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Showing papers on "Semiconductor optical gain published in 1993"


Journal ArticleDOI
TL;DR: In this article, a review of the gain and saturation behavior of semiconductor lasers is presented, with special attention given to rate equation models and to the possibility of so-called gain nonlinearities that might affect the CW and modulation performance.
Abstract: Several approaches have been developed for modelling the gain and saturation behaviour of semiconductor lasers, and this study includes a historical review of these various approaches. Special attention is given to rate equation models and to the possibility of so-called gain nonlinearities that might affect the CW and modulation performance of semiconductor lasers. Discussions are mainly limited to the GaAs/GaAIAs and InGaAsP/InP systems, for which the gain and gain nonlinearities have been most extensively studied.

91 citations


Journal ArticleDOI
TL;DR: In this paper, the properties of a semiconductor laser amplifier as an optical switching gate are investigated experimentally and theoretically with respect to the injection current, optical input power, and cavity resonances.
Abstract: The properties of a semiconductor laser amplifier as optical switching gate are investigated. Particular attention is paid to gain, contrast ratio, and switching time of the device. These properties are studied experimentally and theoretically with respect to the injection current, optical input power, and cavity resonances. The experimental arrangements and the theoretical method are described. As an example of the various applications of semiconductor laser amplifier gates, packet switching experiments with self-routing, employing cascaded switching gates, are reported. In a theoretical analysis the restrictions that the properties of semiconductor laser amplifier gates impose on a larger switching system consisting of many such gates are investigated. >

68 citations


Journal ArticleDOI
TL;DR: A simple plane-wave multimode semiconductor-laser theory valid near threshold under the quasiequilibrium assumption that the total field envelope varies little in the intraband scattering times is given.
Abstract: This paper gives a simple plane-wave multimode semiconductor-laser theory valid near threshold under the quasiequilibrium assumption that the total field envelope varies little in the intraband scattering times. Subject to these limitations, the theory is able to describe the full many-body effects in the semiconductor medium for a variety of field configurations including unidirectional, bidirectional, and two-mirror standing-wave lasers with nonuniform gain distributions. The theory predicts that spatial-hole burning can lead to multimode operation and that bidirectional ring-laser operation cannot occur. Generalization to larger field intensities is discussed within the framework of the quasiequilibrium assumption.

50 citations


Journal ArticleDOI
TL;DR: In this article, an amplitude-modulated semiconductor laser is used to excite a 9.2 GHz Raman transition in a cesium atomic beam with a high signal-to-noise ratio.
Abstract: An amplitude-modulated semiconductor laser is used to excite a 9.2-GHz Raman transition in a cesium atomic beam. Separated-field Ramsey fringes as narrow as 1 kHz wide are observed with a high signal-to-noise ratio, even for semiconductor laser linewidths as wide as 20 MHz. These narrow resonances have potential application in the development of high-accuracy, optically excited atomic clocks.

46 citations


Journal ArticleDOI
TL;DR: In this article, the usefulness and limitations of the concept of the linewidth enhancement factor alpha in semiconductor lasers are examined by considering the laser dynamics without the rate-equation approximation.
Abstract: The usefulness and the limitations of the concept of the linewidth enhancement factor alpha in semiconductor lasers are examined by considering the laser dynamics without the rate-equation approximation. The rate equations with a constant value of alpha can be used for semiconductor lasers operating continuously or modulated directly such that the carrier density does not change significantly during each modulation cycle. A new set of generalized Bloch equations should be used whenever subpicosecond optical pulses are involved. >

45 citations


Journal ArticleDOI
TL;DR: In this article, the operation of distributed-feedback (DFB) with gain coupling was studied and it was shown in detail how this special feature leads to important modifications in the expressions for the modal loss or threshold gain.
Abstract: The two types of distributed-feedback (DFB) lasers with gain coupling, i.e., true gain coupled lasers (with either a gain or loss grating) and second-order index coupled lasers, are shown to be equivalent mathematically and to some extent also physically. The operation of these DFB lasers, partly based on the overlap of the standing wave pattern in the optical power density with the periodic gain/loss variation, is addressed. It is shown in detail how this special feature leads to important modifications in the expressions for the modal loss or threshold gain, the threshold gain difference, the efficiency and the linewidth. >

40 citations


Patent
12 Jan 1993
TL;DR: In this article, a semiconductor laser has an active layer including at least two light-emitting layers having different energy levels, and the signal width of the high-frequency signal is modulated by the modulation circuit in accordance with an information signal.
Abstract: A semiconductor laser device includes a semiconductor laser, a signal generating circuit, a modulation circuit and a drive circuit. The semiconductor laser has an active layer including at least two light-emitting layers having different energy levels. A high-frequency signal having a predetermined frequency is generated by the signal generating circuit. The signal width of the high-frequency signal is modulated by the modulation circuit in accordance with an information signal. The semiconductor laser is driven by the drive circuit in accordance with the signal modulated by the modulation circuit.

39 citations


Journal ArticleDOI
TL;DR: In this article, a 1.55-μm band wavelength division multiplexing (WDM) integrated light source for optical communication is developed and the results of the evaluation are described.
Abstract: Considerable research and development have been done on semiconductor photonic integrated circuits in which various components such as a laser diode and other photonic devices were integrated. In this paper, a 1.55-μm band wavelength division multiplexing (WDM) integrated light source for optical communication is developed and the results of the evaluation are described. Four-channel laser sources were fabricated by integrating tunable semiconductor lasers and semiconductor optical modulators plus multiplexers, and the possibility of using a 2.5-Gbit/s high-density WDM optical transmission system is discussed. After analyzing the problems encountered in the fabrication of these photonic integrated components, the development of a bandgap energy-controlling technique of quantum well structure using the selective metal oxide vapor-phase epitaxial (MOVPE) growth, which is a better fabrication technique, is described. By using this technique, the difficult process of combining the waveguide with a different bandgap energy can be accomplished only by a one-step crystal growing. This simplifies the components fabrication, and a high-coupling efficiency of the waveguide between the integrated elements can be obtained. As an application example, the integrated light source was fabricated by integrating a tunable laser, distributed feedback (DFB) laser, and semiconductor optical modulator. Then the tunable characteristic and the extinction characteristic were verified. This simplifies the fabrication method of the previously difficult method of semiconductor photonic integrated circuits and clarifies the possibility of developing a high-density integrated element.

38 citations


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

28 citations


Patent
21 Oct 1993
TL;DR: In this article, a method for optically reading recorded information by radiating laser light emitted from a semiconductor laser which oscillates in a single longitudinal mode to an information recording medium and by detecting laser light reflected from a recording face of the information record medium is disclosed.
Abstract: A method for optically reading recorded information by radiating laser light emitted from a semiconductor laser which oscillates in a single longitudinal mode to an information recording medium and by detecting laser light reflected from a recording face of the information recording medium is disclosed. In the method, the optical frequency of the laser light is modulated in order that the modulated optical frequency is a periodic function dependent on time, and the absolute value of a time differential coefficient R (Hz/s) of the periodic function, a spectral line width δ ν (Hz) of the laser light, and a time period τ (s) from the time when the laser light is emitted to the time when the laser light reflected from the recording face of the information recording medium reaches the semiconductor laser satisfy the condition of R≧δ ν/τ. The periodic function varies to have a sawtooth waveform or a triangular waveform.

26 citations


Journal ArticleDOI
TL;DR: In this article, a simple technique using a direct optical probe is demonstrated for parasitic-free characterization of many intrinsic laser parameters, including the relaxation resonance frequency, the relaxation rate, the differential and nonlinear gain parameters, the linewidth enhancement factor, and the carrier and photon lifetimes.
Abstract: A simple technique using a direct optical probe is demonstrated for parasitic-free characterization of many intrinsic laser parameters, including the relaxation resonance frequency, the relaxation rate, the differential and nonlinear gain parameters, the linewidth enhancement factor, and the carrier and photon lifetimes. It consists of a single experimental setup and is broadly applicable to semiconductor lasers of different wavelengths and different dynamic bandwidths. >

Journal ArticleDOI
TL;DR: An analytical description of nearly degenerate four-wave mixing in a single-mode semiconductor laser operating above threshold is given by using the rate-equation model in this paper, which is confirmed by the experiment measuring the power amplification of probe and conjugate waves.
Abstract: An analytical description of nearly degenerate four-wave mixing in a single-mode semiconductor laser operating above threshold is given by using the rate-equation model. The theoretical result is confirmed by the experiment measuring the power amplification of probe and conjugate waves. A 155-Mb/s frequency-shift keying optical-transmission system is demonstrated using four-wave mixing in a bulk distributed-feedback laser diode, for wavelength conversion, optical-signal amplification, and data up-streaming. >

Patent
04 Mar 1993
TL;DR: In this article, a harmonic modulation device of waveguide type including a semiconductor laser, a waveguide for generating a nonlinear optical harmonic of the laser by keeping phase matching, and electrodes disposed on the waveguide.
Abstract: There is disclosed a harmonic modulation device of waveguide type including a semiconductor laser, a waveguide for generating a nonlinear optical harmonic of the semiconductor laser by keeping phase matching, means for leading an optical beam of the semiconductor laser to the waveguide, electrodes disposed on the waveguide, and means for modulating a refractive index of the waveguide electro-optically to modulate a phase matching condition and thereby modulate an intensity of the harmonic.

Journal ArticleDOI
TL;DR: In this article, a nonlinear phase-locking scheme was proposed to phase-lock the second harmonic of a laser frequency to the sum frequency of the other two laser frequencies using homodyne detection.

Journal ArticleDOI
TL;DR: An improved coupled-mode model to describe the dynamics of weakly index-guided semiconductor laser arrays is presented, derived from a partial differential equation model that includes the effects of carrier diffusion and gain guiding.
Abstract: We present an improved coupled-mode model to describe the dynamics of weakly index-guided semiconductor laser arrays. The model is derived from a partial differential equation model that includes the effects of carrier diffusion and gain guiding. Results from the two models are compared, and good qualitative and quantitative agreement is obtained.

Journal ArticleDOI
TL;DR: In this paper, the authors analyze the dynamical response of the interacting photon and electron-hole system in short-cavity bulk semiconductor lasers, including many-body effects of the electron−hole plasma and photon system, the interaction of electron−holes pairs and photons, and the selection of photon modes by the cavity.
Abstract: We analyze the dynamical response of the interacting photon and electron–hole system in short-cavity bulk semiconductor lasers, including many-body effects of the electron–hole plasma and photon system, the interaction of electron–hole pairs and photons, and the selection of photon modes by the cavity. Carrier–carrier and carrier-phonon scattering is treated at the level of a quantum Boltzmann equation. Numerical solutions of the coupled equations for spontaneous and stimulated emission and carrier distributions show the development of lasing out of spontaneous emission and the stabilization of laser action connected with gain saturation and spectral hole burning. The saturation of the output intensity and modifications of the relaxation oscillations are investigated.

Patent
Yamanaka Yutaka1
22 Sep 1993
Abstract: A vertical cavity of a rectangular shape having short and long sides (a,b) is defined between first and second mirror layers (2,4). Thus, two resonant wavelengths are obtained in a vertical-to-surface optical semiconductor device having the vertical cavity. The resonant wavelengths (950.0nm, 950.4nm) are shifted in an increasing wavelength direction due to the heat generated in operation of the optical semiconductor device to shifted wavelengths (950.4nm, 950.8nm). Light of the shifted short wavelength (950.4nm) emitted from the first optical semiconductor device has its plane of polarization rotated by 90°, and is then received by the second optical semiconductor device as light of the non-shifted long wavelength .

Journal ArticleDOI
TL;DR: The femtosecond nonlinear gain dynamics in semiconductor laser amplifiers were used for the 3.8 THz frequency conversion of 30 ps pulses by four-wave mixing as mentioned in this paper.
Abstract: The femtosecond nonlinear gain dynamics in semiconductor laser amplifiers were used for the 3.8 THz frequency conversion of 30 ps pulses by four-wave mixing.

Patent
Yoshida Tomoaki1
13 Apr 1993
TL;DR: A planar semiconductor optical device for modulating an optical beam includes an active layer provided on a substrate as discussed by the authors, the active layer having a quantum structure and being laterally surrounded by an optical confinement region which has a refractive index smaller than the effective as discussed by the authors.
Abstract: A planar semiconductor optical device for modulating an optical beam includes an active layer provided on a substrate, the active layer having a quantum structure and being laterally surrounded by an optical confinement region which has a refractive index smaller than the effective refractive index of the active layer.

Proceedings ArticleDOI
01 Dec 1993
TL;DR: In this article, the effects of external optical feedback (OFB) on semiconductor lasers by simulation of the stochastic rate equations are discussed. But the authors focus on the transition to optical chaos and describe three techniques for avoiding this chaotic regime.
Abstract: In this paper we describe some of the effects of external optical feedback (OFB) on semiconductor lasers by simulation of the stochastic rate equations. Particular attention is paid to the laser's transition to optical chaos. In addition, we describe three techniques for avoiding this chaotic regime. The technique of high frequency injection, used in optical recording, can delay the onset of chaos till very high values of OFB. Experimental results are given and are in excellent agreement with the theory. A second technique called occasional proportional feedback can be used with some success to stabilize the chaotic output of semiconductor lasers. The final technique for controlling chaos consists of the optimization of various system and laser parameters so that the laser is least susceptible to OFB.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Patent
17 Feb 1993
TL;DR: In this article, a non-linear optical switch is proposed to switch a signal at a first wavelength in response to a control signal at the second wavelength applied to the optical gain medium.
Abstract: A non-linear optical switch includes a semiconductor optical gain medium. The switch is arranged to switch a signal at a first wavelength in response to a control signal at a second wavelength applied to the optical gain medium. The refractive index of the gain medium is modified in response to the control signal. An optical holding signal at a third wavelength is applied to the gain medium. The optical holding signal pumps the optical gain medium and thereby fixes the Fermi level. The switch may be embodied in OTDM demultiplexers, clock recovery circuits, wavelength converters and other devices.

Proceedings ArticleDOI
07 Oct 1993
TL;DR: In this article, a regime of synchronized excitation of the fundamental modes of oscillation of diffraction- coupled lasers is discussed, where the diffraction coupling coefficient of two open resonators is calculated.
Abstract: A regime of synchronized excitation of the fundamental modes of oscillation of diffraction- coupled lasers is discussed. An example is the elements of a semiconductor laser with `emitting mirrors.' The diffraction-coupling coefficient of two open resonators is calculated, and the stability conditions are found for a synchronized regime of excitation of the lowest even and odd modes of oscillation.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Proceedings Article
02 May 1993
TL;DR: The gain spectrum of a semiconductor laser diode or edge-emitting light emitting diode (LED) is directly related to the active region carrier density (n).
Abstract: The gain spectrum of a semiconductor laser diode (LD) or edge-emitting light emitting diode (LED) is directly related to the active region carrier density (n). The LD gain spectrum. may be obtained1 from the modulation depth of below threshold Fabry-Perot fringes in the emission spectrum (Fig. 1), When high quality antireflection coatings ave applied to both LD facets, the device becomes an LED and a different method is needed for determining LED gain spectra. We make use of the fact that spontaneous emission is amplifed while propagating along the LD or LED index guide. In contrast, non-guided light, which is measured after passing through a window in the substrate, does not grow.

Journal ArticleDOI
TL;DR: In this paper, the advantages of semiconductor lasers that produce shorter wavelengths and the underlying physics that make them difficult to achieve are examined, and the problem of developing a contact to connect the laser, or a blue-green light emitting diode based on the same technology, is examined.
Abstract: The advantages of semiconductor lasers that produce shorter wavelengths and the underlying physics that make them difficult to achieve are examined. The breakthroughs that have brought a semiconductor laser within reach are described. These include advances in fabricating and doping the large bandgap II-VI semiconducting compounds ZnSe and ZnS on which the new lasers are based and the development of quantum well structures. Integrated design, initial performance, and epitaxial fabrication of the first blue-green emitting laser diode heterostructures are discussed. Some alternative approaches are briefly considered. The problem of developing a contact to connect the laser, or a blue-green light emitting diode based on the same technology, is examined. >

Journal ArticleDOI
TL;DR: In this article, the dynamical behavior of Fabry-Perot type semiconductor lasers is modelled, including the relevant many-body Coulomb effects of the excited carriers, and conditions are given under which a parametrization of the full model is possible, allowing simple analytic relations for local gain, refractive index and linewidth enhancement factor.
Abstract: The dynamical behaviour of Fabry-Perot type semiconductor lasers is modelled, including the relevant many-body Coulomb effects of the excited carriers. Conditions are given under which a parametrization of the full model is possible, allowing simple analytic relations for local gain, refractive index and linewidth enhancement factor. The parameters of the simplified model are uniquely determined by the microscopic theory and have to be optimized for the respective operating conditions. The theory is evaluated for bulk and quantum-well GaAs active material and a variety of laser structures, including strongly and weakly index-guided structures, as well as purely guided single-and twin-stripe lasers.

Book ChapterDOI
15 Nov 1993
TL;DR: In this article, the authors address the problems of low output power, self-phase modulation, secondary pulse formation, and timing jitter in mode-locked laser sources, and present a solution to these problems.
Abstract: Mode locked lasers are a compact, inexpensive source of optical pulses. Currently, some problems with semiconductor sources are low output power, self phase modulation, secondary pulse formation, and timing jitter. These problems are addressed here. >

Journal ArticleDOI
TL;DR: In this article, the operational parameters of semiconductor electron-beam-pumped lasers made by a new technology are described, and the lasing regimes and the parameters of EBP semiconductor lasers based on ZnSe, CdS x Se 1−x, Zn x Cd 1− x S, CdrTe, GaAs crystals in the 460-900 nm range have been studied.
Abstract: The operational parameters of semiconductor electron-beam-pumped lasers made by a new technology are described. The lasing regimes and the parameters of electron-beam-pumped semiconductor lasers based on ZnSe, CdS x Se 1− x , Zn x Cd 1− x S, CdTe, GaAs crystals in the 460–900 nm range have been studied. The radiation from these lasers was used to excite generation in a number of media.

Journal ArticleDOI
TL;DR: It is found that a weak injected signal can be detected by measurements of the mean passage time or its variance whenever its frequency is close to the one of the semiconductor lasers in the on state.
Abstract: We calculate the passage-time statistics of a gain-switched single-mode semiconductor laser with a weak, detuned injected signal. Results are given in terms of a relevant scaling parameter. We find that a weak injected signal can be detected by measurements of the mean passage time or its variance whenever its frequency is close to the one of the semiconductor lasers in the on state. In this case, the external signal is resonant with the laser field at the time when amplification becomes possible, and hence it triggers the switch-on more efficiently. The detection bandwidth is of the order of 50 GHz for the case considered.

Journal ArticleDOI
TL;DR: In this article, the optical mode structure and gain of a free-electron laser (FEL) resonator with holes on axis in the small optical signal regime was examined using a matrix formulation.
Abstract: The optical mode structure and gain of a free-electron laser (FEL) resonator with holes on axis in the small optical signal regime is examined using a matrix formulation. A gain matrix, describing optical mode mixing and amplitude gain in the wiggler, is derived from the FEL evolution equations. A loss matrix, describing the effect on the transverse optical mode structure of the resonator end mirrors, is derived using the method of A.G. Fox and T. Li (1960). The laser matrix is the product of the gain and loss matrices. The eigenvectors and eigenvalues of the laser matrix give the transverse optical mode profile and gain of the resonator. The resonator of the Mark III infrared FEL at Duke University and a confocal resonator, for two holes sizes are examined. The results demonstrate the possibility of output coupling through the holes of the Mark III resonator, and the possibility of using the holes of the confocal resonator for gain control. >

Journal ArticleDOI
C. Trappe1, M. Schütze1, M. Raff1, R. Hannot1, Heinrich Kurz1 
TL;DR: In this article, the system aspects of a completely optical surface-sensitive time-of-flight mass spectrometer are presented using picosecond laser pulses for non-thermal desorption of neutrals from semiconductor surfaces and their optical post-ionization.
Abstract: The system aspects of a completely optical surface-sensitive time-of-flight mass spectrometer are presented. Using picosecond laser pulses for non-thermal desorption of neutrals from semiconductor surfaces and their optical post-ionization, a laser based mass spectrometry of extremely high sensitivity has been developed and tested. Initial experimental results are presented concerning the desorption yield from semiconductor surfaces, the saturation of the post-ionization and the useful yield of the system.