processes responsible the differences....

CO2 laser pulse switching by optically excited semiconductors

International Nuclear Information System (INIS)

Silva, V.L. da.

1986-01-01

The construction and the study of a semi-conductor optical switch used for generating short infrared pulses and to analyse the semiconductor characteristics, are presented. The switch response time depends on semiconductor and control laser characteristics. The results obtained using a Ge switch controlled by N 2 , NdYag and Dye lasers are presented. The response time was 50 ns limited by Ge recombination time. The reflectivity increased from 7% to 59% using N 2 laser to control the switch. A simple model for semiconductor optical properties that explain very well the experimental results, is also presented. (author) [pt

Semiconductor optical amplifier-based all-optical gates for high-speed optical processing

DEFF Research Database (Denmark)

Stubkjær, Kristian

2000-01-01

Semiconductor optical amplifiers are useful building blocks for all-optical gates as wavelength converters and OTDM demultiplexers. The paper reviews the progress from simple gates using cross-gain modulation and four-wave mixing to the integrated interferometric gates using cross-phase modulation....... These gates are very efficient for high-speed signal processing and open up interesting new areas, such as all-optical regeneration and high-speed all-optical logic functions...

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)

OPTICAL AND DYNAMIC PROPERTIES OF UNDOPED AND DOPED SEMICONDUCTOR NANOSTRUCTURES

Energy Technology Data Exchange (ETDEWEB)

Grant, C D; Zhang, J Z

2007-09-28

This chapter provides an overview of some recent research activities on the study of optical and dynamic properties of semiconductor nanomaterials. The emphasis is on unique aspects of these properties in nanostructures as compared to bulk materials. Linear, including absorption and luminescence, and nonlinear optical as well as dynamic properties of semiconductor nanoparticles are discussed with focus on their dependence on particle size, shape, and surface characteristics. Both doped and undoped semiconductor nanomaterials are highlighted and contrasted to illustrate the use of doping to effectively alter and probe nanomaterial properties. Some emerging applications of optical nanomaterials are discussed towards the end of the chapter, including solar energy conversion, optical sensing of chemicals and biochemicals, solid state lighting, photocatalysis, and photoelectrochemistry.

Semiconductor nanoparticles with spatial separation of charge carriers: synthesis and optical properties

International Nuclear Information System (INIS)

Vasiliev, Roman B; Dirin, Dmitry N; Gaskov, Alexander M

2011-01-01

The results of studies on core/shell semiconductor nanoparticles with spatial separation of photoexcited charge carriers are analyzed and generalized. Peculiarities of the electronic properties of semiconductor/semiconductor heterojunctions formed inside such particles are considered. Data on the effect of spatial separation of charge carriers on the optical properties of nanoparticles including spectral shifts of the exciton bands, absorption coefficients and electron–hole pair recombination times are presented. Methods of synthesis of core/shell semiconductor nanoparticles in solutions are discussed. Specific features of the optical properties of anisotropic semiconductor nanoparticles with the semiconductor/semiconductor junctions are noted. The bibliography includes 165 references.

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...

Integrated semiconductor twin-microdisk laser under mutually optical injection

Energy Technology Data Exchange (ETDEWEB)

Zou, Ling-Xiu; Liu, Bo-Wen; Lv, Xiao-Meng; Yang, Yue-De; Xiao, Jin-Long; Huang, Yong-Zhen, E-mail: yzhuang@semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2015-05-11

We experimentally study the characteristics of an integrated semiconductor twin-microdisk laser under mutually optical injection through a connected optical waveguide. Based on the lasing spectra, four-wave mixing, injection locking, and period-two oscillation states are observed due to the mutually optical injection by adjusting the injected currents applied to the two microdisks. The enhanced 3 dB bandwidth is realized for the microdisk laser at the injection locking state, and photonic microwave is obtained from the electrode of the microdisk laser under the period-two oscillation state. The plentifully dynamical states similar as semiconductor lasers subject to external optical injection are realized due to strong optical interaction between the two microdisks.

Return-map for semiconductor lasers with optical feedback

DEFF Research Database (Denmark)

Mørk, Jesper; Tromborg, Bjarne; Sabbatier, H.

1999-01-01

It is well known that a semiconductor laser exposed to moderate optical feedback and biased near threshold exhibits the phenomenon of low-frequency intensity fluctuations (LFF). While this behavior can be numerically simulated using the so-called Lang-Kobayshi model, the interpretation of the phe......It is well known that a semiconductor laser exposed to moderate optical feedback and biased near threshold exhibits the phenomenon of low-frequency intensity fluctuations (LFF). While this behavior can be numerically simulated using the so-called Lang-Kobayshi model, the interpretation...

Effects of Coupling Lens on Optical Refrigeration of Semiconductors

International Nuclear Information System (INIS)

Kai, Ding; Yi-Ping, Zeng

2008-01-01

Optical refrigeration of semiconductors is encountering efficiency difficulties caused by nonradiative recombination and luminescence trapping. A commonly used approach for enhancing luminescence efficiency of a semiconductor device is coupling a lens with the device. We quantitatively study the effects of a coupling lens on optical refrigeration based on rate equations and photon recycling, and calculated cooling efficiencies of different coupling mechanisms and of different lens materials. A GaAs/GaInP heterostructure coupled with a homo-epitaxial GaInP hemispherical lens is recommended. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Integrated semiconductor optical sensors for chronic, minimally-invasive imaging of brain function.

Science.gov (United States)

Lee, Thomas T; Levi, Ofer; Cang, Jianhua; Kaneko, Megumi; Stryker, Michael P; Smith, Stephen J; Shenoy, Krishna V; Harris, James S

2006-01-01

Intrinsic optical signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light sources and detectors operating at telecommunications wavelengths in the near-infrared. Such a device will allow for long-term, minimally invasive monitoring of neural activity in freely behaving subjects, and will enable the use of structured illumination patterns to improve system performance. In this work we describe the proposed system and show that near-infrared IOS imaging at wavelengths compatible with semiconductor devices can produce physiologically significant images in mice, even through skull.

Semiconductor processing apparatus with compact free radical source

NARCIS (Netherlands)

Kovalgin, Alexeij Y.; Aarnink, Antonius A.I.

2013-01-01

A semiconductor processing apparatus (1), comprising: a substrate processing chamber (158), defining a substrate support location (156) at which a generally planar semiconductor substrate (300) is supportable; and at least one free radical source (200), including: a precursor gas source (250); an

All-metal coupling and package of semiconductor laser and amplifier with optical fiber

International Nuclear Information System (INIS)

Xu Fenglan; Li Lina; Zhang Yueqing

1992-01-01

The semiconductor laser and optical amplifier made by Changchun Institute of Physics coupled with optical fiber by use of all-metal coupling are represented. The net gain of semiconductor laser amplifier with optical fiber is 14 ∼18 dB

All-semiconductor metamaterial-based optical circuit board at the microscale

International Nuclear Information System (INIS)

Min, Li; Huang, Lirong

2015-01-01

The newly introduced metamaterial-based optical circuit, an analogue of electronic circuit, is becoming a forefront topic in the fields of electronics, optics, plasmonics, and metamaterials. However, metals, as the commonly used plasmonic elements in an optical circuit, suffer from large losses at the visible and infrared wavelengths. We propose here a low-loss, all-semiconductor metamaterial-based optical circuit board at the microscale by using interleaved intrinsic GaAs and doped GaAs, and present the detailed design process for various lumped optical circuit elements, including lumped optical inductors, optical capacitors, optical conductors, and optical insulators. By properly combining these optical circuit elements and arranging anisotropic optical connectors, we obtain a subwavelength optical filter, which can always hold band-stop filtering function for various polarization states of the incident electromagnetic wave. All-semiconductor optical circuits may provide a new opportunity in developing low-power and ultrafast components and devices for optical information processing

BROADBAND TRAVELLING WAVE SEMICONDUCTOR OPTICAL AMPLIFIER

DEFF Research Database (Denmark)

2010-01-01

Broadband travelling wave semiconductor optical amplifier (100, 200, 300, 400, 800) for amplification of light, wherein the amplifier (100, 200, 300, 400, 800) comprises a waveguide region (101, 201, 301, 401, 801) for providing confinement of the light in transverse directions and adapted...

Testing methodologies and systems for semiconductor optical amplifiers

Science.gov (United States)

Wieckowski, Michael

Semiconductor optical amplifiers (SOA's) are gaining increased prominence in both optical communication systems and high-speed optical processing systems, due primarily to their unique nonlinear characteristics. This in turn, has raised questions regarding their lifetime performance reliability and has generated a demand for effective testing techniques. This is especially critical for industries utilizing SOA's as components for system-in-package products. It is important to note that very little research to date has been conducted in this area, even though production volume and market demand has continued to increase. In this thesis, the reliability of dilute-mode InP semiconductor optical amplifiers is studied experimentally and theoretically. The aging characteristics of the production level devices are demonstrated and the necessary techniques to accurately characterize them are presented. In addition, this work proposes a new methodology for characterizing the optical performance of these devices using measurements in the electrical domain. It is shown that optical performance degradation, specifically with respect to gain, can be directly qualified through measurements of electrical subthreshold differential resistance. This metric exhibits a linear proportionality to the defect concentration in the active region, and as such, can be used for prescreening devices before employing traditional optical testing methods. A complete theoretical analysis is developed in this work to explain this relationship based upon the device's current-voltage curve and its associated leakage and recombination currents. These results are then extended to realize new techniques for testing semiconductor optical amplifiers and other similarly structured devices. These techniques can be employed after fabrication and during packaged operation through the use of a proposed stand-alone testing system, or using a proposed integrated CMOS self-testing circuit. Both methods are capable

Optical memory

Science.gov (United States)

Mao, Samuel S; Zhang, Yanfeng

2013-07-02

Optical memory comprising: a semiconductor wire, a first electrode, a second electrode, a light source, a means for producing a first voltage at the first electrode, a means for producing a second voltage at the second electrode, and a means for determining the presence of an electrical voltage across the first electrode and the second electrode exceeding a predefined voltage. The first voltage, preferably less than 0 volts, different from said second voltage. The semiconductor wire is optically transparent and has a bandgap less than the energy produced by the light source. The light source is optically connected to the semiconductor wire. The first electrode and the second electrode are electrically insulated from each other and said semiconductor wire.

Optical double-locked semiconductor lasers

Science.gov (United States)

AlMulla, Mohammad

2018-06-01

Self-sustained period-one (P1) nonlinear dynamics of a semiconductor laser are investigated when both optical injection and modulation are applied for stable microwave frequency generation. Locking the P1 oscillation through modulation on the bias current, injection strength, or detuning frequency stabilizes the P1 oscillation. Through the phase noise variance, the different modulation types are compared. It is demonstrated that locking the P1 oscillation through optical modulation on the output of the master laser outperforms bias-current modulation of the slave laser. Master laser modulation shows wider P1-oscillation locking range and lower phase noise variance. The locking characteristics of the P1 oscillation also depend on the operating conditions of the optical injection system

Optical Properties of Semiconductor Quantum Dots

NARCIS (Netherlands)

Perinetti, U.

2011-01-01

This thesis presents different optical experiments performed on semiconductor quantum dots. These structures allow to confine a small number of electrons and holes to a tiny region of space, some nm across. The aim of this work was to study the basic properties of different types of quantum dots

Optical Biosensors Based on Semiconductor Nanostructures

Directory of Open Access Journals (Sweden)

Raúl J. Martín-Palma

2009-06-01

Full Text Available The increasing availability of semiconductor-based nanostructures with novel and unique properties has sparked widespread interest in their use in the field of biosensing. The precise control over the size, shape and composition of these nanostructures leads to the accurate control of their physico-chemical properties and overall behavior. Furthermore, modifications can be made to the nanostructures to better suit their integration with biological systems, leading to such interesting properties as enhanced aqueous solubility, biocompatibility or bio-recognition. In the present work, the most significant applications of semiconductor nanostructures in the field of optical biosensing will be reviewed. In particular, the use of quantum dots as fluorescent bioprobes, which is the most widely used application, will be discussed. In addition, the use of some other nanometric structures in the field of biosensing, including porous semiconductors and photonic crystals, will be presented.

Entangling quantum-logic gate operated with an ultrabright semiconductor single-photon source.

Science.gov (United States)

Gazzano, O; Almeida, M P; Nowak, A K; Portalupi, S L; Lemaître, A; Sagnes, I; White, A G; Senellart, P

2013-06-21

We demonstrate the unambiguous entangling operation of a photonic quantum-logic gate driven by an ultrabright solid-state single-photon source. Indistinguishable single photons emitted by a single semiconductor quantum dot in a micropillar optical cavity are used as target and control qubits. For a source brightness of 0.56 photons per pulse, the measured truth table has an overlap with the ideal case of 68.4±0.5%, increasing to 73.0±1.6% for a source brightness of 0.17 photons per pulse. The gate is entangling: At a source brightness of 0.48, the Bell-state fidelity is above the entangling threshold of 50% and reaches 71.0±3.6% for a source brightness of 0.15.

Polarization-insensitive quantum-dot coupled quantum-well semiconductor optical amplifier

International Nuclear Information System (INIS)

Huang Lirong; Yu Yi; Tian Peng; Huang Dexiu

2009-01-01

The optical gain of a quantum-dot semiconductor optical amplifier is usually seriously dependent on polarization; we propose a quantum-dot coupled tensile-strained quantum-well structure to obtain polarization insensitivity. The tensile-strained quantum well not only serves as a carrier injection layer of quantum dots but also offers gain to the transverse-magnetic mode. Based on the polarization-dependent coupled carrier rate-equation model, we study carrier competition among quantum well and quantum dots, and study the polarization dependence of the quantum-dot coupled quantum-well semiconductor optical amplifier. We also analyze polarization-dependent photon-mediated carrier distribution among quantum well and quantum dots. It is shown that polarization-insensitive gain can be realized by optimal design

Possible power source found for fiber optic lasers

International Nuclear Information System (INIS)

Krupa, Tyler J.

2000-01-01

Scientists at the US Department of Energy's Sandia National Laboratory are researching ways to use a new semiconductor alloy, indium gallium arsenide nitride (InGaAsN), as as photovoltaic power source for lasers in fiber optics and space communication satellites. The efficiency of electricity-generating solar cells utilizing InGaAsN is predicted to be 40%-nearly twice the efficiency rate of a standard silicon solar cell. The use of InGaAsN in solar cells is a potential power source for satellites and other space systems. (AIP) (c)

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.

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.

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.

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)

Conversion from non-orthogonally to orthogonally polarized optical single-sideband modulation using optically injected semiconductor lasers.

Science.gov (United States)

Hung, Yu-Han; Tseng, Chin-Hao; Hwang, Sheng-Kwang

2018-06-01

This Letter investigates an optically injected semiconductor laser for conversion from non-orthogonally to orthogonally polarized optical single-sideband modulation. The underlying mechanism relies solely on nonlinear laser characteristics and, thus, only a typical semiconductor laser is required as the key conversion unit. This conversion can be achieved for a broadly tunable frequency range up to at least 65 GHz. After conversion, the microwave phase quality, including linewidth and phase noise, is mostly preserved, and simultaneous microwave amplification up to 23 dB is feasible.

High-performance semiconductor optical preamplifier receiver at 10 Gb/s

DEFF Research Database (Denmark)

Mikkelsen, Benny; Jørgensen, Carsten Gudmann; Jensen, N.

1993-01-01

A semiconductor optical preamplifier receiver for bitrates of 10 Gb/s is described. The measured sensitivity is -28 dBm, with a polarization sensitivity of less than 0.5 dB. Using the same transmitter and receiver configuration but with a 980-nm pumped fiber amplifier instead of the semiconductor...... amplifier, the sensitivity is -34 dBm...

Infrared magneto-optical properties of (III, Mn)V ferromagnetic semiconductors

Czech Academy of Sciences Publication Activity Database

Sinova, J.; Jungwirth, Tomáš; Kučera, Jan; MacDonald, A. H.

2003-01-01

Roč. 67, č. 23 (2003), s. 235203-1 - 235203-11 ISSN 0163-1829 R&D Projects: GA ČR GA202/02/0912 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * diluted magnetic semiconductors * magneto-optical properties ac-Hall conductivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.962, year: 2003

Synthesis and optical properties of novel organic-inorganic hybrid nanolayer structure semiconductors

International Nuclear Information System (INIS)

Zhang Sanjun; Lanty, Gaetan; Lauret, Jean-Sebastien; Deleporte, Emmanuelle; Audebert, Pierre; Galmiche, Laurent

2009-01-01

We report on the synthesis of some novel organic-inorganic hybrid 2D perovskite semiconductors (R-(CH 2 ) n NH 3 ) 2 PbX 4 . These semiconductors are self-assembled intercalation nanolayers and have a multi-quantum-well energy level structure. We systematically vary the characteristic of organic groups (R-(CH 2 ) n NH 3 + ) to study the relationship between their structures and the optical properties of (R-(CH 2 ) n NH 3 ) 2 PbX 4 . From optical absorption and photoluminescence spectroscopy experiments performed on series of samples, we find some trends of choosing the organic groups to improve the optical performance of (R-(CH 2 ) n NH 3 ) 2 PbX 4 . A new organic group, which allows synthesis of nanolayer perovskite semiconductors with quite high photoluminescence efficiency and better long-term stability, has been found.

FDTD simulations of near-field mediated semiconductor molecular optical properties

Energy Technology Data Exchange (ETDEWEB)

Zhang, Dai; Sakrow, Marcus; Mihaljevic, Josip; Meixner, Alfred J. [Institute of Physical and Theoretical Chemistry, University Tuebingen, Auf der Morgenstelle 8, Tuebingen (Germany)

2010-07-01

The optical properties of molecules can be dramatically altered when they are in a close proximity of an excited metal antenna. In order to get insight into how the antenna generated near-field influences the optical properties of low quantum yield molecules, we carried out FDTD simulations of a sharp laser-illuminated Au tip approaching to a semiconductor thin film. The time-averaged field distribution between the semiconductor thin film and the tip antenna is calculated regarding to different distances. Our calculation demonstrates that the coupling between the localized plasmon at the tip apex and semiconductor polariton can be achieved building up a distance-dependent high field enhancement. Our experimental results show that such a high field strength enhances not only the excitation process by a factor of 104, but alters the radiative: non-radiative decay rate giving approx. 15 times stronger photoluminescence emission.

Ultrafast dynamics in semiconductor optical amplifiers and all-optical processing: Bulk versus quantum dot devices

DEFF Research Database (Denmark)

Mørk, Jesper; Berg, Tommy Winther; Magnúsdóttir, Ingibjörg

2003-01-01

We discuss the dynamical properties of semiconductor optical amplifiers and the importance for all-optical signal processing. In particular, the dynamics of quantum dot amplifiers is considered and it is suggested that these may be operated at very high bit-rates without significant patterning...

Fiber optical laser spot microscope: A new concept for photoelectrochemical characterization of semiconductor electrodes

OpenAIRE

Carlsson, Per; Holmström, Bertil; Uosaki, Kohei; Kita, Hideaki

1988-01-01

A fiber optical laser spot microscope, which allows the simultaneous measurements of photocurrent and reflected light intensity or the measurement of laser spot photocurrent under the illumination of other light sources, has been developed to study semiconductor/electrolyte interfaces. The capability of this microscope was demonstrated on as-cleaved and Pt-treated p-InSe. The Pt treatment increased the photocurrent and improved the lateral resolution due to the increase of surface reaction ra...

Electronic and optical properties of diamond/organic semiconductor heterostructures

Energy Technology Data Exchange (ETDEWEB)

Gajewski, Wojciech; Garrido, Jose; Niedermeier, Martin; Stutzmann, Martin [Walter Schottky Institute, TU Muenchen, Am Coulombwall 3, 85748 Garching (Germany); Williams, Oliver; Haenen, Ken [Institute for Materials Research, University of Hasselt, Wetenschapspark 1, BE-3590 Diepenbeek (Belgium)

2007-07-01

Different diamond substrates (single crystalline: SCD, poly-crystalline: PCD and nano-crystalline: NCD) were used to investigate the electronic and optical properties of the diamond/organic semiconductor heterostructures. Layers of a poly[ethynyl-(2-decyloxy-5methoxy)benzene] - PEB, pentacene and 4-nitro-biphenyl-4-diazonium cations - Ph-Ph-NO{sub 2} were prepared by spin coating, thermal evaporation and grafting, respectively. The measurements of the electronic transport along the organic layer were performed using a Hg probe as well as Hall effect measurements in the temperature range 70-400 K. The I-V characteristics of the B-doped diamond/organic semiconductor heterostructures were measured at room temperature by means of the Hg probe. Undoped IIa and undoped PCD films were used for a study of the optical and optoelectronic properties of prepared heterostructures. The influence of the organic layer homogeneity and layer thickness on the optical properties will be discussed. Furthermore, preliminary data on perpendicular and parallel transport in the heterostructures layer will be reported.

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

Low-frequency active surface plasmon optics on semiconductors

NARCIS (Netherlands)

Gómez Rivas, J.; Kuttge, M.; Kurz, H.; Haring Bolivar, P.; Sánchez-Gil, J.A.

2006-01-01

A major challenge in the development of surface plasmon optics or plasmonics is the active control of the propagation of surface plasmon polaritons (SPPs). Here, we demonstrate the feasibility of low-frequency active plasmonics using semiconductors. We show experimentally that the Bragg scattering

Semi-analytical model of filtering effects in microwave phase shifters based on semiconductor optical amplifiers

DEFF Research Database (Denmark)

Chen, Yaohui; Xue, Weiqi; Öhman, Filip

2008-01-01

We present a model to interpret enhanced microwave phase shifts based on filter assisted slow and fast light effects in semiconductor optical amplifiers. The model also demonstrates the spectral phase impact of input optical signals.......We present a model to interpret enhanced microwave phase shifts based on filter assisted slow and fast light effects in semiconductor optical amplifiers. The model also demonstrates the spectral phase impact of input optical signals....

Optical Two-Dimensional Spectroscopy of Disordered Semiconductor Quantum Wells and Quantum Dots

Energy Technology Data Exchange (ETDEWEB)

Cundiff, Steven T. [Univ. of Colorado, Boulder, CO (United States)

2016-05-03

This final report describes the activities undertaken under grant "Optical Two-Dimensional Spectroscopy of Disordered Semiconductor Quantum Wells and Quantum Dots". The goal of this program was to implement optical 2-dimensional Fourier transform spectroscopy and apply it to electronic excitations, including excitons, in semiconductors. Specifically of interest are quantum wells that exhibit disorder due to well width fluctuations and quantum dots. In both cases, 2-D spectroscopy will provide information regarding coupling among excitonic localization sites.

Optical trapping with Bessel beams generated from semiconductor lasers

International Nuclear Information System (INIS)

Sokolovskii, G S; Dudelev, V V; Losev, S N; Soboleva, K K; Deryagin, A G; Kuchinskii, V I; Sibbett, W; Rafailov, E U

2014-01-01

In this paper, we study generation of Bessel beams from semiconductor lasers with high beam propagation parameter M 2 and their utilization for optical trapping and manipulation of microscopic particles including living cells. The demonstrated optical tweezing with diodegenerated Bessel beams paves the way to replace their vibronic-generated counterparts for a range of applications towards novel lab-on-a-chip configurations

Ultrashort pulse-propagation effects in a semiconductor optical amplifier: Microscopic theory and experiment

DEFF Research Database (Denmark)

Hughes, S.; Borri, P.; Knorr, A.

2001-01-01

We present microscopic modeling and experimental measurements of femtosecond-pulse interactions in a semiconductor optical amplifier. Two novel nonlinear propagation effects are demonstrated: pulse breakup in the gain regime and pulse compression in the transparency regime. These propagation phen...... phenomena highlight the microscopic origin and important role of adiabatic following in semiconductor optical amplifiers. Fundamental light-matter interactions are discussed in detail and possible applications are highlighted....

Ultrafast Dynamics of Quantum-Dot Semiconductor Optical Amplifiers

DEFF Research Database (Denmark)

Poel, Mike van der; Hvam, Jørn Märcher

2007-01-01

We report on a series of experiments on the dynamical properties of quantum-dot semiconductor optical amplifiers. We show how the amplifier responds to one or several ultrafast (170 fs) pulses in rapid succession and our results demonstrate applicability and ultimate limitations to application...

Quantum confined laser devices optical gain and recombination in semiconductors

CERN Document Server

Blood, Peter

2015-01-01

The semiconductor laser, invented over 50 years ago, has had an enormous impact on the digital technologies that now dominate so many applications in business, commerce and the home. The laser is used in all types of optical fibre communication networks that enable the operation of the internet, e-mail, voice and skype transmission. Approximately one billion are produced each year for a market valued at around $5 billion. Nearly all semiconductor lasers now use extremely thin layers of light emitting materials (quantum well lasers). Increasingly smaller nanostructures are used in the form of quantum dots. The impact of the semiconductor laser is surprising in the light of the complexity of the physical processes that determine the operation of every device. This text takes the reader from the fundamental optical gain and carrier recombination processes in quantum wells and quantum dots, through descriptions of common device structures to an understanding of their operating characteristics. It has a consistent...

Digitally tunable dual wavelength emission from semiconductor ring lasers with filtered optical feedback

International Nuclear Information System (INIS)

Khoder, Mulham; Verschaffelt, Guy; Nguimdo, Romain Modeste; Danckaert, Jan; Leijtens, Xaveer; Bolk, Jeroen

2013-01-01

We report on a novel integrated approach to obtain dual wavelength emission from a semiconductor laser based on on-chip filtered optical feedback. Using this approach, we show experiments and numerical simulations of dual wavelength emission of a semiconductor ring laser. The filtered optical feedback is realized on-chip by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifiers are placed in the feedback loop in order to control the feedback strength of each wavelength channel independently. By tuning the current injected into each of the amplifiers, we can effectively cancel the gain difference between the wavelength channels due to fabrication and material dichroism, thus resulting in stable dual wavelength emission. We also explore the accuracy needed in the operational parameters to maintain this dual wavelength emission. (letter)

Resonantly enhanced nonlinear optics in semiconductor quantum wells: An application to sensitive infrared detection

International Nuclear Information System (INIS)

Yelin, S.F.; Hemmer, P.R.

2002-01-01

A novel class of coherent nonlinear optical phenomena, involving induced transparency in semiconductor quantum wells, is considered in the context of a particular application to sensitive long-wavelength infrared detection. It is shown that the strongest decoherence mechanisms can be suppressed or mitigated, resulting in substantial enhancement of nonlinear optical effects in semiconductor quantum wells

Monolithically integrated quantum dot optical modulator with Semiconductor optical amplifier for short-range optical communications

Science.gov (United States)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

2015-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed. Broadband QD optical gain material was used to achieve Gbps-order high-speed optical data transmission, and an optical gain change as high as approximately 6-7 dB was obtained with a low OGM voltage of 2.0 V. Loss of optical power due to insertion of the device was also effectively compensated for by the SOA section. Furthermore, it was confirmed that the QD-OGM/SOA device helped achieve 6.0-Gbps error-free optical data transmission over a 2.0-km-long photonic crystal fiber. We also successfully demonstrated generation of Gbps-order, high-speed, and error-free optical signals in the >5.5-THz broadband optical frequency bandwidth larger than the C-band. These results suggest that the developed monolithically integrated QD-OGM/SOA device will be an advantageous and compact means of increasing the usable optical frequency channels for short-reach communications.

Two-section semiconductor optical amplifier used as an efficient channel dropping node

DEFF Research Database (Denmark)

Jørgensen, Carsten; Storkfelt, Niels; Durhuus, T.

1992-01-01

High responsivity in a two-section semiconductor optical amplifier/detector, serving as a channel dropping mode is described. A simple receiver constructed using a 50 Ω amplifier with a sensitivity of -30.2 dBm at 140 Mb/s is demonstrated......High responsivity in a two-section semiconductor optical amplifier/detector, serving as a channel dropping mode is described. A simple receiver constructed using a 50 Ω amplifier with a sensitivity of -30.2 dBm at 140 Mb/s is demonstrated...

Synthesis and optical properties of novel organic-inorganic hybrid nanolayer structure semiconductors

Energy Technology Data Exchange (ETDEWEB)

Zhang Sanjun; Lanty, Gaetan; Lauret, Jean-Sebastien [Laboratoire de Photonique Quantique et Moleculaire de l' Ecole Normale Superieure de Cachan, 61 avenue du President Wilson, 94235 Cachan (France); Deleporte, Emmanuelle, E-mail: Emmanuelle.Deleporte@lpqm.ens-cachan.fr [Laboratoire de Photonique Quantique et Moleculaire de l' Ecole Normale Superieure de Cachan, 61 avenue du President Wilson, 94235 Cachan (France); Audebert, Pierre; Galmiche, Laurent [Laboratoire de Photophysique et Photochimie Supramoleculaires et Macromoleculaires de l' Ecole Normale Superieure de Cachan, 61 avenue du President Wilson, 94235 Cachan (France)

2009-06-15

We report on the synthesis of some novel organic-inorganic hybrid 2D perovskite semiconductors (R-(CH{sub 2}){sub n}NH{sub 3}){sub 2}PbX{sub 4}. These semiconductors are self-assembled intercalation nanolayers and have a multi-quantum-well energy level structure. We systematically vary the characteristic of organic groups (R-(CH{sub 2}){sub n}NH{sub 3}{sup +}) to study the relationship between their structures and the optical properties of (R-(CH{sub 2}){sub n}NH{sub 3}){sub 2}PbX{sub 4}. From optical absorption and photoluminescence spectroscopy experiments performed on series of samples, we find some trends of choosing the organic groups to improve the optical performance of (R-(CH{sub 2}){sub n}NH{sub 3}){sub 2}PbX{sub 4}. A new organic group, which allows synthesis of nanolayer perovskite semiconductors with quite high photoluminescence efficiency and better long-term stability, has been found.

Nonlinear optical studies in semiconductor-doped glasses under ...

Indian Academy of Sciences (India)

Abstract. Nonlinear optical studies in semiconductor-doped glasses (SDGs) are per- formed under femtosecond laser pulse excitation. Z-scan experiments with 800 nm wave- length pulses are used to excite SDG samples in the resonance and non-resonance regimes. Schott colour glass filter OG 515 shows stronger ...

Photonic processing and realization of an all-optical digital comparator based on semiconductor optical amplifiers

Science.gov (United States)

Singh, Simranjit; Kaur, Ramandeep; Kaler, Rajinder Singh

2015-01-01

A module of an all-optical 2-bit comparator is analyzed and implemented using semiconductor optical amplifiers (SOAs). By employing SOA-based cross phase modulation, the optical XNOR logic is used to get an A=B output signal, where as AB¯ and A¯B> logics operations are used to realize A>B and Aoperations results along with the wide open eye diagrams are obtained. It is suggested that the proposed system would be promising in all-optical high speed networks and computing systems.

Optical properties of hybrid semiconductor-metal structures

Energy Technology Data Exchange (ETDEWEB)

Kreilkamp, L.E.; Pohl, M.; Akimov, I.A.; Yakovlev, D.R.; Bayer, M. [Experimentelle Physik 2, Technische Universitaet Dortmund, 44221 Dortmund (Germany); Belotelov, V.I.; Zvezdin, A.K. [A.M. Prokhorov General Physics Institute, Russian Academy of Sciences, 119992 Moscow (Russian Federation); Karczewski, G.; Wojtowicz, T. [Institute of Physics, Polish Academy of Sciences, 02668 Warsaw (Poland); Rudzinski, A.; Kahl, M. [Raith GmbH, Konrad-Adenauer-Allee 8, 44263 Dortmund (Germany)

2012-07-01

We study the optical properties of hybrid nanostructures comprising a semiconductor CdTe quantum well (QW) separated by a thin CdMgTe cap layer of 40 nm from a patterned gold film. The CdTe/CdMgTe QW structure with a well width of 10nm was grown by molecular beam epitaxy. The one-dimensional periodic gold films on top were made using e-beam lithography and lift-off process. The investigated structures can be considered as plasmonic crystals because the metal films attached to the semiconductor are patterned with a period in the range from 475 to 600 nm, which is comparable to the surface plasmon-polariton (SPP) wavelength. Angle dependent reflection spectra at room temperature clearly show plasmonic resonances. PL spectra taken at low temperatures of about 10 K under below- and above-barrier illumination show significant modifications compared to the unstructured QW sample. The number of emission lines and their position shift change depending on the excitation energy. The role of exciton-SPP coupling and Schottky barrier at the semiconductor-metal interface are discussed.

Experimental and theoretical investigation of semiconductor optical amplifier (SOA) based all-optical switches

DEFF Research Database (Denmark)

Nielsen, Mads Lønstrup

2004-01-01

This thesis analyzes semiconductor optical amplifier (SOA) based all-optical switches experimentally and through numerical simulations. These devices are candidates for optical signal processing functionalities such as wavelength conversion, regeneration, and logic processing in future transparent......, consisting of an SOA and an asymmetric MZI filter, is analyzed in the small-signal regime, and the obtainable modulation bandwidth is expressed analytically. A new optical spectrum approach to small signal analysis is introduced, and is used to assess the bandwidth enhancing effect of different optical...... filters, as well the impact of the filter phase response. Experiments at 40 Gb/s verify the predictions of the small-signal analysis. Wavelength conversion is demonstrated experimentally at 40 Gb/s using a simple filtering-assisted scheme with an ultra-low optical switching energy, and up to 80 Gb...

Electronic displays using optically pumped luminescent semiconductor nanocrystals

Science.gov (United States)

Weiss, Shimon [Pinole, CA; Schlamp, Michael C [Plainsboro, NJ; Alivisatos, A Paul [Oakland, CA

2011-09-27

A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

All-optical NRZ-to-RZ data format conversion with optically injected laser diode or semiconductor optical amplifier

Science.gov (United States)

Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

2006-09-01

By injecting the optical NRZ data into a Fabry-Perot laser diode (FPLD) synchronously modulated at below threshold condition or a semiconductor optical amplifier (SOA) gain-depleted with a backward injected clock stream, the all-optical non-return to zero (NRZ) to return-to-zero (RZ) format conversion of a STM-64 date-stream for synchronous digital hierarchy (SDH) or an OC-192 data stream for synchronous optical network (SONET) in high-speed fiber-optic communication link can be performed. Without the assistance of any complicated RF electronic circuitry, the output RZ data-stream at bit rate of up to 10 Gbit/s is successfully transformed in the optically NRZ injection-locked FPLD, in which the incoming NRZ data induces gain-switching of the FPLD without DC driving current or at below threshold condition. A power penalty of 1.2 dB is measured after NRZ-to-RZ transformation in the FPLD. Alternatively, the all-optical 10Gbits/s NRZ-to-RZ format conversion can also be demonstrated in a semiconductor optical amplifier under a backward dark-optical-comb injection with its duty-cycle 70%, which is obtained by reshaping from the received data clock at 10 GHz. The incoming optical NRZ data-stream is transformed into a pulsed RZ data-stream with its duty-cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. In contrast to the FPLD, the SOA based NRZ-to-RZ converter exhibits an enhanced extinction ratio from 7 to 13 dB, and BER of 10 -13 at -18.5 dBm. In particular, the power penalty of the received RZ data-stream has greatly improved by 5 dB as compared to that obtained from FPLD.

Optical Nonlinearities and Ultrafast Carrier Dynamics in Semiconductor Quantum Dots

Energy Technology Data Exchange (ETDEWEB)

Klimov, V.; McBranch, D.; Schwarz, C.

1998-08-10

Low-dimensional semiconductors have attracted great interest due to the potential for tailoring their linear and nonlinear optical properties over a wide-range. Semiconductor nanocrystals (NC's) represent a class of quasi-zero-dimensional objects or quantum dots. Due to quantum cordhement and a large surface-to-volume ratio, the linear and nonlinear optical properties, and the carrier dynamics in NC's are significantly different horn those in bulk materials. napping at surface states can lead to a fast depopulation of quantized states, accompanied by charge separation and generation of local fields which significantly modifies the nonlinear optical response in NC's. 3D carrier confinement also has a drastic effect on the energy relaxation dynamics. In strongly confined NC's, the energy-level spacing can greatly exceed typical phonon energies. This has been expected to significantly inhibit phonon-related mechanisms for energy losses, an effect referred to as a phonon bottleneck. It has been suggested recently that the phonon bottleneck in 3D-confined systems can be removed due to enhanced role of Auger-type interactions. In this paper we report femtosecond (fs) studies of ultrafast optical nonlinearities, and energy relaxation and trap ping dynamics in three types of quantum-dot systems: semiconductor NC/glass composites made by high temperature precipitation, ion-implanted NC's, and colloidal NC'S. Comparison of ultrafast data for different samples allows us to separate effects being intrinsic to quantum dots from those related to lattice imperfections and interface properties.

Nonlinear optical effects in pure and N-doped semiconductors

International Nuclear Information System (INIS)

Donlagic, N.S.

2000-01-01

Over the last decades, the nonlinear optical properties of condensed matter systems have been an attractive and fruitful field of research. While the linear response functions of solids provide information about the elementary excitations of the systems, nonlinear optical experiments give insight into the dynamics of the fundamental many-body processes which are initiated by the external excitations. Stimulated by the experimental results, new theoretical concepts and methods have been developed in order to relate the observed phenomena to the microscopic properties of the investigated materials. The present work deals with the study of the nonlinear dynamics of the optical interband polarization in pure and n-doped semiconductors.In the first part of the thesis, the relaxation behavior of optically excited electron-hole pairs in a one-dimensional semiconductor, which are coupled to longitudinal optical phonons with an initial lattice temperature T>0, is studied with the help of quantum kinetic equations. Apart from Hartree-Fock-like Coulomb contributions, these equations contain additional Coulomb terms, the so-called vertex corrections, by which the influence of the electron-electron interaction on the electron-phonon scattering processes is taken into account. The numerical studies indicate that the vertex corrections are essential for a correct description of the excitonic dynamics.In the second part of the thesis, the attention is shifted to the characteristics of the optical response of a one-dimensional n-doped two-band semiconductor whose conduction band has been linearized with respect to the two Fermi points. Due to the linearization it is possible to calculate the linear and nonlinear response functions of the interacting electron system exactly. These response functions are then used in order to determine the linear absorption spectrum and the time-integrated signal of a degenerated four-wave-mixing experiment. It is shown that the well-known features

Analytical models of optical response in one-dimensional semiconductors

International Nuclear Information System (INIS)

Pedersen, Thomas Garm

2015-01-01

The quantum mechanical description of the optical properties of crystalline materials typically requires extensive numerical computation. Including excitonic and non-perturbative field effects adds to the complexity. In one dimension, however, the analysis simplifies and optical spectra can be computed exactly. In this paper, we apply the Wannier exciton formalism to derive analytical expressions for the optical response in four cases of increasing complexity. Thus, we start from free carriers and, in turn, switch on electrostatic fields and electron–hole attraction and, finally, analyze the combined influence of these effects. In addition, the optical response of impurity-localized excitons is discussed. - Highlights: • Optical response of one-dimensional semiconductors including excitons. • Analytical model of excitonic Franz–Keldysh effect. • Computation of optical response of impurity-localized excitons

NaAuS chicken-wire-like semiconductor: Electronic structure and optical properties

International Nuclear Information System (INIS)

Reshak, A.H.; Khan, Saleem Ayaz; Kamarudin, H.; Bila, Jiri

2014-01-01

Highlights: • Chicken wire like semiconductor NaAuS was investigated. • Good agreement with experimental data was found. • Electronic charge density of chicken wire like semiconductor NaAuS was obtained. • The calculated uniaxial anisotropy is −0.0005, indicating the strong anisotropy. -- Abstract: The electronic structure, charge density and optical properties of NaAuS a chicken-wire-like semiconductor was calculated using full potential linear augmented plane wave based on density functional theory. The Ceperley-Alder local density approximation, Perdew Becke Ernzerhof Generalized gradient approximation and Engel Voskov Generalized Gradient Approximation were applied to solve the exchange correlation potential. The investigation of band structures and density of states elucidates that Engle Vasko Generalized Gradient Approximation shows close agreement to the experimental data. The calculated valence charge density shows pure ionic nature of Au–Au bond. It becomes partially covalent when Au is connected with two Na atoms. The linear optical susceptibilities of chicken-wire-like NaAuS semiconductor are calculated so as to obtain further insight into the electronic properties. The uniaxial anisotropy is −0.0005, indicating the strong anisotropy of the dielectric function in the NaAuS a chicken-wire-like semiconductor

NaAuS chicken-wire-like semiconductor: Electronic structure and optical properties

Energy Technology Data Exchange (ETDEWEB)

Reshak, A.H. [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Khan, Saleem Ayaz, E-mail: sayaz_usb@yahoo.com [Institute of Complex Systems, FFPW, CENAKVA, University of South Bohemia in CB, Nove Hrady 37333 (Czech Republic); Kamarudin, H. [Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Bila, Jiri [Department of Instrumentation and Control Engineering, Faculty of Mechanical Engineering, CTU in Prague, Technicka 4, 166 07 Prague 6 (Czech Republic)

2014-01-05

Highlights: • Chicken wire like semiconductor NaAuS was investigated. • Good agreement with experimental data was found. • Electronic charge density of chicken wire like semiconductor NaAuS was obtained. • The calculated uniaxial anisotropy is −0.0005, indicating the strong anisotropy. -- Abstract: The electronic structure, charge density and optical properties of NaAuS a chicken-wire-like semiconductor was calculated using full potential linear augmented plane wave based on density functional theory. The Ceperley-Alder local density approximation, Perdew Becke Ernzerhof Generalized gradient approximation and Engel Voskov Generalized Gradient Approximation were applied to solve the exchange correlation potential. The investigation of band structures and density of states elucidates that Engle Vasko Generalized Gradient Approximation shows close agreement to the experimental data. The calculated valence charge density shows pure ionic nature of Au–Au bond. It becomes partially covalent when Au is connected with two Na atoms. The linear optical susceptibilities of chicken-wire-like NaAuS semiconductor are calculated so as to obtain further insight into the electronic properties. The uniaxial anisotropy is −0.0005, indicating the strong anisotropy of the dielectric function in the NaAuS a chicken-wire-like semiconductor.

All-optical wavelength conversion at bit rates above 10 Gb/s using semiconductor optical amplifiers

DEFF Research Database (Denmark)

Jørgensen, Carsten; Danielsen, Søren Lykke; Stubkjær, Kristian

1997-01-01

This work assesses the prospects for high-speed all-optical wavelength conversion using the simple optical interaction with the gain in semiconductor optical amplifiers (SOAs) via the interband carrier recombination. Operation and design guidelines for conversion speeds above 10 Gb/s are described...... and the various tradeoffs are discussed. Experiments at bit rates up to 40 Gb/s are presented for both cross-gain modulation (XGM) and cross-phase modulation (XPM) in SOAs demonstrating the high-speed capability of these techniques...

Analog direct-modulation behavior of semiconductor laser transmitters using optical FM demodulation

NARCIS (Netherlands)

Yabre, G.S.

1998-01-01

In this paper, we report a theoretical investigation of the analog modulation performance of a semiconductor laser transmitter which employs the direct optical FM demodulation. This analysis is based on the rate equations in which Langevin noise functions are included. The optical FM response has

Fast optical recording media based on semiconductor nanostructures for image recording and processing

International Nuclear Information System (INIS)

Kasherininov, P. G.; Tomasov, A. A.

2008-01-01

Fast optical recording media based on semiconductor nanostructures (CdTe, GaAs) for image recording and processing with a speed to 10 6 cycle/s (which exceeds the speed of known recording media based on metal-insulator-semiconductor-(liquid crystal) (MIS-LC) structures by two to three orders of magnitude), a photosensitivity of 10 -2 V/cm 2 , and a spatial resolution of 5-10 (line pairs)/mm are developed. Operating principles of nanostructures as fast optical recording media and methods for reading images recorded in such media are described. Fast optical processors for recording images in incoherent light based on CdTe crystal nanostructures are implemented. The possibility of their application to fabricate image correlators is shown.

High speed all optical logic gates based on quantum dot semiconductor optical amplifiers.

Science.gov (United States)

Ma, Shaozhen; Chen, Zhe; Sun, Hongzhi; Dutta, Niloy K

2010-03-29

A scheme to realize all-optical Boolean logic functions AND, XOR and NOT using semiconductor optical amplifiers with quantum-dot active layers is studied. nonlinear dynamics including carrier heating and spectral hole-burning are taken into account together with the rate equations scheme. Results show with QD excited state and wetting layer serving as dual-reservoir of carriers, as well as the ultra fast carrier relaxation of the QD device, this scheme is suitable for high speed Boolean logic operations. Logic operation can be carried out up to speed of 250 Gb/s.

Quantum theory of the optical and electronic properties of semiconductors

CERN Document Server

Haug, Hartmut

1990-01-01

The current technological revolution in the development of computing devices has created a demand for a textbook on the quantum theory of the electronic and optical properties of semiconductors and semiconductor devices. This book successfully fulfills this need. Based on lectures given by the authors, it is a comprehensive introduction for researchers or graduate-level students to the subject. Certain sections can also serve as a graduate-level textbook for use in solid state physics courses or for more specialized courses. The final chapters establish a direct link to current research in sem

Effect of temperature and phonons on the spectral properties of a multi-level semiconductor quantum dot single-photon source

DEFF Research Database (Denmark)

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

2009-01-01

Since it was realized that efficient quantum computing can be performed using single photons and standard linear optics elements, immense international research activity has been aimed at developing semiconductor quantum dot (QD) single-photon sources (SPS). In order to optimise the design of SPS...... us to study complicated multi-level QDs, not possible within the commonly used independent boson model (IBM)....

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

DEFF Research Database (Denmark)

Xu, Jing; Ding, Yunhong; Peucheret, Christophe

2011-01-01

We propose and demonstrate the use of a single semiconductor optical amplifier (SOA) and optical filtering to time demultiplex tributaries from an optical time division multiplexing-differential phase shift keying (OTDM-DPSK) signal. The scheme takes advantage of the fact that phase variations...... added to the target channel by cross-phase modulation from the control signal are effectively subtracted in the differential demodulation scheme employed for DPSK signals. Demultiplexing from 80 to 40 Gbit=s is demonstrated with moderate power penalty using an SOA with recovery time twice as long...

Microscopic investigations of the terahertz and the extreme nonlinear optical response of semiconductors

Energy Technology Data Exchange (ETDEWEB)

Golde, Daniel

2010-06-22

In the major part of this Thesis, we discuss the linear THz response of semiconductor nanostructures based on a microscopic theory. Here, two different problems are investigated: intersubband transitions in optically excited quantum wells and the THz plasma response of two-dimensional systems. In the latter case, we analyze the response of correlated electron and electron-hole plasmas. Extracting the plasma frequency from the linear response, we find significant deviations from the commonly accepted two-dimensional plasma frequency. Besides analyzing the pure plasma response, we also consider an intermediate regime where the response of the electron-hole plasma consists of a mixture of plasma contributions and excitonic transitions. A quantitative experiment-theory comparison provides novel insights into the behavior of the system at the transition from one regime to the other. The discussion of the intersubband transitions mainly focuses on the coherent superposition of the responses from true THz transitions and the ponderomotively accelerated carriers. We present a simple method to directly identify ponderomotive effects in the linear THz response. Apart from that, the excitonic contributions to intersubband transitions are investigated. The last part of the present Thesis deals with a completely different regime. Here, the extreme nonlinear optical response of low-dimensional semiconductor structures is discussed. Formally, extreme nonlinear optics describes the regime of light-matter interaction where the exciting field is strong enough such that the Rabi frequency is comparable to or larger than the characteristic transition frequency of the investigated system. Here, the Rabi frequency is given by the product of the electrical field strength and the dipole-matrix element of the respective transition. Theoretical investigations have predicted a large number of novel nonlinear effects arising for such strong excitations. Some of them have been observed in

Use of a reflective semiconductor optical amplifier and dual-ring architecture design to produce a stable multi-wavelength fiber laser

International Nuclear Information System (INIS)

Yeh, Chien-Hung; Chow, Chi-Wai; Lu, Shao-Sheng

2014-01-01

In this work, we propose and demonstrate a multi-wavelength laser source produced by utilizing a C-band reflective semiconductor optical amplifier (RSOA) with a dual-ring fiber cavity. Here, the laser cavity consists of an RSOA, a 1 × 2 optical coupler, a 2 × 2 optical coupler and a polarization controller. As a result, thirteen to eighteen wavelengths around the L band could be generated simultaneously when the bias current of the C-band RSOA was driven at 30–70 mA. In addition, the output stabilities of the power and wavelength are also discussed. (paper)

Use of a reflective semiconductor optical amplifier and dual-ring architecture design to produce a stable multi-wavelength fiber laser

Science.gov (United States)

Yeh, Chien-Hung; Chow, Chi-Wai; Lu, Shao-Sheng

2014-05-01

In this work, we propose and demonstrate a multi-wavelength laser source produced by utilizing a C-band reflective semiconductor optical amplifier (RSOA) with a dual-ring fiber cavity. Here, the laser cavity consists of an RSOA, a 1 × 2 optical coupler, a 2 × 2 optical coupler and a polarization controller. As a result, thirteen to eighteen wavelengths around the L band could be generated simultaneously when the bias current of the C-band RSOA was driven at 30-70 mA. In addition, the output stabilities of the power and wavelength are also discussed.

Non-equilibrium carrier efect in the optical properties of semiconductors

International Nuclear Information System (INIS)

Teschke, O.

1980-01-01

The time-resolved reflectivity of picosecond pulses from optically excited carrier distributions can provide important information about the energy relaxation rates of hot electrons and holes in semiconductors. the basic optical properties of non-equilibrium carrier distributions of GaAs are discussed. A semi-empirical analysis of the reflectivity spectrum is presented and the contributions of different effects are estimated. The results are in qualitative agreement with recent experiments employing dye lasers. (Author) [pt

Excitonic optical bistability in n-type doped semiconductors

International Nuclear Information System (INIS)

Nguyen Ba An; Le Thi Cat Tuong

1991-07-01

A resonant monochromatic pump laser generates coherent excitons in an n-type doped semiconductor. Both exciton-exciton and exciton-donor interactions come into play. The former interaction can give rise to the appearance of optical bistability which is heavily influenced by the latter one. When optical bistability occurs at a fixed laser frequency both its holding intensity and hysteresis loop size are shown to decrease with increasing donor concentration. Two possibilities are suggested for experimentally determining one of the two parameters of the system - the exciton-donor coupling constant and the donor concentration, if the other parameter is known beforehand. (author). 36 refs, 2 figs

2R Regeneration in Concatenated Semiconductor Optical Amplifiers and Electroabsorbers

DEFF Research Database (Denmark)

Christiansen, Lotte Jin; Xu, Lin; Yvind, Kresten

2004-01-01

We present a novel 2R regenerator with a large level separation and steep step a sharp, adjustable threshold based on concatenated semiconductor optical amplifiers and electroabsorbers. We demonstrate demonstrate improvements in both extinction-ratio and BER sensitivity atfor a 10 Gb/s NRZ signal....

All-optical pulse data generation in a semiconductor optical amplifier gain controlled by a reshaped optical clock injection

Science.gov (United States)

Lin, Gong-Ru; Chang, Yung-Cheng; Yu, Kun-Chieh

2006-05-01

Wavelength-maintained all-optical pulse data pattern transformation based on a modified cross-gain-modulation architecture in a strongly gain-depleted semiconductor optical amplifier (SOA) is investigated. Under a backward dark-optical-comb injection with 70% duty-cycle reshaping from the received data clock at 10GHz, the incoming optical data stream is transformed into a pulse data stream with duty cycle, rms timing jitter, and conversion gain of 15%, 4ps, and 3dB, respectively. The high-pass filtering effect of the gain-saturated SOA greatly improves the extinction ratio of data stream by 8dB and reduces its bit error rate to 10-12 at -18dBm.

Internal optical bistability of quasi-two-dimensional semiconductor nanoheterostructures

Science.gov (United States)

Derevyanchuk, Oleksandr V.; Kramar, Natalia K.; Kramar, Valeriy M.

2018-01-01

We represent the results of numerical computations of the frequency and temperature domains of possible realization of internal optical bistability in flat quasi-two-dimensional semiconductor nanoheterostructures with a single quantum well (i.e., nanofilms). Particular computations have been made for a nanofilm of layered semiconductor PbI2 embedded in dielectric medium, i.e. ethylene-methacrylic acid (E-MAA) copolymer. It is shown that an increase in the nanofilm's thickness leads to a long-wave shift of the frequency range of the manifestation the phenomenon of bistability, to increase the size of the hysteresis loop, as well as to the expansion of the temperature interval at which the realization of this phenomenon is possible.

Monolithically integrated quantum dot optical modulator with semiconductor optical amplifier for thousand and original band optical communication

Science.gov (United States)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Matsumoto, Atsushi; Kawanishi, Tetsuya

2016-04-01

A monolithically integrated quantum dot (QD) optical gain modulator (OGM) with a QD semiconductor optical amplifier (SOA) was successfully developed with T-band (1.0 µm waveband) and O-band (1.3 µm waveband) QD optical gain materials for Gbps-order, high-speed optical data generation. The insertion loss due to coupling between the device and the optical fiber was effectively compensated for by the SOA section. It was also confirmed that the monolithic QD-OGM/SOA device enabled >4.8 Gbps optical data generation with a clear eye opening in the T-band. Furthermore, we successfully demonstrated error-free 4.8 Gbps optical data transmissions in each of the six wavelength channels over a 10-km-long photonic crystal fiber using the monolithic QD-OGM/SOA device in multiple O-band wavelength channels, which were generated by the single QD gain chip. These results suggest that the monolithic QD-OGM/SOA device will be advantageous in ultra-broadband optical frequency systems that utilize the T+O-band for short- and medium-range optical communications.

Fast optical detecting media based on semiconductor nanostructures for recording images obtained using charges of free photocarriers

International Nuclear Information System (INIS)

Kasherininov, P. G.; Tomasov, A. A.; Beregulin, E. V.

2011-01-01

Available published data on the properties of optical recording media based on semiconductor structures are reviewed. The principles of operation, structure, parameters, and the range of application for optical recording media based on MIS structures formed of photorefractive crystals with a thick layer of insulator and MIS structures with a liquid crystal as the insulator (the MIS LC modulators), as well as the effect of optical bistability in semiconductor structures (semiconductor MIS structures with nanodimensionally thin insulator (TI) layer, M(TI)S nanostructures). Special attention is paid to recording media based on the M(TI)S nanostructures promising for fast processing of highly informative images and to fabrication of optoelectronic correlators of images for noncoherent light.

Layer-by-layer assembly of multicolored semiconductor quantum dots towards efficient blue, green, red and full color optical films

International Nuclear Information System (INIS)

Zhang Jun; Li Qian; Di Xiaowei; Liu Zhiliang; Xu Gang

2008-01-01

Multicolored semiconductor quantum dots have shown great promise for construction of miniaturized light-emitting diodes with compact size, low weight and cost, and high luminescent efficiency. The unique size-dependent luminescent property of quantum dots offers the feasibility of constructing single-color or full-color output light-emitting diodes with one type of material. In this paper, we have demonstrated the facile fabrication of blue-, green-, red- and full-color-emitting semiconductor quantum dot optical films via a layer-by-layer assembly technique. The optical films were constructed by alternative deposition of different colored quantum dots with a series of oppositely charged species, in particular, the new use of cationic starch on glass substrates. Semiconductor ZnSe quantum dots exhibiting blue emission were deposited for fabrication of blue-emitting optical films, while semiconductor CdTe quantum dots with green and red emission were utilized for construction of green- and red-emitting optical films. The assembly of integrated blue, green and red semiconductor quantum dots resulted in full-color-emitting optical films. The luminescent optical films showed very bright emitting colors under UV irradiation, and displayed dense, smooth and efficient luminous features, showing brighter luminescence in comparison with their corresponding quantum dot aqueous colloid solutions. The assembled optical films provide the prospect of miniaturized light-emitting-diode applications.

A study on the optical parts for a semiconductor laser module

Energy Technology Data Exchange (ETDEWEB)

Oh, Jun-Girl; Lee, Dong-Kil; Kim, Yang-Gyu; Lee, Kwang-Hoon; Park, Young-Sik [Korea Photonics Technology Institute, Gwangju (Korea, Republic of); Jang, Kwang-Ho [Hanvit Optoline, Gwangju (Korea, Republic of); Kang, Seung-Goo [COSET, Gwangju (Korea, Republic of)

2014-11-15

A semiconductor laser module consists of a LD (laser diode) chip that generates a laser beam, two cylindrical lenses to collimate the laser beam, a high-reflection mirror to produce a large output by collecting the laser beam, a collimator lens to guide the laser beam to an optical fiber and a protection filter to block reflected laser light that might damage the LD chip. The cylindrical lenses used in a semiconductor laser module are defined as FACs (fast axis collimators) and SACs (slow axis collimators) and are attached to the system module to control the shape of the laser beam. The FAC lens and the SAC lens are made of a glass material to protect the lenses from thermal deformation. In addition, they have aspheric shapes to improve optical performances. This paper presents a mold core grinding process for an asymmetrical aspheric lens and a GMP (glass molding press), what can be used to make aspheric cylindrical lenses for use as FACs or SACs, and a protection filter made by using IAD (ion-beam-assisted deposition). Finally, we developed the aspheric cylindrical lenses and the protection filter for a 10-W semiconductor laser module.

All-optical OR/NOR Bi-functional logic gate by using cross-gain modulation in semiconductor optical amplifiers

International Nuclear Information System (INIS)

Choi, Kyoung Sun; Byun, Young Tae; Lee, Seok; Jhon, Young Min

2010-01-01

An OR/NOR bi-functional all-optical logic gate has been experimentally demonstrated at 10 Gbit/s by using cross-gain modulation (XGM) in only 2 semiconductor optical amplifiers (SOAs). One SOA was used for NOR operation and the other SOA was used for inversion to obtain OR operation. Numerical simulation has also been performed, which coincided well with the experimental results.

New nonlinear optical effect: self-reflection phenomenon due to exciton-biexciton-light interaction in semiconductors

Science.gov (United States)

Khadzhi, P. I.; Lyakhomskaya, K. D.; Nadkin, L. Y.; Markov, D. A.

2002-05-01

The characteristic peculiarities of the self-reflection of a strong electromagnetic wave in a system of coherent excitons and biexcitons due to the exciton-photon interaction and optical exciton-biexciton conversion in semiconductors were investigated as one of the manifestations of nonlinear optical Stark-effect. It was found that a monotonously decreasing standing wave with an exponential decreasing spatial tail is formed in the semiconductor. Under the action of the field of a strong pulse, an optically homogeneous medium is converted, into the medium with distributed feedback. The appearance of the spatially separated narrow pears of the reflective index, extinction and reflection coefficients is predicted.

Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor Failure Conditions

DEFF Research Database (Denmark)

Gao, Feng; Loh, P.C.; Vilathgamuwa, D.M.

2007-01-01

reconfigure the gating signals in order to tolerate the failed semiconductor devices without significantly decreasing the ac output quality and amplitude by properly using the inherent boost characteristic of Z-source network. In addition, the Z-source dual inverters can maintain the zero common mode voltage...... under semiconductor failure conditions, which is the unique characteristic attained by the dual inverters only. Lastly, all theoretical findings are verified in PLECS simulations....

NONLINEAR OPTICAL PHENOMENA: Self-reflection in a system of excitons and biexcitons in semiconductors

Science.gov (United States)

Khadzhi, P. I.; Lyakhomskaya, K. D.

1999-10-01

The characteristic features of the self-reflection of a powerful electromagnetic wave in a system of coherent excitons and biexcitons in semiconductors were investigated as one of the manifestations of the nonlinear optical skin effect. It was found that a monotonically decreasing standing wave with an exponentially falling spatial tail is formed in the surface region of a semiconductor. Under the influence of the field of a powerful pulse, an optically homogeneous medium is converted into one with distributed feedback. The appearance of spatially separated narrow peaks of the refractive index, extinction coefficient, and reflection coefficient is predicted.

Quantum of optical absorption in two-dimensional semiconductors.

Science.gov (United States)

Fang, Hui; Bechtel, Hans A; Plis, Elena; Martin, Michael C; Krishna, Sanjay; Yablonovitch, Eli; Javey, Ali

2013-07-16

The optical absorption properties of free-standing InAs nanomembranes of thicknesses ranging from 3 nm to 19 nm are investigated by Fourier transform infrared spectroscopy. Stepwise absorption at room temperature is observed, arising from the interband transitions between the subbands of 2D InAs nanomembranes. Interestingly, the absorptance associated with each step is measured to be ∼1.6%, independent of thickness of the membranes. The experimental results are consistent with the theoretically predicted absorptance quantum, AQ = πα/nc for each set of interband transitions in a 2D semiconductor, where α is the fine structure constant and nc is an optical local field correction factor. Absorptance quantization appears to be universal in 2D systems including III-V quantum wells and graphene.

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

Structural and optical studies of local disorder sensitivity in natural organic-inorganic self-assembled semiconductors

Energy Technology Data Exchange (ETDEWEB)

Vijaya Prakash, G; Pradeesh, K [Nanophotonics Lab, Department of Physics, Indian Institute of Technology Delhi, New Delhi (India); Ratnani, R; Saraswat, K [Department of Pure and Applied Chemistry, MDS University, Ajmer (India); Light, M E [School of Chemistry, University of Southampton, Southampton (United Kingdom); Baumberg, J J, E-mail: prakash@physics.iitd.ac.i [Nanophotonic Centre, Cavendish Laboratory, University Cambridge, Cambridge CB3 OHE (United Kingdom)

2009-09-21

The structural and optical spectra of two related lead iodide (PbI) based self-assembled hybrid organic-inorganic semiconductors are compared. During the synthesis, depending on the bridging of organic moiety intercalated between the PbI two-dimensional planes, different crystal structures are produced. These entirely different networks show different structural and optical features, including excitonic bandgaps. In particular, the modified organic environment of the excitons is sensitive to the local disorder both in single crystal and thin film forms. Such information is vital for incorporating these semiconductors into photonic device architectures.

Semiconductor optical amplifiers for the 1000-1100-nm spectral range

International Nuclear Information System (INIS)

Lobintsov, A A; Shramenko, M V; Yakubovich, S D

2008-01-01

Two types of semiconductor optical amplifiers (SOAs) based on a double-layer quantum-well (InGa)As/(GaAl)As/GaAs heterostructure are investigated. The optical gain of more than 30 dB and saturation output power of more than 30 mW are achived at 1060 nm in pigtailed SOA modules. These SOAs used as active elements of a tunable laser provide rapid continuous tuning within 85 nm and 45 nm at output powers of 0.5 mW and more than 30 mW, respectively. (active media, lasers, and amplifiers)

Optical generation and control of quantum coherence in semiconductor nanostructures

CERN Document Server

Slavcheva, Gabriela

2010-01-01

The unprecedented control of coherence that can be exercised in quantum optics of atoms and molecules has stimulated increasing efforts in extending it to solid-state systems. One motivation to exploit the coherent phenomena comes from the emergence of the quantum information paradigm, however many more potential device applications ranging from novel lasers to spintronics are all bound up with issues in coherence. The book focuses on recent advances in the optical control of coherence in excitonic and polaritonic systems as model systems for the complex semiconductor dynamics towards the goal

Performance Evaluation of Three-Level Z-Source Inverters Under Semiconductor-Failure Conditions

DEFF Research Database (Denmark)

Gao, Feng; Loh, Poh Chiang; Blaabjerg, Frede

2009-01-01

This paper evaluates and proposes various compensation methods for three-level Z-source inverters under semiconductor-failure conditions. Unlike the fault-tolerant techniques used in traditional three-level inverters, where either an extra phase-leg or collective switching states are used......, the proposed methods for three-level Z-source inverters simply reconfigure their relevant gating signals so as to ride-through the failed semiconductor conditions smoothly without any significant decrease in their ac-output quality and amplitude. These features are partly attributed to the inherent boost...... under semiconductor-failure conditions. For verifying these described performance features, PLECS simulation and experimental testing were performed with some results captured and shown in a later section for visual confirmation....

A Novel Defect Inspection Method for Semiconductor Wafer Based on Magneto-Optic Imaging

Science.gov (United States)

Pan, Z.; Chen, L.; Li, W.; Zhang, G.; Wu, P.

2013-03-01

The defects of semiconductor wafer may be generated from the manufacturing processes. A novel defect inspection method of semiconductor wafer is presented in this paper. The method is based on magneto-optic imaging, which involves inducing eddy current into the wafer under test, and detecting the magnetic flux associated with eddy current distribution in the wafer by exploiting the Faraday rotation effect. The magneto-optic image being generated may contain some noises that degrade the overall image quality, therefore, in this paper, in order to remove the unwanted noise present in the magneto-optic image, the image enhancement approach using multi-scale wavelet is presented, and the image segmentation approach based on the integration of watershed algorithm and clustering strategy is given. The experimental results show that many types of defects in wafer such as hole and scratch etc. can be detected by the method proposed in this paper.

Acousto-optic modulation of III-V semiconductor multiple quantum wells

International Nuclear Information System (INIS)

Smith, D.L.; Kogan, S.M.; Ruden, P.P.; Mailhiot, C.

1996-01-01

We present an analysis of the effect of surface acoustic waves (SAW close-quote s) on the optical properties of III-V semiconductor multiple quantum wells (MQW close-quote s). Modulation spectra at the fundamental and second harmonic of the SAW frequency are presented. The SAW modulates the optical properties of the MQW primarily by changing optical transition energies. The SAW generates both strains, which modulate the transition energies by deformation potential effects, and electric fields, which modulate the transition energies by the quantum confined Stark effect. We find that modulation of the transition energies by strain effects is usually more important than by electric-field effects. If large static electric fields occur in the MQW, the SAW-generated electric field can mix with the static field to give optical modulation, which is comparable in magnitude to modulation from the deformation potential effect. If there are no large static electric fields, modulation by the SAW-generated fields is negligible. A large static electric field distributes oscillator strength among the various optical transitions so that no single transition is as strong as the primary allowed transitions without a static electric field. To achieve the maximum modulation for fixed SAW parameters, it is best to modulate a strong optical transition. Thus optimum modulation occurs when there are no large static electric fields present and that modulation is primarily from deformation potential effects. We specifically consider Ga x In 1-x As/Ga x Al 1-x As MQW close-quote s grown on (100) and (111) oriented substrates, but our general conclusions apply to other type I MQW close-quote s fabricated from III-V semiconductors. copyright 1996 The American Physical Society

Fault localization and analysis in semiconductor devices with optical-feedback infrared confocal microscopy

International Nuclear Information System (INIS)

Sarmiento, Raymund; Cemine, Vernon Julius; Tagaca, Imee Rose; Salvador, Arnel; Mar Blanca, Carlo; Saloma, Caesar

2007-01-01

We report on a cost-effective optical setup for characterizing light-emitting semiconductor devices with optical-feedback confocal infrared microscopy and optical beam-induced resistance change.We utilize the focused beam from an infrared laser diode to induce local thermal resistance changes across the surface of a biased integrated circuit (IC) sample. Variations in the multiple current paths are mapped by scanning the IC across the focused beam. The high-contrast current maps allow accurate differentiation of the functional and defective sites, or the isolation of the surface-emittingp-i-n devices in the IC. Optical beam-induced current (OBIC) is not generated since the incident beam energy is lower than the bandgap energy of the p-i-n device. Inhomogeneous current distributions in the IC become apparent without the strong OBIC background. They are located at a diffraction-limited resolution by referencing the current maps against the confocal reflectance image that is simultaneously acquired via optical-feedback detection. Our technique permits the accurate identification of metal and semiconductor sites as well as the classification of different metallic structures according to thickness, composition, or spatial inhomogeneity

Non-Drude optical conductivity of (III, Mn)V ferromagnetic semiconductors

Czech Academy of Sciences Publication Activity Database

Yang, S.R. E.; Sinova, J.; Jungwirth, Tomáš; Shim, Y. P.; MacDonald, A. H.

2003-01-01

Roč. 67, č. 4 (2003), s. 045205-1 - 045205-7 ISSN 0163-1829 R&D Projects: GA ČR GA202/02/0912; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : non-Drude optical conductivity * ferromagnetic semiconductors Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.962, year: 2003

Optical approach to thermopower and conductivity measurements in thin-film semiconductors

International Nuclear Information System (INIS)

Dersch, H.; Amer, N.M.

1984-01-01

An optical beam deflection technique is applied to measure the Joule and Peltier heat generated by electric currents through thin-film semiconductors. The method yields a spatially resolved conductivity profile and allows the determination of Peltier coefficients. Results obtained on doped hydrogenated amorphous silicon films are presented

Interband magneto-optical transitions in a layer of semiconductor nano-rings

NARCIS (Netherlands)

Voskoboynikov, O.; Wijers, Christianus M.J.; Liu, J.L.; Lee, C.P.

2005-01-01

We have developed a quantitative theory of the collective electromagnetic response of layers of semiconductor nano-rings. The response can be controlled by means of an applied magnetic field through the optical Aharonov-Bohm effect and is ultimately required for the design of composite materials. We

Semiconductor sensor for optically measuring polarization rotation of optical wavefronts using rare earth iron garnets

Science.gov (United States)

Duncan, Paul G.

2002-01-01

Described are the design of a rare earth iron garnet sensor element, optical methods of interrogating the sensor element, methods of coupling the optical sensor element to a waveguide, and an optical and electrical processing system for monitoring the polarization rotation of a linearly polarized wavefront undergoing external modulation due to magnetic field or electrical current fluctuation. The sensor element uses the Faraday effect, an intrinsic property of certain rare-earth iron garnet materials, to rotate the polarization state of light in the presence of a magnetic field. The sensor element may be coated with a thin-film mirror to effectively double the optical path length, providing twice the sensitivity for a given field strength or temperature change. A semiconductor sensor system using a rare earth iron garnet sensor element is described.

On-demand semiconductor single-photon source with near-unity indistinguishability.

Science.gov (United States)

He, Yu-Ming; He, Yu; Wei, Yu-Jia; Wu, Dian; Atatüre, Mete; Schneider, Christian; Höfling, Sven; Kamp, Martin; Lu, Chao-Yang; Pan, Jian-Wei

2013-03-01

Single-photon sources based on semiconductor quantum dots offer distinct advantages for quantum information, including a scalable solid-state platform, ultrabrightness and interconnectivity with matter qubits. A key prerequisite for their use in optical quantum computing and solid-state networks is a high level of efficiency and indistinguishability. Pulsed resonance fluorescence has been anticipated as the optimum condition for the deterministic generation of high-quality photons with vanishing effects of dephasing. Here, we generate pulsed single photons on demand from a single, microcavity-embedded quantum dot under s-shell excitation with 3 ps laser pulses. The π pulse-excited resonance-fluorescence photons have less than 0.3% background contribution and a vanishing two-photon emission probability. Non-postselective Hong-Ou-Mandel interference between two successively emitted photons is observed with a visibility of 0.97(2), comparable to trapped atoms and ions. Two single photons are further used to implement a high-fidelity quantum controlled-NOT gate.

Analysis of the Vignale-Kohn current functional in the calculation of the optical spectra of semiconductors

NARCIS (Netherlands)

Berger, J. A.; de Boeij, P. L.; van Leeuwen, R.

In this work, we investigate the Vignale-Kohn current functional when applied to the calculation of optical spectra of semiconductors. We discuss our results for silicon. We found qualitatively similar results for other semiconductors. These results show that there are serious limitations to the

EDITORIAL: Extreme Ultraviolet Light Sources for Semiconductor Manufacturing

Science.gov (United States)

Attwood, David

2004-12-01

The International Technology Roadmap for Semiconductors (ITRS) [1] provides industry expectations for high volume computer chip fabrication a decade into the future. It provides expectations to anticipated performance and requisite specifications. While the roadmap provides a collective projection of what international industry expects to produce, it does not specify the technology that will be employed. Indeed, there are generally several competing technologies for each two or three year step forward—known as `nodes'. Recent successful technologies have been based on KrF (248 nm), and now ArF (193 nm) lasers, combined with ultraviolet transmissive refractive optics, in what are known as step and scan exposure tools. Less fortunate technologies in the recent past have included soft x-ray proximity printing and, it appears, 157 nm wavelength F2 lasers. In combination with higher numerical aperture liquid emersion optics, 193 nm is expected to be used for the manufacture of leading edge chip performance for the coming five years. Beyond that, starting in about 2009, the technology to be employed is less clear. The leading candidate for the 2009 node is extreme ultraviolet (EUV) lithography, however this requires that several remaining challenges, including sufficient EUV source power, be overcome in a timely manner. This technology is based on multilayer coated reflective optics [2] and an EUV emitting plasma. Following Moore's Law [3] it is expected, for example, that at the 2009 `32 nm node' (printable patterns of 32 nm half-pitch), isolated lines with 18 nm width will be formed in resist (using threshold effects), and that these will be further narrowed to 13 nm in transfer to metalized electronic gates. These narrow features are expected to provide computer chips of 19 GHz clock frequency, with of the order of 1.5 billion transistors per chip [1]. This issue of Journal of Physics D: Applied Physics contains a cluster of eight papers addressing the critical

An integrated semiconductor device enabling non-optical genome sequencing.

Science.gov (United States)

Rothberg, Jonathan M; Hinz, Wolfgang; Rearick, Todd M; Schultz, Jonathan; Mileski, William; Davey, Mel; Leamon, John H; Johnson, Kim; Milgrew, Mark J; Edwards, Matthew; Hoon, Jeremy; Simons, Jan F; Marran, David; Myers, Jason W; Davidson, John F; Branting, Annika; Nobile, John R; Puc, Bernard P; Light, David; Clark, Travis A; Huber, Martin; Branciforte, Jeffrey T; Stoner, Isaac B; Cawley, Simon E; Lyons, Michael; Fu, Yutao; Homer, Nils; Sedova, Marina; Miao, Xin; Reed, Brian; Sabina, Jeffrey; Feierstein, Erika; Schorn, Michelle; Alanjary, Mohammad; Dimalanta, Eileen; Dressman, Devin; Kasinskas, Rachel; Sokolsky, Tanya; Fidanza, Jacqueline A; Namsaraev, Eugeni; McKernan, Kevin J; Williams, Alan; Roth, G Thomas; Bustillo, James

2011-07-20

The seminal importance of DNA sequencing to the life sciences, biotechnology and medicine has driven the search for more scalable and lower-cost solutions. Here we describe a DNA sequencing technology in which scalable, low-cost semiconductor manufacturing techniques are used to make an integrated circuit able to directly perform non-optical DNA sequencing of genomes. Sequence data are obtained by directly sensing the ions produced by template-directed DNA polymerase synthesis using all-natural nucleotides on this massively parallel semiconductor-sensing device or ion chip. The ion chip contains ion-sensitive, field-effect transistor-based sensors in perfect register with 1.2 million wells, which provide confinement and allow parallel, simultaneous detection of independent sequencing reactions. Use of the most widely used technology for constructing integrated circuits, the complementary metal-oxide semiconductor (CMOS) process, allows for low-cost, large-scale production and scaling of the device to higher densities and larger array sizes. We show the performance of the system by sequencing three bacterial genomes, its robustness and scalability by producing ion chips with up to 10 times as many sensors and sequencing a human genome.

Direct optical band gap measurement in polycrystalline semiconductors: A critical look at the Tauc method

International Nuclear Information System (INIS)

Dolgonos, Alex; Mason, Thomas O.; Poeppelmeier, Kenneth R.

2016-01-01

The direct optical band gap of semiconductors is traditionally measured by extrapolating the linear region of the square of the absorption curve to the x-axis, and a variation of this method, developed by Tauc, has also been widely used. The application of the Tauc method to crystalline materials is rooted in misconception–and traditional linear extrapolation methods are inappropriate for use on degenerate semiconductors, where the occupation of conduction band energy states cannot be ignored. A new method is proposed for extracting a direct optical band gap from absorption spectra of degenerately-doped bulk semiconductors. This method was applied to pseudo-absorption spectra of Sn-doped In 2 O 3 (ITO)—converted from diffuse-reflectance measurements on bulk specimens. The results of this analysis were corroborated by room-temperature photoluminescence excitation measurements, which yielded values of optical band gap and Burstein–Moss shift that are consistent with previous studies on In 2 O 3 single crystals and thin films. - Highlights: • The Tauc method of band gap measurement is re-evaluated for crystalline materials. • Graphical method proposed for extracting optical band gaps from absorption spectra. • The proposed method incorporates an energy broadening term for energy transitions. • Values for ITO were self-consistent between two different measurement methods.

Experimental investigations of optical nonlinearities in semiconductor-doped glass waveguides

International Nuclear Information System (INIS)

Dannberg, P.; Possner, T.; Braeuer, A.; Bartuch, U.

1988-01-01

Both, thermal and electronic optical nonlinearities are studied in semiconductor-doped glass (SDG) waveguides which are fabricated in commercially available sharp-cut filters by Cs + -K + ion exchange. The relaxation time in photodarkened substrates is measured to be 30 ps. By means of a prism coupling set-up the saturation value of the nonlinear index change is determined. Furthermore, a high stability dual-beam interferometer is presented for the measurement of both, thermal and electronic nonlinear refractive index n 2 in planar waveguides. Conclusions about the application of SDG to opto-optical switching are given. (author)

On the estimation of matrix elements for optical transitions in semiconductors

International Nuclear Information System (INIS)

Hassan, A.R.

1992-09-01

A semi-empirical method is used to calculate the numerical values of the interband momentum matrix elements of the allowed optical transitions in semiconductors. This method is based on the evaluation of the ratio of the two-photon and one-photon absorption coefficients and the compare the result with the corresponding experimental values in a number of semiconductors both for direct and indirect transition processes. The numerical values of the momentum matrix elements are compared with the convenient theoretical calculations available. The result is found to agree fairly well with the corresponding values computed using the k-vector · p-vector perturbation theory. (author). 19 refs, 2 figs, 2 tabs

ZnO - Wide Bandgap Semiconductor and Possibilities of Its Application in Optical Waveguide Structures

Directory of Open Access Journals (Sweden)

Struk Przemysław

2014-08-01

Full Text Available The paper presents the results of investigations concerning the application of zinc oxide - a wideband gap semiconductor in optical planar waveguide structures. ZnO is a promising semiconducting material thanks to its attractive optical properties. The investigations were focused on the determination of the technology of depositions and the annealing of ZnO layers concerning their optical properties. Special attention was paid to the determination of characteristics of the refractive index of ZnO layers and their coefficients of spectral transmission within the UV-VIS-NIR range. Besides that, also the mode characteristics and the attenuation coefficients of light in the obtained waveguide structures have been investigated. In the case of planar waveguides, in which the ZnO layers have not been annealed after their deposition, the values of the attenuation coefficient of light modes amount to a~ 30 dB/cm. The ZnO layers deposited on the heated substrate and annealed by rapid thermal annealing in an N2 and O2 atmosphere, are characterized by much lower values of the attenuation coefficients: a~ 3 dB/cm (TE0 and TM0 modes. The ZnO optical waveguides obtained according to our technology are characterized by the lowest values of the attenuation coefficients a encountered in world literature concerning the problem of optical waveguides based on ZnO. Studies have shown that ZnO layers elaborated by us can be used in integrated optic systems, waveguides, optical modulators and light sources.

Spectral characteristics of DFB lasers in presence of a semiconductor optical amplifier

DEFF Research Database (Denmark)

Champagne, A.; Camel, J.; Maciejko, R.

2002-01-01

The problem of the linewidth degradation in systems using distributed-feedback lasers together with strained-layer multi-quantum-well semiconductor optical amplifiers (SOAs) is examined. A numerical model combining finite element calculations in the transverse x - y plane and a longitudinal model...

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.

Limit of detection of a fiber optics gyroscope using a super luminescent radiation source

International Nuclear Information System (INIS)

Sandoval R, G.E.; Nikolaev, V.A.

2003-01-01

The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which is determined with the shot noise. (Author)

Limit of detection of a fiber optics gyroscope using a super luminescent radiation source

CERN Document Server

Sandoval, G E

2003-01-01

The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which i...

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.

Return-map for low-frequency fluctuations in semiconductor lasers with optical feedback

DEFF Research Database (Denmark)

Mørk, Jesper; Sabbatier, H.; Sørensen, Mads Peter

1999-01-01

We show that the phenomenon of low-frequency fluctuations (LFF) , commonly observed in semiconductor lasers with optical feedback, can be explained by a simple return-map, implying a tremendous simplification in the description of the slow time-scale dynamics of the system. Experimentally observed...

Optical switching of nuclear spin-spin couplings in semiconductors.

Science.gov (United States)

Goto, Atsushi; Ohki, Shinobu; Hashi, Kenjiro; Shimizu, Tadashi

2011-07-05

Two-qubit operation is an essential part of quantum computation. However, solid-state nuclear magnetic resonance quantum computing has not been able to fully implement this functionality, because it requires a switchable inter-qubit coupling that controls the time evolutions of entanglements. Nuclear dipolar coupling is beneficial in that it is present whenever nuclear-spin qubits are close to each other, while it complicates two-qubit operation because the qubits must remain decoupled to prevent unwanted couplings. Here we introduce optically controllable internuclear coupling in semiconductors. The coupling strength can be adjusted externally through light power and even allows on/off switching. This feature provides a simple way of switching inter-qubit couplings in semiconductor-based quantum computers. In addition, its long reach compared with nuclear dipolar couplings allows a variety of options for arranging qubits, as they need not be next to each other to secure couplings.

Optical switching of nuclear spin–spin couplings in semiconductors

Science.gov (United States)

Goto, Atsushi; Ohki, Shinobu; Hashi, Kenjiro; Shimizu, Tadashi

2011-01-01

Two-qubit operation is an essential part of quantum computation. However, solid-state nuclear magnetic resonance quantum computing has not been able to fully implement this functionality, because it requires a switchable inter-qubit coupling that controls the time evolutions of entanglements. Nuclear dipolar coupling is beneficial in that it is present whenever nuclear–spin qubits are close to each other, while it complicates two-qubit operation because the qubits must remain decoupled to prevent unwanted couplings. Here we introduce optically controllable internuclear coupling in semiconductors. The coupling strength can be adjusted externally through light power and even allows on/off switching. This feature provides a simple way of switching inter-qubit couplings in semiconductor-based quantum computers. In addition, its long reach compared with nuclear dipolar couplings allows a variety of options for arranging qubits, as they need not be next to each other to secure couplings. PMID:21730962

High gain semiconductor optical amplifier — Laser diode at visible wavelength

KAUST Repository

Shen, Chao; Lee, Changmin; Ng, Tien Khee; Nakamura, Shuji; Speck, James S.; DenBaars, Steven P.; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

2017-01-01

We reported on the first experimental demonstration of a two-section semipolar InGaN-based laser diode with monolithically integrated semiconductor optical amplifier (SOA-LD). The onset of amplification effect was measured at 4V SOA bias (VSOA). The SOA-LD shows a large gain of 5.32 dB at Vsoa = 6 V.

High gain semiconductor optical amplifier — Laser diode at visible wavelength

KAUST Repository

Shen, Chao

2017-02-07

We reported on the first experimental demonstration of a two-section semipolar InGaN-based laser diode with monolithically integrated semiconductor optical amplifier (SOA-LD). The onset of amplification effect was measured at 4V SOA bias (VSOA). The SOA-LD shows a large gain of 5.32 dB at Vsoa = 6 V.

Fine structure and optical pumping of spins in individual semiconductor quantum dots

Science.gov (United States)

Bracker, Allan S.; Gammon, Daniel; Korenev, Vladimir L.

2008-11-01

We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information.

Fine structure and optical pumping of spins in individual semiconductor quantum dots

International Nuclear Information System (INIS)

Bracker, Allan S; Gammon, Daniel; Korenev, Vladimir L

2008-01-01

We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information

Spectrum analysis of a voltage source converter due to semiconductor voltage drops

DEFF Research Database (Denmark)

Rasmussen, Tonny Wederberg; Eltouki, Mustafa

2017-01-01

It is known that power electronic voltage source converters are non-ideal. This paper presents a state-of-the-art review on the effect of semiconductor voltage drop on the output voltage spectrum, using single-phase H-bridge two-level converter topology with natural sampled pulse width modulation....... The paper describes the analysis of output voltage spectrum, when the semiconductor voltage drop is added. The results of the analysis of the spectral contribution including and excluding semiconductor voltage drop reveal a good agreement between the theoretical results, simulations and laboratory...

Materials and Reliability Handbook for Semiconductor Optical and Electron Devices

CERN Document Server

Pearton, Stephen

2013-01-01

Materials and Reliability Handbook for Semiconductor Optical and Electron Devices provides comprehensive coverage of reliability procedures and approaches for electron and photonic devices. These include lasers and high speed electronics used in cell phones, satellites, data transmission systems and displays. Lifetime predictions for compound semiconductor devices are notoriously inaccurate due to the absence of standard protocols. Manufacturers have relied on extrapolation back to room temperature of accelerated testing at elevated temperature. This technique fails for scaled, high current density devices. Device failure is driven by electric field or current mechanisms or low activation energy processes that are masked by other mechanisms at high temperature. The Handbook addresses reliability engineering for III-V devices, including materials and electrical characterization, reliability testing, and electronic characterization. These are used to develop new simulation technologies for device operation and ...

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)

Material Engineering for Monolithic Semiconductor Mode-Locked Lasers

DEFF Research Database (Denmark)

Kulkova, Irina

This thesis is devoted to the materials engineering for semiconductor monolithic passively mode-locked lasers (MLLs) as a compact energy-efficient source of ultrashort optical pulses. Up to the present day, the achievement of low-noise sub-picosecond pulse generation has remained a challenge...

Ordering-induced changes in the optical spectra of semiconductor alloys

International Nuclear Information System (INIS)

Bernard, J.E.; Wei, S.; Wood, D.M.; Zunger, A.

1988-01-01

It is shown how the recently predicted and subsequently observed spontaneous long-range ordering of pseudobinary A/sub 0.5/B/sub 0.5/C isovalent semiconductor alloys into the (AC) 1 (BC) 1 superlattice structure (a CuAuI-type crystal) gives rise to characteristic changes in the optical and photoemission spectra. We predict new direct transitions and substantial splittings of transitions absent in the disordered alloy

Amplified spontaneous emission spectrum and gain characteristic of a two-electrode semiconductor optical amplifier

International Nuclear Information System (INIS)

Wang Hanchao; Huang Lirong; Shi Zhongwei

2011-01-01

A two-electrode multi-quantum-well semiconductor optical amplifier is designed and fabricated. The amplified spontaneous emission (ASE) spectrum and gain were measured and analyzed. It is shown that the ASE spectrum and gain characteristic are greatly influencedby the distribution of the injection current density. By changing the injection current density of two electrodes, the full width at half maximum, peak wavelength, peak power of the ASE spectrum and the gain characteristic can be easily controlled. (semiconductor devices)

Semiconductor Lasers Stability, Instability and Chaos

CERN Document Server

Ohtsubo, Junji

2008-01-01

This monograph describes fascinating recent progress in the field of chaos, stability and instability of semiconductor lasers. Applications and future prospects are discussed in detail. The book emphasizes the various dynamics induced in semiconductor lasers by optical and electronic feedback, optical injection, and injection current modulation. Recent results of both theoretical and experimental investigations are presented. Demonstrating applications of semiconductor laser chaos, control and noise, Semiconductor Lasers describes suppression and chaotic secure communications. For those who are interested in optics but not familiar with nonlinear systems, a brief introduction to chaos analysis is presented.

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...

Micro-combs: A novel generation of optical sources

Science.gov (United States)

Pasquazi, Alessia; Peccianti, Marco; Razzari, Luca; Moss, David J.; Coen, Stéphane; Erkintalo, Miro; Chembo, Yanne K.; Hansson, Tobias; Wabnitz, Stefan; Del'Haye, Pascal; Xue, Xiaoxiao; Weiner, Andrew M.; Morandotti, Roberto

2018-01-01

-integrated technologies. Indeed, it is well acknowledged by the electronics industry that future generations of computer processing chips will inevitably require an extremely high density of copper-based interconnections, significantly increasing the chip power dissipation to beyond practical levels [15-17]; hence, conventional approaches to chip design must undergo radical changes. On-chip optical networks, or optical interconnects, can offer high speed and low energy per-transferred-bit, and micro-resonators are widely seen as a key component to interface the electronic world with photonics. Many information technology industries have recently focused on the development of integrated ring resonators to be employed for electrically-controlled light modulators [14-17], greatly advancing the maturity of micro-resonator technology as a whole. Recently [11-13], the demonstration of OFC sources in micro-resonators fabricated in electronic (i.e. in complementary metal oxide semiconductor (CMOS)) compatible platforms has given micro-cavities an additional appeal, with the possibility of exploiting them as light sources in microchips. This scenario is creating fierce competition in developing highly efficient OFC generators based on micro-cavities which can radically change the nature of information transport and processing. Even in telecommunications, perhaps a more conventional environment for optical technologies, novel time-division multiplexed optical systems will require extremely stable optical clocks at ultra-high pulse repetition-rates towards the THz scale. Furthermore, arbitrary pulse generators based on OFC [18,19] are seen as one of the most promising solutions for this next generation of high-capacity optical coherent communication systems. This review will summarise the recent exciting achievements in the field of micro-combs, namely optical frequency combs based on high-Q micro-resonators, with a perspective on both the potential of this technology, as well as the open questions

Optical Resonance of A Three-Level System in Semiconductor Quantum Dots

Directory of Open Access Journals (Sweden)

Nguyen Van Hieu

2017-11-01

Full Text Available The optical resonance of a three-level system of the strongly correlated electrons in the twolevel semiconductor quantum dot interacting with the linearly polarized monochromatic electromagnetic radiation is studied. With the application of the Green function method the expressions of the state vectors and the energies of the stationary states of the system in the regime of the optical resonance are derived. The Rabi oscillations of the electron populations at different levels as well as the Rabi splitting of the peaks in the photon emission spectra are investigated. PACS numbers: 71.35.-y, 78.55.-m, 78.67.Hc

Nonlinear optics response of semiconductor quantum wells under high magnetic fields

International Nuclear Information System (INIS)

Chemla, D.S.

1993-07-01

Recent investigations on the nonlinear optical response of semiconductor quantum wells in a strong perpendicular magnetic field, H, are reviewed. After some introductory material the evolution of the linear optical properties of GaAs QW's as a function of H is discussed; an examination is made of how the magneto-excitons (MX) extrapolate continuously between quasi-2D QW excitons (X) when H = 0, and pairs of Landau levels (LL) when H → ∞. Next, femtosecond time resolved investigations of their nonlinear optical response are presented; the evolution of MX-MX interactions with increasing H is stressed. Finally, how, as the dimensionality is reduced by application of H, the number of scattering channels is limited and relaxation of electron-hole pairs is affected. How nonlinear optical spectroscopy can be exploited to access the relaxation of angular momentum within magneto-excitons is also discussed

Linewidth broadening in a distributed feedback laser integrated with a semiconductor optical amplifier

DEFF Research Database (Denmark)

Champagne, A.; Camel, J.; Maciejko, R.

2002-01-01

The problem of the linewidth degradation in systems using distributed-feedback lasers together with strained-layer multi-quantum-well semiconductor optical amplifiers (SOAs) is examined. A modified expression for the linewidth in the case of antireflection-coated SOA output facets is derived and ...

Development of integrated semiconductor optical sensors for functional brain imaging

Science.gov (United States)

Lee, Thomas T.

Optical imaging of neural activity is a widely accepted technique for imaging brain function in the field of neuroscience research, and has been used to study the cerebral cortex in vivo for over two decades. Maps of brain activity are obtained by monitoring intensity changes in back-scattered light, called Intrinsic Optical Signals (IOS), that correspond to fluctuations in blood oxygenation and volume associated with neural activity. Current imaging systems typically employ bench-top equipment including lamps and CCD cameras to study animals using visible light. Such systems require the use of anesthetized or immobilized subjects with craniotomies, which imposes limitations on the behavioral range and duration of studies. The ultimate goal of this work is to overcome these limitations by developing a single-chip semiconductor sensor using arrays of sources and detectors operating at near-infrared (NIR) wavelengths. A single-chip implementation, combined with wireless telemetry, will eliminate the need for immobilization or anesthesia of subjects and allow in vivo studies of free behavior. NIR light offers additional advantages because it experiences less absorption in animal tissue than visible light, which allows for imaging through superficial tissues. This, in turn, reduces or eliminates the need for traumatic surgery and enables long-term brain-mapping studies in freely-behaving animals. This dissertation concentrates on key engineering challenges of implementing the sensor. This work shows the feasibility of using a GaAs-based array of vertical-cavity surface emitting lasers (VCSELs) and PIN photodiodes for IOS imaging. I begin with in-vivo studies of IOS imaging through the skull in mice, and use these results along with computer simulations to establish minimum performance requirements for light sources and detectors. I also evaluate the performance of a current commercial VCSEL for IOS imaging, and conclude with a proposed prototype sensor.

Method of developing all-optical trinary JK, D-type, and T-type flip-flops using semiconductor optical amplifiers.

Science.gov (United States)

Garai, Sisir Kumar

2012-04-10

To meet the demand of very fast and agile optical networks, the optical processors in a network system should have a very fast execution rate, large information handling, and large information storage capacities. Multivalued logic operations and multistate optical flip-flops are the basic building blocks for such fast running optical computing and data processing systems. In the past two decades, many methods of implementing all-optical flip-flops have been proposed. Most of these suffer from speed limitations because of the low switching response of active devices. The frequency encoding technique has been used because of its many advantages. It can preserve its identity throughout data communication irrespective of loss of light energy due to reflection, refraction, attenuation, etc. The action of polarization-rotation-based very fast switching of semiconductor optical amplifiers increases processing speed. At the same time, tristate optical flip-flops increase information handling capacity.

Microwave phase shifter with controllable power response based on slow- and fast-light effects in semiconductor optical amplifiers.

Science.gov (United States)

Xue, Weiqi; Sales, Salvador; Capmany, José; Mørk, Jesper

2009-04-01

We suggest and experimentally demonstrate a method for increasing the tunable rf phase shift of semiconductor waveguides while at the same time enabling control of the rf power. This method is based on the use of slow- and fast-light effects in a cascade of semiconductor optical amplifiers combined with the use of spectral filtering to enhance the role of refractive index dynamics. A continuously tunable phase shift of approximately 240 degrees at a microwave frequency of 19 GHz is demonstrated in a cascade of two semiconductor optical amplifiers, while maintaining an rf power change of less than 1.6 dB. The technique is scalable to more amplifiers and should allow realization of an rf phase shift of 360 degrees.

The dynamical complexity of optically injected semiconductor lasers

International Nuclear Information System (INIS)

Wieczorek, S.; Krauskopf, B.; Simpson, T.B.; Lenstra, D.

2005-01-01

This report presents a modern approach to the theoretical and experimental study of complex nonlinear behavior of a semiconductor laser with optical injection-an example of a widely applied and technologically relevant forced nonlinear oscillator. We show that the careful bifurcation analysis of a rate equation model yields (i) a deeper understanding of already studied physical phenomena, and (ii) the discovery of new dynamical effects, such as multipulse excitability. Different instabilities, cascades of bifurcations, multistability, and sudden chaotic transitions, which are often viewed as independent, are in fact logically connected into a consistent web of bifurcations via special points called organizing centers. This theoretical bifurcation analysis has predictive power, which manifests itself in good agreement with experimental measurements over a wide range of parameters and diversity of dynamics. While it is dealing with the specific system of an optically injected laser, our work constitutes the state-of-the-art in the understanding and modeling of a nonlinear physical system in general

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...

Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

KAUST Repository

Li, Yuan

2014-12-03

We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

Optical conductivity and optical effective mass in a high-mobility organic semiconductor: Implications for the nature of charge transport

KAUST Repository

Li, Yuan; Yi, Yuanping; Coropceanu, Veaceslav; Bredas, Jean-Luc

2014-01-01

We present a multiscale modeling of the infrared optical properties of the rubrene crystal. The results are in very good agreement with the experimental data that point to nonmonotonic features in the optical conductivity spectrum and small optical effective masses. We find that, in the static-disorder approximation, the nonlocal electron-phonon interactions stemming from low-frequency lattice vibrations can decrease the optical effective masses and lead to lighter quasiparticles. On the other hand, the charge-transport and infrared optical properties of the rubrene crystal at room temperature are demonstrated to be governed by localized carriers driven by inherent thermal disorders. Our findings underline that the presence of apparently light carriers in high-mobility organic semiconductors does not necessarily imply bandlike transport.

Destruction-polymerization transformations as a source of radiation-induced extended defects in chalcogenide glassy semiconductors

International Nuclear Information System (INIS)

Shpotyuk, Oleh; Filipecki, Jacek; Shpotyuk, Mykhaylo

2013-01-01

Long-wave shift of the optical transmission spectrum in the region of fundamental optical absorption edge is registered for As 2 S 3 chalcogenide glassy semiconductors after γ-irradiation. This effect is explained in the frameworks of the destruction-polymerization transformations concept by accepting the switching of the heteropolar As-S covalent bonds into homopolar As-As ones. It is assumed that (As 4 + ; S 1 - ) defect pairs are created under such switching. Formula to calculate content of the induced defects in chalcogenide glassy semiconductors is proposed. It is assumed that defects concentration depends on energy of broken covalent bond, bond-switching energy balance, correlation energy, optical band-gap and energy of excitation light. It is shown that theoretically calculated maximally possible content of radiation-induced defects in As 2 S 3 is about 1.6% while concentration of native defects is negligible. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Coherent Optical Generation of a 6 GHz Microwave Signal with Directly Phase Locked Semiconductor DFB Lasers

DEFF Research Database (Denmark)

Gliese, Ulrik Bo; Nielsen, Torben Nørskov; Bruun, Marlene

1992-01-01

Experimental results of a wideband heterodyne second order optical phase locked loop with 1.5 ¿m semiconductor lasers are presented. The loop has a bandwidth of 180 MHz, a gain of 181 dBHz and a propagation delay of only 400 ps. A beat signal of 8 MHz linewidth is phase locked to become a replica...... of a microwave reference source close to carrier with a noise level of ¿125 dBc/Hz. The total phase variance of the locked carrier is 0.04 rad2 and carriers can be generated in a continuous range from 3 to 18 GHz. The loop reliability is excellent with an average time to cycle slip of 1011 seconds...

Effects of two-photon absorption on all optical logic operation based on quantum-dot semiconductor optical amplifiers

Science.gov (United States)

Zhang, Xiang; Dutta, Niloy K.

2018-01-01

We investigate all-optical logic operation in quantum-dot semiconductor optical amplifier (QD-SOA) based Mach-Zehnder interferometer considering the effects of two-photon absorption (TPA). TPA occurs during the propagation of sub-picosecond pulses in QD-SOA, which leads to a change in carrier recovery dynamics in quantum-dots. We utilize a rate equation model to take into account carrier refill through TPA and nonlinear dynamics including carrier heating and spectral hole burning in the QD-SOA. The simulation results show the TPA-induced pumping in the QD-SOA can reduce the pattern effect and increase the output quality of the all-optical logic operation. With TPA, this scheme is suitable for high-speed Boolean logic operation at 320 Gb/s.

The structural and optical constants of Ag2S semiconductor nanostructure in the Far-Infrared.

Science.gov (United States)

Zamiri, Reza; Abbastabar Ahangar, Hossein; Zakaria, Azmi; Zamiri, Golnoosh; Shabani, Mehdi; Singh, Budhendra; Ferreira, J M F

2015-01-01

In this paper a template-free precipitation method was used as an easy and low cost way to synthesize Ag2S semiconductor nanoparticles. The Kramers-Kronig method (K-K) and classical dispersion theory was applied to calculate the optical constants of the prepared samples, such as the reflective index n(ω) and dielectric constant ε(ω) in Far-infrared regime. Nanocrystalline Ag2S was synthesized by a wet chemical precipitation method. Ag2S nanoparticle was characterized by X-ray diffraction, Scanning Electron Microscopy, UV-visible, and FT-IR spectrometry. The refinement of the monoclinic β-Ag2S phase yielded a structure solution similar to the structure reported by Sadanaga and Sueno. The band gap of Ag2S nanoparticles is around 0.96 eV, which is in good agreement with previous reports for the band gap energy of Ag2S nanoparticles (0.9-1.1 eV). The crystallite size of the synthesized particles was obtained by Hall-Williamson plot for the synthesized Ag2S nanoparticles and it was found to be 217 nm. The Far-infrared optical constants of the prepared Ag2S semiconductor nanoparticles were evaluated by means of FTIR transmittance spectra data and K-K method. Graphical abstractThe Far-infrared optical constants of Ag2S semiconductor nanoparticles.

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...

Proposal for the momentum-resolved and time-resolved optical measurement of the current distribution in semiconductors.

Science.gov (United States)

Liu, Jiang-Tao; Su, Fu-Hai; Deng, Xin-Hua; Wang, Hai

2012-05-21

The two-color optical coherence absorption spectrum (QUIC-AB) of semiconductors in the presence of a charge current is investigated. We find that the QUIC-AB depends strongly not only on the amplitude of the electron current but also on the direction of the electron current. Thus, the amplitude and the angular distribution of current in semiconductors can be detected directly in real time with the QUIC-AB.

Applied optics

International Nuclear Information System (INIS)

Orszag, A.; Antonetti, A.

1988-01-01

The 1988 progress report, of the Applied Optics laboratory, of the (Polytechnic School, France), is presented. The optical fiber activities are focused on the development of an optical gyrometer, containing a resonance cavity. The following domains are included, in the research program: the infrared laser physics, the laser sources, the semiconductor physics, the multiple-photon ionization and the nonlinear optics. Investigations on the biomedical, the biological and biophysical domains are carried out. The published papers and the congress communications are listed [fr

Studies of optical properties and applications of some mixed ternary semiconductors

International Nuclear Information System (INIS)

Ghosh, P.S.; Ghosh, D.K.; Samanta, L.K.

1989-01-01

Refractive indices of some mixed compound semiconductors below the bandgap are presented on the basis of some fundamental parameters and the effect of lattice mismatch on the refractive index step is also studied. The results help to design a variety of opto-electronic devices for the use in optical fiber communication and heterostructure lasers. The calculated values agree well with available experimental values thus justifying the approach. (author)

Sequential x-ray diffraction topography at 1-BM x-ray optics testing beamline at the advanced photon source

Energy Technology Data Exchange (ETDEWEB)

Stoupin, Stanislav, E-mail: sstoupin@aps.anl.gov; Shvyd’ko, Yuri; Trakhtenberg, Emil; Liu, Zunping; Lang, Keenan; Huang, Xianrong; Wieczorek, Michael; Kasman, Elina; Hammonds, John; Macrander, Albert; Assoufid, Lahsen [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States)

2016-07-27

We report progress on implementation and commissioning of sequential X-ray diffraction topography at 1-BM Optics Testing Beamline of the Advanced Photon Source to accommodate growing needs of strain characterization in diffractive crystal optics and other semiconductor single crystals. The setup enables evaluation of strain in single crystals in the nearly-nondispersive double-crystal geometry. Si asymmetric collimator crystals of different crystallographic orientations were designed, fabricated and characterized using in-house capabilities. Imaging the exit beam using digital area detectors permits rapid sequential acquisition of X-ray topographs at different angular positions on the rocking curve of a crystal under investigation. Results on sensitivity and spatial resolution are reported based on experiments with high-quality Si and diamond crystals. The new setup complements laboratory-based X-ray topography capabilities of the Optics group at the Advanced Photon Source.

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.

Plasma Processing of Metallic and Semiconductor Thin Films in the Fisk Plasma Source

Science.gov (United States)

Lampkin, Gregory; Thomas, Edward, Jr.; Watson, Michael; Wallace, Kent; Chen, Henry; Burger, Arnold

1998-01-01

The use of plasmas to process materials has become widespread throughout the semiconductor industry. Plasmas are used to modify the morphology and chemistry of surfaces. We report on initial plasma processing experiments using the Fisk Plasma Source. Metallic and semiconductor thin films deposited on a silicon substrate have been exposed to argon plasmas. Results of microscopy and chemical analyses of processed materials are presented.

All-optical 1st- and 2nd-order differential equation solvers with large tuning ranges using Fabry-Pérot semiconductor optical amplifiers.

Science.gov (United States)

Chen, Kaisheng; Hou, Jie; Huang, Zhuyang; Cao, Tong; Zhang, Jihua; Yu, Yuan; Zhang, Xinliang

2015-02-09

We experimentally demonstrate an all-optical temporal computation scheme for solving 1st- and 2nd-order linear ordinary differential equations (ODEs) with tunable constant coefficients by using Fabry-Pérot semiconductor optical amplifiers (FP-SOAs). By changing the injection currents of FP-SOAs, the constant coefficients of the differential equations are practically tuned. A quite large constant coefficient tunable range from 0.0026/ps to 0.085/ps is achieved for the 1st-order differential equation. Moreover, the constant coefficient p of the 2nd-order ODE solver can be continuously tuned from 0.0216/ps to 0.158/ps, correspondingly with the constant coefficient q varying from 0.0000494/ps(2) to 0.006205/ps(2). Additionally, a theoretical model that combining the carrier density rate equation of the semiconductor optical amplifier (SOA) with the transfer function of the Fabry-Pérot (FP) cavity is exploited to analyze the solving processes. For both 1st- and 2nd-order solvers, excellent agreements between the numerical simulations and the experimental results are obtained. The FP-SOAs based all-optical differential-equation solvers can be easily integrated with other optical components based on InP/InGaAsP materials, such as laser, modulator, photodetector and waveguide, which can motivate the realization of the complicated optical computing on a single integrated chip.

Four distributed feedback laser array integrated with multimode-interference and semiconductor optical amplifier

International Nuclear Information System (INIS)

Ma Li; Zhu Hong-Liang; Liang Song; Zhao Ling-Juan; Chen Ming-Hua

2013-01-01

Monolithic integration of four 1.55-μm-range InGaAsP/InP distributed feedback (DFB) lasers using varied ridge width with a 4 × 1-multimode-interference (MMI) optical combiner and a semiconductor optical amplifier (SOA) is demonstrated. The average output power and the threshold current are 1.8 mW and 35 mA, respectively, when the injection current of the SOA is 100 mA, with a side mode suppression ratio (SMSR) exceeding 40 dB. The four channels have a 1-nm average channel spacing and can operate separately or simultaneously. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Fully tunable 360° microwave photonic phase shifter based on a single semiconductor optical amplifier.

Science.gov (United States)

Sancho, Juan; Lloret, Juan; Gasulla, Ivana; Sales, Salvador; Capmany, José

2011-08-29

A fully tunable microwave photonic phase shifter involving a single semiconductor optical amplifier (SOA) is proposed and demonstrated. 360° microwave phase shift has been achieved by tuning the carrier wavelength and the optical input power injected in an SOA while properly profiting from the dispersion feature of a conveniently designed notch filter. It is shown that the optical filter can be advantageously employed to switch between positive and negative microwave phase shifts. Numerical calculations corroborate the experimental results showing an excellent agreement.

Photoacoustic Techniques for Trace Gas Sensing Based on Semiconductor Laser Sources

Directory of Open Access Journals (Sweden)

Vincenzo Spagnolo

2009-12-01

Full Text Available The paper provides an overview on the use of photoacoustic sensors based on semiconductor laser sources for the detection of trace gases. We review the results obtained using standard, differential and quartz enhanced photoacoustic techniques.

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.

Metallic nanoshells with semiconductor cores: optical characteristics modified by core medium properties.

Science.gov (United States)

Bardhan, Rizia; Grady, Nathaniel K; Ali, Tamer; Halas, Naomi J

2010-10-26

It is well-known that the geometry of a nanoshell controls the resonance frequencies of its plasmon modes; however, the properties of the core material also strongly influence its optical properties. Here we report the synthesis of Au nanoshells with semiconductor cores of cuprous oxide and examine their optical characteristics. This material system allows us to systematically examine the role of core material on nanoshell optical properties, comparing Cu(2)O core nanoshells (ε(c) ∼ 7) to lower core dielectric constant SiO(2) core nanoshells (ε(c) = 2) and higher dielectric constant mixed valency iron oxide nanoshells (ε(c) = 12). Increasing the core dielectric constant increases nanoparticle absorption efficiency, reduces plasmon line width, and modifies plasmon energies. Modifying the core medium provides an additional means of tailoring both the near- and far-field optical properties in this unique nanoparticle system.

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

Effective Linewidth of Semiconductor Lasers for Coherent Optical Data Links

DEFF Research Database (Denmark)

Iglesias Olmedo, Miguel; Pang, Xiaodan; Schatz, Richard

2016-01-01

name “Effective Linewidth”. We derive this figure of merit analytically, explore it by numerical simulations and experimentally validate our results by transmitting a 28 Gbaud DP-16QAM over an optical link. Our investigations cover the use of semiconductor lasers both in the transmitter side...... and as a local oscillator at the receiver. The obtained results show that our proposed “effective linewidth” is easy to measure and accounts for frequency noise more accurately, and hence the penalties associated to phase noise in the received signal....

Access to long-term optical memories using photon echoes retrieved from semiconductor spins

Science.gov (United States)

Langer, L.; Poltavtsev, S. V.; Yugova, I. A.; Salewski, M.; Yakovlev, D. R.; Karczewski, G.; Wojtowicz, T.; Akimov, I. A.; Bayer, M.

2014-11-01

The ability to store optical information is important for both classical and quantum communication. Achieving this in a comprehensive manner (converting the optical field into material excitation, storing this excitation, and releasing it after a controllable time delay) is greatly complicated by the many, often conflicting, properties of the material. More specifically, optical resonances in semiconductor quantum structures with high oscillator strength are inevitably characterized by short excitation lifetimes (and, therefore, short optical memory). Here, we present a new experimental approach to stimulated photon echoes by transferring the information contained in the optical field into a spin system, where it is decoupled from the optical vacuum field and may persist much longer. We demonstrate this for an n-doped CdTe/(Cd,Mg)Te quantum well, the storage time of which could be increased by more than three orders of magnitude, from the picosecond range up to tens of nanoseconds.

Modelling colliding-pulse mode-locked semiconductor lasers

DEFF Research Database (Denmark)

Bischoff, Svend

or to determine the optimum operation conditions. The purpose of this thesis is to elucidate some of the physics of interest in the field of semiconductor laser modelling, semiconductor optics and fiber optics. To be more specific we will investigate: The Colliding-Pulse Mode-Locked (CPM) Quantum Well (QW) laser...... diode; the excitonic semiconductor response for varying material thickness in the case of linear optics; and modulational instability of electromagnetic waves in media with spatially varying non-linearity....

The system of digital-image optical microscope in semiconductor particle detector development

International Nuclear Information System (INIS)

Han Lixiang; Li Zhankui; Jin Genming; Wang Zhusheng; Xiao Guoqing

2009-01-01

Optical microscopic detection is very important in the process of semiconductor particle detector development. A system of digital-image optical microscope has been constructed with rather low price, which performance is comparable with the moderate-level imports. The system mounts powerful dry objective, and a 2μm resolution could be achieved. Observations with bright and dark field, polarized light,and interference light can be carried out on it. The system have large area on-line monitor,and the photographic device can be controlled by PC. It can be used in the control of defects and contaminations, pattern test, identification of crystal backing, inspection of the smoothness and the flatness of the crystal surface. It can also be used in some precise procedures, such as test, assembly, packaging and repairing. The quality of the bond could be examined by observing the appearance of the bond point and the microscopic structure of the solder. The surface fluctuation can be precisely measured under the microscope with the technology of multi-beam interference. In the article, the application of this system for semiconductor particle detector development has been illustrated, and the construction information has been described in detail. (authors)

Long axial imaging range using conventional swept source lasers in optical coherence tomography via re-circulation loops

Science.gov (United States)

Bradu, Adrian; Jackson, David A.; Podoleanu, Adrian

2018-03-01

Typically, swept source optical coherence tomography (SS-OCT) imaging instruments are capable of a longer axial range than their camera based (CB) counterpart. However, there are still various applications that would take advantage for an extended axial range. In this paper, we propose an interferometer configuration that can be used to extend the axial range of the OCT instruments equipped with conventional swept-source lasers up to a few cm. In this configuration, the two arms of the interferometer are equipped with adjustable optical path length rings. The use of semiconductor optical amplifiers in the two rings allows for compensating optical losses hence, multiple paths depth reflectivity profiles (Ascans) can be combined axially. In this way, extremely long overall axial ranges are possible. The use of the recirculation loops produces an effect equivalent to that of extending the coherence length of the swept source laser. Using this approach, the achievable axial imaging range in SS-OCT can reach values well beyond the limit imposed by the coherence length of the laser, to exceed in principle many centimeters. In the present work, we demonstrate axial ranges exceeding 4 cm using a commercial swept source laser and reaching 6 cm using an "in-house" swept source laser. When used in a conventional set-up alone, both these lasers can provide less than a few mm axial range.

CENTRAL WAVELENGTH ADJUSTMENT OF LIGHT EMITTING SOURCE IN INTERFEROMETRIC SENSORS BASED ON FIBER-OPTIC BRAGG GRATINGS

Directory of Open Access Journals (Sweden)

A. S. Aleynik

2015-09-01

Full Text Available The paper is focused on the investigation of fiber-optic interferometric sensor based on the array of fiber Bragg gratings. Reflection spectra displacement mechanism of the fiber Bragg gratings under the external temperature effects and the static pressure is described. The experiment has shown that reflection spectra displacement of Bragg gratings reduces the visibility of the interference pattern. A method of center wavelength adjustment is proposed for the optical radiation source in accord ance with the current Bragg gratings reflection spectra based on the impulse relative modulation of control signal for the Peltier element controller. The semiconductor vertical-cavity surface-emitting laser controlled by a pump driver is used as a light source. The method is implemented by the Peltier element controller regulating and stabilizing the light source temperature, and a programmable logic-integrated circuit monitoring the Peltier element controller. The experiment has proved that the proposed method rendered possible to regulate the light source temperature at a pitch of 0.05 K and adjust the optical radiation source center wavelength at a pitch of 0.05 nm. Experimental results have revealed that the central wavelength of the radiation adjustment at a pitch of 0.005 nm gives the possibility for the capacity of the array consisting of four opticalfiber sensors based on the fiber Bragg gratings. They are formed in one optical fiber under the Bragg grating temperature change from 0° C to 300° C and by the optical fiber mechanical stretching by the force up to 2 N.

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...

Self-slowdown and -advancement of fs pulses in a quantum-dot semiconductor optical amplifier

DEFF Research Database (Denmark)

Poel, Mike van der; Mørk, Jesper; Hvam, Jørn Märcher

2005-01-01

We demonstrate changes in the propagation time of 180 femtosecond pulses in a quantum-dot semiconductor optical amplifier as function of pulse input power and bias current. The results interpreted as a result of pulse reshaping by gain saturation but are also analogous to coherent population osci...

Bistability and low-frequency fluctuations in semiconductor lasers with optical feedback: a theoretical analysis

DEFF Research Database (Denmark)

Mørk, Jesper; Tromborg, Bjarne; Christiansen, Peter Leth

1988-01-01

Near-threshold operation of a semiconductor laser exposed to moderate optical feedback may lead to low-frequency fluctuations. In the same region, a kink is observed in the light-current characteristic. Here it is demonstrated that these nonlinear phenomena are predicted by a noise driven multimode...

Ring-shaped active mode-locked tunable laser using quantum-dot semiconductor optical amplifier

Science.gov (United States)

Zhang, Mingxiao; Wang, Yongjun; Liu, Xinyu

2018-03-01

In this paper, a lot of simulations has been done for ring-shaped active mode-locked lasers with quantum-dot semiconductor optical amplifier (QD-SOA). Based on the simulation model of QD-SOA, we discussed about the influence towards mode-locked waveform frequency and pulse caused by QD-SOA maximum mode peak gain, active layer loss coefficient, bias current, incident light pulse, fiber nonlinear coefficient. In the meantime, we also take the tunable performance of the laser into consideration. Results showed QD-SOA a better performance than original semiconductor optical amplifier (SOA) in recovery time, line width, and nonlinear coefficients, which makes it possible to output a locked-mode impulse that has a higher impulse power, narrower impulse width as well as the phase is more easily controlled. After a lot of simulations, this laser can realize a 20GHz better locked-mode output pulse after 200 loops, where the power is above 17.5mW, impulse width is less than 2.7ps, moreover, the tunable wavelength range is between 1540nm-1580nm.

Comprehensive experimental analysis of nonlinear dynamics in an optically-injected semiconductor laser

Directory of Open Access Journals (Sweden)

Kevin Schires

2011-09-01

Full Text Available We present the first comprehensive experimental study, to our knowledge, of the routes between nonlinear dynamics induced in a semiconductor laser under external optical injection based on an analysis of time-averaged measurements of the optical and RF spectra and phasors of real-time series of the laser output. The different means of analysis are compared for several types of routes and the benefits of each are discussed in terms of the identification and mapping of the nonlinear dynamics. Finally, the results are presented in a novel audio/video format that describes the evolution of the dynamics with the injection parameters.

All-optical clocked flip-flops and random access memory cells using the nonlinear polarization rotation effect of low-polarization-dependent semiconductor optical amplifiers

Science.gov (United States)

Wang, Yongjun; Liu, Xinyu; Tian, Qinghua; Wang, Lina; Xin, Xiangjun

2018-03-01

Basic configurations of various all-optical clocked flip-flops (FFs) and optical random access memory (RAM) based on the nonlinear polarization rotation (NPR) effect of low-polarization-dependent semiconductor optical amplifiers (SOA) are proposed. As the constituent elements, all-optical logic gates and all-optical SR latches are constructed by taking advantage of the SOA's NPR switch. Different all-optical FFs (AOFFs), including SR-, D-, T-, and JK-types as well as an optical RAM cell were obtained by the combination of the proposed all-optical SR latches and logic gates. The effectiveness of the proposed schemes were verified by simulation results and demonstrated by a D-FF and 1-bit RAM cell experimental system. The proposed all-optical clocked FFs and RAM cell are significant to all-optical signal processing.

Optically pumped terahertz sources

Institute of Scientific and Technical Information of China (English)

ZHONG Kai; SHI Wei; XU DeGang; LIU PengXiang; WANG YuYe; MEI JiaLin; YAN Chao; FU ShiJie; YAO JianQuan

2017-01-01

High-power terahertz (THz) generation in the frequency range of0.1-10 THz has been a fast-developing research area ever since the beginning of the THz boom two decades ago,enabling new technological breakthroughs in spectroscopy,communication,imaging,etc.By using optical (laser) pumping methods with near-or mid-infrared (IR) lasers,flexible and practical THz sources covering the whole THz range can be realized to overcome the shortage of electronic THz sources and now they are playing important roles in THz science and technology.This paper overviews various optically pumped THz sources,including femtosecond laser based ultrafast broadband THz generation,monochromatic widely tunable THz generation,single-mode on-chip THz source from photomixing,and the traditional powerful THz gas lasers.Full descriptions from basic principles to the latest progress are presented and their advantages and disadvantages are discussed as well.It is expected that this review gives a comprehensive reference to researchers in this area and additionally helps newcomers to quickly gain understanding of optically pumped THz sources.

Optical and optoelectronic properties of nanostructures based on wide-bandgap semiconductors

International Nuclear Information System (INIS)

Kalden, Joachim

2010-01-01

Recently, more and more research is done on nitride nanostructures in order to control the electrical and optical properties in a more sophisticated manner for optimized light-matter-interaction and extraction efficiency. In this context, the work presented in this thesis has been carried out, concentrating on two main topics. One aspect is the characterization of InGaN quantum dots (QDs). QDs possess a unique atom-like density of states for electrons, allowing for generation and manipulation of discrete electronic states. This thesis contains the analysis of QDs embedded in optoelectronic devices such as LEDs. Measurements of the electroluminescence (EL) of QD ensembles as well as single QDs are presented. Especially QD EL obtained at higher temperatures up to 150 K is a main achievement of this work. Furthermore, the photoluminescence (PL) of QD multilayer structures has been examined and discussed in detail. Experiments on the optical amplification in these multilayers have been carried out for the first time, yielding a maximum optical gain of g(max)/(mod)=50/cm. Another main aspect of solid state lighting is the efficient light extraction from light sources. For this purpose, pillar microcavities based on nitrides have been investigated. This type of optical resonator possesses a discrete optical mode structure due to the three-dimensional optical confinement in these structures. For optimal light-matter coupling conditions, this leads to an enhanced extraction efficiency. In this context, studies on QD pillar microcavities (MCs) processed by focused ion beam milling from planar MC structures are presented. After a detailed analysis of the photonic properties of these pillar MCs, a temperature-variation method to tune the cavity in resonance with QD emission is demonstrated, yielding a five-fold enhancement of the extraction efficiency. These experiments were carried out on selenide-based structures which possess a very high structural quality. An alternative

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

Isotope effects on the optical spectra of semiconductors

Science.gov (United States)

Cardona, Manuel; Thewalt, M. L. W.

2005-10-01

Since the end of the cold war, macroscopic amounts of separated stable isotopes of most elements have been available “off the shelf” at affordable prices. Using these materials, single crystals of many semiconductors have been grown and the dependence of their physical properties on isotopic composition has been investigated. The most conspicuous effects observed have to do with the dependence of phonon frequencies and linewidths on isotopic composition. These affect the electronic properties of solids through the mechanism of electron-phonon interaction, in particular, in the corresponding optical excitation spectra and energy gaps. This review contains a brief introduction to the history, availability, and characterization of stable isotopes, including their many applications in science and technology. It is followed by a concise discussion of the effects of isotopic composition on the vibrational spectra, including the influence of average isotopic masses and isotopic disorder on the phonons. The final sections deal with the effects of electron-phonon interaction on energy gaps, the concomitant effects on the luminescence spectra of free and bound excitons, with particular emphasis on silicon, and the effects of isotopic composition of the host material on the optical transitions between the bound states of hydrogenic impurities.

Ratiometric, filter-free optical sensor based on a complementary metal oxide semiconductor buried double junction photodiode.

Science.gov (United States)

Yung, Ka Yi; Zhan, Zhiyong; Titus, Albert H; Baker, Gary A; Bright, Frank V

2015-07-16

We report a complementary metal oxide semiconductor integrated circuit (CMOS IC) with a buried double junction (BDJ) photodiode that (i) provides a real-time output signal that is related to the intensity ratio at two emission wavelengths and (ii) simultaneously eliminates the need for an optical filter to block Rayleigh scatter. We demonstrate the BDJ platform performance for gaseous NH3 and aqueous pH detection. We also compare the BDJ performance to parallel results obtained by using a slew scanned fluorimeter (SSF). The BDJ results are functionally equivalent to the SSF results without the need for any wavelength filtering or monochromators and the BDJ platform is not prone to errors associated with source intensity fluctuations or sensor signal drift. Copyright © 2015 Elsevier B.V. All rights reserved.

Nonlinear optical diagnostic of semimagnetic semiconductors Pb1-xYb xX (X = S, Se, Te)

International Nuclear Information System (INIS)

Nouneh, K.; Kityk, I.V.; Viennois, R.; Benet, S.; Charar, S.; Plucinski, K.J.

2007-01-01

Nonlinear optical measurements were performed to elucidate the influence of magnetic ions on the behavior of charge carriers in magnetic semiconductors-Pb 1-x Yb x X (X = S, Se, Te at x = 1-3%). It was shown that nonlinear optical methods could be used as sensitive tools for investigations of electron-phonon anharmonicity near low-temperature semiconductor-insulator phase transitions. There exists a difference between surface and bulk-like contributions to the nonlinear optical effects. It was shown that only low-temperature Two Photon Absorption (TPA) oscillator may be related to the number of the electron-phonon anharmonic modes responsible for the observed phase transformation. The explanation of the anomalous temperature dependences is given in accordance with dipole momentum's behaviors determined by low-temperature spin-spin interactions and by electron-phonon anharmonic interactions. We have discovered that low-temperature dependence of specific heat of Pb 1-x R x Te (R = Yb, Pr with x = 3% and 1.6%, respectively) exhibits a non-magnetic order caused by large electron-phonon contributions and structural disorder effects

Ultrafast supercontinuum fiber-laser based pump-probe scanning magneto-optical Kerr effect microscope for the investigation of electron spin dynamics in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution.

Science.gov (United States)

Henn, T; Kiessling, T; Ossau, W; Molenkamp, L W; Biermann, K; Santos, P V

2013-12-01

We describe a two-color pump-probe scanning magneto-optical Kerr effect microscope which we have developed to investigate electron spin phenomena in semiconductors at cryogenic temperatures with picosecond time and micrometer spatial resolution. The key innovation of our microscope is the usage of an ultrafast "white light" supercontinuum fiber-laser source which provides access to the whole visible and near-infrared spectral range. Our Kerr microscope allows for the independent selection of the excitation and detection energy while avoiding the necessity to synchronize the pulse trains of two separate picosecond laser systems. The ability to independently tune the pump and probe wavelength enables the investigation of the influence of excitation energy on the optically induced electron spin dynamics in semiconductors. We demonstrate picosecond real-space imaging of the diffusive expansion of optically excited electron spin packets in a (110) GaAs quantum well sample to illustrate the capabilities of the instrument.

Attenuation of an optical wave propagating in a waveguide, formed by layers of a semiconductor heterostructure, owing to scattering on inhomogeneities

International Nuclear Information System (INIS)

Bogatov, Alexandr P; Burmistrov, I S

1999-01-01

The scattering of an optical wave, propagating in a waveguide made up of layers of a semiconductor heterostructure, is analysed. The attenuation coefficient of the wave is found both for quasi-homogeneous single-crystal layers of a semiconductor solid solution and for layers containing quantum dots. (active media)

Ten years optically pumped semiconductor lasers: review, state-of-the-art, and future developments

Science.gov (United States)

Kannengiesser, Christian; Ostroumov, Vasiliy; Pfeufer, Volker; Seelert, Wolf; Simon, Christoph; von Elm, Rüdiger; Zuck, Andreas

2010-02-01

Optically Pumped Semiconductor Lasers - OPSLs - have been introduced in 2001. Their unique features such as power scalability and wavelength flexibility, their excellent beam parameters, power stability and reliability opened this pioneering technology access to a wide range of applications such as flow cytometry, confocal microscopy, sequencing, medical diagnosis and therapy, semiconductor inspection, graphic arts, forensic, metrology. This talk will introduce the OPSL principles and compare them with ion, diode and standard solid state lasers. It will revue the first 10 years of this exciting technology, its current state and trends. In particular currently accessible wavelengths and power ranges, frequency doubling, ultra-narrow linewidth possibilities will be discussed. A survey of key applications will be given.

Electronic, Optical, and Thermal Properties of Reduced-Dimensional Semiconductors

Science.gov (United States)

Huang, Shouting

Reduced-dimensional materials have attracted tremendous attention because of their new physics and exotic properties, which are of great interests for fundamental science. More importantly, the manipulation and engineering of matter on an atomic scale yield promising applications for many fields including nanoelectronics, nanobiotechnology, environments, and renewable energy. Because of the unusual quantum confinement and enhanced surface effect of reduced-dimensional materials, traditional empirical models suffer from necessary but unreliable parameters extracted from previously-studied bulk materials. In this sense, quantitative, parameter-free approaches are highly useful for understanding properties of reduced-dimensional materials and, furthermore, predicting their novel applications. The first-principles density functional theory (DFT) is proven to be a reliable and convenient tool. In particular, recent progress in many-body perturbation theory (MBPT) makes it possible to calculate excited-state properties, e.g., quasiparticle (QP) band gap and optical excitations, by the first-principles approach based on DFT. Therefore, during my PhD study, I employed first-principles calculations based on DFT and MBPT to systematically study fundamental properties of typical reduced-dimensional semiconductors, i.e., the electronic structure, phonons, and optical excitations of core-shell nanowires (NWs) and graphene-like two-dimensional (2D) structures of current interests. First, I present first-principles studies on how to engineer band alignments of nano-sized radial heterojunctions, Si/Ge core-shell NWs. Our calculation reveals that band offsets in these one-dimensional (1D) nanostructures can be tailored by applying axial strain or varying core-shell sizes. In particular, the valence band offset can be efficiently tuned across a wide range and even be diminished via applied strain. Two mechanisms contribute to this tuning of band offsets. Furthermore, varying the

Magneto-optical transitions in multilayer semiconductor nanocrystals

CERN Document Server

Climente, J; Jaskolski, W; Aliaga, J I

2003-01-01

Absorption spectra of chemically synthesized uniform and multilayer semiconductor nanocrystals in a magnetic field are investigated theoretically. The nanocrystals are modelled by spherical barrier/well potentials. The electron states are calculated within the effective mass model. A four-band k centre dot p Hamiltonian, accounting for the valence subband mixing, is used to obtain the hole states. The magneto-optical transition spectrum depends strongly on the size and composition of the nanocrystals. In the case of small uniform quantum dots, only the linear Zeeman splitting of the electron and hole energy levels is observed even for very strong magnetic fields. In larger nanocrystals, the quadratic magnetic interaction turns out to be important and the transition spectrum becomes complicated. The most complicated influence of the magnetic field is found in quantum dot-quantum well systems in which the lowest electron and hole states are localized in a thin spherical layer. It is shown that transitions that ...

Optical conductivity calculation of a k.p model semiconductor GaAs incorporating first-order electron-hole vertex correction

Science.gov (United States)

Nurhuda, Maryam; Aziz Majidi, Muhammad

2018-04-01

The role of excitons in semiconducting materials carries potential applications. Experimental results show that excitonic signals also appear in optical absorption spectra of semiconductor system with narrow gap, such as Gallium Arsenide (GaAs). While on the theoretical side, calculation of optical spectra based purely on Density Functional Theory (DFT) without taking electron-hole (e-h) interactions into account does not lead to the appearance of any excitonic signal. Meanwhile, existing DFT-based algorithms that include a full vertex correction through Bethe-Salpeter equation may reveal an excitonic signal, but the algorithm has not provided a way to analyze the excitonic signal further. Motivated to provide a way to isolate the excitonic effect in the optical response theoretically, we develop a method of calculation for the optical conductivity of a narrow band-gap semiconductor GaAs within the 8-band k.p model that includes electron-hole interactions through first-order electron-hole vertex correction. Our calculation confirms that the first-order e-h vertex correction reveals excitonic signal around 1.5 eV (the band gap edge), consistent with the experimental data.

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)....

FY1995 ultra-high performance semiconductor lasers for advanced optical information network; 1995 nendo kodo hikari joho tsushinmo e muketa kyokugen seino handotai laser

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

The purpose of this research was to study and develop ultra-high performance semiconductor light source devices that should facilitate construction of advanced optical information networks. The semiconductor devices mentioned above are enhanced and integrated versions of distributed feedback (DFB) lasers based on 'gain coupling', which the group of the research coordinator has been investigating as a pioneer in the world. This research aimed at development of ultra-high performance semiconductor lasers that surpass the first generation conventional DFB lasers in any respect, by strengthening important device characteristics for system applications of the gain-coupled DFB lasers. The achievements of this research are listed below : 1. In-situ characterization of As-P exchange in MOVPE 2. Development of 1.55 {mu}m gain-coupled DFB lasers of absorptive grating type 3. Establishment of measurement technique for gain-coupling coefficients 4. Enlargement of small signal modulation response by the absorptive grating 5. Prediction of lower analog modulation distortion 6. Characterization of reflection-induced noise 7. Proposal and Demonstration of wavelength trimming 8. Proposal and Fabrication of GC DFB laser triode (NEDO)

Characterization of CdSe-nanocrystals used in semiconductors for aerospace applications: Production and optical properties

Directory of Open Access Journals (Sweden)

Maroof A. Hegazy

2014-06-01

Full Text Available Semiconductor nanocrystals (NC’s are the materials with dimensions less than 10 nm. When the dimensions of nanocrystals are reduced the bulk bohr diameter, the photo generated electron-hole pair becomes confined and nanocrystal exhibits size dependent upon optical properties. This work is focused on the studying of CdSe semiconductor nanocrystals. These nanocrystals are considered as one of the most widely studies semiconductors because of their size – tunable optical properties from the visible spectrum. CdSe-nanocrystals are produced and obtained throughout the experimental setup initiated at Nano-NRIAG Unit (NNU, which has been constructed and assembled at NRIAG institute. This unit has a specific characterization for preparing chemical compositions, which may be used for solar cell fabrications and space science technology. The materials prepared included cadmium oxide and selinid have sizes ranging between 2.27 nm and 3.75 nm. CdSe-nanocrystals are synthesized in “TOP/TOPO (tri–octyl phosphine/tri–octyl phosphine oxide. Diagnostic tools, include UV analysis, TEM microscope, and X-ray diffraction, which are considered for the analytical studies of the obtained materials. The results show that, in this size regime, the generated particles have unique optical properties, which is achieved from the UV analysis. Also, the TEM image analysis shows the size and shape of the produced particles. These studies are carried out to optimize the photoluminescent efficiency of these nanoparticles. Moreover, the data revealed that, the grain size of nanocrystals is dependent upon the growth time in turn, it leads to a change in the energy gap. Some applications of this class of materials are outlined.

Nonlinear effects in ultralong semiconductor optical amplifiers for optical communications. Physics and applications

Energy Technology Data Exchange (ETDEWEB)

Runge, Patrick

2010-10-19

The presented work discusses physical properties of ultralong semiconductor optical amplifiers (UL-SOAs) and some of their possible applications in optical communication systems. At the beginning of this thesis the analytical framework for the optical properties of UL-SOAs is presented. Based on this theoretical description, a numerical simulation model is derived used for the investigation of this thesis. To obtain from the simulation model realistic results the important properties of UL-SOAs have to be included, e.g., being the saturation of the main part of the device. In this saturated part of the device, fast intraband effects dominate over the slow interband effects. The intention of UL-SOAs is to make use of these pronounced fast intraband effects in applications. Due to the short relaxation times of the fast intraband effects, they can be used for high-speed signal processing (>20 GBaud). With the help of an additional continuous wave (CW) signal propagating with the data signal in the UL-SOA, the capability for all-optical signal processing with 100 Gbit/s on-off keying RZ-50% pseudo random bit sequence signals has been demonstrated in this thesis. With an optimised device under proper driving conditions, bit pattern effects are negligible compared to the degradation due to amplified spontaneous emission. The suppression of the bit pattern effects can be ascribed to the additional CW signal operating as a holding beam. Investigations of the UL-SOA's driving condition showed that the data signal's extinction ratio (ER) can be regenerated if the two input signals are co-polarised and the data signal has a shorter wavelength than the CW signal. These two and other driving conditions have indicated, that parametric amplification due to four-wave mixing (FWM) (Bogatov-like effect) is the reason for the ER improvement. Moreover, due to the additional CW signal, all-optical wavelength conversion (AOWC) is possible which can be combined with the ER

Demonstration of tunable microwave photonic notch filters using slow and fast light effects in semiconductor optical amplifiers

DEFF Research Database (Denmark)

Xue, Weiqi; Sales, Salvador; Mørk, Jesper

2009-01-01

We introduce a novel scheme based on slow and fast light effects in semiconductor optical amplifiers, to implement a microwave photonic notch filter with ~100% fractional tuning range at a microwave frequency of 30 GHz....

Effect of the depolarization field on coherent optical properties in semiconductor quantum dots

Science.gov (United States)

Mitsumori, Yasuyoshi; Watanabe, Shunta; Asakura, Kenta; Seki, Keisuke; Edamatsu, Keiichi; Akahane, Kouichi; Yamamoto, Naokatsu

2018-06-01

We study the photon echo spectrum of self-assembled semiconductor quantum dots using femtosecond light pulses. The spectrum shape changes from a single-peaked to a double-peaked structure as the time delay between the two excitation pulses is increased. The spectrum change is reproduced by numerical calculations, which include the depolarization field induced by the biexciton-exciton transition as well as the conventional local-field effect for the exciton-ground-state transition in a quantum dot. Our findings suggest that various optical transitions in tightly localized systems generate a depolarization field, which renormalizes the resonant frequency with a change in the polarization itself, leading to unique optical properties.

Open-Source 3D-Printable Optics Equipment

Science.gov (United States)

Zhang, Chenlong; Anzalone, Nicholas C.; Faria, Rodrigo P.; Pearce, Joshua M.

2013-01-01

Just as the power of the open-source design paradigm has driven down the cost of software to the point that it is accessible to most people, the rise of open-source hardware is poised to drive down the cost of doing experimental science to expand access to everyone. To assist in this aim, this paper introduces a library of open-source 3-D-printable optics components. This library operates as a flexible, low-cost public-domain tool set for developing both research and teaching optics hardware. First, the use of parametric open-source designs using an open-source computer aided design package is described to customize the optics hardware for any application. Second, details are provided on the use of open-source 3-D printers (additive layer manufacturing) to fabricate the primary mechanical components, which are then combined to construct complex optics-related devices. Third, the use of the open-source electronics prototyping platform are illustrated as control for optical experimental apparatuses. This study demonstrates an open-source optical library, which significantly reduces the costs associated with much optical equipment, while also enabling relatively easily adapted customizable designs. The cost reductions in general are over 97%, with some components representing only 1% of the current commercial investment for optical products of similar function. The results of this study make its clear that this method of scientific hardware development enables a much broader audience to participate in optical experimentation both as research and teaching platforms than previous proprietary methods. PMID:23544104

Open-source 3D-printable optics equipment.

Science.gov (United States)

Zhang, Chenlong; Anzalone, Nicholas C; Faria, Rodrigo P; Pearce, Joshua M

2013-01-01

Just as the power of the open-source design paradigm has driven down the cost of software to the point that it is accessible to most people, the rise of open-source hardware is poised to drive down the cost of doing experimental science to expand access to everyone. To assist in this aim, this paper introduces a library of open-source 3-D-printable optics components. This library operates as a flexible, low-cost public-domain tool set for developing both research and teaching optics hardware. First, the use of parametric open-source designs using an open-source computer aided design package is described to customize the optics hardware for any application. Second, details are provided on the use of open-source 3-D printers (additive layer manufacturing) to fabricate the primary mechanical components, which are then combined to construct complex optics-related devices. Third, the use of the open-source electronics prototyping platform are illustrated as control for optical experimental apparatuses. This study demonstrates an open-source optical library, which significantly reduces the costs associated with much optical equipment, while also enabling relatively easily adapted customizable designs. The cost reductions in general are over 97%, with some components representing only 1% of the current commercial investment for optical products of similar function. The results of this study make its clear that this method of scientific hardware development enables a much broader audience to participate in optical experimentation both as research and teaching platforms than previous proprietary methods.

Open-source 3D-printable optics equipment.

Directory of Open Access Journals (Sweden)

Chenlong Zhang

Full Text Available Just as the power of the open-source design paradigm has driven down the cost of software to the point that it is accessible to most people, the rise of open-source hardware is poised to drive down the cost of doing experimental science to expand access to everyone. To assist in this aim, this paper introduces a library of open-source 3-D-printable optics components. This library operates as a flexible, low-cost public-domain tool set for developing both research and teaching optics hardware. First, the use of parametric open-source designs using an open-source computer aided design package is described to customize the optics hardware for any application. Second, details are provided on the use of open-source 3-D printers (additive layer manufacturing to fabricate the primary mechanical components, which are then combined to construct complex optics-related devices. Third, the use of the open-source electronics prototyping platform are illustrated as control for optical experimental apparatuses. This study demonstrates an open-source optical library, which significantly reduces the costs associated with much optical equipment, while also enabling relatively easily adapted customizable designs. The cost reductions in general are over 97%, with some components representing only 1% of the current commercial investment for optical products of similar function. The results of this study make its clear that this method of scientific hardware development enables a much broader audience to participate in optical experimentation both as research and teaching platforms than previous proprietary methods.

Semiconductor quantum-dot lasers and amplifiers

DEFF Research Database (Denmark)

Hvam, Jørn Märcher; Borri, Paola; Ledentsov, N. N.

2002-01-01

-power surface emitting VCSELs. We investigated the ultrafast dynamics of quantum-dot semiconductor optical amplifiers. The dephasing time at room temperature of the ground-state transition in semiconductor quantum dots is around 250 fs in an unbiased amplifier, decreasing to below 50 fs when the amplifier...... is biased to positive net gain. We have further measured gain recovery times in quantum dot amplifiers that are significantly lower than in bulk and quantum-well semiconductor optical amplifiers. This is promising for future demonstration of quantum dot devices with high modulation bandwidth...

Interband optical pulse injection locking of quantum dot mode-locked semiconductor laser.

Science.gov (United States)

Kim, Jimyung; Delfyett, Peter J

2008-07-21

We experimentally demonstrate optical clock recovery from quantum dot mode-locked semiconductor lasers by interband optical pulse injection locking. The passively mode-locked slave laser oscillating on the ground state or the first excited state transition is locked through the injection of optical pulses generated via the opposite transition bands, i.e. the first excited state or the ground state transition from the hybridly mode-locked master laser, respectively. When an optical pulse train generated via the first excited state from the master laser is injected to the slave laser oscillating via ground state, the slave laser shows an asymmetric locking bandwidth around the nominal repetition rate of the slave laser. In the reverse injection case of, i.e. the ground state (master laser) to the first excited state (slave laser), the slave laser does not lock even though both lasers oscillate at the same cavity frequency. In this case, the slave laser only locks to higher injection rates as compared to its own nominal repetition rate, and also shows a large locking bandwidth of 6.7 MHz.

The pursuit of electrically-driven organic semiconductor lasers

NARCIS (Netherlands)

Bisri, Satria Zulkarnaen; Takenobu, Taishi; Iwasa, Yoshihiro

2014-01-01

Organic semiconductors have many favourable and plastic-like optical properties that are promising for the development of low energy consuming laser devices. Although optically-pumped organic semiconductor lasers have been demonstrated since the early days of lasers, electrically-driven organic

Fabrication of highly nonlinear germano-silicate glass optical fiber incorporated with PbTe semiconductor quantum dots using atomization doping process and its optical nonlinearity.

Science.gov (United States)

Ju, Seongmin; Watekar, Pramod R; Han, Won-Taek

2011-01-31

Germano-silicate glass optical fiber incorporated with PbTe semiconductor quantum dots (SQDs) in the core was fabricated by using the atomization process in modified chemical vapor deposition (MCVD) process. The absorption bands attributed to PbTe semiconductor quantum dots in the fiber core were found to appear at around 687 nm and 1055 nm. The nonlinear refractive index measured by the long-period fiber grating (LPG) pair method upon pumping with laser diode at 976.4 nm was estimated to be ~1.5 × 10(-16) m2/W.

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...

Method of making a self-aligned schottky metal semi-conductor field effect transistor with buried source and drain

International Nuclear Information System (INIS)

Bol, I.

1984-01-01

A semi-conductor structure and particularly a high speed VLSI Self-Aligned Schottky Metal Semi-Conductor Field Effect Transistor with buried source and drain, fabricated by the ion implantation of source and drain areas at a predetermined range of depths followed by very localized laser annealing to electrically reactivate the amorphous buried source and drain areas thereby providing effective vertical separation of the channel from the buried source and drain respectively. Accordingly, spatial separations between the self-aligned gate-to-drain, and gate-to-source can be relatively very closely controlled by varying the doping intensity and duration of the implantation thereby reducing the series resistance and increasing the operating speed

Broadband superluminescent diodes and semiconductor optical amplifiers for the spectral range 750 - 800 nm

International Nuclear Information System (INIS)

Il'chenko, S N; Kostin, Yu O; Kukushkin, I A; Ladugin, M A; Lapin, P I; Lobintsov, A A; Marmalyuk, Aleksandr A; Yakubovich, S D

2011-01-01

We have studied superluminescent diodes (SLDs) and semiconductor optical amplifiers (SOAs) based on an (Al x Ga 1-x )As/GaAs single quantum well structure with an Al content x ∼ 0.1 in a 10-nm-thick active layer. Depending on the length of the active channel, the single-mode fibre coupled cw output power of the SLDs is 1 to 30 mW at a spectral width of about 50 nm. The width of the optical gain band in the active channel exceeds 40 nm. Preliminary operating life tests have demonstrated that the devices are sufficiently reliable. (lasers)

Absorption properties of metal-semiconductor hybrid nanoparticles.

Science.gov (United States)

Shaviv, Ehud; Schubert, Olaf; Alves-Santos, Marcelo; Goldoni, Guido; Di Felice, Rosa; Vallée, Fabrice; Del Fatti, Natalia; Banin, Uri; Sönnichsen, Carsten

2011-06-28

The optical response of hybrid metal-semiconductor nanoparticles exhibits different behaviors due to the proximity between the disparate materials. For some hybrid systems, such as CdS-Au matchstick-shaped hybrids, the particles essentially retain the optical properties of their original components, with minor changes. Other systems, such as CdSe-Au dumbbell-shaped nanoparticles, exhibit significant change in the optical properties due to strong coupling between the two materials. Here, we study the absorption of these hybrids by comparing experimental results with simulations using the discrete dipole approximation method (DDA) employing dielectric functions of the bare components as inputs. For CdS-Au nanoparticles, the DDA simulation provides insights on the gold tip shape and its interface with the semiconductor, information that is difficult to acquire by experimental means alone. Furthermore, the qualitative agreement between DDA simulations and experimental data for CdS-Au implies that most effects influencing the absorption of this hybrid system are well described by local dielectric functions obtained separately for bare gold and CdS nanoparticles. For dumbbell shaped CdSe-Au, we find a shortcoming of the electrodynamic model, as it does not predict the "washing out" of the optical features of the semiconductor and the metal observed experimentally. The difference between experiment and theory is ascribed to strong interaction of the metal and semiconductor excitations, which spectrally overlap in the CdSe case. The present study exemplifies the employment of theoretical approaches used to describe the optical properties of semiconductors and metal nanoparticles, to achieve better understanding of the behavior of metal-semiconductor hybrid nanoparticles.

Quantum theory of the electronic and optical properties of low-dimensional semiconductor systems

Science.gov (United States)

Lau, Wayne Heung

This thesis examines the electronic and optical properties of low-dimensional semiconductor systems. A theory is developed to study the electron-hole generation-recombination process of type-II semimetallic semiconductor heterojunctions based on a 3 x 3 k·p matrix Hamiltonian (three-band model) and an 8 x 8 k·p matrix Hamiltonian (eight-band model). A novel electron-hole generation and recombination process, which is called activationless generation-recombination process, is predicted. It is demonstrated that the current through the type-II semimetallic semiconductor heterojunctions is governed by the activationless electron-hole generation-recombination process at the heterointerfaces, and that the current-voltage characteristics are essentially linear. A qualitative agreement between theory and experiments is observed. The numerical results of the eight-band model are compared with those of the threeband model. Based on a lattice gas model, a theory is developed to study the influence of a random potential on the ionization equilibrium conditions for bound electron-hole pairs (excitons) in III--V semiconductor heterostructures. It is demonstrated that ionization equilibrium conditions for bound electron-hole pairs change drastically in the presence of strong disorder. It is predicted that strong disorder promotes dissociation of excitons in III--V semiconductor heterostructures. A theory of polariton (photon dressed by phonon) spontaneous emission in a III--V semiconductor doped with semiconductor quantum dots (QDs) or quantum wells (QWs) is developed. For the first time, superradiant and subradiant polariton spontaneous emission phenomena in a polariton-QD (QW) coupled system are predicted when the resonance energies of the two identical QDs (QWs) lie outside the polaritonic energy gap. It is also predicted that when the resonance energies of the two identical QDs (QWs) lie inside the polaritonic energy gap, spontaneous emission of polariton in the polariton

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.

Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

International Nuclear Information System (INIS)

Chang-Hwan Kim

2003-01-01

Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms

Optically Detected Magnetic Resonance and Thermal Activation Spectroscopy Study of Organic Semiconductors

Energy Technology Data Exchange (ETDEWEB)

Kim, Chang-Hwan [Iowa State Univ., Ames, IA (United States)

2003-01-01

Organic electronic materials are a new class of emerging materials. Organic light emitting devices (OLEDs) are the most promising candidates for future flat panel display technologies. The photophysical characterization is the basic research step one must follow to understand this new class of materials and devices. The light emission properties are closely related to the transport properties of these materials. The objective of this dissertation is to probe the relation between transport and photophysical properties of organic semiconductors. The transport characteristics were evaluated by using thermally stimulated current and thermally stimulated luminescence techniques. The photoluminescence detected magnetic resonance and photoluminescence quantum yield studies provide valuable photophysical information on this class of materials. OLEDs are already in the market. However, detailed studies on the degradation mechanisms are still lacking. Since both optically detected magnetic resonance and thermal activation spectroscopy probe long-lived defect-related states in organic semiconductors, the combined study generates new insight on the OLED operation and degradation mechanisms.

III-nitride semiconductors and their modern devices

CERN Document Server

2013-01-01

This book is dedicated to GaN and its alloys AlGaInN (III-V nitrides), semiconductors with intrinsic properties well suited for visible and UV light emission and electronic devices working at high temperature, high frequency, and harsh environments. There has been a rapid growth in the industrial activity relating to GaN, with GaN now ranking at the second position (after Si) among all semiconductors. This is mainly thanks to LEDs, but also to the emergence of lasers and high power and high frequency electronics. GaN-related research activities are also diversifying, ranging from advanced optical sources and single electron devices to physical, chemical, and biological sensors, optical detectors, and energy converters. All recent developments of nitrides and of their technology are gathered here in a single volume, with chapters written by world leaders in the field. This third book of the series edited by B. Gil is complementary to the preceding two, and is expected to offer a modern vision of nitrides and...

Time-resolved optically-detected magnetic resonance of II-VI diluted-magnetic-semiconductor heterostructures

Energy Technology Data Exchange (ETDEWEB)

Ivanov, V.Yu.; Karczewski, G. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Godlewski, M. [Institute of Physics, Polish Academy of Sciences, 02-668 Warsaw (Poland); Dept. Mathem. and Natural Sci. College of Sci., Card. S. Wyszynski Univ., Warsaw (Poland); Yakovlev, D.R. [Experimental Physics 2, University of Dortmund, 44221 Dortmund (Germany); A. F. Ioffe Physico-Technical Institute, 194017 St. Petersburg (Russian Federation); Ryabchenko, S.M. [Institute of Physics NAS Ukraine, 03028 Kiev (Ukraine); Waag, A. [Institute of Semiconductor Technology, Braunschweig Technical University, 38106 Braunschweig (Germany)

2007-01-15

Time-resolved optically-detected magnetic resonance (ODMR) technique was used to study spin dynamics of Mn{sup 2+} ions in (Zn,Mn)Se- and (Cd,Mn)Te-based diluted magnetic semiconductor quantum wells. Times of spin-lattice relaxation have been measured directly from a dynamical shift of exciton luminescence lines after a pulsed impact of 60 GHz microwave radiation. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Monolithically integrated quantum dot optical gain modulator with semiconductor optical amplifier for 10-Gb/s photonic transmission

Science.gov (United States)

Yamamoto, Naokatsu; Akahane, Kouichi; Umezawa, Toshimasa; Kawanishi, Tetsuya

2015-03-01

Short-range interconnection and/or data center networks require high capacity and a large number of channels in order to support numerous connections. Solutions employed to meet these requirements involve the use of alternative wavebands to increase the usable optical frequency range. We recently proposed the use of the T- and O-bands (Thousand band: 1000-1260 nm, Original band: 1260-1360 nm) as alternative wavebands because large optical frequency resources (>60 THz) can be easily employed. In addition, a simple and compact Gb/s-order high-speed optical modulator is a critical photonic device for short-range communications. Therefore, to develop an optical modulator that acts as a highfunctional photonic device, we focused on the use of self-assembled quantum dots (QDs) as a three-dimensional (3D) confined structure because QD structures are highly suitable for realizing broadband optical gain media in the T+O bands. In this study, we use the high-quality broadband QD optical gain to develop a monolithically integrated QD optical gain modulator (QD-OGM) device that has a semiconductor optical amplifier (QD-SOA) for Gb/s-order highspeed optical data generation in the 1.3-μm waveband. The insertion loss of the device can be compensated through the SOA, and we obtained an optical gain change of up to ~7 dB in the OGM section. Further, we successfully demonstrate a 10-Gb/s clear eye opening using the QD-OGM/SOA device with a clock-data recovery sequence at the receiver end. These results suggest that the monolithic QD-EOM/SOA is suitable for increasing the number of wavelength channels for smart short-range communications.

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.

Modeling of Semiconductor Optical Amplifier Gain Characteristics for Amplification and Switching

Science.gov (United States)

Mahad, Farah Diana; Sahmah, Abu; Supa'at, M.; Idrus, Sevia Mahdaliza; Forsyth, David

2011-05-01

The Semiconductor Optical Amplifier (SOA) is presently commonly used as a booster or pre-amplifier in some communication networks. However, SOAs are also a strong candidate for utilization as multi-functional elements in future all-optical switching, regeneration and also wavelength conversion schemes. With this in mind, the purpose of this paper is to simulate the performance of the SOA for improved amplification and switching functions. The SOA is modeled and simulated using OptSim software. In order to verify the simulated results, a MATLAB mathematical model is also used to aid the design of the SOA. Using the model, the gain difference between simulated and mathematical results in the unsaturated region is <1dB. The mathematical analysis is in good agreement with the simulation result, with only a small offset due to inherent software limitations in matching the gain dynamics of the SOA.

Low-frequency fluctuation in multimode semiconductor laser subject to optical feedback

Institute of Scientific and Technical Information of China (English)

Xu Zhang; Huiying Ye; Zhaoxin Song

2008-01-01

Dynamics of a semiconductor laser subject to moderate optical feedback operating in the low-frequency fluctuation regime is numerically investigated.Multimode Lang-Kobayashi(LK)equations show that the low-frequency intensity dropout including the total intensity and sub-modes intensity is accompanied by sudden dropout simultaneously,which is in good agreement with experimental observation.The power fluctuation is quite annoying in practical applications,therefore it becomes important to study the mechanism of power fluctuation.It is also shown that many factors,such as spontaneous emission noise and feedback parameter,may influence power fluctuation larger than previously expected.

The fabrication of carbon nanotube field-effect transistors with semiconductors as the source and drain contact materials.

Science.gov (United States)

Xiao, Z; Camino, F E

2009-04-01

Sb(2)Te(3) and Bi(2)Te(2)Se semiconductor materials were used as the source and drain contact materials in the fabrication of carbon nanotube field-effect transistors (CNTFETs). Ultra-purified single-walled carbon nanotubes (SWCNTs) were ultrasonically dispersed in N-methyl pyrrolidone solvent. Dielectrophoresis was used to deposit and align SWCNTs for fabrication of CNTFETs. The Sb(2)Te(3)- and Bi(2)Te(2)Se-based CNTFETs demonstrate p-type metal-oxide-silicon-like I-V curves with high on/off drain-source current ratio at large drain-source voltages and good saturation of drain-source current with increasing drain-source voltage. The fabrication process developed is novel and has general meaning, and could be used for the fabrication of SWCNT-based integrated devices and systems with semiconductor contact materials.

Nonlinear properties of quantum dot semiconductor optical amplifiers at 1.3 μm Invited Paper

Institute of Scientific and Technical Information of China (English)

D. Bimberg; C. Meuer; M. L(a)mmlin; S. Liebich; J. Kim; A. Kovsh; I. Krestnikov; G. Eisenstein

2008-01-01

@@ The dynamics of nonlinear processes in quantum dot (QD) semiconductor optical amplifiers (SOAs) are investigated. Using small-signal measurements, the suitabilities of cross-gain and cross-phase modulation as well as four wave mixing (FWM) for wavelength conversion are examined. The cross-gain modulation is found to be suitable for wavelength conversion up to a frequency of 40 GHz.

Advanced materials for the optical delay line of frequency pulse modulator on the basis of semiconductor laser

International Nuclear Information System (INIS)

Abrarov, S.M.

1999-01-01

In the paper some materials which can be sued as an optical delay line of the pulse frequency modulator are considered. The structure and the principle are described as a modulator consisting of a laser diode with two Fabry Perot resonators and an optical wave guide providing a feedback loop. The optical wave guide fulfills the function of delay line and links the two resonators. The pulse sequence of the radiation of the semiconductor laser arises due to failure and recovery of optical generation. The pulse frequency modulation can be carried out by the action of electrical tension field on the electro optic martial of the wave guide. The selection of three electro-optic crystals for making of the optical wave guide of the considered modulator is justified. (author)

Semiconductor thin films directly from minerals—study of structural, optical, and transport characteristics of Cu2O thin films from malachite mineral and synthetic CuO

International Nuclear Information System (INIS)

Balasubramaniam, K.R.; Kao, V.M.; Ravichandran, J.; Rossen, P.B.; Siemons, W.; Ager, J.W.

2012-01-01

We demonstrate the proof-of-concept of using an abundantly occurring natural ore, malachite (Cu 2 CO 3 (OH) 2 ) to directly yield the semiconductor Cu 2 O to be used as an active component of a functional thin film based device. Cu 2 O is an archetype hole-conducting semiconductor that possesses several interesting characteristics particularly useful for solar cell applications, including low cost, non-toxicity, good hole mobility, large minority carrier diffusion length, and a direct energy gap ideal for efficient absorption. In this article, we compare the structural, optical, and electrical transport characteristics of Cu 2 O thin films grown from the natural mineral malachite and synthetic CuO targets. Growth from either source material results in single-phase, fully epitaxial cuprous oxide thin films as determined by x-ray diffraction. The films grown from malachite have strong absorption coefficients ( 10 4 cm −1 ), a direct allowed optical bandgap ( 2.4 eV), and majority carrier hole mobilities ( 35 cm 2 V −1 s −1 at room temperature) that compare well with films grown from the synthetic target as well as with previously reported values. Our work demonstrates that minerals could be useful to directly yield the active components in functional devices and suggests a route for the exploration of low cost energy conversion and storage technologies. - Highlights: ► Semiconductor thin films directly from minerals ► Chemistry and structure evolution of the films obtained from mineral target is very similar to that films obtained from high-purity synthetic targets. ► Quite interestingly, transport and optical characteristics are also found to be similar.

Direct solar pumping of semiconductor lasers: A feasibility study

Science.gov (United States)

Anderson, Neal G.

1992-01-01

This report describes results of NASA Grant NAG-1-1148, entitled Direct Solar Pumping of Semiconductor Lasers: A Feasibility Study. The goals of this study were to provide a preliminary assessment of the feasibility of pumping semiconductor lasers in space with directly focused sunlight and to identify semiconductor laser structures expected to operate at the lowest possible focusing intensities. It should be emphasized that the structures under consideration would provide direct optical-to-optical conversion of sunlight into laser light in a single crystal, in contrast to a configuration consisting of a solar cell or storage battery electrically pumping a current injection laser. With external modulation, such lasers could perhaps be efficient sources for intersatellite communications. We proposed specifically to develop a theoretical model of semiconductor quantum-well lasers photopumped by a broadband source, test it against existing experimental data where possible, and apply it to estimating solar pumping requirements and identifying optimum structures for operation at low pump intensities. These tasks have been accomplished, as described in this report of our completed project. The report is organized as follows: Some general considerations relevant to the solar-pumped semiconductor laser problem are discussed in Section 2, and the types of structures chosen for specific investigation are described. The details of the laser model we developed for this work are then outlined in Section 3. In Section 4, results of our study are presented, including designs for optimum lattice-matched and strained-layer solar-pumped quantum-well lasers and threshold pumping estimates for these structures. It was hoped at the outset of this work that structures could be identified which could be expected to operate continuously at solar photoexcitation intensities of several thousand suns, and this indeed turned out to be the case as described in this section. Our project is

Using a Semiconductor-to-Metal Transition to Control Optical Transmission through Subwavelength Hole Arrays

Directory of Open Access Journals (Sweden)

E. U. Donev

2008-01-01

Full Text Available We describe a simple configuration in which the extraordinary optical transmission effect through subwavelength hole arrays in noble-metal films can be switched by the semiconductor-to-metal transition in an underlying thin film of vanadium dioxide. In these experiments, the transition is brought about by thermal heating of the bilayer film. The surprising reverse hysteretic behavior of the transmission through the subwavelength holes in the vanadium oxide suggest that this modulation is accomplished by a dielectric-matching condition rather than plasmon coupling through the bilayer film. The results of this switching, including the wavelength dependence, are qualitatively reproduced by a transfer matrix model. The prospects for effecting a similar modulation on a much faster time scale by using ultrafast laser pulses to trigger the semiconductor-to-metal transition are also discussed.

TE-TM dynamics in a semiconductor laser subject to polarization-rotated optical feedback

International Nuclear Information System (INIS)

Heil, T.; Uchida, A.; Davis, P.; Aida, T.

2003-01-01

We present a comprehensive experimental characterization of the dynamics of semiconductor lasers subject to polarization-rotated optical feedback. We find oscillatory instabilities appearing for large feedback levels and disappearing at large injection currents, which we classify in contrast to the well-known conventional optical-feedback-induced dynamics. In addition, we compare our experiments to theoretical results of a single-mode model assuming incoherence of the optical feedback, and we identify differences concerning the average power of the laser. Hence, we develop an alternative model accounting for both polarizations, where the emission of the dominant TE mode is injected with delay into the TM mode of the laser. Numerical simulations using this model show good qualitative agreement with our experimental results, correctly reproducing the parameter dependences of the dynamics. Finally, we discuss the application of polarization-rotated-feedback induced instabilities in chaotic carrier communication systems

Demonstration and optimisation of an ultrafast all-optical AND logic gate using four-wave mixing in a semiconductor optical amplifier

International Nuclear Information System (INIS)

Razaghi, M; Nosratpour, A; Das, N K

2013-01-01

We have proposed an all-optical AND logic gate based on four-wave mixing (FWM) in a semiconductor optical amplifier (SOA) integrated with an optical filter. In the scheme proposed, the preferred logical function can be performed without using a continuous-wave (cw) signal. The modified nonlinear Schroedinger equation (MNLSE) is used for the modelling wave propagation in a SOA. The MNLSE takes into account all nonlinear effects relevant to pico- and sub-picosecond pulse durations and is solved by the finite-difference beam-propagation method (FD-BPM). Based on the simulation results, the optimal output signal with a 40-fJ energy can be obtained at a bit rate of 50 Gb s -1 . In the simulations, besides the nonlinearities included in the model, the pattern effect of the signals propagating in the SOA medium and the effect of the input signal bit rate are extensively investigated to optimise the system performance. (optical logic elements)

Dynamics of modal power distribution in a multimode semiconductor laser with optical feedback

International Nuclear Information System (INIS)

Buldu, J M; Trull, J; Torrent, M C; GarcIa-Ojalvo, J; Mirasso, Claudio R

2002-01-01

The dynamics of power distribution between longitudinal modes of a multimode semiconductor laser subjected to external optical feedback is experimentally analysed in the low-frequency fluctuation regime. Power dropouts in the total light intensity are invariably accompanied by sudden activations of several longitudinal modes. These activations are seen not to be simultaneous to the dropouts, but to occur after them. The phenomenon is statistically analysed in a systematic way, and the corresponding delay is estimated. (letter to the editor)

Dynamics of modal power distribution in a multimode semiconductor laser with optical feedback

Energy Technology Data Exchange (ETDEWEB)

Buldu, J M [Departament de FIsica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, E-08222 Terrassa (Spain); Trull, J [Departament de FIsica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, E-08222 Terrassa (Spain); Torrent, M C [Departament de FIsica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, E-08222 Terrassa (Spain); GarcIa-Ojalvo, J [Departament de FIsica i Enginyeria Nuclear, Universitat Politecnica de Catalunya, Colom 11, E-08222 Terrassa (Spain); Mirasso, Claudio R [Departament de FIsica, Universitat de les Illes Balears, E-07071 Palma de Mallorca (Spain)

2002-02-01

The dynamics of power distribution between longitudinal modes of a multimode semiconductor laser subjected to external optical feedback is experimentally analysed in the low-frequency fluctuation regime. Power dropouts in the total light intensity are invariably accompanied by sudden activations of several longitudinal modes. These activations are seen not to be simultaneous to the dropouts, but to occur after them. The phenomenon is statistically analysed in a systematic way, and the corresponding delay is estimated. (letter to the editor)

Effect of disorder and defects in ion-implanted semiconductors optical and photothermal characterization

CERN Document Server

Willardson, R K; Christofides, Constantinos; Ghibaudo, Gerard

1997-01-01

Defects in ion-implanted semiconductors are important and will likely gain increased importance as annealing temperatures are reduced with successive IC generations. Novel implant approaches, such as MdV implantation, create new types of defects whose origin and annealing characteristics will need to be addressed. Publications in this field mainly focus on the effects of ion implantation on the material and the modification in the implanted layer after high temperature annealing. The editors of this volume and Volume 45 focus on the physics of the annealing kinetics of the damaged layer. An overview of characterization tehniques and a critical comparison of the information on annealing kinetics is also presented. Key Features * Provides basic knowledge of ion implantation-induced defects * Focuses on physical mechanisms of defect annealing * Utilizes electrical, physical, and optical characterization tools for processed semiconductors * Provides the basis for understanding the problems caused by the defects g...

Microscopic theory of coherent and incoherent optical properties of semiconductor heterostructures

Energy Technology Data Exchange (ETDEWEB)

Schaefer, Martin

2008-09-02

An important question is whether there is a regime in which lasing from indirect semiconductors is possible. Thus, we discuss this question in this thesis. It is shown that under incoherent emission conditions it is possible to create an exciton condensate in multiple-quantum-well (MQW) systems. The influence of a MQW structure on the exciton lifetime is investigated. For the description of the light-matter interaction of a QW in the coherent excitation regime, the semiconductor Bloch equation (SBE) are used. The incoherent regime is described by the semiconductor luminescence equations (SLE). In principle it is even possible to couple SBE and SLE. The resulting theory is able to describe interactions between coherent and incoherent processes we investigate both, the coherent and the incoherent light-emission regime. Thus we define the investigated system and introduce the many-body Hamiltonian that describes consistently the light-matter interaction in the classical and the quantum limit. We introduce the SBE that allow to compute the light-matter interaction in the coherent scenario. The extended scattering model is used to investigate the absorption of a Ge QW for different time delays after the excitations. In this context, we analyze whether there is a regime in which optical gain can be realized. Then we apply a transfer-matrix method to include into our calculations the influence of the dielectric environment on the optical response. Thereafter the SLE for a MQW system are introduced. We derive a scheme that allows for decoupling environmental effects from the pure PL-emission properties of the QW. The PL of the actual QW system is obtained by multiplying this filter function and the free-space PL that describes the quantum emission into a medium with spatially constant background-refractive index. It is studied how the MQW-Bragg structure influences the PL-emission properties compared to the emission of a single QW device. As a last feature, it is shown

Gain and Index Dynamics in Semiconductor Lasers

DEFF Research Database (Denmark)

Hvam, Jørn Märcher

Semiconductor optical amplifiers (SOAs) provide ultrafast, i.e. broadband components for optical communication systems. They enter not only as signal generators and amplifiers, but also as nonlinear elements for ultrafast signal processing such as wavelength conversion, switching, and regeneration...... changed character from bulk semiconductor to quantum wells and most recently to quantum dots. By quantum confinement of the carriers, the light-matter interactions can be significantly modified and the optical properties, including dynamics, can be engineered to match the required functionalities...

Preparations and Characterizations of Luminescent Two Dimensional Organic-inorganic Perovskite Semiconductors

Directory of Open Access Journals (Sweden)

Sanjun Zhang

2010-05-01

Full Text Available This article reviews the synthesis, structural and optical characterizations of some novel luminescent two dimensional organic-inorganic perovskite (2DOIP semiconductors. These 2DOIP semiconductors show a self-assembled nano-layered structure, having the electronic structure of multi-quantum wells. 2DOIP thin layers and nanoparticles have been prepared through different methods. The structures of the 2DOIP semiconductors are characterized by atomic force microscopy and X-ray diffraction. The optical properties of theb DOIP semiconductors are characterized from absorption and photoluminescence spectra measured at room and low temperatures. Influences of different components, in particular the organic parts, on the structural and optical properties of the 2DOIP semiconductors are discussed.

Homogeneous spectral spanning of terahertz semiconductor lasers with radio frequency modulation.

Science.gov (United States)

Wan, W J; Li, H; Zhou, T; Cao, J C

2017-03-08

Homogeneous broadband and electrically pumped semiconductor radiation sources emitting in the terahertz regime are highly desirable for various applications, including spectroscopy, chemical sensing, and gas identification. In the frequency range between 1 and 5 THz, unipolar quantum cascade lasers employing electron inter-subband transitions in multiple-quantum-well structures are the most powerful semiconductor light sources. However, these devices are normally characterized by either a narrow emission spectrum due to the narrow gain bandwidth of the inter-subband optical transitions or an inhomogeneous broad terahertz spectrum from lasers with heterogeneous stacks of active regions. Here, we report the demonstration of homogeneous spectral spanning of long-cavity terahertz semiconductor quantum cascade lasers based on a bound-to-continuum and resonant phonon design under radio frequency modulation. At a single drive current, the terahertz spectrum under radio frequency modulation continuously spans 330 GHz (~8% of the central frequency), which is the record for single plasmon waveguide terahertz lasers with a bound-to-continuum design. The homogeneous broadband terahertz sources can be used for spectroscopic applications, i.e., GaAs etalon transmission measurement and ammonia gas identification.

Optical self-injection mode-locking of semiconductor optical amplifier fiber ring with electro-absorption modulation—fundamentals and applications

International Nuclear Information System (INIS)

Chi, Yu-Chieh; Lin, Gong-Ru

2013-01-01

The optical self-injection mode-locking of a semiconductor optical amplifier incorporated fiber ring laser (SOAFL) with spectrally sliced multi-channel carriers is demonstrated for applications. The synthesizer-free SOAFL pulse-train is delivered by optical injection mode-locking with a 10 GHz self-pulsed electro-absorption modulator (EAM). Such a coupled optical and electronic resonator architecture facilitates a self-feedback oscillation with a higher Q-factor and lower phase/intensity noises when compared with conventional approaches. The theoretical model of such an injection-mode-locking SOAFL is derived to improve the self-pulsating performance of the optical return-to-zero (RZ) carrier, thus providing optimized pulsewidth, pulse extinction ratio, effective Q-factor, frequency variation and timing jitter of 11.4 ps, 9.1 dB, 4 × 10 5 , −1 bi-directional WDM transmission network with down-stream RZ binary phase-shift keying (RZ-BPSK) and up-stream re-modulated RZ on–off-keying (RZ-OOK) formats. Under BPSK/OOK bi-directional data transmission, the self-pulsed harmonic mode-locking SOAFL simultaneously provides four to six WDM channels for down-stream RZ-BPSK and up-stream RZ-OOK formats with receiving sensitivities of −17 and −15.2 dBm at a bit error rate of 10 −9 , respectively. (paper)

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.

Output power PDF of a saturated semiconductor optical amplifier: Second-order noise contributions by path integral method

DEFF Research Database (Denmark)

Öhman, Filip; Mørk, Jesper; Tromborg, Bjarne

2007-01-01

We have developed a second-order small-signal model for describing the nonlinear redistribution of noise in a saturated semiconductor optical amplifier. In this paper, the details of the model are presented. A numerical example is used to compare the model to statistical simulations. We show that...

Optimisation of 40 Gb/s wavelength converters based on four-wave mixing in a semiconductor optical amplifier

DEFF Research Database (Denmark)

Schulze, K.; Petersen, Martin Nordal; Herrera, J.

2007-01-01

The optimum operating powers and wavelengths for a 40 Gb/s wavelength converter based on four-wave mixing in a semiconductor 14 optical amplifier are inferred from experimental results. From these measurements, some general rules of thumb are derived for this kind of devices. Generally, the optim...

Purcell effect for active tuning of light scattering from semiconductor optical antennas.

Science.gov (United States)

Holsteen, Aaron L; Raza, Søren; Fan, Pengyu; Kik, Pieter G; Brongersma, Mark L

2017-12-15

Subwavelength, high-refractive index semiconductor nanostructures support optical resonances that endow them with valuable antenna functions. Control over the intrinsic properties, including their complex refractive index, size, and geometry, has been used to manipulate fundamental light absorption, scattering, and emission processes in nanostructured optoelectronic devices. In this study, we harness the electric and magnetic resonances of such antennas to achieve a very strong dependence of the optical properties on the external environment. Specifically, we illustrate how the resonant scattering wavelength of single silicon nanowires is tunable across the entire visible spectrum by simply moving the height of the nanowires above a metallic mirror. We apply this concept by using a nanoelectromechanical platform to demonstrate active tuning. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

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.

Figures of merit for microwave photonic phase shifters based on semiconductor optical amplifiers.

Science.gov (United States)

Sancho, Juan; Lloret, Juan; Gasulla, Ivana; Sales, Salvador; Capmany, José

2012-05-07

We theoretically and experimentally compare the performance of two fully tunable phase shifter structures based on semiconductor optical amplifiers (SOA) by means of several figures of merit common to microwave photonic systems. A single SOA stage followed by a tailored notch filter is compared with a cascaded implementation comprising three SOA-based phase shifter stages. Attention is focused on the assessment of the RF net gain, noise figure and nonlinear distortion. Recommendations on the performance optimization of this sort of approaches are detailed.

FY1995 research on nonlinear optical devices using super-lattice semiconductors; 1995 nendo chokoshi active hisenkei soshi wo mochiita chokosoku hikari seigyo gijutsu no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-03-01

The purpose is to develop technologies on efficient generation and control of femtosecond optical pulses using a novel semiconductor optical devices. We studied a modelocked Cr:forsterite laser pumped by a diode pumped Nd:YVO4 laser. Both Kerr lens mode locking and semi-conductor saturable absorber initiated mode locking have been achieved. The minimum pulse width for pure Kerr lens mode locking is 26.4 fs, while for the semiconductor saturable absorber initiated mode locking, the pulse width is 36 fs. The latter is very resistant to the environment perturbations. We also present the measured dispersion data for the forsterite crystal and the SESAM, and discuss the dispersion compensation technique. (NEDO)

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

Review on the dynamics of semiconductor nanowire lasers

Science.gov (United States)

Röder, Robert; Ronning, Carsten

2018-03-01

Semiconductor optoelectronic devices have contributed tremendously to the technological progress in the past 50-60 years. Today, they also play a key role in nanophotonics stimulated by the inherent limitations of electronic integrated circuits and the growing demand for faster communications on chip. In particular, the field of ‘nanowire photonics’ has emerged including the search for coherent light sources with a nano-scaled footprint. The past decade has been dedicated to find suitable semiconductor nanowire (NW) materials for such nanolasers. Nowadays, such NW lasers consistently work at room temperature covering a huge spectral range from the ultraviolet down to the mid-infrared depending on the band gap of the NW material. Furthermore, first approaches towards the modification and optimization of such NW laser devices have been demonstrated. The underlying dynamics of the electronic and photonic NW systems have also been studied very recently, as they need to be understood in order to push the technological relevance of nano-scaled coherent light sources. Therefore, this review will first present novel measurement approaches in order to study the ultrafast temporal and optical mode dynamics of individual NW laser devices. Furthermore, these fundamental new insights are reviewed and deeply discussed towards the efficient control and adjustment of the dynamics in semiconductor NW lasers.

Optical properties of Amorphous Semiconductors Part- II: Theory and analysis of optical properties

International Nuclear Information System (INIS)

Hogarth, C. A.

1997-01-01

The atomic and band structural properties of solids have been studied. Reflectance is concerned in spectroscopic measurement of transmission and absorption, since the incident light intensity must be corrected for the loss of light by reflection and which does not penetrate beyond the surface of the material studied.The procedure for estimating E opt and n from the absorption edge of an amorphous semiconductor has been discussed. In high refractive index glasses there is a general correlation between n and the density of the glasses and in designing a particular glass for an optical purpose this can provide a useful guide to composition. The Gladstone-Dale refractivity and the Newton-Drude refractivity have been calculated for different value of b and these relations have been tested for telluride semiconducting glasses and give reasonable agreement in estimations of n directly from the density ρ. 33 refs., 10 figs

Laser semiconductor diode integrated with frequency doubler

International Nuclear Information System (INIS)

Tighineanu, I.; Dorogan, V.; Suruceanu, G.

2003-01-01

The invention relates to the technology of optoelectronic semiconductor devices and may be used in the production of laser semiconductor diodes integrated with optical nonlinear elements. The laser semiconductor diode integrated with frequency doubler includes a semiconductor substrate, a laser structure with waveguide. metal contacts in the waveguide of the laser structure it is formed a nanostructured field so that the nanostructure provides for the fulfillment of the phase synchronism conditions

A High-Performance Optical Memory Array Based on Inhomogeneity of Organic Semiconductors.

Science.gov (United States)

Pei, Ke; Ren, Xiaochen; Zhou, Zhiwen; Zhang, Zhichao; Ji, Xudong; Chan, Paddy Kwok Leung

2018-03-01

Organic optical memory devices keep attracting intensive interests for diverse optoelectronic applications including optical sensors and memories. Here, flexible nonvolatile optical memory devices are developed based on the bis[1]benzothieno[2,3-d;2',3'-d']naphtho[2,3-b;6,7-b']dithiophene (BBTNDT) organic field-effect transistors with charge trapping centers induced by the inhomogeneity (nanosprouts) of the organic thin film. The devices exhibit average mobility as high as 7.7 cm 2 V -1 s -1 , photoresponsivity of 433 A W -1 , and long retention time for more than 6 h with a current ratio larger than 10 6 . Compared with the standard floating gate memory transistors, the BBTNDT devices can reduce the fabrication complexity, cost, and time. Based on the reasonable performance of the single device on a rigid substrate, the optical memory transistor is further scaled up to a 16 × 16 active matrix array on a flexible substrate with operating voltage less than 3 V, and it is used to map out 2D optical images. The findings reveal the potentials of utilizing [1]benzothieno[3,2-b][1]benzothiophene (BTBT) derivatives as organic semiconductors for high-performance optical memory transistors with a facile structure. A detailed study on the charge trapping mechanism in the derivatives of BTBT materials is also provided, which is closely related to the nanosprouts formed inside the organic active layer. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical identifications of flat-spectrum radio sources

International Nuclear Information System (INIS)

Condon, J.J.; Condon, M.A.; Broderick, J.J.; Davis, M.M.

1983-01-01

A complete sample of radio sources with S> or =0.3 Jy at 1400 MHz, +24 0 0 , and low-frequency spectral indices α(408, 1400) or =+0.5 are usually in empty fields. The lower limits that can be assigned to the radio-optical spectral indices α/sub RO/ of these sources are significantly higher than the median α/sub RO/ of the sources with flat high-frequency spectra, so the optical characteristics of the two classes of radio source are intrinsically different. The radio and optical fluxes of flat-spectrum QSO's appear to be correlated, at least when averaged over 10 2 --10 3 yr

Two-fluid hydrodynamic model for semiconductors

DEFF Research Database (Denmark)

Maack, Johan Rosenkrantz; Mortensen, N. Asger; Wubs, Martijn

2018-01-01

The hydrodynamic Drude model (HDM) has been successful in describing the optical properties of metallic nanostructures, but for semiconductors where several different kinds of charge carriers are present an extended theory is required. We present a two-fluid hydrodynamic model for semiconductors...

Optically induced Hall effect in semiconductors

Energy Technology Data Exchange (ETDEWEB)

Idrish Miah, M; Gray, E Mac A, E-mail: m.miah@griffith.edu.a [Nanoscale Science and Technology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)

2009-03-01

We describe an experiment which investigates the effect of a longitudinal electric field on the spin-polarized carriers generated by a circularly polarized light in semiconductors. Our experiment observes the effect as a Hall voltage resulting from nonequilibrium magnetization induced by the spin-carrier electrons accumulating at the transverse boundaries of the sample as a result of asymmetries in scattering for spin-up and spin-down electrons in the presence of spin-orbit interaction. It is found that the effect depends on the longitudinal electric field and doping density as well as on temperature. The results are presented by discussing the dominant spin relaxation mechanisms in semiconductors.

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....

System and carrier for optical images and holographic information recording

International Nuclear Information System (INIS)

Andries, A.; Bivol, V.; Iovu, M

2002-01-01

The invention relates to the semiconducting silverless photography, in particular to the technique for optical information recording and may be used in microphotography for manifacture of microfiches, microfilms, storage disks, i the multiplication and copying technique, in holography, in micro- and optoelectronics, cinematography etc. The system for optical images and holographic information recording includes an optical exposure system, an information carrier , containing a dielectric substrate with the first electrode, a photosensitive element and the second electrode, arranged in consecutive order, a constant and impulse voltage source, a means for climbing and movement of the information carrier, a control unit for connection of the voltage source to the electroconducting strate, a personal computer, connected to the control unit of the recording modes ,to the exposure system and the information carrier, an electrooptical transparency, connected to the computer by means of the matching unit. The carrier for optical images and holographic information recording contains a dielectric substrate, a photosensitive element formed of a layer of the vitreous chalcogenic semiconductor and a layer of the crystalline or amorphous semiconductor, forming a heterojunction, the photosensitive element is arranged between two electrodes , one of which is made transparent , in such case rge layer of the vitreous chalcogenic semiconductor comes into contact with the superior transparent electrode, subjected to exposure

The role of input chirp on phase shifters based on slow and fast light effects in semiconductor optical amplifiers

DEFF Research Database (Denmark)

Xue, Weiqi; Chen, Yaohui; Öhman, Filip

2009-01-01

We experimentally investigate the initial chirp dependence of slow and fast light effects in a semiconductor optical amplifier followed by an optical filter. It is shown that the enhancement of the phase shift due to optical filtering strongly depends on the chirp of the input optical signal. We...... demonstrate ~120º phase delay as well as ~170º phase advance at a microwave frequency of 19 GHz for different optimum values of the input chirp. The experimental results are shown to be in good agreement with numerical results based on a four-wave mixing model. Finally, a simple physical explanation based...

Gain transient control for wavelength division multiplexed access networks using semiconductor optical amplifiers

DEFF Research Database (Denmark)

Gibbon, Timothy Braidwood; Osadchiy, Alexey Vladimirovich; Kjær, Rasmus

2009-01-01

Gain transients can severely hamper the upstream network performance in wavelength division multiplexed (WDM) access networks featuring erbium doped fiber amplifiers (EDFAs) or Raman amplification. We experimentally demonstrate for the first time using 10 Gb/s fiber transmission bit error rate...... measurements how a near-saturated semiconductor optical amplifier (SOA) can be used to control these gain transients. An SOA is shown to reduce the penalty of transients originating in an EDFA from 2.3 dB to 0.2 dB for 10 Gb/s transmission over standard single mode fiber using a 231-1 PRBS pattern. The results...... suggest that a single SOA integrated within a WDM receiver at the metro node could offer a convenient all-optical solution for upstream transient controlin WDM access networks....

Optics education for machine operators in the semiconductor industry: moving beyond button pushing

Science.gov (United States)

Karakekes, Meg; Currier, Deborah

1995-10-01

In the competitive semiconductor manufacturing industry, employees who operate equipment are able to make greater contributions if they understand how the equipment works. By understanding the 'why' behind the 'what', the equipment operators can better partner with other technical staff to produce quality integrated circuits efficiently and effectively. This additional knowledge also opens equipment operators to job enrichment and enlargement opportunities. Advanced Micro Devices (AMD) is in the process of upgrading the skills of its equipment operators. This paper is an overview of a pilot program that employs optics education to upgrade stepper operators' skills. The paper starts with stepper tasks that require optics knowledge, examines teaching methods, reports both end-of-course and three months post-training knowledge retention, and summarizes how the training has impacted the production floor.

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...

System tests of radiation hard optical links for the ATLAS semiconductor tracker

International Nuclear Information System (INIS)

Charlton, D.G.; Dowell, J.D.; Homer, R.J.; Jovanovic, P.; Kenyon, I.R.; Mahout, G.; Shaylor, H.R.; Wilson, J.A.; Rudge, A.; Fopma, J.; Mandic, I.; Nickerson, R.B.; Shield, P.; Wastie, R.; Weidberg, A.R.; Eek, L.-O.; Go, A.; Lund-Jensen, B.; Pearce, M.; Soederqvist, J.; Morrissey, M.; White, D.J.

2000-01-01

A prototype optical data and Timing, Trigger and Control transmission system based on LEDs and PIN-diodes has been constructed. The system would be suitable in terms of radiation hardness and radiation length for use in the ATLAS SemiConductor Tracker. Bit error rate measurements were performed for the data links and for the links distributing the Timing, Trigger and Control data from the counting room to the front-end modules. The effects of cross-talk between the emitters and receivers were investigated. The advantages of using Vertical Cavity Surface Emitting Lasers (VCSELs) instead of LEDs are discussed

Optical implementation of neural learning algorithms based on cross-gain modulation in a semiconductor optical amplifier

Science.gov (United States)

Li, Qiang; Wang, Zhi; Le, Yansi; Sun, Chonghui; Song, Xiaojia; Wu, Chongqing

2016-10-01

Neuromorphic engineering has a wide range of applications in the fields of machine learning, pattern recognition, adaptive control, etc. Photonics, characterized by its high speed, wide bandwidth, low power consumption and massive parallelism, is an ideal way to realize ultrafast spiking neural networks (SNNs). Synaptic plasticity is believed to be critical for learning, memory and development in neural circuits. Experimental results have shown that changes of synapse are highly dependent on the relative timing of pre- and postsynaptic spikes. Synaptic plasticity in which presynaptic spikes preceding postsynaptic spikes results in strengthening, while the opposite timing results in weakening is called antisymmetric spike-timing-dependent plasticity (STDP) learning rule. And synaptic plasticity has the opposite effect under the same conditions is called antisymmetric anti-STDP learning rule. We proposed and experimentally demonstrated an optical implementation of neural learning algorithms, which can achieve both of antisymmetric STDP and anti-STDP learning rule, based on the cross-gain modulation (XGM) within a single semiconductor optical amplifier (SOA). The weight and height of the potentitation and depression window can be controlled by adjusting the injection current of the SOA, to mimic the biological antisymmetric STDP and anti-STDP learning rule more realistically. As the injection current increases, the width of depression and potentitation window decreases and height increases, due to the decreasing of recovery time and increasing of gain under a stronger injection current. Based on the demonstrated optical STDP circuit, ultrafast learning in optical SNNs can be realized.

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 ( .

Optimizing magneto-optical effects in the ferromagnetic semiconductor GaMnAs

International Nuclear Information System (INIS)

Riahi, H.; Thevenard, L.; Maaref, M.A.; Gallas, B.; Lemaître, A.; Gourdon, C

2015-01-01

A trilayer of the ferromagnetic semiconductor GaMnAs, a SiO 2 buffer layer and a piezoelectric ZnO layer, is investigated in view of its use in device implementation to study surface acoustic wave-assisted magnetization switching. The magneto-optical properties: Kerr rotation and ellipticity and magnetic contrast in Kerr microscopy images are investigated as a function of temperature. While the ZnO layer prevents any good quality imaging of magnetic domains, we show that with the SiO 2 layer only the polar Kerr rotation and the magnetic contrast are increased by a factor of 2. This result is in good quantitative agreement with calculations using an optical interference model and could be further improved. The detrimental effects of the dielectric layers capping on the Curie temperature and coercive field of the GaMnAs layer can be kept to a reasonable level. - Highlights: • GaMnAs/SiO 2 /ZnO studied for surface acoustic wave assisted magnetization switching. • The Kerr rotation and magneticcontrast increase by a factor 2 with SiO 2 on GaMnAs. • Good quantitative agreement with an optical interference model. • Little detrimental effect of SiO 2 and ZnO on the ferromagnetic properties of GaMnAs

High resolution optical spectroscopy of air-induced electrical instabilities in n-type polymer semiconductors.

Science.gov (United States)

Di Pietro, Riccardo; Sirringhaus, Henning

2012-07-03

We use high-resolution charge-accumulation optical spectroscopy to measure charge accumulation in the channel of an n-type organic field-effect transistor. We monitor the degradation of device performance in air, correlate the onset voltage shift with the reduction of charge accumulated in the polymer semiconductor, and explain the results in view of the redox reaction between the polymer, water and oxygen in the accumulation layer. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Optical bandgap of semiconductor nanostructures: Methods for experimental data analysis

Science.gov (United States)

Raciti, R.; Bahariqushchi, R.; Summonte, C.; Aydinli, A.; Terrasi, A.; Mirabella, S.

2017-06-01

Determination of the optical bandgap (Eg) in semiconductor nanostructures is a key issue in understanding the extent of quantum confinement effects (QCE) on electronic properties and it usually involves some analytical approximation in experimental data reduction and modeling of the light absorption processes. Here, we compare some of the analytical procedures frequently used to evaluate the optical bandgap from reflectance (R) and transmittance (T) spectra. Ge quantum wells and quantum dots embedded in SiO2 were produced by plasma enhanced chemical vapor deposition, and light absorption was characterized by UV-Vis/NIR spectrophotometry. R&T elaboration to extract the absorption spectra was conducted by two approximated methods (single or double pass approximation, single pass analysis, and double pass analysis, respectively) followed by Eg evaluation through linear fit of Tauc or Cody plots. Direct fitting of R&T spectra through a Tauc-Lorentz oscillator model is used as comparison. Methods and data are discussed also in terms of the light absorption process in the presence of QCE. The reported data show that, despite the approximation, the DPA approach joined with Tauc plot gives reliable results, with clear advantages in terms of computational efforts and understanding of QCE.

Combined Electrical, Optical and Nuclear Investigations of Impurities and Defects in II-VI Semiconductors

CERN Multimedia

2002-01-01

% IS325 \\\\ \\\\ To achieve well controlled bipolar conductivity in II-VI semiconductors represents a fundamental problem in semiconductor physics. The doping problems are controversely discussed, either in terms of self compensation or of compensation and passivation by unintentionally introduced impurities. \\\\ \\\\It is the goal of our experiments at the new ISOLDE facility, to shed new light on these problems and to look for ways to circumvent it. For this aim the investigation of impurities and native defects and the interaction between each other shall be investigated. The use of radioactive ion beams opens the access to controlled site selective doping of only one sublattice via nuclear transmutation. The compensating and passivating mechanisms will be studied by combining nuclear, electrical and optical methods like Perturbed Angular Correlation~(PAC), Hall Effect~(HE), Deep Level Transient Spectroscopy~(DLTS), Photoluminescence Spectroscopy~(PL) and electron paramagnetic resonance (EPR). \\\\ \\\\We intend to ...

Nanostructured pyronin Y thin films as a new organic semiconductor: Linear/nonlinear optics, band gap and dielectric properties

Energy Technology Data Exchange (ETDEWEB)

Zahran, H.Y. [Metallurgical Lab.1, Nanoscience Laboratory for Environmental and Bio-medical Applications (NLEBA), Semiconductor Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Yahia, I.S., E-mail: dr_isyahia@yahoo.com [Metallurgical Lab.1, Nanoscience Laboratory for Environmental and Bio-medical Applications (NLEBA), Semiconductor Lab., Department of Physics, Faculty of Education, Ain Shams University, Roxy, 11757 Cairo (Egypt); Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia); Alamri, F.H. [Advanced Functional Materials & Optoelectronic Laboratory (AFMOL), Department of Physics, Faculty of Science, King Khalid University, P.O. Box 9004, Abha (Saudi Arabia)

2017-05-15

Pyronin Y dye (PY) is a kind of xanthene derivatives. Thin films of pyronin Y were deposited onto highly cleaned glass substrates using low-cost/spin coating technique. The structure properties of pyronin Y thin films with different thicknesses were investigated by using X-ray diffraction (XRD) and atomic force microscope (AFM). PY thin films for all the studied thicknesses have an amorphous structure supporting the short range order of the grain size. AFM supports the nanostructure with spherical/clusters morphologies of the investigated thin films. The optical constants of pyronin Y thin films for various thicknesses were studied by using UV–vis–NIR spectrophotometer in the wavelength range 350–2500 nm. The transmittance T(λ), reflectance R(λ) spectral and absorbance (abs(λ)) were obtained for all film thicknesses at room temperature and the normal light incident. These films showed a high transmittance in the wide scale wavelengths. For different thicknesses of the studied thin films, the optical band gaps were determined and their values around 2 eV. Real and imaginary dielectric constants, dissipation factor and the nonlinear optical parameters were calculated in the wavelengths to the range 300–2500 nm. The pyronin Y is a new organic semiconductor with a good optical absorption in UV–vis regions and it is suitable for nonlinear optical applications. - Highlights: • Pyronin Y (PY) nanostructured thin films were deposited by using spin coating technique. • XRD/AFM were used to study the structure of PY films. • The optical band gap was calculated on the basis of Tauc's model. • Linear/nonlinear optical parameters are calculated and interpreted via the applied optical theories. • PY thin films is a new organic semiconductor for its application in optoelectronic devices.

Fundamentals and Applications of Semiconductor Nanocrystals : A study on the synthesis, optical properties, and interactions of quantum dots

NARCIS (Netherlands)

Koole, R.

2008-01-01

This thesis focuses on both the fundamental aspects as well as applications of colloidal semiconductor nanocrystals, also called quantum dots (QDs). Due to the unique size-dependent optical and electronic properties of QDs, they hold great promise for a wide range of applications like solar cells,

Optically induced bistable states in metal/tunnel-oxide/semiconductor /MTOS/ junctions

Science.gov (United States)

Lai, S. K.; Dressendorfer, P. V.; Ma, T. P.; Barker, R. C.

1981-01-01

A new switching phenomenon in metal-oxide semiconductor tunnel junction has been discovered. With a sufficiently large negative bias applied to the electrode, incident visible light of intensity greater than about 1 microW/sq cm causes the reverse-biased junction to switch from a low-current to a high-current state. It is believed that hot-electron-induced impact ionization provides the positive feedback necessary for switching, and causes the junction to remain in its high-current state after the optical excitation is removed. The junction may be switched back to the low-current state electrically. The basic junction characteristics have been measured, and a simple model for the switching phenomenon has been developed.

Coherent diffractive imaging methods for semiconductor manufacturing

Science.gov (United States)

Helfenstein, Patrick; Mochi, Iacopo; Rajeev, Rajendran; Fernandez, Sara; Ekinci, Yasin

2017-12-01

The paradigm shift of the semiconductor industry moving from deep ultraviolet to extreme ultraviolet lithography (EUVL) brought about new challenges in the fabrication of illumination and projection optics, which constitute one of the core sources of cost of ownership for many of the metrology tools needed in the lithography process. For this reason, lensless imaging techniques based on coherent diffractive imaging started to raise interest in the EUVL community. This paper presents an overview of currently on-going research endeavors that use a number of methods based on lensless imaging with coherent light.

Synthesis and characterization of a new organic semiconductor material

Energy Technology Data Exchange (ETDEWEB)

Tiffour, Imane [Laboratoire de Génie Physique, Département de Physique, Université de Tiaret, Tiaret 14000 (Algeria); Faculté des Sciences et Technologies, Université Mustapha Stambouli, Mascara 29000 (Algeria); Dehbi, Abdelkader [Laboratoire de Génie Physique, Département de Physique, Université de Tiaret, Tiaret 14000 (Algeria); Mourad, Abdel-Hamid I., E-mail: ahmourad@uaeu.ac.ae [Mechanical Engineering Department, Faculty of Engineering, United Arab Emirates University, Al-Ain, P.O. Box 15551 (United Arab Emirates); Belfedal, Abdelkader [Faculté des Sciences et Technologies, Université Mustapha Stambouli, Mascara 29000 (Algeria); LPCMME, Département de Physique, Université d' Oran Es-sénia, 3100 Oran (Algeria)

2016-08-01

The objective of this study is to create an ideal mixture of Acetaminophen/Curcumin leading to a new and improved semiconductor material, by a study of the electrical, thermal and optical properties. This new material will be compared with existing semiconductor technology to discuss its viability within the industry. The electrical properties were investigated using complex impedance spectroscopy and optical properties were studied by means of UV-Vis spectrophotometry. The electric conductivity σ, the dielectric constant ε{sub r}, the activation energy E{sub a}, the optical transmittance T and the gap energy E{sub g} have been investigated in order to characterize our organic material. The electrical conductivity of the material is approximately 10{sup −5} S/m at room temperature, increasing the temperature causes σ to increase exponentially to approximately 10{sup −4} S/m. The activation energy obtained for the material is equal to 0.49 ± 0.02 ev. The optical absorption spectra show that the investigating material has absorbance in the visible range with a maximum wavelength (λ{sub max}) 424 nm. From analysis, the absorption spectra it was found the optical band gap equal to 2.6 ± 0.02 eV and 2.46 ± 0.02 eV for the direct and indirect transition, respectively. In general, the study shows that the developed material has characteristics of organic semiconductor material that has a promising future in the field of organic electronics and their potential applications, e.g., photovoltaic cells. - Highlights: • Development of a new organic acetaminophen/Curcumin semiconductor material. • The developed material has characteristics of an organic semiconductor. • It has electrical conductivity comparable to available organic semiconductors. • It has high optical transmittance and low permittivity/dielectric constant.

Synthesis and characterization of a new organic semiconductor material

International Nuclear Information System (INIS)

Tiffour, Imane; Dehbi, Abdelkader; Mourad, Abdel-Hamid I.; Belfedal, Abdelkader

2016-01-01

The objective of this study is to create an ideal mixture of Acetaminophen/Curcumin leading to a new and improved semiconductor material, by a study of the electrical, thermal and optical properties. This new material will be compared with existing semiconductor technology to discuss its viability within the industry. The electrical properties were investigated using complex impedance spectroscopy and optical properties were studied by means of UV-Vis spectrophotometry. The electric conductivity σ, the dielectric constant ε_r, the activation energy E_a, the optical transmittance T and the gap energy E_g have been investigated in order to characterize our organic material. The electrical conductivity of the material is approximately 10"−"5 S/m at room temperature, increasing the temperature causes σ to increase exponentially to approximately 10"−"4 S/m. The activation energy obtained for the material is equal to 0.49 ± 0.02 ev. The optical absorption spectra show that the investigating material has absorbance in the visible range with a maximum wavelength (λ_m_a_x) 424 nm. From analysis, the absorption spectra it was found the optical band gap equal to 2.6 ± 0.02 eV and 2.46 ± 0.02 eV for the direct and indirect transition, respectively. In general, the study shows that the developed material has characteristics of organic semiconductor material that has a promising future in the field of organic electronics and their potential applications, e.g., photovoltaic cells. - Highlights: • Development of a new organic acetaminophen/Curcumin semiconductor material. • The developed material has characteristics of an organic semiconductor. • It has electrical conductivity comparable to available organic semiconductors. • It has high optical transmittance and low permittivity/dielectric constant.

Fundamentals of semiconductors physics and materials properties

CERN Document Server

Yu, Peter Y

2005-01-01

Provides detailed explanations of the electronic, vibrational, transport, and optical properties of semiconductors. This textbook emphasizes understanding the physical properties of Si and similar tetrahedrally coordinated semiconductors and features an extensive collection of tables of material parameters, figures, and problems.

Synthesis, optical properties and photostability of novel fluorinated organic–inorganic hybrid (R–NH3)2PbX4 semiconductors

International Nuclear Information System (INIS)

Wei, Y; Lauret, J-S; Deleporte, E; Audebert, P; Galmiche, L

2013-01-01

We report on the synthesis and the optical properties of several novel semiconductors (R–NH 3 ) 2 PbX 4 (X = Br − , I − or Cl − ). These semiconductors are two-dimensional organic–inorganic perovskite (2DOIP) materials and have multiple quantum-well energy level structures. We vary the organic components (R-NH 3 + ), introducing fluorine atoms into the organic part, on the phenyl ring of the amine. We discuss its influence on the self-organization ability and long-term photostability of the 2DOIPs. The trends of introducing fluorine atoms on the self-organization and long-term photostability of 2DOIPs are obtained by analysing the optical experimental results, and show that the influence of the fluorine position on the benzene ring is quite important. The most promising compounds seem to be the ones with the fluorine atom sitting on the para position of the phenyl group. (paper)

33rd International Conference on the Physics of Semiconductors

International Nuclear Information System (INIS)

2017-01-01

Preface to the Proceedings of the 33rd International Conference on the Physics of Semiconductors, Beijing, 2016 Shaoyun Huang 1 , Yingjie Xing 1 , Yang Ji 2 , Dapeng Yu 3 , and Hongqi Xu 1 1 Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871, China 2 SKLSM, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China 3 State Key Laboratory for Mesoscopic Physics, Department of Physics, Peking University, Beijing 100871, China From July 31 st to August 5 th , 2016, the 33rd International Conference on the Physics of Semiconductors (ICPS 2016) was held in Beijing, China, with a great success. The International Conference on the Physics of Semiconductors began in the 1950’s and is a premier biennial meeting for reporting all aspects of semiconductor physics including electronic, structural, optical, magnetic and transport properties. Reflecting the state of the art developments in semiconductor physics, ICPS 2016 served as an international forum for scholars, researchers, and specialists across the globe to discuss future research directions and technological advancements. The main topics of ICPS 2016 included: • Material growth, structural properties and characterization, phonons • Wide-bandgap semiconductors • Narrow-bandgap semiconductors • Carbon: nanotubes and graphene • 2D Materials beyond graphene • Organic semiconductors • Topological states of matter, topological Insulators and Weyl semimetals • Transport in heterostructures • Quantum Hall effects • Spintronics and spin phenomena • Electron devices and applications • Optical properties, optoelectronics, solar cells • Quantum optics, nanophotonics • Quantum information • Other topics in semiconductor physics and devices • Special topic: Majorana fermions in solid state (paper)

The optical constants of the organic thin films in the case of xanthats adsorption at the surface of semiconductors minerals

International Nuclear Information System (INIS)

Todoran, Radu; Todoran, Daniela

2008-01-01

The paper present the determinations of some kinetic parameters that characterize the kinetics of the adsorption phenomenon of some organic xanthate molecule on the surface of some natural semiconductor mineral (galena, sphalerite) in order to understand the inward mechanism of this phenomenon. Among the methods of inquiry that allow kinetics determination in situ the optical ones were chosen relying on the change of the liquid-mineral semiconductor interface, and permitting continuous inquires without disturbing the inward development of the processes. Into the computation, we took into the consideration the physical values which feature the roughness of the solid surface, the diffusion into liquid media and the energetic non-homogeneities of the surface. The R s /R p =f(θ) characteristic helps us to establish the thickness of the adsorbed layer, as well as to determine the optical parameters of the thin film. the experimental results allow us to get some information on the mineral and mineral-solution of xanthate, as well allow us to get some information on the parameters which, in correlation with other proportions experimentally determined - could had as to estimations of the dynamic of the surface of a semiconductor solid body. (Author)

Annual report of the Applied Optics Laboratory, 1985

International Nuclear Information System (INIS)

1986-01-01

Research on optical fiber coupling by evanescent fields; fiber optics resonators; infrared lasers; remote measurement by laser; dephasing time in GaAs; heat transfer in thin silicon films; quantum wells; a picosecond electron source; modeling of III-V semiconductors; nonlinear optics properties of materials; femtosecond spectroscopy of the internal dynamics of proteins; computer simulation of protein dynamics; electron solvation; reactions of radicals in micella phase; sarcoma; and medical applications of pulsed lasers is presented [fr

Annual report of the Applied Optics Laboratory, 1986

International Nuclear Information System (INIS)

1987-01-01

Research on optical fiber coupling by evanescent fields; fiber optics resonators; infrared lasers; remote measurement by laser; dephasing time in GaAs; heat transfer in thin silicon films; quantum wells; a picosecond electron source; modeling of III-V semiconductors; nonlinear optics properties of materials; femtosecond spectroscopy of the internal dynamics of proteins; computer simulation of protein dynamics; electron solvation; reactions of radicals in micella phase; sarcoma; and medical applications of pulsed lasers is presented [fr

Optical surfacing via linear ion source

International Nuclear Information System (INIS)

Wu, Lixiang; Wei, Chaoyang; Shao, Jianda

2017-01-01

We present a concept of surface decomposition extended from double Fourier series to nonnegative sinusoidal wave surfaces, on the basis of which linear ion sources apply to the ultra-precision fabrication of complex surfaces and diffractive optics. The modified Fourier series, or sinusoidal wave surfaces, build a relationship between the fabrication process of optical surfaces and the surface characterization based on power spectral density (PSD) analysis. Also, we demonstrate that the one-dimensional scanning of linear ion source is applicable to the removal of mid-spatial frequency (MSF) errors caused by small-tool polishing in raster scan mode as well as the fabrication of beam sampling grating of high diffractive uniformity without a post-processing procedure. The simulation results show that optical fabrication with linear ion source is feasible and even of higher output efficiency compared with the conventional approach.

Optical surfacing via linear ion source

Energy Technology Data Exchange (ETDEWEB)

Wu, Lixiang, E-mail: wulx@hdu.edu.cn [Key Lab of RF Circuits and Systems of Ministry of Education, Zhejiang Provincial Key Lab of LSI Design, Microelectronics CAD Center, College of Electronics and Information, Hangzhou Dianzi University, Hangzhou (China); Wei, Chaoyang, E-mail: siomwei@siom.ac.cn [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Shao, Jianda, E-mail: jdshao@siom.ac.cn [Key Laboratory of Materials for High Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2017-04-15

We present a concept of surface decomposition extended from double Fourier series to nonnegative sinusoidal wave surfaces, on the basis of which linear ion sources apply to the ultra-precision fabrication of complex surfaces and diffractive optics. The modified Fourier series, or sinusoidal wave surfaces, build a relationship between the fabrication process of optical surfaces and the surface characterization based on power spectral density (PSD) analysis. Also, we demonstrate that the one-dimensional scanning of linear ion source is applicable to the removal of mid-spatial frequency (MSF) errors caused by small-tool polishing in raster scan mode as well as the fabrication of beam sampling grating of high diffractive uniformity without a post-processing procedure. The simulation results show that optical fabrication with linear ion source is feasible and even of higher output efficiency compared with the conventional approach.

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

High-order optical nonlinearities in nanocomposite films dispersed with semiconductor quantum dots at high concentrations

International Nuclear Information System (INIS)

Tomita, Yasuo; Matsushima, Shun-suke; Yamagami, Ryu-ichi; Jinzenji, Taka-aki; Sakuma, Shohei; Liu, Xiangming; Izuishi, Takuya; Shen, Qing

2017-01-01

We describe the nonlinear optical properties of inorganic-organic nanocomposite films in which semiconductor CdSe quantum dots as high as 6.8 vol.% are dispersed. Open/closed Z-scan measurements, degenerate multi-wave mixing and femtosecond pump-probe/transient grating measurements are conducted. It is shown that the observed fifth-order optical nonlinearity has the cascaded third-order contribution that becomes prominent at high concentrations of CdSe QDs. It is also shown that there are picosecond-scale intensity-dependent and nanosecond-scale intensity-independent decay components in absorptive and refractive nonlinearities. The former is caused by the Auger process, while the latter comes from the electron-hole recombination process. (paper)

Flexible power 90W to 120W ArF immersion light source for future semiconductor lithography

Science.gov (United States)

Burdt, R.; Thornes, J.; Duffey, T.; Bibby, T.; Rokitski, R.; Mason, E.; Melchior, J.; Aggarwal, T.; Haran, D.; Wang, J.; Rechtsteiner, G.; Haviland, M.; Brown, D.

2014-03-01

Semiconductor market demand for improved performance at lower cost continues to drive enhancements in excimer light source technologies. Increased output power, reduced variability in key light source parameters, and improved beam stability are required of the light source to support immersion lithography, multi-patterning, and 450mm wafer applications in high volume semiconductor manufacturing. To support future scanner needs, Cymer conducted a technology demonstration program to evaluate the design elements for a 120W ArFi light source. The program was based on the 90W XLR 600ix platform, and included rapid power switching between 90W and 120W modes to potentially support lot-to-lot changes in desired power. The 120W requirements also included improved beam stability in an exposure window conditionally reduced by 20%. The 120W output power is achieved by efficiency gains in system design, keeping system input power at the same level as the 90W XLR 600ix. To assess system to system variability, detailed system testing was conducted from 90W - 120W with reproducible results.

Hydrogenated dilute nitride semiconductors theory, properties, and applications

CERN Document Server

Ciatto, Gianluca

2015-01-01

""The electrical and optical properties of the technologically and scientifically important dilute nitride semiconductors are strongly influenced by the introduction of atomic hydrogen. This volume is an excellent summary and resource for the most recent understanding of experimental results and state-of-the-art theoretical studies of the formation, reversibility, and microscopic structure of nitrogen-hydrogen complexes in these materials. The book details how a wide variety of experimental techniques have provided a detailed understanding of the role of hydrogen. It is the premier sourc

Carrier-phonon interaction in semiconductor quantum dots

Energy Technology Data Exchange (ETDEWEB)

Seebeck, Jan

2009-03-10

In recent years semiconductor quantum dots have been studied extensively due to their wide range of possible applications, predominantly for light sources. For successful applications, efficient carrier scattering processes as well as a detailed understanding of the optical properties are of central importance. The aims of this thesis are theoretical investigations of carrier scattering processes in InGaAs/GaAs quantum dots on a quantum-kinetic basis. A consistent treatment of quasi-particle renormalizations and carrier kinetics for non-equilibrium conditions is presented, using the framework of non-equilibrium Green's functions. The focus of our investigations is the interaction of carriers with LO phonons. Important for the understanding of the scattering mechanism are the corresponding quasi-particle properties. Starting from a detailed study of quantum-dot polarons, scattering and dephasing processes are discussed for different temperature regimes. The inclusion of polaron and memory effects turns out to be essential for the description of the carrier kinetics in quantum-dot systems. They give rise to efficient scattering channels and the obtained results are in agreement with recent experiments. Furthermore, a consistent treatment of the carrier-LO-phonon and the carrier-carrier interaction is presented for the optical response of semiconductor quantum dots, both giving rise to equally important contributions to the dephasing. Beside the conventional GaAs material system, currently GaN based light sources are of high topical interest due to their wide range of possible emission frequencies. In this material additionally intrinsic properties like piezoelectric fields and strong band-mixing effects have to be considered. For the description of the optical properties of InN/GaN quantum dots a procedure is presented, where the material properties obtained from an atomistic tight-binding approach are combined with a many-body theory for non

Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

International Nuclear Information System (INIS)

Andreeva, E V; Il'chenko, S N; Lobintsov, A A; Shramenko, M V; Ladugin, M A; Marmalyuk, A A; Yakubovich, S D

2013-01-01

A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

Broadband semiconductor optical amplifiers of the spectral range 750 – 1100 nm

Energy Technology Data Exchange (ETDEWEB)

Andreeva, E V; Il' chenko, S N; Lobintsov, A A; Shramenko, M V [Superlum Diodes Ltd., Moscow (Russian Federation); Ladugin, M A [' Sigm Plyus' Ltd, Moscow (Russian Federation); Marmalyuk, A A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation); Yakubovich, S D [Moscow State Institute of Radio-Engineering, Electronics and Automation (Technical University), Moscow (Russian Federation)

2013-11-30

A line of travelling-wave semiconductor optical amplifiers (SOAs) based on heterostructures used for production of broadband superluminescent diodes is developed. The pure small-signal gains of the developed SOA modules are about 25 dB, while the gain bandwidths at a level of –10 dB reach 50 – 100 nm. As a whole, the SOA modules cover the IR spectral range from 750 to 1100 nm. The SOAs demonstrate a high reliability at a single-mode fibre-coupled cw output power up to 50 mW. Examples of application of two of the developed SOA modules as active elements of broadband fast-tunable lasers are presented. (lasers)

Terahertz plasmonics with semiconductor surfaces and antennas

NARCIS (Netherlands)

Gómez Rivas, J.; Berrier, A.

2009-01-01

Semiconductors have a Drude-like behavior at terahertz (THz) frequencies similar to metals at optical frequencies. Narrow band gap semiconductors have a dielectric constant with a negative real component and a relatively small imaginary component. This permittivity is characteristic of noble metals

Thermal and Optical Modulation of the Carrier Mobility in OTFTs Based on an Azo-anthracene Liquid Crystal Organic Semiconductor.

Science.gov (United States)

Chen, Yantong; Li, Chao; Xu, Xiuru; Liu, Ming; He, Yaowu; Murtaza, Imran; Zhang, Dongwei; Yao, Chao; Wang, Yongfeng; Meng, Hong

2017-03-01

One of the most striking features of organic semiconductors compared with their corresponding inorganic counterparts is their molecular diversity. The major challenge in organic semiconductor material technology is creating molecular structural motifs to develop multifunctional materials in order to achieve the desired functionalities yet to optimize the specific device performance. Azo-compounds, because of their special photoresponsive property, have attracted extensive interest in photonic and optoelectronic applications; if incorporated wisely in the organic semiconductor groups, they can be innovatively utilized in advanced smart electronic applications, where thermal and photo modulation is applied to tune the electronic properties. On the basis of this aspiration, a novel azo-functionalized liquid crystal semiconductor material, (E)-1-(4-(anthracen-2-yl)phenyl)-2-(4-(decyloxy)phenyl)diazene (APDPD), is designed and synthesized for application in organic thin-film transistors (OTFTs). The UV-vis spectra of APDPD exhibit reversible photoisomerizaton upon photoexcitation, and the thin films of APDPD show a long-range orientational order based on its liquid crystal phase. The performance of OTFTs based on this material as well as the effects of thermal treatment and UV-irradiation on mobility are investigated. The molecular structure, stability of the material, and morphology of the thin films are characterized by thermal gravimetric analysis (TGA), polarizing optical microscopy (POM), (differential scanning calorimetry (DSC), UV-vis spectroscopy, atomic force microscopy (AFM), and scanning tunneling microscopy (STM). This study reveals that our new material has the potential to be applied in optical sensors, memories, logic circuits, and functional switches.

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.

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.

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

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...

Anisotropy-based crystalline oxide-on-semiconductor material

Science.gov (United States)

McKee, Rodney Allen; Walker, Frederick Joseph

2000-01-01

A semiconductor structure and device for use in a semiconductor application utilizes a substrate of semiconductor-based material, such as silicon, and a thin film of a crystalline oxide whose unit cells are capable of exhibiting anisotropic behavior overlying the substrate surface. Within the structure, the unit cells of the crystalline oxide are exposed to an in-plane stain which influences the geometric shape of the unit cells and thereby arranges a directional-dependent quality of the unit cells in a predisposed orientation relative to the substrate. This predisposition of the directional-dependent quality of the unit cells enables the device to take beneficial advantage of characteristics of the structure during operation. For example, in the instance in which the crystalline oxide of the structure is a perovskite, a spinel or an oxide of similarly-related cubic structure, the structure can, within an appropriate semiconductor device, exhibit ferroelectric, piezoelectric, pyroelectric, electro-optic, ferromagnetic, antiferromagnetic, magneto-optic or large dielectric properties that synergistically couple to the underlying semiconductor substrate.

Controlling the speed of light in semiconductor waveguides: Physics and applications

DEFF Research Database (Denmark)

Mørk, Jesper; Xue, Weiqi; Chen, Yaohui

2009-01-01

We review the physics of slow and fast light effects in semiconductor optical waveguides. Recent experimental and theoretical results on enhancing the phase shift using optical filtering are presented and applications in microwave photonics are discussed.......We review the physics of slow and fast light effects in semiconductor optical waveguides. Recent experimental and theoretical results on enhancing the phase shift using optical filtering are presented and applications in microwave photonics are discussed....

Optimizing magneto-optical effects in the ferromagnetic semiconductor GaMnAs

Energy Technology Data Exchange (ETDEWEB)

Riahi, H., E-mail: hassenriahi1987@gmail.com [Laboratoire Matériaux Molécules et Applications, IPEST, Université de Carthage, La Marsa (Tunisia); Thevenard, L. [CNRS, UMR7588, Institut des Nanosciences de Paris, 4 place Jussieu, 75005 Paris (France); Sorbonne Universités, UPMC Université Paris 06, UMR7588, 4 place Jussieu, 75005 Paris (France); Maaref, M.A. [Laboratoire Matériaux Molécules et Applications, IPEST, Université de Carthage, La Marsa (Tunisia); Gallas, B. [CNRS, UMR7588, Institut des Nanosciences de Paris, 4 place Jussieu, 75005 Paris (France); Sorbonne Universités, UPMC Université Paris 06, UMR7588, 4 place Jussieu, 75005 Paris (France); Lemaître, A. [Laboratoire de Photonique et de Nanostructures – CNRS, Route de Nozay, 91460 Marcoussis (France); Gourdon, C [CNRS, UMR7588, Institut des Nanosciences de Paris, 4 place Jussieu, 75005 Paris (France); Sorbonne Universités, UPMC Université Paris 06, UMR7588, 4 place Jussieu, 75005 Paris (France)

2015-12-01

A trilayer of the ferromagnetic semiconductor GaMnAs, a SiO{sub 2} buffer layer and a piezoelectric ZnO layer, is investigated in view of its use in device implementation to study surface acoustic wave-assisted magnetization switching. The magneto-optical properties: Kerr rotation and ellipticity and magnetic contrast in Kerr microscopy images are investigated as a function of temperature. While the ZnO layer prevents any good quality imaging of magnetic domains, we show that with the SiO{sub 2} layer only the polar Kerr rotation and the magnetic contrast are increased by a factor of 2. This result is in good quantitative agreement with calculations using an optical interference model and could be further improved. The detrimental effects of the dielectric layers capping on the Curie temperature and coercive field of the GaMnAs layer can be kept to a reasonable level. - Highlights: • GaMnAs/SiO{sub 2}/ZnO studied for surface acoustic wave assisted magnetization switching. • The Kerr rotation and magneticcontrast increase by a factor 2 with SiO{sub 2} on GaMnAs. • Good quantitative agreement with an optical interference model. • Little detrimental effect of SiO{sub 2} and ZnO on the ferromagnetic properties of GaMnAs.

EDITORIAL The 23rd Nordic Semiconductor Meeting The 23rd Nordic Semiconductor Meeting

Science.gov (United States)

Ólafsson, Sveinn; Sveinbjörnsson, Einar

2010-12-01

A Nordic Semiconductor Meeting is held every other year with the venue rotating amongst the Nordic countries of Denmark, Finland, Iceland, Norway and Sweden. The focus of these meetings remains 'original research and science being carried out on semiconductor materials, devices and systems'. Reports on industrial activity have usually featured. The topics have ranged from fundamental research on point defects in a semiconductor to system architecture of semiconductor electronic devices. Proceedings from these events are regularly published as a topical issue of Physica Scripta. All of the papers in this topical issue have undergone critical peer review and we wish to thank the reviewers and the authors for their cooperation, which has been instrumental in meeting the high scientific standards and quality of the series. This meeting of the 23rd Nordic Semiconductor community, NSM 2009, was held at Háskólatorg at the campus of the University of Iceland, Reykjavik, Iceland, 14-17 June 2009. Support was provided by the University of Iceland. Almost 50 participants presented a broad range of topics covering semiconductor materials and devices as well as related material science interests. The conference provided a forum for Nordic and international scientists to present and discuss new results and ideas concerning the fundamentals and applications of semiconductor materials. The meeting aim was to advance the progress of Nordic science and thus aid in future worldwide technological advances concerning technology, education, energy and the environment. Topics Theory and fundamental physics of semiconductors Emerging semiconductor technologies (for example III-V integration on Si, novel Si devices, graphene) Energy and semiconductors Optical phenomena and optical devices MEMS and sensors Program 14 June Registration 13:00-17:00 15 June Meeting program 09:30-17:00 and Poster Session I 16 June Meeting program 09:30-17:00 and Poster Session II 17 June Excursion and dinner

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

Optical properties of quasiperiodically arranged semiconductor nanostructures

Energy Technology Data Exchange (ETDEWEB)

Werchner, Marco

2009-12-18

This work consists of two parts which are entitled ''One-Dimensional Resonant Fibonacci Quasicrystals'' and ''Resonant Tunneling of Light in Silicon Nanostructures''. A microscopic theory has been applied to investigate the optical properties of the respective semiconductor nanostructures. The studied one-dimensional resonant Fibonacci quasicrystals consist of GaAs quantum wells (QW) that are separated by either a large spacer L or a small one S. These spacers are arranged according to the Fibonacci sequence LSLLSLSL.. The average spacing satisfies a generalized Bragg condition with respect to the 1s-exciton resonance of the QWs. A theory, that makes use of the transfer-matrix method and that allows for the microscopic description of many-body effects such as excitation-induced dephasing caused by the Coulomb scattering of carriers, has been applied to compute the optical spectra of such structures. A pronounced sharp reflectivity minimum is found in the vicinity of the heavy-hole resonance both in the measured as well as in the calculated linear 54-QW spectra. Specifically, the influence of the carrier density, of the QW arrangement, of a detuning away from the exact Bragg condition, of the average spacing as well as of the ratio of the optical path lengths of the large and small spacers L and S, respectively, and of the QW number on the optical properties of the samples have been studied. Additionally, self-similarity among reflection spectra corresponding to different QW numbers that exceed a Fibonacci number by one is observed, which identifies certain spectral features as true fingerprints of the Fibonacci spacing. In the second part, resonant tunneling of light in stacked structures consisting of alternating parallel layers of silicon and air have been studied theoretically.Light may tunnel through the air barrier due to the existence of evanescent waves inside the air layers if the neighboring silicon layer is close

Optical observations of binary X-ray sources

International Nuclear Information System (INIS)

Boynton, P.E.

1975-01-01

The contribution to the recent progress in astronomy made by optical observations is pointed out. The optical properties of X-ray sources help to establish the physical nature of these objects. The current observational evidence on the binary X-ray sources HZ Her/Her X-1 and HDE 226868/Cyg X-1 is reported. (P.J.S.)

Electrons and Phonons in Semiconductor Multilayers

Science.gov (United States)

Ridley, B. K.

1996-11-01

This book provides a detailed description of the quantum confinement of electrons and phonons in semiconductor wells, superlattices and quantum wires, and shows how this affects their mutual interactions. It discusses the transition from microscopic to continuum models, emphasizing the use of quasi-continuum theory to describe the confinement of optical phonons and electrons. The hybridization of optical phonons and their interactions with electrons are treated, as are other electron scattering mechanisms. The book concludes with an account of the electron distribution function in three-, two- and one-dimensional systems, in the presence of electrical or optical excitation. This text will be of great use to graduate students and researchers investigating low-dimensional semiconductor structures, as well as to those developing new devices based on these systems.

Group IV all-semiconductor spintronics. Materials aspects and optical spin selection rules

Energy Technology Data Exchange (ETDEWEB)

Sircar, Narayan

2012-04-03

In the scope of the present thesis various aspects for the realization of spintronic applications based on group IV semiconductors are discussed. This work comprises a refined material characterization of the magnetic semiconductor GeMn. We furthermore present efforts to utilize this material as spin injector for a Si-based optical spintronic device. Applying transmission electron microscopy and atom probe tomography, we are able to resolve a vertical anisotropy in the self-assembly, leading to the stacking of well-defined clusters in the growth direction. Three-dimensional atom distribution maps confirm that clusters are built from a nonstoichiometric GeMn alloy and exhibit a high-Mn-concentration core with a decreasing Mn concentration toward a shell. An amorphous nature of the cluster cores as well as the crystallinity of the shells, coherent with the surrounding Ge lattice, are revealed in scanning transmission electron microscopy. We localize a strain field surrounding each GeMn cluster by scanning transmission electron microscopy. The importance of strain to the stacking phenomenon of the clusters becomes clear in studies of Ge/GeMn superlattice structures, where a vertical spatial correlation of clusters over 30 nm-thick Ge spacer layers is observed. We present evidence that electrical transport properties of the p-type GeMn thin films fabricated on high-resistivity Ge substrates are severely influenced by parallel conduction through the substrate. It is shown that substrate conduction persists also for wellconducting degenerate p-type reference thin films, giving rise to an effective two-layer conduction scheme. GeMn thin films fabricated on these substrates exhibit only a negligible magnetoresistance effect. Before integrating GeMn in an optical spintronic device, some key aspects important for an understanding of the optical injection and detection of carrier spins in Si and Si-based heterostructures are clarified in the second part of this thesis. In

Reflection technique for thermal mapping of semiconductors

Science.gov (United States)

Walter, Martin J.

1989-06-20

Semiconductors may be optically tested for their temperatures by illuminating them with tunable monochromatic electromagnetic radiation and observing the light reflected off of them. A transition point will occur when the wavelength of the light corresponds with the actual band gap energy of the semiconductor. At the transition point, the image of the semiconductor will appreciably darken as the light is transmitted through it, rather than being reflected off of it. The wavelength of the light at the transition point corresponds to the actual band gap energy and the actual temperature of the semiconductor.

Porous and Nanoporous Semiconductors and Emerging Applications

Directory of Open Access Journals (Sweden)

Helmut Föll

2006-01-01

Full Text Available Pores in single-crystalline semiconductors can be produced in a wide range of geometries and morphologies, including the “nanometer” regime. Porous semiconductors may have properties completely different from the bulk, and metamaterials with, for example, optical properties not encountered in natural materials are emerging. Possible applications of porous semiconductors include various novel sensors, but also more “exotic” uses as, for example, high explosives or electrodes for micro-fuel cells. The paper briefly reviews pore formation (including more applied aspects of large area etching, properties of porous semiconductors, and emerging applications.

Microwave phase shifter with controllable power response based on slow-and fast-light effects in semiconductor optical amplifiers

DEFF Research Database (Denmark)

Xue, Weiqi; Sales, Salvador; Capmany, Jose

2009-01-01

with the use of spectral filtering to enhance the role of refractive index dynamics. A continuously tunable phase shift of 240° at a microwave frequency of 19 GHz is demonstrated in a cascade of two semiconductor optical amplifiers, while maintaining an rf power change of less than 1.6 dB. The technique...

Measurement of the linewidth enhancement factor based on nonlinear polarization rotation of semiconductor optical amplifier.

Science.gov (United States)

Liu, Guodong; Wu, Chongqing; Wang, Fu; Zhang, Tianyong; Shang, Chao; Gao, Kaiqiang

2015-06-01

A simple measurement scheme of the linewidth enhancement factor based on the nonlinear polarization rotation of a semiconductor optical amplifier is proposed. Considering the polarization dependent gain, the relationship between the linewidth enhancement factor and the Stokes vector was derived theoretically. It is proven that the linewidth enhancement factor can be calculated directly from the Stokes parameters without any other assistant measurement system. The results demonstrate that the linewidth enhancement factor varies in a small range from 10.5 to 8.5 for TE mode and from 8.2 to 5.8 for TM mode, respectively, when the input optical power varies from 50 μW to 1 mW and the bias current varies from 90 to 170 mA.

A transfer function approach to the small-signal response of saturated semiconductor optical amplifiers

DEFF Research Database (Denmark)

Nielsen, Mads Lønstrup; Blumenthal, D. J.; Mørk, Jesper

2000-01-01

A theoretical analysis of the small-signal frequency response (SSFR) of a wavelength converter based on cross-gain modulation in a semiconductor optical amplifier with a finite waveguide loss is presented. We use a transfer function formalism to explain the resonant behavior of the frequency...... response. The limitations to the magnitude of the spectral overshoot are also accounted for. Operating with the data and CW signals in a co-propagating configuration, we End that the resonance only exists for a finite waveguide loss. In a counter-propagating scheme, a resonance can exist regardless...

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.

Slow and fast light effects in semiconductor optical amplifiers for applications in microwave photonics

DEFF Research Database (Denmark)

Xue, Weiqi

This thesis analyzes semiconductor optical amplifiers based slow and fast light effects with particular focus on the applications in microwave photonics. We conceive novel ideas and demonstrate a great enhancement of light slow down. Furthermore, by cascading several slow light stages, >360 degree...... microwave phase shifts over a bandwidth of several tens of gigahertz are achieved. These also satisfy the basic requirements of microwave photonic systems. As an application demonstration, a tunable microwave notch filter is realized, where slow light based phase shifters provide 100% fractional tuning over...

Localization and Imaging of Integrated Circuit Defect Using Simple Optical Feedback Detection

Directory of Open Access Journals (Sweden)

Vernon Julius Cemine

2004-12-01

Full Text Available High-contrast microscopy of semiconductor and metal edifices in integrated circuits is demonstrated by combining laser-scanning confocal reflectance microscopy, one-photon optical-beam-induced current (1P-OBIC imaging, and optical feedback detection via a commercially available semiconductor laser that also serves as the excitation source. The confocal microscope has a compact in-line arrangement with no external photodetector. Confocal and 1P-OBIC images are obtained simultaneously from the same focused beam that is scanned across the sample plane. Image pairs are processed to generate exclusive high-contrast distributions of the semiconductor, metal, and dielectric sites in a GaAs photodiode array sample. The method is then utilized to demonstrate defect localization and imaging in an integrated circuit.

ON THE ARTIFICIAL SEMICONDUCTOR MATERIALS | Adelabu ...

African Journals Online (AJOL)

For about the last three decades, semiconductor technology began to make its most apparent impact in Solid State Electronics. The field of photonics, which combines laser physics, electro-optics and nonlinear optics has expanded tremendously. Notably, modern light wave communications exemplify photonic systems.

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.

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

THE USE OF POLARIZATION EFFECTS IN SEMICONDUCTOR OPTICAL AMPLIFIERS TO PERFORM ALL-OPTICAL SIGNAL PROCESSING EL USO DE EFECTOS DE POLARIZACIÓN EN AMPLIFICADORES ÓPTICOS SEMICONDUCTORES PARA REALIZAR EL PROCESAMIENTO DE SEÑALES EN EL DOMINIO ÓPTICO

Directory of Open Access Journals (Sweden)

Brendan F Kennedy

2007-12-01

Full Text Available As the need for higher and higher bandwidths in telecommunication systems continues, it is widely predicted that at some point in the future optical processing will need to be performed all-optically. Several techniques have been proposed to perform such all-optical signal processing. In this paper a technique based on the nonlinear rotation in the state of polarization of an optical signal injected into a bulk semiconductor optical amplifier is discussed. An experiment to perform wavelength conversion at 2.5 Gbit/s based on this effect is presented. The performance of the wavelength converter is tested in both co- and counter-propagation, and wavelength independent wavelength conversion is found in the non-inverted co-propagation setup.En los servicios de telecomunicaciones, la necesidad de hacer uso intensivo de las aplicaciones ha presionado por un constante incremento del ancho de banda. Particularmente una de las tecnologías más promisorias, que ha permitido estos incrementos de ancho de banda, son los elementos ópticos, de tal manera que en las redes de comunicación los elementos electrónicos sean sustituidos por dichos elementos ópticos. En esta publicación se discute una técnica basada en la rotación no lineal del estado de polarización de una señal óptica conectada al amplificador semiconductor óptico. Se presenta un experimento, basado en este efecto, para realizar la conversión a 2,5 Gbits/s. La característica del conversor de longitud onda es probada en propagación directa e inversa. Se ha encontrado que conversión de la longitud de onda es independiente de longitud de onda (la conversión no depende del valor de la longitud de onda en la modalidad de propagación directa no invertida.

Hyperentangled photon sources in semiconductor waveguides

DEFF Research Database (Denmark)

Kang, Dongpeng; Helt, L. G.; Zhukovsky, Sergei

2014-01-01

We propose and analyze the performance of a technique to generate mode and polarization hyperentangled photons in monolithic semiconductor waveguides using two concurrent type-II spontaneous parametric down-conversion (SPDC) processes. These two SPDC processes are achieved by waveguide engineering...

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

Microscopic theory of photon-correlation spectroscopy in strong-coupling semiconductors

Energy Technology Data Exchange (ETDEWEB)

Schneebeli, Lukas

2009-11-27

While many quantum-optical phenomena are already well established in the atomic systems, like the photon antibunching, squeezing, Bose-Einstein condensation, teleportation, the quantum-optical investigations in semiconductors are still at their beginning. The fascinating results observed in the atomic systems inspire physicists to demonstrate similar quantum-optical effects also in the semiconductor systems. In contrast to quantum optics with dilute atomic gases, the semiconductors exhibit a complicated many-body problem which is dominated by the Coulomb interaction between the electrons and holes and by coupling with the semiconductor environment. This makes the experimental observation of similar quantum-optical effects in semiconductors demanding. However, there are already experiments which have verified nonclassical effects in semiconductors. In particular, experiments have demonstrated that semiconductor quantum dots (QDs) can exhibit the single-photon emission and generation of polarization-entangled photon pairs. In fact, both atom and QD systems, embedded within a microcavity, have become versatile platforms where one can perform systematic quantum-optics investigations as well as development work toward quantum-information applications. Another interesting field is the strong-coupling regime in which the light-matter coupling exceeds both the decoherence rate of the atom or QD and the cavity resulting in a reversible dynamics between light and matter excitations. In the strong-coupling regime, the Jaynes-Cummings ladder is predicted and shows a photon-number dependent splitting of the new dressed strong-coupling states which are the polariton states of the coupled light-matter system. Although the semiclassical effect of the vacuum Rabi splitting has already been observed in QDs, the verification of the quantum-mechanical Jaynes-Cummings splitting is still missing mainly due to the dephasing. Clearly, the observation of the Jaynes-Cummings ladder in QDs

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

Calibration of Ge(Li) semiconductor detector by method using agar volume source

International Nuclear Information System (INIS)

Yanase, Nobuyuki; Kasai, Atsushi

1979-12-01

The Ge(Li) semiconductor detector was calibrated for measurements of environmental samples. The radioisotopes used for standard sources are 22 Na, 51 Cr, 56 Co, 57 Co, 133 Ba, 137 Cs, 144 Ce and 241 Am. These are mixed with hot agar aqueous solution and fixed uniformly in a cylindrical plastic case in cooling. The agar volume source is advantageous in handling over the fluid aqueous source. The prepared cylindrical standard sources are in diameters 6 and 8 cm and thicknesses 1, 5, 10, 20, 30 and 40 mm (only for 8 cm diameter). The radioactivities of prepared standard sources are between 0.03 μCi and 0.2 μCi. It takes only a week to make the calibration except data processing. The obtained full energy peak efficiency curves include 5 - 10% error due to preparation of agar source, reference radioactivity data of purchased standard solutions, reference data of branching ratio of gamma-ray and sum effect. The efficiency curves, however, are sufficient for quantitative analysis of environmental samples. (author)

Noise properties of semiconductor waveguides with alternating sections of saturable gain and absorption

DEFF Research Database (Denmark)

Öhman, Filip; Bischoff, Svend; Tromborg, Bjarne

We investigate the dynamical noise properties of saturable semiconductor devices for optical signal processing. A trade-off between noise redistribution and extinction ratio improvement has to be made for all-optical regeneration.......We investigate the dynamical noise properties of saturable semiconductor devices for optical signal processing. A trade-off between noise redistribution and extinction ratio improvement has to be made for all-optical regeneration....

Optical XOR gate

Science.gov (United States)

Vawter, G. Allen

2013-11-12

An optical XOR gate is formed as a photonic integrated circuit (PIC) from two sets of optical waveguide devices on a substrate, with each set of the optical waveguide devices including an electroabsorption modulator electrically connected in series with a waveguide photodetector. The optical XOR gate utilizes two digital optical inputs to generate an XOR function digital optical output. The optical XOR gate can be formed from III-V compound semiconductor layers which are epitaxially deposited on a III-V compound semiconductor substrate, and operates at a wavelength in the range of 0.8-2.0 .mu.m.

Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

International Nuclear Information System (INIS)

Oh, Changhoon; Ryoo, Hoonchul; Lee, Hyungwoo; Hahn, Jae W.; Kim, Se-Yeon; Yi, Hun-Jung

2010-01-01

We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES. The performance of the SROES was also verified by detecting the correlation between the distribution of a fluorine radical in inductively coupled plasma etch process and the etch rate of a SiO 2 film on a silicon wafer.

Large area UV light source with a semiconductor cathode

International Nuclear Information System (INIS)

Salamov, B. G.; Ciftci, Y. Oe.; Colakoglu, K.

2002-01-01

The light emission (LE) in the UV and visible (blue) range generated by a planar gas discharge system (PGDS) with a semiconductor cathode (SC) are studied. New light source offer high-intensity narrow-band emission at various UV and visible wavelengths (330 - 440 nm). Spectra in N 2 is presented, as well as intensity vs pressure curves for the main peaks of the spectrum. The use of source offers several advantages: PGDS can be extremely efficient energy converters transforming and amplifying a relatively low-powered photon flux incident on the receiving surface of the SC into a flux of high-energy particles over extended areas, i.e. electron, ions, photons. Thus, extremely bright UV and visible sources can be built. LE characteristics of the space in the PGDS are complex, depending on the emitting medium and species. By using the IR light to excite the SC of the system, we have shown that the discharge light emission (DLE) of the device with the N 2 in the gap can serve as an efficient source of the UV radiation if gas pressure and electric field are sufficiently high. This is realized due to the effect of the stabilisation of the spatially homogeneous mode of the discharge in a narrow gap with a large emitting area of SC. Special features of DLE render it highly promising for the development of sources with a large area of the emitting surface, high spatial uniformity of UV radiation, and fast dynamics of these devices. This low cost, high power light sources can provide an interesting alternative to conventional UV lamps

Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

International Nuclear Information System (INIS)

Mario Agio

2002-01-01

This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser

Optical Properties and Wave Propagation in Semiconductor-Based Two-Dimensional Photonic Crystals

Energy Technology Data Exchange (ETDEWEB)

Agio, Mario [Iowa State Univ., Ames, IA (United States)

2002-12-31

This work is a theoretical investigation on the physical properties of semiconductor-based two-dimensional photonic crystals, in particular for what concerns systems embedded in planar dielectric waveguides (GaAs/AlGaAs, GaInAsP/InP heterostructures, and self-standing membranes) or based on macro-porous silicon. The photonic-band structure of photonic crystals and photonic-crystal slabs is numerically computed and the associated light-line problem is discussed, which points to the issue of intrinsic out-of-lane diffraction losses for the photonic bands lying above the light line. The photonic states are then classified by the group theory formalism: each mode is related to an irreducible representation of the corresponding small point group. The optical properties are investigated by means of the scattering matrix method, which numerically implements a variable-angle-reflectance experiment; comparison with experiments is also provided. The analysis of surface reflectance proves the existence of selection rules for coupling an external wave to a certain photonic mode. Such rules can be directly derived from symmetry considerations. Lastly, the control of wave propagation in weak-index contrast photonic-crystal slabs is tackled in view of designing building blocks for photonic integrated circuits. The proposed designs are found to comply with the major requirements of low-loss propagation, high and single-mode transmission. These notions are then collected to model a photonic-crystal combiner for an integrated multi-wavelength-source laser.

CCST [Center for Compound Semiconductor Technology] research briefs

International Nuclear Information System (INIS)

Zipperian, T.E.; Voelker, E.R.

1989-12-01

This paper discusses the following topics: theoretical predictions of valence and conduction band offsets in III-V semiconductors; reflectance modulation of a semiconductor superlattice optical mirror; magnetoquantum oscillations of the phonon-drag thermoelectric power in quantum wells; correlation between photoluminescence line shape and device performance of p-channel strained-layer materials; control of threading dislocations in heteroepitaxial structures; improved growth of CdTe on GaAs by patterning; role of structure threading dislocations in relaxation of highly strained single-quantum-well structures; InAlAs growth optimization using reflection mass spectrometry; nonvolatile charge storage in III-V heterostructures; optically triggered thyristor switches; InAsSb strained-layer superlattice infrared detectors with high detectivities; resonant periodic gain surface-emitting semiconductor lasers; performance advantages of strained-quantum-well lasers in AlGaAs/InGaAs; optical integrated circuit for phased-array radar antenna control; and deposition and novel device fabrication from Tl 2 Ca 2 Ba 2 Cu 3 O y thin films

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

Enhanced performance of semiconductor optical amplifier at high direct modulation speed with birefringent fiber loop

Directory of Open Access Journals (Sweden)

K. E. Zoiros

2014-07-01

Full Text Available We employ a birefringent fiber loop (BFL for enhancing the performance of a semiconductor optical amplifier (SOA which is directly modulated. By properly exploiting the BFL comb-like spectral response, we show that the SOA can be directly modulated at a data rate which is more than five times faster than that enabled by the SOA electrical bandwidth. The experimental results, which include chirp measurements, demonstrate the significant improvements achieved in the performance of the directly modulated SOA with the help of the BFL.

Blue emitting organic semiconductors under high pressure

DEFF Research Database (Denmark)

Knaapila, Matti; Guha, Suchismita

2016-01-01

This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure and inter......This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure...... and intermolecular self-organization that typically determine transport and optical emission in π-conjugated oligomers and polymers. In this context, hydrostatic pressure through diamond anvil cells has proven to be an elegant tool to control structure and interactions without chemical intervention. This has been...... and intermolecular interactions on optical excitations, electron–phonon interaction, and changes in backbone conformations. This picture is connected to the optical high pressure studies of other π-conjugated systems and emerging x-ray scattering experiments from polyfluorenes which provides a structure-property map...

Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

DEFF Research Database (Denmark)

Lawætz, Peter

1969-01-01

The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering...... of the very-short-range nature of interactions in a covalent semiconductor....

Water-Soluble CdTe/CdS Core/Shell Semiconductor Nanocrystals: How Their Optical Properties Depend on the Synthesis Methods

Directory of Open Access Journals (Sweden)

Brener R. C. Vale

2016-10-01

Full Text Available We conducted a comparative synthesis of water-soluble CdTe/CdS colloidal nanocrystalline semiconductors of the core/shell type. We prepared the CdS shell using two different methods: a one-pot approach and successive ionic layer adsorption and reaction (SILAR; in both cases, we used 3-mercaptopropionic acid (MPA as the surface ligand. In the one-pot approach, thiourea was added over the freshly formed CdTe dispersion, and served as the sulfur source. We achieved thicker CdS layers by altering the Cd:S stoichiometric ratio (1:1, 1:2, 1:4, and 1:8. The Cd:S ratios 1:1 and 1:2 furnished the best optical properties; these ratios also made the formation of surface defects less likely. For CdTe/CdS obtained using SILAR, we coated the surface of three differently sized CdTe cores (2.17, 3.10, and 3.45 nm with one to five CdS layers using successive injections of the Cd2+ and S2– ions. The results showed that the core size influenced the optical properties of the materials. The deposition of three to five layers over the surface of smaller CdTe colloidal nanocrystals generated strain effects on the core/shell structure.

Polar optical phonons in a semiconductor quantum-well: The complete matching problem

International Nuclear Information System (INIS)

Nieto, J.M.; Comas, F.

2007-01-01

Confined polar optical phonons in a semiconductor quantum-well (QW) are studied by applying a phenomenological theory which was proposed a few years ago and is based on a continuum approach. This theory considers the coupled character of the electromechanical vibrations and takes due account of both the electric and mechanical boundary conditions. In the present work, we have applied the so-called complete matching problem in contrast with all previous published works on the subject, where more restrictive approximate boundary conditions has been applied. We also consider the effects of strains at the interfaces on the phonon spectra. Comparisons with previous works are made, while we focused on the study of a ZnTe/CdTe/ZnTe QW

Band Engineering Small Bandgap p-Type Semiconductors: Investigations of their Optical and Photoelectrochemical Properties

Science.gov (United States)

Zoellner, Brandon

Mixed-metal oxides containing Mn(II), Cu(I), Ta(V), Nb(V), and V(V) were investigated for their structures and properties as new p-type semiconductors and in the potential applications involving the photocatalytic conversion of water into hydrogen and oxygen. Engineering of the bandgaps was achieved by combining metal cations that have halffilled (Mn 3d5) or filled (Cu 3d10) d-orbitals together with metal cations that have empty (V/Nb/Ta 3/4/5 d0) d-orbitals. The research described herein focuses on the synthesis, optical, electronic, and photocatalytic properties of the metal-oxide semiconductors MnV2O6, Cu3VO 4, CuNb1-xTaxO3, and Cu5(Ta1-xNbx)11O30. Powder X-ray diffraction was used to probe their phase purity as well as atomic-level crystallographic details, i.e. shifts of lattice parameters, chemical compositions, and changes in local bonding environments. Optical measurements revealed visible-light bandgap sizes of ˜1.17 eV (Cu3VO4), ˜1.45 eV (MnV2O6), ˜1.89-1.97 eV (CuNb1-xTa xO3), and ˜1.97-2.50 eV (Cu5(Ta1-xNb x)11O30). The latter two were found to systematically vary as a function of composition. Electrochemical impedance spectroscopy measurements of MnV2O6 and Cu3VO 4 provided the first experimental characterization of the energetic positions of the valence and conduction bands with respect to the water oxidation and reduction potentials, as well as confirmed the p-type nature of each semiconductor. The valence and conduction band energies were found to be suitable for driving either one or both of the water-splitting half reaction (i.e. 2H+ → H2 and 2H2O → O2 + 4H+). Photoelectrochemical measurements on polycrystalline films of the Cu(I)-based semiconductors under visible-light irradiation produced cathodic currents indicative of p-type semiconductor character and chemical reduction at their surfaces in the electrolyte solution. The stability of the photocurrents was increased by the addition of CuO oxide particles either externally deposited or

An optical system for controlling ion source parameters

International Nuclear Information System (INIS)

Zhang Baifang; Liu Zhenhao; Jiang Yi; Xu Zhengjia

1999-01-01

An optical control system used for adjusting the source's parameters of an ion separator is described. There are two slice microcomputers at HV terminal and the ground respectively. These microcomputers communicate each other with the full-duplex mode through two pieces of optical fiber, in which many parameters are time-share transmitted in the form of optical pulse. This system can stabilize the arc current and temperature, adjust and display all parameters and has safe-guard ability. At HV terminal, the optical coupling technique is used for connecting the CPU and the ion source, and at the ground the CPU can communicate with a control microcomputer

Strain-tuning of the optical properties of semiconductor nanomaterials by integration onto piezoelectric actuators

Science.gov (United States)

Martín-Sánchez, Javier; Trotta, Rinaldo; Mariscal, Antonio; Serna, Rosalía; Piredda, Giovanni; Stroj, Sandra; Edlinger, Johannes; Schimpf, Christian; Aberl, Johannes; Lettner, Thomas; Wildmann, Johannes; Huang, Huiying; Yuan, Xueyong; Ziss, Dorian; Stangl, Julian; Rastelli, Armando

2018-01-01

The tailoring of the physical properties of semiconductor nanomaterials by strain has been gaining increasing attention over the last years for a wide range of applications such as electronics, optoelectronics and photonics. The ability to introduce deliberate strain fields with controlled magnitude and in a reversible manner is essential for fundamental studies of novel materials and may lead to the realization of advanced multi-functional devices. A prominent approach consists in the integration of active nanomaterials, in thin epitaxial films or embedded within carrier nanomembranes, onto Pb(Mg1/3Nb2/3)O3-PbTiO3-based piezoelectric actuators, which convert electrical signals into mechanical deformation (strain). In this review, we mainly focus on recent advances in strain-tunable properties of self-assembled InAs quantum dots (QDs) embedded in semiconductor nanomembranes and photonic structures. Additionally, recent works on other nanomaterials like rare-earth and metal-ion doped thin films, graphene and MoS2 or WSe2 semiconductor two-dimensional materials are also reviewed. For the sake of completeness, a comprehensive comparison between different procedures employed throughout the literature to fabricate such hybrid piezoelectric-semiconductor devices is presented. It is shown that unprocessed piezoelectric substrates (monolithic actuators) allow to obtain a certain degree of control over the nanomaterials’ emission properties such as their emission energy, fine-structure-splitting in self-assembled InAs QDs and semiconductor 2D materials, upconversion phenomena in BaTiO3 thin films or piezotronic effects in ZnS:Mn films and InAs QDs. Very recently, a novel class of micro-machined piezoelectric actuators have been demonstrated for a full control of in-plane stress fields in nanomembranes, which enables producing energy-tunable sources of polarization-entangled photons in arbitrary QDs. Future research directions and prospects are discussed.

Additional compound semiconductor nanowires for photonics

Science.gov (United States)

Ishikawa, F.

2016-02-01

GaAs related compound semiconductor heterostructures are one of the most developed materials for photonics. Those have realized various photonic devices with high efficiency, e. g., lasers, electro-optical modulators, and solar cells. To extend the functions of the materials system, diluted nitride and bismide has been paid attention over the past decade. They can largely decrease the band gap of the alloys, providing the greater tunability of band gap and strain status, eventually suppressing the non-radiative Auger recombinations. On the other hand, selective oxidation for AlGaAs is a vital technique for vertical surface emitting lasers. That enables precisely controlled oxides in the system, enabling the optical and electrical confinement, heat transfer, and mechanical robustness. We introduce the above functions into GaAs nanowires. GaAs/GaAsN core-shell nanowires showed clear redshift of the emitting wavelength toward infrared regime. Further, the introduction of N elongated the carrier lifetime at room temperature indicating the passivation of non-radiative surface recombinations. GaAs/GaAsBi nanowire shows the redshift with metamorphic surface morphology. Selective and whole oxidations of GaAs/AlGaAs core-shell nanowires produce semiconductor/oxide composite GaAs/AlGaOx and oxide GaOx/AlGaOx core-shell nanowires, respectively. Possibly sourced from nano-particle species, the oxide shell shows white luminescence. Those property should extend the functions of the nanowires for their application to photonics.

Spherical distribution structure of the semiconductor laser diode stack for pumping

International Nuclear Information System (INIS)

Zhao Tianzhuo; Yu Jin; Liu Yang; Zhang Xue; Ma Yunfeng; Fan Zhongwei

2011-01-01

A semiconductor laser diode stack is used for pumping and 8 semiconductor laser diode arrays of the stack are put on a sphere, and the output of every bar is specially off-axis compressed to realize high coupling efficiency. The output beam of this semiconductor laser diode stack is shaped by a hollow duct to the laser active medium. The efficiency of the hollow light pipe, which is used for semiconductor laser diode stack coupling, is analyzed by geometric optics and ray tracing. Geometric optics analysis diagnoses the reasons for coupling loss and guides the design of the structure. Ray tracing analyzes the relation between the structural parameters and the output characteristics of this pumping system, and guides parameter optimization. Simulation and analysis results show that putting the semiconductor laser diode arrays on a spherical surface can increase coupling efficiency, reduce the optimum duct length and improve the output energy field distribution. (semiconductor devices)

Optical Imaging of Ionizing Radiation from Clinical Sources.

Science.gov (United States)

Shaffer, Travis M; Drain, Charles Michael; Grimm, Jan

2016-11-01

Nuclear medicine uses ionizing radiation for both in vivo diagnosis and therapy. Ionizing radiation comes from a variety of sources, including x-rays, beam therapy, brachytherapy, and various injected radionuclides. Although PET and SPECT remain clinical mainstays, optical readouts of ionizing radiation offer numerous benefits and complement these standard techniques. Furthermore, for ionizing radiation sources that cannot be imaged using these standard techniques, optical imaging offers a unique imaging alternative. This article reviews optical imaging of both radionuclide- and beam-based ionizing radiation from high-energy photons and charged particles through mechanisms including radioluminescence, Cerenkov luminescence, and scintillation. Therapeutically, these visible photons have been combined with photodynamic therapeutic agents preclinically for increasing therapeutic response at depths difficult to reach with external light sources. Last, new microscopy methods that allow single-cell optical imaging of radionuclides are reviewed. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

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

Controlling the unstable emission of a semiconductor laser subject to conventional optical feedback with a filtered feedback branch.

Science.gov (United States)

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

2009-05-25

We show the advantages of controlling the unstable dynamics of a semiconductor laser subject to conventional optical feedback by means of a second filtered feedback branch. We give an overview of the analytical solutions of the double cavity feedback and show numerically that the region of stabilization is much larger when using a second branch with filtered feedback than when using a conventional feedback one.

Controlling the unstable emission of a semiconductor laser subject to conventional optical feedback with a filtered feedback branch

OpenAIRE

Ermakov, Ilya; Tronciu, Vasile; Colet, Pere; Mirasso, Claudio R.

2009-01-01

We show the advantages of controlling the unstable dynamics of a semiconductor laser subject to conventional optical feedback by means of a second filtered feedback branch. We give an overview of the analytical solutions of the double cavity feedback and show numerically that the region of stabilization is much larger when using a second branch with filtered feedback than when using a conventional feedback one.

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...

Method of Promoting Single Crystal Growth During Melt Growth of Semiconductors

Science.gov (United States)

Su, Ching-Hua (Inventor)

2013-01-01

The method of the invention promotes single crystal growth during fabrication of melt growth semiconductors. A growth ampoule and its tip have a semiconductor source material placed therein. The growth ampoule is placed in a first thermal environment that raises the temperature of the semiconductor source material to its liquidus temperature. The growth ampoule is then transitioned to a second thermal environment that causes the semiconductor source material in the growth ampoule's tip to attain a temperature that is below the semiconductor source material's solidus temperature. The growth ampoule so-transitioned is then mechanically perturbed to induce single crystal growth at the growth ampoule's tip.

25 Gbit/s differential phase-shift-keying signal generation using directly modulated quantum-dot semiconductor optical amplifiers

International Nuclear Information System (INIS)

Zeghuzi, A.; Schmeckebier, H.; Stubenrauch, M.; Bimberg, D.; Meuer, C.; Schubert, C.; Bunge, C.-A.

2015-01-01

Error-free generation of 25-Gbit/s differential phase-shift keying (DPSK) signals via direct modulation of InAs quantum-dot (QD) based semiconductor optical amplifiers (SOAs) is experimentally demonstrated with an input power level of −5 dBm. The QD SOAs emit in the 1.3-μm wavelength range and provide a small-signal fiber-to-fiber gain of 8 dB. Furthermore, error-free DPSK modulation is achieved for constant optical input power levels from 3 dBm down to only −11 dBm for a bit rate of 20 Gbit/s. Direct phase modulation of QD SOAs via current changes is thus demonstrated to be much faster than direct gain modulation

Electronic structure of ferromagnetic semiconductor Ga1-xMnxAs probed by sub-gap magneto-optical spectroscopy

OpenAIRE

Acbas, G.; Kim, M. -H.; Cukr, M.; Novak, V.; Scarpulla, M. A.; Dubon, O. D.; Jungwirth, T.; Sinova, Jairo; Cerne, J.

2009-01-01

We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronic structure of Ga1-xMnxAs near the Fermi energy. The band structure of this archetypical dilute-moment ferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements of the unpolarized infrared absorption and their phenomenological impurity-band interpretation. The infrared magneto-optical effects we study arise directly from the spin-splitting of the carrier ...

Tunable and broadband microwave frequency combs based on a semiconductor laser with incoherent optical feedback

International Nuclear Information System (INIS)

Zhao Mao-Rong; Wu Zheng-Mao; Deng Tao; Zhou Zhen-Li; Xia Guang-Qiong

2015-01-01

Based on a semiconductor laser (SL) with incoherent optical feedback, a novel all-optical scheme for generating tunable and broadband microwave frequency combs (MFCs) is proposed and investigated numerically. The results show that, under suitable operation parameters, the SL with incoherent optical feedback can be driven to operate at a regular pulsing state, and the generated MFCs have bandwidths broader than 40 GHz within a 10 dB amplitude variation. For a fixed bias current, the line spacing (or repetition frequency) of the MFCs can be easily tuned by varying the feedback delay time and the feedback strength, and the tuning range of the line spacing increases with the increase in the bias current. The linewidth of the MFCs is sensitive to the variation of the feedback delay time and the feedback strength, and a linewidth of tens of KHz can be achieved through finely adjusting the feedback delay time and the feedback strength. In addition, mappings of amplitude variation, repetition frequency, and linewidth of MFCs in the parameter space of the feedback delay time and the feedback strength are presented. (paper)

A Practical Guide to Experimental Geometrical Optics

Science.gov (United States)

Garbovskiy, Yuriy A.; Glushchenko, Anatoliy V.

2017-12-01

Preface; 1. Markets of optical materials, components, accessories, light sources and detectors; 2. Introduction to optical experiments: light producing, light managing, light detection and measuring; 3. Light detectors based on semiconductors: photoresistors, photodiodes in a photo-galvanic regime. Principles of operation and measurements; 4. Linear light detectors based on photodiodes; 5. Basic laws of geometrical optics: experimental verification; 6. Converging and diverging thin lenses; 7. Thick lenses; 8. Lens systems; 9. Simple optical instruments I: the eye and the magnifier, eyepieces and telescopes; 10. Simple optical instruments II: light illuminators and microscope; 11. Spherical mirrors; 12. Introduction to optical aberrations; 13. Elements of optical radiometry; 14. Cylindrical lenses and vials; 15. Methods of geometrical optics to measure refractive index; 16. Dispersion of light and prism spectroscope; 17. Elements of computer aided optical design; Index.

Packaged semiconductor laser optical phase locked loop for photonic generation, processing and transmission of microwave signals

DEFF Research Database (Denmark)

Langley, L.N.; Elkin, M.D.; Edege, C.

1999-01-01

In this paper, we present the first fully packaged semiconductor laser optical phase-locked loop (OPLL) microwave photonic transmitter. The transmitter is based on semiconductor lasers that are directly phase locked without the use of any other phase noise-reduction mechanisms. In this transmitter......, the lasers have a free-running summed linewidth of 6 MHz and the OPLL has a feedback bandwidth of 70 MHz, A state-of-the-art performance is obtained, with a total phase-error variance of 0.05 rad(2) (1-GHz bandwidth) and a carrier phase-error variance of 7x10(-4) rad(2) in a 15-MHz bandwidth. Carriers...... are generated in the range of 7-14 GHz. The OPLL transmitter has been fully packaged for practical use in field trials. This is the first time this type of transmitter has been fabricated in a packaged state which is a significant advance on the route to practical application....

Effect of wetting-layer density of states on the gain and phase recovery dynamics of quantum-dot semiconductor optical amplifiers

International Nuclear Information System (INIS)

Kim, Jungho; Yu, Bong-Ahn

2015-01-01

We numerically investigate the effect of the wetting-layer (WL) density of states on the gain and phase recovery dynamics of quantum-dot semiconductor optical amplifiers in both electrical and optical pumping schemes by solving 1088 coupled rate equations. The temporal variations of the ultrafast gain and phase recovery responses at the ground state (GS) are calculated as a function of the WL density of states. The ultrafast gain recovery responses do not significantly depend on the WL density of states in the electrical pumping scheme and the three optical pumping schemes such as the optical pumping to the WL, the optical pumping to the excited state ensemble, and the optical pumping to the GS ensemble. The ultrafast phase recovery responses are also not significantly affected by the WL density of states except the optical pumping to the WL, where the phase recovery component caused by the WL becomes slowed down as the WL density of states increases. (paper)

Apparatus for testing semiconductor devices and capacitors

International Nuclear Information System (INIS)

York, R.A.

1984-01-01

An apparatus is provided for testing semiconductor devices. The apparatus tests the impedance of the semiconductor devices in both conducting and non-conducting states to detect semiconductors whose impedance in the conducting state is too high or whose impedance in the non-conducting state is too low. The apparatus uses a battery source for low voltage d.c. The circuitry for detecting when the impedance is too high in the conducting state includes a lamp in series with the battery source and the semiconductor device, whereby the impedance of the semiconductor device determines whether sufficient current will flow through the lamp to cause the lamp to illuminate. A d.c. to d.c. converter is provided to boost the voltage from the battery source to a relatively high voltage d.c. The relatively high voltage d.c. can be connected by a switch to circuitry for detecting when the impedance of the semiconductor device in the non-conducting state is too low. The circuitry for detecting when the impedance of the semiconductor device is too low includes a resistor which senses the current flowing in the device and converts the current into a voltage proportional to the leakage current. This voltage is then compared against a fixed reference. Further circuitry is provided for providing a visual indication when the voltage representative of leakage in relation to the reference signal indicates that there is excessive current flow through the semiconductor device

Carrier dynamics in inhomogeneously broadened InAs/AlGaInAs/InP quantum-dot semiconductor optical amplifiers

Energy Technology Data Exchange (ETDEWEB)

Karni, O., E-mail: oulrik@tx.technion.ac.il; Mikhelashvili, V.; Eisenstein, G. [Electrical Engineering Department, Technion—Israel Institute of Technology, Haifa 32000 (Israel); Kuchar, K. J. [Electrical Engineering Department, Technion—Israel Institute of Technology, Haifa 32000 (Israel); Institute of Physics, Wroclaw University of Technology, Wroclaw 50-370 (Poland); Capua, A. [Electrical Engineering Department, Technion—Israel Institute of Technology, Haifa 32000 (Israel); IBM Almaden Research Center, San Jose, 95120 California (United States); Sęk, G.; Misiewicz, J. [Institute of Physics, Wroclaw University of Technology, Wroclaw 50-370 (Poland); Ivanov, V.; Reithmaier, J. P. [Technische Physik, Institute of Nanostructure Technology and Analytics, CINSaT, University of Kassel, Kassel D-34132 (Germany)

2014-03-24

We report on a characterization of fundamental gain dynamics in recently developed InAs/InP quantum-dot semiconductor optical amplifiers. Multi-wavelength pump-probe measurements were used to determine gain recovery rates, following a powerful optical pump pulse, at various wavelengths for different bias levels and pump excitation powers. The recovery was dominated by coupling between the electronic states in the quantum-dots and the high energy carrier reservoir via capture and escape mechanisms. These processes determine also the wavelength dependencies of gain saturation depth and the asymptotic gain recovery level. Unlike quantum-dash amplifiers, these quantum-dots exhibit no instantaneous gain response, confirming their quasi zero-dimensional nature.

Semiconductor composition containing iron, dysprosium, and terbium

Science.gov (United States)

Pooser, Raphael C.; Lawrie, Benjamin J.; Baddorf, Arthur P.; Malasi, Abhinav; Taz, Humaira; Farah, Annettee E.; Kalyanaraman, Ramakrishnan; Duscher, Gerd Josef Mansfred; Patel, Maulik K.

2017-09-26

An amorphous semiconductor composition includes 1 to 70 atomic percent iron, 15 to 65 atomic percent dysprosium, 15 to 35 atomic percent terbium, balance X, wherein X is at least one of an oxidizing element and a reducing element. The composition has an essentially amorphous microstructure, an optical transmittance of at least 50% in at least the visible spectrum and semiconductor electrical properties.

FDML swept source at 1060 nm using a tapered amplifier

DEFF Research Database (Denmark)

Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang

2010-01-01

We present a novel frequency-swept light source working at 1060nm that utilizes a tapered amplifier as gain medium. These devices feature significantly higher saturation power than conventional semiconductor optical amplifiers and can thus improve the limited output power of swept sources in this...... an axial resolution of 15 µm in air (~11µm in tissue) for OCT applications can be achieved....

Below-bandgap photoreflection spectroscopy of semiconductor laser structures

International Nuclear Information System (INIS)

Sotnikov, Aleksandr E; Chernikov, Maksim A; Ryabushkin, Oleg A; Trubenko, P; Moshegov, N; Ovchinnikov, A

2004-01-01

A new method of modulated light reflection - below-bandgap photoreflection, is considered. Unlike the conventional photoreflection method, the proposed method uses optical pumping by photons of energy smaller than the bandgap of any layer of a semiconductor structure under study. Such pumping allows one to obtain the modulated reflection spectrum for all layers of the structure without excitation of photoluminescence. This method is especially promising for the study of wide-gap semiconductors. The results of the study of semiconductor structures used in modern high-power multimode semiconductor lasers are presented. (laser applications and other topics in quantum electronics)

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.

Electronic and optical properties of defect CdIn_2Te_4 chalcopyrite semiconductor: A first principle approach

International Nuclear Information System (INIS)

Mishra, S.; Ganguli, B.

2016-01-01

We present detailed study of structural, electronic and optical properties of CdIn_2Te_4 compound. The calculations are carried out using Density Functional theory based Tight Binding Linear Muffin Tin Orbital method. The compound is found to be direct band gap semiconductor with a band gap of 1.03 eV. The band gap is within the limit of LDA underestimation. The calculated structural parameters agree well with the available experimental values. We find a decrements of 9.6% in band gap and significant effects on overall electronic and optical properties due to structural distortions. These effects on optical properties come mainly from the change in transition probability. An-isotropic nature of optical properties get enhanced due to structural distortion. The Calculated real & imaginary parts of dielectric constant and static dielectric constant agree well with the available experimental result. - Highlights: • We present ab-initio calculations of electronic & optical properties of CdIn_2Te_4. • Band gap get reduced by 9.6% due to structural distortion. • Structural distortion has significant effects on optical properties. • Anisotropic nature of optical response functions get enhanced by structural distortion. • Calculated dielectric constant agrees with experimental value.

Optical laser systems at the Linac Coherent Light Source

Energy Technology Data Exchange (ETDEWEB)

Minitti, Michael P.; Robinson, Joseph S.; Coffee, Ryan N.; Edstrom, Steve; Gilevich, Sasha; Glownia, James M.; Granados, Eduardo; Hering, Philippe; Hoffmann, Matthias C.; Miahnahri, Alan; Milathianaki, Despina; Polzin, Wayne; Ratner, Daniel; Tavella, Franz; Vetter, Sharon; Welch, Marc; White, William E.; Fry, Alan R., E-mail: alanfry@slac.stanford.edu [Linac Coherent Light Source, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

2015-04-22

This manuscript serves as a reference to describe the optical laser sources and capabilities at the Linac Coherent Light Source. Ultrafast optical lasers play an essential role in exploiting the unique capabilities of recently commissioned X-ray free-electron laser facilities such as the Linac Coherent Light Source (LCLS). Pump–probe experimental techniques reveal ultrafast dynamics in atomic and molecular processes and reveal new insights in chemistry, biology, material science and high-energy-density physics. This manuscript describes the laser systems and experimental methods that enable cutting-edge optical laser/X-ray pump–probe experiments to be performed at LCLS.

Centralized light-source optical access network based on polarization multiplexing.

Science.gov (United States)

Grassi, Fulvio; Mora, José; Ortega, Beatriz; Capmany, José

2010-03-01

This paper presents and demonstrates a centralized light source optical access network based on optical polarization multiplexing technique. By using two optical sources emitting light orthogonally polarized in the Central Node for downstream and upstream operations, the Remote Node is kept source-free. EVM values below telecommunication standard requirements have been measured experimentally when bidirectional digital signals have been transmitted over 10 km of SMF employing subcarrier multiplexing technique in the electrical domain.

Proceedings of the IEEE laser and electro-optics society annual meeting

International Nuclear Information System (INIS)

Hudson, M.J.B.; Raney, H.; Raney, D.; Spalaris, C.N.

1990-01-01

This book is covered under the following headings: Electro-optic systems; Emerging laser technology; Optical sensors and measurements; Optoelectronics; Semiconductor diode lasers; Solid state lasers; UV and short wavelength; Applied optical diagnostics of semiconductor materials and devices symposium and optical sensors and measurements; and Applied optical diagnostics of semiconductor materials and devices symposium

Cost-Effective Brillouin Optical Time-Domain Analysis Sensor Using a Single Optical Source and Passive Optical Filtering

Directory of Open Access Journals (Sweden)

H. Iribas

2016-01-01

Full Text Available We present a simplified configuration for distributed Brillouin optical time-domain analysis sensors that aims to reduce the cost of the sensor by reducing the number of components required for the generation of the two optical waves involved in the sensing process. The technique is based on obtaining the pump and probe waves by passive optical filtering of the spectral components generated in a single optical source that is driven by a pulsed RF signal. The optical source is a compact laser with integrated electroabsorption modulator and the optical filters are based on fiber Bragg gratings. Proof-of-concept experiments demonstrate 1 m spatial resolution over a 20 km sensing fiber with a 0.9 MHz precision in the measurement of the Brillouin frequency shift, a performance similar to that of much more complex setups. Furthermore, we discuss the factors limiting the sensor performance, which are basically related to residual spectral components in the filtering process.

Electric-dipole absorption resonating with longitudinal optical phonon-plasmon system and its effect on dispersion relations of interface phonon polariton modes in metal/semiconductor-stripe structures

Science.gov (United States)

Sakamoto, Hironori; Takeuchi, Eito; Yoshida, Kouki; Morita, Ken; Ma, Bei; Ishitani, Yoshihiro

2018-01-01

Interface phonon polaritons (IPhPs) in nano-structures excluding metal components are thoroughly investigated because they have lower loss in optical emission or absorption and higher quality factors than surface plasmon polaritons. In previous reports, it is found that strong infrared (IR) absorption is based on the interaction of p-polarized light and materials, and the resonance photon energy highly depends on the structure size and angle of incidence. We report the optical absorption by metal/semiconductor (bulk-GaAs and thin film-AlN)-stripe structures in THz to mid-IR region for the electric field of light perpendicular to the stripes, where both of s- and p-polarized light are absorbed. The absorption resonates with longitudinal optical (LO) phonon or LO phonon-plasmon coupling (LOPC) modes, and thus is independent of the angle of incidence or structure size. This absorption is attributed to the electric dipoles by the optically induced polarization charges at the metal/semiconductor, heterointerfaces, or interfaces of high electron density layers and depression ones. The electric permittivity is modified by the formation of these dipoles. It is found to be indispensable to utilize our form of altered permittivity to explain the experimental dispersion relations of metal/semiconductor-IPhP and SPhP in these samples. This analysis reveals that the IPhPs in the stripe structures of metal/AlN-film on a SiC substrate are highly confined in the AlN film, while the permittivity of the structures of metal/bulk-GaAs is partially affected by the electric-dipoles. The quality factors of the electric-dipole absorption are found to be 42-54 for undoped samples, and the value of 62 is obtained for Al/AlN-IPhP. It is thought that metal-contained structures are not obstacles to mode energy selectivity in phonon energy region of semiconductors.

46 CFR 183.360 - Semiconductor rectifier systems.

Science.gov (United States)

2010-10-01

... 46 Shipping 7 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 183.360 Section 183.360... TONS) ELECTRICAL INSTALLATION Power Sources and Distribution Systems § 183.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents...

Ab initio description of the diluted magnetic semiconductor Ga1-xMnxAs: Ferromagnetism, electronic structure, and optical response

Science.gov (United States)

Craco, L.; Laad, M. S.; Müller-Hartmann, E.

2003-12-01

Motivated by a study of various experiments describing the electronic and magnetic properties of the diluted magnetic semiconductor Ga1-xMnxAs, we investigate its physical response in detail using a combination of first-principles band structure with methods based on dynamical mean field theory to incorporate strong, dynamical correlations, and intrinsic as well as extrinsic disorder in one single theoretical picture. We show how ferromagnetism is driven by double exchange (DE), in agreement with very recent observations, along with a good quantitative description of the details of the electronic structure, as probed by scanning tunneling microscopy and optical conductivity. Our results show how ferromagnetism can be driven by DE even in diluted magnetic semiconductors with small carrier concentration.

Limit of detection of a fiber optics gyroscope using a super luminescent radiation source; Limite de deteccion de un giroscopio de fibra optica usando una fuente de radiacion superluminiscente

Energy Technology Data Exchange (ETDEWEB)

Sandoval R, G.E. [Laboratorio de Optica Aplicada, Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510 Mexico D.F. (Mexico); Nikolaev, V.A. [Departamento de Optica y Radiofisica Cuantica, Universidad Estatal de Telecomunicaciones de San Petersburgo, M.A. Bonch-Bruyevich, Kanal Moika 61, Saint Petersburg 191186, (Russian Federation)

2003-07-01

The main objective of this work is to establish the dependence of characteristics of the fiber optics gyroscope (FOG) with respect to the parameters of the super luminescent emission source based on doped optical fiber with rare earth elements (Super luminescent Fiber Source, SFS), argument the pumping rate election of the SFS to obtain characteristics limits of the FOG sensibility. By using this type of emission source in the FOG is recommend to use the rate when the direction of the pumping signal coincide with the super luminescent signal. The most results are the proposition and argumentation of the SFS election as emission source to be use in the FOG of the phase type. Such a decision allow to increase the characteristics of the FOG sensibility in comparison with the use of luminescent source of semiconductors emission which are extensively used in the present time. The use of emission source of the SFS type allow to come closer to the threshold of the obtained sensibility limit (detection limit) which is determined with the shot noise. (Author)

Radiation tolerance of amorphous semiconductors

International Nuclear Information System (INIS)

Nicolaides, R.V.; DeFeo, S.; Doremus, L.W.

1976-01-01

In an attempt to determine the threshold radiation damage in amorphous semiconductors, radiation tests were performed on amorphous semiconductor thin film materials and on threshold and memory devices. The influence of flash x-rays and neutron radiation upon the switching voltages, on- and off-state characteristics, dielectric response, optical transmission, absorption band edge and photoconductivity were measured prior to, during and following irradiation. These extensive tests showed the high radiation tolerance of amorphous semiconductor materials. Electrical and optical properties, other than photoconductivity, have a neutron radiation tolerance threshold above 10 17 nvt in the steady state and 10 14 nvt in short (50 μsec to 16 msec) pulses. Photoconductivity increases by 1 1 / 2 orders of magnitude at the level of 10 14 nvt (short pulses of 50 μsec). Super flash x-rays up to 5000 rads (Si), 20 nsec, do not initiate switching in off-state samples which are voltage biased up to 90 percent of the threshold voltage. Both memory and threshold amorphous devices are capable of switching on and off during nuclear radiation transients at least as high as 2 x 10 14 nvt in 50 μsec pulses

Integrating magnetism into semiconductor electronics

Energy Technology Data Exchange (ETDEWEB)

Zakharchenya, Boris P; Korenev, Vladimir L [A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg (Russian Federation)

2005-06-30

The view of a ferromagnetic-semiconducting hybrid structure as a single tunable system is presented. Based on an analysis of existing experiments it is shown that, contrary to a 'common sense', a nonmagnetic semiconductor is capable of playing an important role in controlling ferromagnetism. Magnetic properties of a hybrid (the hysteresis loop and the spatial orientation of magnetization) can be tuned both optically and electrically by utilizing semiconductor-making the hybrid an electronic-write-in and electronic-read-out elementary storage unit. (methodological notes)

Integrating magnetism into semiconductor electronics

International Nuclear Information System (INIS)

Zakharchenya, Boris P; Korenev, Vladimir L

2005-01-01

The view of a ferromagnetic-semiconducting hybrid structure as a single tunable system is presented. Based on an analysis of existing experiments it is shown that, contrary to a 'common sense', a nonmagnetic semiconductor is capable of playing an important role in controlling ferromagnetism. Magnetic properties of a hybrid (the hysteresis loop and the spatial orientation of magnetization) can be tuned both optically and electrically by utilizing semiconductor-making the hybrid an electronic-write-in and electronic-read-out elementary storage unit. (methodological notes)

Semiconductor lasers and herterojunction leds

CERN Document Server

Kressel, Henry

2012-01-01

Semiconductor Lasers and Heterojunction LEDs presents an introduction to the subject of semiconductor lasers and heterojunction LEDs. The book reviews relevant basic solid-state and electromagnetic principles; the relevant concepts in solid state physics; and the p-n junctions and heterojunctions. The text also describes stimulated emission and gain; the relevant concepts in electromagnetic field theory; and the modes in laser structures. The relation between electrical and optical properties of laser diodes; epitaxial technology; binary III-V compounds; and diode fabrication are also consider

46 CFR 129.360 - Semiconductor-rectifier systems.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor-rectifier systems. 129.360 Section 129.360... INSTALLATIONS Power Sources and Distribution Systems § 129.360 Semiconductor-rectifier systems. (a) Each semiconductor-rectifier system must have an adequate heat-removal system to prevent overheating. (b) If a...

46 CFR 120.360 - Semiconductor rectifier systems.

Science.gov (United States)

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Semiconductor rectifier systems. 120.360 Section 120.360... INSTALLATION Power Sources and Distribution Systems § 120.360 Semiconductor rectifier systems. (a) Each semiconductor rectifier system must have an adequate heat removal system that prevents overheating. (b) Where a...

Optical-cell model based on the lasing competition of mode structures with different Q-factors in high-power semiconductor lasers

Energy Technology Data Exchange (ETDEWEB)

Podoskin, A. A., E-mail: podoskin@mail.ioffe.ru; Shashkin, I. S.; Slipchenko, S. O.; Pikhtin, N. A.; Tarasov, I. S. [Russian Academy of Sciences, Ioffe Institute (Russian Federation)

2015-08-15

A model describing the operation of a completely optical cell, based on the competition of lasing of Fabry-Perot cavity modes and the high-Q closed mode in high-power semiconductor lasers is proposed. Based on rate equations, the conditions of lasing switching between Fabry-Perot modes for ground and excited lasing levels and the closed mode are considered in the case of increasing internal optical loss under conditions of high current pump levels. The optical-cell operation conditions in the mode of a high-power laser radiation switch (reversible mode-structure switching) and in the mode of a memory cell with bistable irreversible lasing switching between mode structures with various Q-factors are considered.

Inspection of imprint lithography patterns for semiconductor and patterned media

Science.gov (United States)

Resnick, Douglas J.; Haase, Gaddi; Singh, Lovejeet; Curran, David; Schmid, Gerard M.; Luo, Kang; Brooks, Cindy; Selinidis, Kosta; Fretwell, John; Sreenivasan, S. V.

2010-03-01

Imprint lithography has been shown to be an effective technique for replication of nano-scale features. Acceptance of imprint lithography for manufacturing will require demonstration that it can attain defect levels commensurate with the requirements of cost-effective device production. This work summarizes the results of defect inspections of semiconductor masks, wafers and hard disks patterned using Jet and Flash Imprint Lithography (J-FILTM). Inspections were performed with optical and e-beam based automated inspection tools. For the semiconductor market, a test mask was designed which included dense features (with half pitches ranging between 32 nm and 48 nm) containing an extensive array of programmed defects. For this work, both e-beam inspection and optical inspection were used to detect both random defects and the programmed defects. Analytical SEMs were then used to review the defects detected by the inspection. Defect trends over the course of many wafers were observed with another test mask using a KLA-T 2132 optical inspection tool. The primary source of defects over 2000 imprints were particle related. For the hard drive market, it is important to understand the defectivity of both the template and the imprinted disk. This work presents a methodology for automated pattern inspection and defect classification for imprint-patterned media. Candela CS20 and 6120 tools from KLA-Tencor map the optical properties of the disk surface, producing highresolution grayscale images of surface reflectivity, scattered light, phase shift, etc. Defects that have been identified in this manner are further characterized according to the morphology

Multipulse dynamics of a passively mode-locked semiconductor laser with delayed optical feedback

Science.gov (United States)

Jaurigue, Lina; Krauskopf, Bernd; Lüdge, Kathy

2017-11-01

Passively mode-locked semiconductor lasers are compact, inexpensive sources of short light pulses of high repetition rates. In this work, we investigate the dynamics and bifurcations arising in such a device under the influence of time delayed optical feedback. This laser system is modelled by a system of delay differential equations, which includes delay terms associated with the laser cavity and feedback loop. We make use of specialised path continuation software for delay differential equations to analyse the regime of short feedback delays. Specifically, we consider how the dynamics and bifurcations depend on the pump current of the laser, the feedback strength, and the feedback delay time. We show that an important role is played by resonances between the mode-locking frequencies and the feedback delay time. We find feedback-induced harmonic mode locking and show that a mismatch between the fundamental frequency of the laser and that of the feedback cavity can lead to multi-pulse or quasiperiodic dynamics. The quasiperiodic dynamics exhibit a slow modulation, on the time scale of the gain recovery rate, which results from a beating with the frequency introduced in the associated torus bifurcations and leads to gain competition between multiple pulse trains within the laser cavity. Our results also have implications for the case of large feedback delay times, where a complete bifurcation analysis is not practical. Namely, for increasing delay, there is an ever-increasing degree of multistability between mode-locked solutions due to the frequency pulling effect.

Optical Characteristics of a Multichannel Hybrid Integrated Light Source for Ultra-High-Bandwidth Optical Interconnections

Directory of Open Access Journals (Sweden)

Takanori Shimizu

2015-11-01

Full Text Available The optical characteristics of a multi-channel hybrid integrated light source were described for an optical interconnection with a bandwidth of over 10 Tbit/s. The power uniformity of the relative intensity of a 1000-channel light source was shown, and the minimum standard deviation s of the optical power of the 200 output ports at each 25-channel laser diode (LD array was estimated to be 0.49 dB. This hybrid integrated light source is expected to be easily adaptable to a photonics-electronics convergence system for ultra-high-bandwidth interchip interconnections.

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.

Electron and nuclear spin system polarization in semiconductors by light

Energy Technology Data Exchange (ETDEWEB)

Zakharchenya, B; Flejsher, V

1981-02-01

Discussed are the principles of optical electron spin orientation, dynamic polarization and cooling of nuclear spin systems in optical electron orientation, and behavioural characteristics of bound electron and nuclear spin systems of a semiconductor in the optical orientation situation.

Optically pumped polarized H- ion source

International Nuclear Information System (INIS)

Anderson, L.W.

1986-01-01

The current status and future prospects for the optically pumped polarized H - ion source are discussed. At the present time H - ion currents of 60 μA and with a polarization of 65% have been produced. The ion current and polarization can be increased significantly if the optically pumped Na charge exchange target density and polarization can be increased. Studies of wall surfaces that permit many bounces before depolarizing the Na electron spin and studies of radiation trapping in optically pumped Na indicate that the Na target density and polarization can be increased substantially. 27 refs., 6 figs., 2 tabs

Tuned sources of submillimetre radiation

International Nuclear Information System (INIS)

Berezhnyj, V.L.

1981-01-01

The main present directions of development of sources of frequency coherent tuned radiation of electromagnetic waves in the submillimeter range: nonlinear mixing of different frequencies; semiconductor lasers; molecular lasers with optical pumping; relativistic electron beams in a magnetic field as submillimeter radiation sources; submillimeter radiation sources on the basis of SHF classical electrovacuum devices - are considered. The designs of generator systems and their specifications are presented. The main parameters of electromagnetic radiation of different sources, such as: power, stability, frequency, tuning range - are presented. The methods of improving sources and electromagnetic radiation parameters are proposed. The examples of possible applications of submillimeter radiation in different spheres of science and technology are given [ru

Slow and fast light effects in semiconductor waveguides for applications in microwave photonics

DEFF Research Database (Denmark)

Mørk, Jesper; Öhman, Filip; Xue, Weiqi

2008-01-01

We review the physics of slow and fast light effects in semiconductor waveguides. Different schemes for achieving optically or electronically controlled phase shifts are introduced and explained.......We review the physics of slow and fast light effects in semiconductor waveguides. Different schemes for achieving optically or electronically controlled phase shifts are introduced and explained....

Electron and nuclear spin system polarization in semiconductors by light

International Nuclear Information System (INIS)

Zakharchenya, B.; Flejsher, V.

1981-01-01

Discussed are the principles of optical electron spin orientation, dynamic polarization and cooling of nuclear spin systems in optical electron orientation, and behavioural characteristics of bound electron and nuclear spin systems of a semiconductor in the optical orientation situation. (J.P.)

Semiconductor plasmonic crystals: active control of THz extinction

International Nuclear Information System (INIS)

Schaafsma, M C; Rivas, J Gómez

2013-01-01

We investigate theoretically the enhanced THz extinction by periodic arrays of semiconductor particles. Scattering particles of doped semiconductors can sustain localized surface plasmon polaritons, which can be diffractively coupled giving rise to surface lattice resonances. These resonances are characterized by a large extinction and narrow bandwidth, which can be tuned by controlling the charge carrier density in the semiconductor. The underlaying mechanism leading to this tuneability is explained using the coupled dipole approximation and considering GaAs as the semiconductor. The enhanced THz extinction in arrays of GaAs particles could be tuned in a wide range by optical pumping of charge carriers. (invited article)

Comparative Analysis of Semiconductor Power Losses of Galvanically Isolated Quasi-Z-Source and Full-Bridge Boost DC-DC Converters

Directory of Open Access Journals (Sweden)

Kosenko Roman

2015-07-01

Full Text Available This paper compares semiconductor losses of the galvanically isolated quasi-Z-source converter and full-bridge boost DC-DC converter with active clamping circuit. Operation principle of both converters is described. Short design guidelines are provided as well. Results of steady state analysis are used to calculate semiconductor power losses for both converters. Analytical expressions are derived for all types of semiconductor power losses present in these converters. The theoretical results were verified by means of numerical simulation performed in the PSIM simulation software. Its add-on module “Thermal module” was used to estimate semiconductor power losses using the datasheet parameters of the selected semiconductor devices. Results of calculations and simulation study were obtained for four operating points with different input voltage and constant input current to compare performance of the converters in renewable applications, like photovoltaic, where input voltage and power can vary significantly. Power loss breakdown is detailed and its dependence on the converter output power is analyzed. Recommendations are given for the use of the converter topologies in applications with low input voltage and relatively high input current.

Metal-coated semiconductor nanostructures and simulation of photon extraction and coupling to optical fibers for a solid-state single-photon source

International Nuclear Information System (INIS)

Suemune, Ikuo; Nakajima, Hideaki; Liu, Xiangming; Odashima, Satoru; Asano, Tomoya; Iijima, Hitoshi; Huh, Jae-Hoon; Idutsu, Yasuhiro; Sasakura, Hirotaka; Kumano, Hidekazu

2013-01-01

We have realized metal-coated semiconductor nanostructures for a stable and efficient single-photon source (SPS) and demonstrated improved single-photon extraction efficiency by the selection of metals and nanostructures. We demonstrate with finite-difference time-domain (FDTD) simulations that inclination of a pillar sidewall, which changes the structure to a nanocone, is effective in improving the photon extraction efficiency. We demonstrate how such nanocone structures with inclined sidewalls are fabricated with reactive ion etching. With the optimized design, a photon extraction efficiency to outer airside as high as ∼97% generated from a quantum dot in a nanocone structure is simulated, which is the important step in realizing SPS on-demand operations. We have also examined the direct contact of such a metal-embedded nanocone structure with a single-mode fiber facet as a simple and practical method for preparing fiber-coupled SPS and demonstrated practical coupling efficiencies of ∼16% with FDTD simulation. (paper)

Ultrafast Spectroscopy of Semiconductor Devices

DEFF Research Database (Denmark)

Borri, Paola; Langbein, Wolfgang; Hvam, Jørn Marcher

1999-01-01

In this work we present an experimental technique for investigating ultrafast carrier dynamics in semiconductor optical amplifiers at room temperature. These dynamics, influenced by carrier heating, spectral hole-burning and two-photon absorption, are very important for device applications in inf...

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...

Deep UV Semiconductor Sources for Advanced Planetary Science Instruments, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — This proposal addresses the need for miniature, narrow-linewidth, deep UV optical sources that operate at very low ambient temperatures for use in advanced in situ...

Photocatalytic semiconductors synthesis, characterization, and environmental applications

CERN Document Server

Hernández-Ramírez, Aracely

2014-01-01

This critical volume examines the different methods used for the synthesis of a great number of photocatalysts, including TiO2, ZnO and other modified semiconductors, as well as characterization techniques used for determining the optical, structural and morphological properties of the semiconducting materials. Additionally, the authors discuss photoelectrochemical methods for determining the light activity of the photocatalytic semiconductors by means of measurement of properties such as band gap energy, flat band potential and kinetics of hole and electron transfer. Photocatalytic Semiconductors: Synthesis, Characterization and Environmental Applications provide an overview of the semiconductor materials from first- to third-generation photocatalysts and their applications in wastewater treatment and water disinfection. The book further presents economic and toxicological aspects in the production and application of photocatalytic materials.

Synthesis, Characterization, and Ultrafast Dynamics of Metal, Metal Oxide, and Semiconductor Nanomaterials

OpenAIRE

Wheeler, Damon Andreas

2013-01-01

SYNTHESIS, CHARACTERIZATION, AND ULTRAFAST DYNAMICS OF METAL, METAL OXIDE, AND SEMICONDUCTOR NANOMATERIALSABSTRACTThe optical properties of each of the three main classes of inorganic nanomaterials, metals, metal oxides, and semiconductors differ greatly due to the intrinsically different nature of the materials. These optical properties are among the most fascinating and useful aspects of nanomaterials with applications spanning cancer treatment, sensors, lasers, and solar cells. One techn...

Many-particle theory of optical properties in low-dimensional nanostructures. Dynamics in single-walled carbon nanotubes and semiconductor quantum dots

Energy Technology Data Exchange (ETDEWEB)

Malic, Ermin

2008-09-02

This work focuses on the theoretical investigation of optical properties of low-dimensional nanostructures, specifically single-walled carbon nanotubes (CNTs) and self-assembled InAs/GaAs quantum dots (QDs). The density-matrix formalism is applied to explain recent experimental results and to give insight into the underlying physics. A microscopic calculation of the absorption coefficient and the Rayleigh scattering cross section is performed by a novel approach combining the density-matrix formalism with the tight-binding wave functions. The calculated spectra of metallic nanotubes show a double-peaked structure resulting from the trigonal warping effect. The intensity ratios of the four lowest-lying transitions in both absorption and Rayleigh spectra can be explained by the different behavior of the optical matrix elements along the high-symmetry lines K-{gamma} and K-M. The Rayleigh line shape is predicted to be asymmetric, with an enhanced cross section for lower photon energies arising from non-resonant contributions of the optical susceptibility. Furthermore, the Coulomb interaction is shown to be maximal when the momentum transfer is low. For intersubband processes with a perpendicular momentum transfer, the coupling strength is reduced to less than 5%. The chirality and diameter dependence of the excitonic binding energy and the transition frequency are presented in Kataura plots. Furthermore, the influence of the surrounding environment on the optical properties of CNTs is investigated. Extending the confinement to all three spatial dimensions, semiconductor Bloch equation are derived to describe the dynamics in QD semiconductor lasers and amplifiers. A detailed microscopic analysis of the nonlinear turn-on dynamics of electrically pumped InAs/GaAs QD lasers is performed, showing the generation of relaxation oscillations on a nanosecond time scale in both the photon and charge carrier density. The theory predicts a strong damping of relaxation oscillations

Many-particle theory of optical properties in low-dimensional nanostructures. Dynamics in single-walled carbon nanotubes and semiconductor quantum dots

International Nuclear Information System (INIS)

Malic, Ermin

2008-01-01

This work focuses on the theoretical investigation of optical properties of low-dimensional nanostructures, specifically single-walled carbon nanotubes (CNTs) and self-assembled InAs/GaAs quantum dots (QDs). The density-matrix formalism is applied to explain recent experimental results and to give insight into the underlying physics. A microscopic calculation of the absorption coefficient and the Rayleigh scattering cross section is performed by a novel approach combining the density-matrix formalism with the tight-binding wave functions. The calculated spectra of metallic nanotubes show a double-peaked structure resulting from the trigonal warping effect. The intensity ratios of the four lowest-lying transitions in both absorption and Rayleigh spectra can be explained by the different behavior of the optical matrix elements along the high-symmetry lines K-Γ and K-M. The Rayleigh line shape is predicted to be asymmetric, with an enhanced cross section for lower photon energies arising from non-resonant contributions of the optical susceptibility. Furthermore, the Coulomb interaction is shown to be maximal when the momentum transfer is low. For intersubband processes with a perpendicular momentum transfer, the coupling strength is reduced to less than 5%. The chirality and diameter dependence of the excitonic binding energy and the transition frequency are presented in Kataura plots. Furthermore, the influence of the surrounding environment on the optical properties of CNTs is investigated. Extending the confinement to all three spatial dimensions, semiconductor Bloch equation are derived to describe the dynamics in QD semiconductor lasers and amplifiers. A detailed microscopic analysis of the nonlinear turn-on dynamics of electrically pumped InAs/GaAs QD lasers is performed, showing the generation of relaxation oscillations on a nanosecond time scale in both the photon and charge carrier density. The theory predicts a strong damping of relaxation oscillations

Electrical conductivity, optical properties and mechanical stability of 3, 4, 9, 10-perylenetetracarboxylic dianhidride based organic semiconductor

Science.gov (United States)

Pandey, Mayank; Joshi, Girish M.; Deshmukh, Kalim; Nath Ghosh, Narendra; Nambi Raj, N. Arunai

2015-05-01

The 3, 4, 9, 10-perylenetetracarboxylic dianhydride (PTCDA) doped polymer films were prepared with Polypyrrole (PPy) and Polyvinyl alcohol (PVA) polymers by solution-casting. The change in structure and chemical composition of samples was identified by XRD and FTIR respectively. The UV-visible spectroscopy demonstrates the optical characteristics and band gap properties of sample. The homogeneous morphology of sample for higher wt% of PTCDA was examined by atomic force microscopy (AFM). The differential scanning calorimetry (DSC) results demonstrate the decrease in melting temperature (Tm) and degree of crystallinity (χc%) of polymeric organic semiconductor. The mechanical property demonstrates the high tensile strength and improved plasticity nature. Impedance spectroscopy was evaluated to determine the conductivity response of polymeric organic semiconductor. The highest DC conductivity (2.08×10-3 S/m) was obtained for 10 wt% of PTCDA at 140 °C. The decrease in activation energy (Ea) represents the non-Debye process and was evaluated from the slope of ln σdc vs. 103/T plot.

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.

Optical technologies for extreme-ultraviolet and soft X-ray coherent sources

International Nuclear Information System (INIS)

Canova, Federico; Poletto, Luca

2015-01-01

The book reviews the most recent achievements in optical technologies for XUV and X-ray coherent sources. Particular attention is given to free-electron-laser facilities, but also to other sources available at present, such as synchrotrons, high-order laser harmonics and X-ray lasers. The optical technologies relevant to each type of source are discussed. In addition, the main technologies used for photon handling and conditioning, namely multilayer mirrors, adaptive optics, crystals and gratings are explained. Experiments using coherent light received during the last decades a lot of attention for the X-ray regime. Strong efforts were taken for the realization of almost fully coherent sources, e.g. the free-electron lasers, both as independent sources in the femtosecond and attosecond regimes and as seeding sources for free-electron-lasers and X-ray gas lasers. In parallel to the development of sources, optical technologies for photon handling and conditioning of such coherent and intense X-ray beams advanced. New problems were faced for the realization of optical components of beamlines demanding to manage coherent X-ray photons, e.g. the preservation of coherence and time structure of ultra short pulses.

Self-reflection in a system of excitons and biexcitons in semiconductors

International Nuclear Information System (INIS)

Khadzhi, P I; Lyakhomskaya, K D

1999-01-01

The characteristic features of the self-reflection of a powerful electromagnetic wave in a system of coherent excitons and biexcitons in semiconductors were investigated as one of the manifestations of the nonlinear optical skin effect. It was found that a monotonically decreasing standing wave with an exponentially falling spatial tail is formed in the surface region of a semiconductor. Under the influence of the field of a powerful pulse, an optically homogeneous medium is converted into one with distributed feedback. The appearance of spatially separated narrow peaks of the refractive index, extinction coefficient, and reflection coefficient is predicted. (nonlinear optical phenomena)

X-ray Optics for BES Light Source Facilities

Energy Technology Data Exchange (ETDEWEB)

Mills, Dennis [Argonne National Lab. (ANL), Argonne, IL (United States); Padmore, Howard [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lessner, Eliane [Dept. of Energy (DOE), Washington DC (United States). Office of Science

2013-03-27

Each new generation of synchrotron radiation sources has delivered an increase in average brightness 2 to 3 orders of magnitude over the previous generation. The next evolution toward diffraction-limited storage rings will deliver another 3 orders of magnitude increase. For ultrafast experiments, free electron lasers (FELs) deliver 10 orders of magnitude higher peak brightness than storage rings. Our ability to utilize these ultrabright sources, however, is limited by our ability to focus, monochromate, and manipulate these beams with X-ray optics. X-ray optics technology unfortunately lags behind source technology and limits our ability to maximally utilize even today’s X-ray sources. With ever more powerful X-ray sources on the horizon, a new generation of X-ray optics must be developed that will allow us to fully utilize these beams of unprecedented brightness. The increasing brightness of X-ray sources will enable a new generation of measurements that could have revolutionary impact across a broad area of science, if optical systems necessary for transporting and analyzing X-rays can be perfected. The high coherent flux will facilitate new science utilizing techniques in imaging, dynamics, and ultrahigh-resolution spectroscopy. For example, zone-plate-based hard X-ray microscopes are presently used to look deeply into materials, but today’s resolution and contrast are restricted by limitations of the current lithography used to manufacture nanodiffractive optics. The large penetration length, combined in principle with very high spatial resolution, is an ideal probe of hierarchically ordered mesoscale materials, if zone-plate focusing systems can be improved. Resonant inelastic X-ray scattering (RIXS) probes a wide range of excitations in materials, from charge-transfer processes to the very soft excitations that cause the collective phenomena in correlated electronic systems. However, although RIXS can probe high-energy excitations, the most exciting and

X-ray Optics for BES Light Source Facilities

International Nuclear Information System (INIS)

Mills, Dennis; Padmore, Howard; Lessner, Eliane

2013-01-01

Each new generation of synchrotron radiation sources has delivered an increase in average brightness 2 to 3 orders of magnitude over the previous generation. The next evolution toward diffraction-limited storage rings will deliver another 3 orders of magnitude increase. For ultrafast experiments, free electron lasers (FELs) deliver 10 orders of magnitude higher peak brightness than storage rings. Our ability to utilize these ultrabright sources, however, is limited by our ability to focus, monochromate, and manipulate these beams with X-ray optics. X-ray optics technology unfortunately lags behind source technology and limits our ability to maximally utilize even today's X-ray sources. With ever more powerful X-ray sources on the horizon, a new generation of X-ray optics must be developed that will allow us to fully utilize these beams of unprecedented brightness. The increasing brightness of X-ray sources will enable a new generation of measurements that could have revolutionary impact across a broad area of science, if optical systems necessary for transporting and analyzing X-rays can be perfected. The high coherent flux will facilitate new science utilizing techniques in imaging, dynamics, and ultrahigh-resolution spectroscopy. For example, zone-plate-based hard X-ray microscopes are presently used to look deeply into materials, but today's resolution and contrast are restricted by limitations of the current lithography used to manufacture nanodiffractive optics. The large penetration length, combined in principle with very high spatial resolution, is an ideal probe of hierarchically ordered mesoscale materials, if zone-plate focusing systems can be improved. Resonant inelastic X-ray scattering (RIXS) probes a wide range of excitations in materials, from charge-transfer processes to the very soft excitations that cause the collective phenomena in correlated electronic systems. However, although RIXS can probe high-energy excitations, the most exciting

Solid-state NMR of inorganic semiconductors.

Science.gov (United States)

Yesinowski, James P

2012-01-01

Studies of inorganic semiconductors by solid-state NMR vary widely in terms of the nature of the samples investigated, the techniques employed to observe the NMR signal, and the types of information obtained. Compared with the NMR of diamagnetic non-semiconducting substances, important differences often result from the presence of electron or hole carriers that are the hallmark of semiconductors, and whose theoretical interpretation can be involved. This review aims to provide a broad perspective on the topic for the non-expert by providing: (1) a basic introduction to semiconductor physical concepts relevant to NMR, including common crystal structures and the various methods of making samples; (2) discussions of the NMR spin Hamiltonian, details of some of the NMR techniques and strategies used to make measurements and theoretically predict NMR parameters, and examples of how each of the terms in the Hamiltonian has provided useful information in bulk semiconductors; (3) a discussion of the additional considerations needed to interpret the NMR of nanoscale semiconductors, with selected examples. The area of semiconductor NMR is being revitalized by this interest in nanoscale semiconductors, the great improvements in NMR detection sensitivity and resolution that have occurred, and the current interest in optical pumping and spintronics-related studies. Promising directions for future research will be noted throughout.

Multicanonical evaluation of the tails of the probability density function of semiconductor optical amplifier output power fluctuations

DEFF Research Database (Denmark)

Tromborg, Bjarne; Reimer, Michael; Yevick, David

2010-01-01

This paper presents a multicanonical Monte Carlo method for simulating the tails of a pdf distribution of the filtered output power from a semiconductor optical amplifier down to values of the order of 10−40. The influence of memory effects on the pdf is examined in order to demonstrate the manner...... in which the calculated pdf approaches the true pdf with increasing integration time. The simulated pdf is shown to be in good agreement with a second order analytic expression for the pdf....

Semiconductor nanostructures for infrared applications

NARCIS (Netherlands)

Zurauskiene, N.; Asmontas, S.; Dargys, A.; Kundrotas, J.; Janssen, G.; Goovaerts, E.; Marcinkevicius, S.; Koenraad, P.M.; Wolter, J.H.; Leon, R.

2004-01-01

We present the results of time-resolved photoluminescence (TRPL) and optically detected microwave resonance (ODMR) spectroscopy investigations of semiconductor quantum dots and quantum wells. The ODMR spectra of InAs/GaAs QDs were detected via modulation of the total intensity of the QDs emission

Switchable semiconductor optical fiber laser incorporating AWG and broadband FBG with high SMSR

International Nuclear Information System (INIS)

Ahmad, H; Zulkifli, M Z; Thambiratnam, K; Latiff, A A; Harun, S W

2009-01-01

In this paper we propose and demonstrate a switchable wavelength fiber laser (SWFL) using a semiconductor optical amplifier (SOA) together with an arrayed waveguide grating (AWG). The proposed SOA-based SWFL is capable of generating up to 14 lasing channels from 1530.1 nm to 1534.9 nm at a channel spacing of 0.8 nm (100 GHz) and a bandwidth of 11.8 and 10.2 nm respectively. The EDFA-based SWFL has a higher peak power at –5 dBm, while to SOA-based SWFL has a peak power of only –10 dBm. However, the SOA-based SWFL exhibits a much better SMSR of between 10 to 20 dB as compared to the SMSR of the EDFA-based SWFL due to the inhomogeneous broadening properties of the SOA

Gain dynamics and saturation in semiconductor quantum dot amplifiers

DEFF Research Database (Denmark)

Berg, Tommy Winther; Mørk, Jesper; Hvam, Jørn Märcher

2004-01-01

Quantum dot (QD)-based semiconductor optical amplifiers offer unique properties compared with conventional devices based on bulk or quantum well material. Due to the bandfilling properties of QDs and the existence of a nearby reservoir of carriers in the form of a wetting layer, QD semiconductor...... optical amplifiers may be operated in regimes of high linearity, i.e. with a high saturation power, but can also show strong and fast nonlinearities by breaking the equilibrium between discrete dot states and the continuum of wetting layer states. In this paper, we analyse the interplay of these two...

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....

Ultrafast all-optical signal processing using semiconductor optical amplifiers

NARCIS (Netherlands)

Li, Z.

2007-01-01

As the bit rate of one wavelength channel and the number of channels keep increasing in the telecommunication networks thanks to the advancement of optical transmission technologies, switching is experiencing the transition from the electrical domain to the optical domain. All-optical signal

Organic semiconductors in sensor applications

CERN Document Server

Malliaras, George; Owens, Róisín

2008-01-01

Organic semiconductors offer unique characteristics such as tunability of electronic properties via chemical synthesis, compatibility with mechanically flexible substrates, low-cost manufacturing, and facile integration with chemical and biological functionalities. These characteristics have prompted the application of organic semiconductors and their devices in physical, chemical, and biological sensors. This book covers this rapidly emerging field by discussing both optical and electrical sensor concepts. Novel transducers based on organic light-emitting diodes and organic thin-film transistors, as well as systems-on-a-chip architectures are presented. Functionalization techniques to enhance specificity are outlined, and models for the sensor response are described.

High-resolution photoluminescence studies of single semiconductor quantum dots

DEFF Research Database (Denmark)

Leosson, Kristjan; Østergaard, John Erland; Jensen, Jacob Riis

2000-01-01

Semiconductor quantum dots, especially those formed by self-organized growth, are considered a promising material system for future optical devices [1] and the optical properties of quantum dot ensembles have been investigated in detail over the past years. Recently, considerable interest has...

Plasmonic doped semiconductor nanocrystals: Properties, fabrication, applications and perspectives

Science.gov (United States)

Kriegel, Ilka; Scotognella, Francesco; Manna, Liberato

2017-02-01

Degenerately doped semiconductor nanocrystals (NCs) are of recent interest to the NC community due to their tunable localized surface plasmon resonances (LSPRs) in the near infrared (NIR). The high level of doping in such materials with carrier densities in the range of 1021cm-3 leads to degeneracy of the doping levels and intense plasmonic absorption in the NIR. The lower carrier density in degenerately doped semiconductor NCs compared to noble metals enables LSPR tuning over a wide spectral range, since even a minor change of the carrier density strongly affects the spectral position of the LSPR. Two classes of degenerate semiconductors are most relevant in this respect: impurity doped semiconductors, such as metal oxides, and vacancy doped semiconductors, such as copper chalcogenides. In the latter it is the density of copper vacancies that controls the carrier concentration, while in the former the introduction of impurity atoms adds carriers to the system. LSPR tuning in vacancy doped semiconductor NCs such as copper chalcogenides occurs by chemically controlling the copper vacancy density. This goes in hand with complex structural modifications of the copper chalcogenide crystal lattice. In contrast the LSPR of degenerately doped metal oxide NCs is modified by varying the doping concentration or by the choice of host and dopant atoms, but also through the addition of capacitive charge carriers to the conduction band of the metal oxide upon post-synthetic treatments, such as by electrochemical- or photodoping. The NIR LSPRs and the option of their spectral fine-tuning make accessible important new features, such as the controlled coupling of the LSPR to other physical signatures or the enhancement of optical signals in the NIR, sensing application by LSPR tracking, energy production from the NIR plasmon resonance or bio-medical applications in the biological window. In this review we highlight the recent advances in the synthesis of various different plasmonic

Metal-optic and Plasmonic Semiconductor-based Nanolasers

Science.gov (United States)

2012-05-07

after, 65 the sample was placed into a load-lock to deposit 5 nm of titanium dioxide. The tita - nium dioxide serves as a dielectric (although it is a...into a load-lock to deposit 5 nm of titanium dioxide. The tita - nium dioxide serves as a dielectric (although it is a large-bandgap semiconductor) to

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.

Introduction to the Physics of Diluted Magnetic Semiconductors

CERN Document Server

Gaj, Jan A

2010-01-01

The book deals with diluted magnetic semiconductors, a class of materials important to the emerging field of spintronics. In these materials semiconducting properties, both transport and optical, are influenced by the presence of magnetic ions. It concentrates on basic physical mechanisms (e.g. carrier-ion and ion-ion interactions) and resulting phenomena (e.g. magnetic polaron formation and spin relaxation). Introduction to the Physics of Diluted Magnetic Semiconductors is addressed to graduate-level and doctoral students and young researchers entering the field. The authors have been actively involved in the creation of this branch of semiconductor physics.

Semiconductor nanostructures on silicon. Carrier dynamics, optical amplification and lasing; Halbleiternanostrukturen auf Silizium. Ladungstraegerdynamik, optischer Verstaerker und Laser

Energy Technology Data Exchange (ETDEWEB)

Lange, Christoph

2008-12-11

Two material systems that can be grown epitaxially on a silicon substrate are experimentally investigated with respect to their optical properties. Quantum wells (qw) of Germanium were experimentally investigated by spectrally resolved white-light pump-probe-absorption spectroscopy at room temperature. A second material class is Ga(NAsP), which was grown as quantum wells on a silicon substrate matching the lattice constant of the substrate. The basic optical properties were determined using the variable stripe-length method. In order to relate the results to those of established materials, a selection of comparable III/V semiconductors were measured in the same setups. The pump-probe measurements on (GaIn)As quantum wells exhibited a much more rapid scattering. In these material systems, quite similar optical gain values of 10{sup -3}/QW were found with decay times of several 100 ps. For (GaIn)(NAs), slightly higher values were determined. Using the variable stripe-length method, GaSb quantum wells with dot-like morphology were investigated. (orig.)

Optical observations of binary X-ray sources

International Nuclear Information System (INIS)

Charles, P.

1982-01-01

Here I shall consider only those systems where the compact object is a neutron star (or in a few cases perhaps a black hole). Since van Paradijs (1982) has recently produced an excellent and comprehensive review of optical observations of compact galactic X-ray sources I shall summarise the basic properties of the optical counterparts and discuss a few representative systems in some detail. (orig./WL)

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.

III–V quantum light source and cavity-QED on Silicon

Science.gov (United States)

Luxmoore, I. J.; Toro, R.; Pozo-Zamudio, O. Del; Wasley, N. A.; Chekhovich, E. A.; Sanchez, A. M.; Beanland, R.; Fox, A. M.; Skolnick, M. S.; Liu, H. Y.; Tartakovskii, A. I.

2013-01-01

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon's indirect band-gap. III–V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III–V material grown directly on silicon substrates. The high quality of the III–V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens-up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems. PMID:23393621

III-V quantum light source and cavity-QED on silicon.

Science.gov (United States)

Luxmoore, I J; Toro, R; Del Pozo-Zamudio, O; Wasley, N A; Chekhovich, E A; Sanchez, A M; Beanland, R; Fox, A M; Skolnick, M S; Liu, H Y; Tartakovskii, A I

2013-01-01

Non-classical light sources offer a myriad of possibilities in both fundamental science and commercial applications. Single photons are the most robust carriers of quantum information and can be exploited for linear optics quantum information processing. Scale-up requires miniaturisation of the waveguide circuit and multiple single photon sources. Silicon photonics, driven by the incentive of optical interconnects is a highly promising platform for the passive optical components, but integrated light sources are limited by silicon's indirect band-gap. III-V semiconductor quantum-dots, on the other hand, are proven quantum emitters. Here we demonstrate single-photon emission from quantum-dots coupled to photonic crystal nanocavities fabricated from III-V material grown directly on silicon substrates. The high quality of the III-V material and photonic structures is emphasized by observation of the strong-coupling regime. This work opens-up the advantages of silicon photonics to the integration and scale-up of solid-state quantum optical systems.

Fourier domain mode-locked swept source at 1050 nm based on a tapered amplifier

DEFF Research Database (Denmark)

Marschall, Sebastian; Klein, Thomas; Wieser, Wolfgang

2010-01-01

While swept source optical coherence tomography (OCT) in the 1050 nm range is promising for retinal imaging, there are certain challenges. Conventional semiconductor gain media have limited output power, and the performance of high-speed Fourier domain mode-locked (FDML) lasers suffers from...

Carrier scattering in metals and semiconductors

CERN Document Server

Gantmakher, VF

1987-01-01

The transport properties of solids, as well as the many optical phenomena in them are determined by the scattering of current carriers. ``Carrier Scattering in Metals and Semiconductors'' elucidates the state of the art in the research on the scattering mechanisms for current carriers in metals and semiconductors and describes experiments in which these mechanisms are most dramatically manifested.The selection and organization of the material is in a form to prepare the reader to reason independently and to deal just as independently with available theoretical results and experimental

Optical characterisation of III-V nitride-based multiphase and diluted magnetic semiconductors

International Nuclear Information System (INIS)

Wegscheider, M.

2009-01-01

The present work is devoted to the investigation of the optical properties of transition metal doped Gallium nitride. The Gallium nitride layers are epitaxially grown in a full metalorganic chemical vapour deposition process whereas the transition metals iron or manganese as well as the n and p-type dopants silicon and magnesium are incorporated simultaneously. Background and driving force of the realization of such material systems is basically the evocation of ferromagnetic spin alignment where free carriers ensure the correspondence between the localized spin state provided by the metal ions. The production of completely new devices for semiconductor industries based on the possibility to switch on or off the ferrimagnetic alignment by changing the free carrier concentration can be expected in the near future. In this context photoluminescence studies in the ultraviolet and mid infrared spectral range at temperatures between the liquid helium point and room temperature at atmospheric pressure were made. These measurements basically provide information on optical transitions between the conduction and valence band and deep defects as well as on crystal field forced transitions within the d-orbitals of the metal ion involved. In this context valuable knowledge could have been gained on doping concentrations, growth fashions and parameters, formation of secondary phases as well as on the doping efficiency and incorporation sites of the metal atoms. (author) [de

Network connectivity enhancement by exploiting all optical multicast in semiconductor ring laser

Science.gov (United States)

Siraj, M.; Memon, M. I.; Shoaib, M.; Alshebeili, S.

2015-03-01

The use of smart phone and tablet applications will provide the troops for executing, controlling and analyzing sophisticated operations with the commanders providing crucial documents directly to troops wherever and whenever needed. Wireless mesh networks (WMNs) is a cutting edge networking technology which is capable of supporting Joint Tactical radio System (JTRS).WMNs are capable of providing the much needed bandwidth for applications like hand held radios and communication for airborne and ground vehicles. Routing management tasks can be efficiently handled through WMNs through a central command control center. As the spectrum space is congested, cognitive radios are a much welcome technology that will provide much needed bandwidth. They can self-configure themselves, can adapt themselves to the user requirement, provide dynamic spectrum access for minimizing interference and also deliver optimal power output. Sometimes in the indoor environment, there are poor signal issues and reduced coverage. In this paper, a solution utilizing (CR WMNs) over optical network is presented by creating nanocells (PCs) inside the indoor environment. The phenomenon of four-wave mixing (FWM) is exploited to generate all-optical multicast using semiconductor ring laser (SRL). As a result same signal is transmitted at different wavelengths. Every PC is assigned a unique wavelength. By using CR technology in conjunction with PC will not only solve network coverage issue but will provide a good bandwidth to the secondary users.

Semiconductor radiation detectors: device physics

National Research Council Canada - National Science Library

Lutz, Gerhard

1999-01-01

..., including nuclear physics, elementary particle physics, optical and x-ray astronomy, medicine, and materials testing - and the number of applications is growing continually. Closely related, and initiated by the application of semiconductors, is the development of low-noise low-power integrated electronics for signal readout. The success of semicond...

Synchronously pumped optical parametric oscillation in periodically poled lithium niobate with 1-W average output power

NARCIS (Netherlands)

Graf, T.; McConnell, G.; Ferguson, A.I.; Bente, E.A.J.M.; Burns, D.; Dawson, M.D.

1999-01-01

We report on a rugged all-solid-state laser source of near-IR radiation in the range of 1461–1601 nm based on a high-power Nd:YVO4 laser that is mode locked by a semiconductor saturable Bragg reflector as the pump source of a synchronously pumped optical parametric oscillator with a periodically

Fast physical random bit generation with chaotic semiconductor lasers

Science.gov (United States)

Uchida, Atsushi; Amano, Kazuya; Inoue, Masaki; Hirano, Kunihito; Naito, Sunao; Someya, Hiroyuki; Oowada, Isao; Kurashige, Takayuki; Shiki, Masaru; Yoshimori, Shigeru; Yoshimura, Kazuyuki; Davis, Peter

2008-12-01

Random number generators in digital information systems make use of physical entropy sources such as electronic and photonic noise to add unpredictability to deterministically generated pseudo-random sequences. However, there is a large gap between the generation rates achieved with existing physical sources and the high data rates of many computation and communication systems; this is a fundamental weakness of these systems. Here we show that good quality random bit sequences can be generated at very fast bit rates using physical chaos in semiconductor lasers. Streams of bits that pass standard statistical tests for randomness have been generated at rates of up to 1.7 Gbps by sampling the fluctuating optical output of two chaotic lasers. This rate is an order of magnitude faster than that of previously reported devices for physical random bit generators with verified randomness. This means that the performance of random number generators can be greatly improved by using chaotic laser devices as physical entropy sources.

Linking optical and infrared observations with gravitational wave sources through transient variability

International Nuclear Information System (INIS)

Stubbs, C W

2008-01-01

Optical and infrared observations have thus far detected more celestial cataclysms than have been seen in gravity waves (GW). This argues that we should search for gravity wave signatures that correspond to transient variables seen at optical wavelengths, at precisely known positions. There is an unknown time delay between the optical and gravitational transient, but knowing the source location precisely specifies the corresponding time delays across the gravitational antenna network as a function of the GW-to-optical arrival time difference. Optical searches should detect virtually all supernovae that are plausible gravitational radiation sources. The transient optical signature expected from merging compact objects is not as well understood, but there are good reasons to expect detectable transient optical/IR emission from most of these sources as well. The next generation of deep wide-field surveys (for example PanSTARRS and LSST) will be sensitive to subtle optical variability, but we need to fill the 'blind spots' that exist in the galactic plane, and for optically bright transient sources. In particular, a galactic plane variability survey at λ∼ 2 μm seems worthwhile. Science would benefit from closer coordination between the various optical survey projects and the gravity wave community

Study of the spectral width of intermode beats and optical spectrum of an actively mode-locked three-mirror semiconductor laser

International Nuclear Information System (INIS)

Zakharyash, Valerii F; Kashirsky, Aleksandr V; Klementyev, Vasilii M; Kuznetsov, Sergei A; Pivtsov, V S

2005-01-01

Various oscillation regimes of an actively mode-locked semiconductor laser are studied experimentally. Two types of regimes are found in which the minimal spectral width (∼3.5 kHz) of intermode beats is achieved. The width of the optical spectrum of modes is studied as a function of their locking and the feedback coefficients. The maximum width of the spectrum is ∼3.7 THz. (control of laser radiation parameters)

Optical, Electrical and Photocatalytic Properties of the Ternary Semiconductors ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS

Directory of Open Access Journals (Sweden)

Sandra Andrea Mayén-Hernández

2014-01-01

Full Text Available The effects of vacuum annealing at different temperatures on the optical, electrical and photocatalytic properties of polycrystalline and amorphous thin films of the ternary semiconductor alloys ZnxCd1-xS, CuxCd1-xS and CuxZn1-xS were investigated in stacks of binary semiconductors obtained by chemical bath deposition. The electrical properties were measured at room temperature using a four-contact probe in the Van der Pauw configuration. The energy band gap of the films varied from 2.30 to 2.85 eV. The photocatalytic activity of the semiconductor thin films was evaluated by the degradation of an aqueous methylene blue solution. The thin film of ZnxCd1-xS annealed under vacuum at 300°C exhibited the highest photocatalytic activity.

Ultrafast photoinduced charge separation in metal-semiconductor nanohybrids.

Science.gov (United States)

Mongin, Denis; Shaviv, Ehud; Maioli, Paolo; Crut, Aurélien; Banin, Uri; Del Fatti, Natalia; Vallée, Fabrice

2012-08-28

Hybrid nano-objects formed by two or more disparate materials are among the most promising and versatile nanosystems. A key parameter in their properties is interaction between their components. In this context we have investigated ultrafast charge separation in semiconductor-metal nanohybrids using a model system of gold-tipped CdS nanorods in a matchstick architecture. Experiments are performed using an optical time-resolved pump-probe technique, exciting either the semiconductor or the metal component of the particles, and probing the light-induced change of their optical response. Electron-hole pairs photoexcited in the semiconductor part of the nanohybrids are shown to undergo rapid charge separation with the electron transferred to the metal part on a sub-20 fs time scale. This ultrafast gold charging leads to a transient red-shift and broadening of the metal surface plasmon resonance, in agreement with results for free clusters but in contrast to observation for static charging of gold nanoparticles in liquid environments. Quantitative comparison with a theoretical model is in excellent agreement with the experimental results, confirming photoexcitation of one electron-hole pair per nanohybrid followed by ultrafast charge separation. The results also point to the utilization of such metal-semiconductor nanohybrids in light-harvesting applications and in photocatalysis.

32nd International Conference on the Physics of Semiconductors

Energy Technology Data Exchange (ETDEWEB)

Chelikowsky, James [Univ. of Texas, Austin, TX (United States)

2016-10-17

The International Conference on the Physics of Semiconductors (ICPS) continues a series of biennial conferences that began in the 1950's. ICPS is the premier meeting for reporting all aspects of semiconductor physics including electronic, structural, optical, magnetic and transport properties with an emphasis on new materials and their applications. The meeting will reflect the state of art in the semiconductor physics field and will serve as a forum where scholars, researchers, and specialists can interact to discuss future research directions and technological advancements. The conference typically draws 1,000 international physicists, scientists, and students. This is one of the largest science meetings on semiconductors and related materials to be held in the United States.

Optical-feedback semiconductor laser Michelson interferometer for displacement measurements with directional discrimination

International Nuclear Information System (INIS)

Rodrigo, Peter John; Lim, May; Saloma, Caesar

2001-01-01

An optical-feedback semiconductor laser Michelson interferometer (OSMI) is presented for measuring microscopic linear displacements without ambiguity in the direction of motion. The two waves from the interferometer arms, one from the reference mirror and the other from the reflecting moving target, are fed back into the lasing medium (λ=830 nm), causing variations in the laser output power. We model the OSMI into an equivalent Fabry-Perot resonator and derive the dependence of the output power (and the junction voltage) on the path difference between the two interferometer arms. Numerical and experimental results consistently show that the laser output power varies periodically (period, λ/2) with path difference. The output power variation exhibits an asymmetric behavior with the direction of motion, which is used to measure, at subwavelength resolution, the displacement vector (both amplitude and direction) of the moving sample. Two samples are considered in the experiments: (i) a piezoelectric transducer and (ii) an audio speaker

Compensation of nonlinearity in a fiber-optic transmission system using frequency-degenerate phase conjugation through counter-propagating dual pump FWM in a semiconductor optical amplifier

Science.gov (United States)

Anchal, Abhishek; K, Pradeep Kumar; O'Duill, Sean; Anandarajah, Prince M.; Landais, Pascal

2018-04-01

We present a scheme of frequency-degenerate mid-span spectral inversion (MSSI) for nonlinearity compensation in fiber-optic transmission systems. The spectral inversion is obtained by using counter-propagating dual pump four-wave mixing in a semiconductor optical amplifier (SOA). Frequency-degeneracy between signal and conjugate is achieved by keeping two pump frequencies symmetrical about the signal frequency. We simulate the performance of MSSI for nonlinearity compensation by scrutinizing the improvement of the Q-factor of a 200 Gbps QPSK signal transmitted over a standard single mode fiber, as a function of launch power for different span lengths and number of spans. We demonstrate a 7.5 dB improvement in the input power dynamic range and an almost 83% increase in the transmission length for optimum MSSI parameters of -2 dBm pump power and 400 mA SOA current.

Systematization of efficiency correction for gamma-ray disk sources with semiconductor detectors

International Nuclear Information System (INIS)

Chatani, Hiroshi

1999-01-01

Full energy peak efficiency correction for disk sources has been systematically studied using the mapping method with two high-purity germanium detectors and two low-energy photon spectrometers. The following are found using only single-line (i.e., no coincidence summing loses) γ-rays: (1) The efficiency distributions on a plane parallel to the entrance window of semiconductor detectors is in perfect accord with Gaussian curves inside the circumference of the cylindrical Ge crystal, however, they deviate from the curves outside the circumference. (2) The width parameters of the Gaussian function fitted to the efficiency distributions have a systematic relationship with γ-ray energy. (3) The mapping method is of practical use and has satisfactory accuracy

Semiconductor laser using multimode interference principle

Science.gov (United States)

Gong, Zisu; Yin, Rui; Ji, Wei; Wu, Chonghao

2018-01-01

Multimode interference (MMI) structure is introduced in semiconductor laser used in optical communication system to realize higher power and better temperature tolerance. Using beam propagation method (BPM), Multimode interference laser diode (MMI-LD) is designed and fabricated in InGaAsP/InP based material. As a comparison, conventional semiconductor laser using straight single-mode waveguide is also fabricated in the same wafer. With a low injection current (about 230 mA), the output power of the implemented MMI-LD is up to 2.296 mW which is about four times higher than the output power of the conventional semiconductor laser. The implemented MMI-LD exhibits stable output operating at the wavelength of 1.52 μm and better temperature tolerance when the temperature varies from 283.15 K to 293.15 K.

Dual-Source Swept-Source Optical Coherence Tomography Reconstructed on Integrated Spectrum

Directory of Open Access Journals (Sweden)

Shoude Chang

2012-01-01

Full Text Available Dual-source swept-source optical coherence tomography (DS-SSOCT has two individual sources with different central wavelengths, linewidth, and bandwidths. Because of the difference between the two sources, the individually reconstructed tomograms from each source have different aspect ratio, which makes the comparison and integration difficult. We report a method to merge two sets of DS-SSOCT raw data in a common spectrum, on which both data have the same spectrum density and a correct separation. The reconstructed tomographic image can seamlessly integrate the two bands of OCT data together. The final image has higher axial resolution and richer spectroscopic information than any of the individually reconstructed tomography image.

Electronic, elastic and optical properties of ZnGeP{sub 2} semiconductor under hydrostatic pressures

Energy Technology Data Exchange (ETDEWEB)

Tripathy, S.K.; Kumar, V., E-mail: vkumar52@hotmail.com

2014-03-15

The electronic, elastic and optical properties of zinc germanium phosphide, ZnGeP{sub 2}, semiconductor have been studied using local density approximation (LDA) method within the density functional theory (DFT). The lattice constants (a and c), band structure, density of states (DOS), bulk modulus (B) and pressure derivative of bulk modulus (B′) have been discussed. The value of pseudo-direct band gap (E{sub g}) at Γ point has been calculated. The pressure dependences of elastic stiffness coefficients (C{sub ij}), Zener anisotropy factor (A), Poisson's ratio (ν), Young modulus (Y) and shear modulus (G) have also been calculated. The ratio of B/G shows that that ZnGeP{sub 2} is ductile in nature. The optical properties have been discussed in detail under three different pressures in the energy range 0–22 eV. The calculated values of all parameters are compared with the available experimental values and the values reported by different workers. Reasonably good agreement has been obtained between them.

Wannier-Frenkel hybrid exciton in organic-semiconductor quantum dot heterostructures

International Nuclear Information System (INIS)

Birman, Joseph L.; Huong, Nguyen Que

2007-01-01

The formation of a hybridization state of Wannier Mott exciton and Frenkel exciton in different hetero-structure configurations involving quantum dots is investigated. The hybrid excitons exist at the interfaces of the semiconductors quantum dots and the organic medium, having unique properties and a large optical non-linearity. The coupling at resonance is very strong and tunable by changing the parameters of the systems (dot radius, dot-dot distance, generation of the organic dendrites and the materials of the system etc...). Different semiconductor quantum dot-organic material combination systems have been considered such as a semiconductor quantum dot lattice embedded in an organic host, a semiconductor quantum dot at the center of an organic dendrite, a semiconductor quantum dot coated by an organic shell

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

Near-IR Spectral Imaging of Semiconductor Absorption Sites in Integrated Circuits

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E. C. Samson

2004-12-01

Full Text Available We derive spectral maps of absorption sites in integrated circuits (ICs by varying the wavelength of the optical probe within the near-IR range. This method has allowed us to improve the contrast of the acquired images by revealing structures that have a different optical absorption from neighboring sites. A false color composite image from those acquired at different wavelengths is generated from which the response of each semiconductor structure can be deduced. With the aid of the spectral maps, nonuniform absorption was also observed in a semiconductor structure located near an electrical overstress defect. This method may prove important in failure analysis of ICs by uncovering areas exhibiting anomalous absorption, which could improve localization of defective edifices in the semiconductor parts of the microchip