Showing papers on "Semiconductor optical gain published in 1986"
TL;DR: In this paper, it was shown that the nonlinear effects are strong enough that the possibility of chaotic behavior should be of no concern and that gain nonlinearities should be included when gain switching is used for the generation of picosecond pulses.
Abstract: The mode gain in semiconductor lasers decreases with an increase in power due to nonlinear processes such as spectral hole burning. When these small nonlinearities are included in the single‐mode rate equations, it is found that they can eliminate the previously predicted sequence of period‐doubling bifurcations leading to chaos in directly modulated semiconductor lasers. For InGaAsP lasers used in optical communication systems, the nonlinear effects are strong enough that the possibility of chaotic behavior should be of no concern. The results also show that gain nonlinearities should be included when gain switching is used for the generation of picosecond pulses.
105 citations
TL;DR: In this paper, a new type of current injection semiconductor laser with rare earth dopant in the active layer for achieving stable, single longitudinal mode operation was proposed, where the rare earth/semiconductor combination was chosen such that the wavelengths of the dominant emission from the trivalent rare earth ion internal 4f−4f transitions are shorter than that of the band-edge emission of the host semiconductor.
Abstract: We propose a new type of current injection semiconductor laser with rare‐earth dopant in the active layer for achieving stable, single longitudinal mode operation. In this laser, the rare‐earth/semiconductor combination is chosen such that the wavelengths of the dominant emission from the trivalent rare‐earth ion internal 4f‐4f transitions are shorter than that of the band‐edge emission of the host semiconductor. Spectrally, the narrow optical gain due to the rare‐earth ion transition will superimpose on top of the broad gain peak of the host semiconductor. Such laser diodes will attain lasing action at the rare‐earth transition wavelength resulting in single longitudinal mode operation with conventional Fabry–Perot cavity. Furthermore, reproducible precise lasing wavelength insensitive to temperature variation should be possible. Such a proposed rare‐earth/semiconductor injection laser was investigated with erbium doping in the GaInAsP (λ=1.55 μm) active layer of the heteroepitaxial ridge‐overgrown lase...
70 citations
TL;DR: In this paper, the authors demonstrated the operation of an optical switch requiring less than 1 f ǫJ (7000 photons) of incident optical energy, which significantly advances the possibility for realization of high throughput optical signal processing and digital optical computing.
Abstract: We have demonstrated the operation of an optical switch requiring less than 1 f J (<7000 photons) of incident optical energy. The switch operates at room temperature, is compatible with optical communication systems, and is cascadable because it has gain. The switching times (on and off) are determined to be less than 1 ns. This device significantly advances the possibility for realization of high throughput optical signal processing and digital optical computing.
58 citations
TL;DR: In this article, the authors review the current state of phase-locked array design with emphasis on the means for achieving fundamental mode operation, and the potential of various array structures to operate in a single, diffraction limited output beam is evaluated.
Abstract: Semiconductor diode lasers can be combined into monolithic phase-locked arrays that operate to continuous-wave (CW) powers in excess of 1 W and exhibit well-defined output beams to hundreds of mW. Applications of arrays include high-speed optical recording, high-speed printing, free-space communications, and efficient pumping of solid-state lasers. The authors review the current state of phase-locked array design with emphasis on the means for achieving fundamental mode operation. Models for understanding and predicting the behavior of phase-locked arrays are discussed, and the potential of various array structures to operate in a single, diffraction-limited output beam is evaluated.
57 citations
Patent•
19 May 1986TL;DR: In this paper, a frequency selective feedback laser diode is disposed on the same semiconductor crystal with a power amplifier having a diverging active area which causes emitted light to be distributed over a large exit facet area.
Abstract: An integrated semiconductor source of high-power, single spatial mode, narrow spectral mode modulated radiation. A frequency selective feedback laser diode is disposed on the same semiconductor crystal with a power amplifier having a diverging active area which causes emitted light to be distributed over a large exit facet area.
39 citations
TL;DR: In this paper, the results of the analysis of the dynamic properties of semiconductor laser amplifiers are also presented; subnanosecond and femto-Joule switching, critical slowing down and output spiking due to self-tuning at the onset of light injection have been analyzed.
Abstract: Optical memory, differential amplification and optical limiting have been experimentally achieved in an AlGaAs laser amplifier, demonstrating the feasibility of nonlinear optical signal processing using semiconductor laser amplifiers. The results of the analysis of the dynamic properties of semiconductor laser amplifiers are also presented; subnanosecond and femto-Joule switching, critical slowing down and output spiking due to self-tuning at the onset of light injection have been analyzed.
30 citations
TL;DR: In this article, a review of reported results for optical bistability in semiconductors, with especial reference to that occurring in laser structures, is given, and estimates are made of likely improvements that may occur in power-speed trade-offs for these devices.
Abstract: A review is given of reported results for optical bistability in semiconductors, with especial reference to that occurring in laser structures. Estimates are made of likely improvements that may occur in power-speed trade-offs for these devices. It is concluded that laser amplifier bistability offers comparable or, in some cases, better total energy budgets than for other forms and has the useful attribute of optical gain. However, extreme wavelength sensitivity and difficulty in forming large two-dimensional arrays using today's technology mitigate against use of the amplifier for large-scale optical logic. These two factors may be avoided by the use of self-electro-optic effect devices (SEEDs), which are less wavelength-sensitive, and by multiple-quantum-well dispersive etalons in the case of requirements for large amounts of parallel processing.
20 citations
TL;DR: In this paper, the relationship between facet reflectivity and gain bandwidth in semiconductor optical amplifiers is discussed and the first high-resolution measurements of the gain spectrum of InGaAsP 1.5 µ amplifiers are presented.
Abstract: We discuss the relationship between facet reflectivity and gain bandwidth in semiconductor optical amplifiers and present the first high-resolution measurements of the gain spectrum of InGaAsP 1 · 5 µ optical amplifiers. The relatively smooth gain spectrum and high output power of near-travelling-wave amplifiers are compared with those of Fabry-Perot amplifiers.
19 citations
16 citations
Patent•
30 Dec 1986TL;DR: In this paper, reflectivity at both facets of the resonator at the oscillation wavelength is selected to be higher than the reflectivity of the semiconductor crystal of the laser device, but smaller than 1, thereby stabilizing the light oscillation with a low S/N ratio.
Abstract: In a TRS (twin ridge substrate) type semiconductor laser, reflectivity at both facets of the resonator at the oscillation wavelength is selected to be higher than the reflectivity of the semiconductor crystal of the laser device, but smaller than 1, thereby stabilizing the light oscillation with a low S/N ratio.
14 citations
TL;DR: In this paper, the effect of nonlinear gain on the single-frequency behavior of semiconductor lasers was analyzed using a two-mode rate-equation model, and it was shown that the asymmetric nature of non-linear gain is responsible for bringing the sidemode above threshold when the power in the main mode exceeds a critical level.
Abstract: The effect of nonlinear gain on the single-frequency behaviour of semiconductor lasers is analysed using a two-mode rate-equation model. We find that the asymmetric nature of the nonlinear gain is responsible for bringing the sidemode above threshold when the power in the main mode exceeds a critical level. We obtain an analytic expression for the critical current density at which the sidemode reaches threshold and apply it to discuss the single-frequency range of distributed-feedback semiconductor lasers.
Patent•
17 Mar 1986
TL;DR: In this paper, a phase locked two-dimensional semiconductor laser array is disclosed that emits a unified wavefront using columns of individual lasers, each laser having a slant mirror between it and other lasers in its column.
Abstract: A phase locked two-dimensional semiconductor laser array is disclosed that emits a unified wavefront using columns of individual lasers, each laser having a slant mirror between it and other lasers in its column. The individual lasers are all evanescently coupled to the neighboring lasers. The slant mirrors reflect the light from the lasers next to it upwards out of the face of the array. The phase locking is accomplished by the evanescent wave coupling. The plane (uniform) wavefront is accomplished by the design of the array in which: each laser in an i th column forms an optical path length of x i with the slant mirror adjacent to it; and the optical path length between mirrors and lasers in the (i+l) th column is given by: x i =x i+l ±n(λ/2) where λ equals a measure of wavelength of the light transmitted out of the array, and n is an odd integer.
TL;DR: A wide variety of semiconductor and metal films have been grown, doped, or etched by laser photochemical processes as discussed by the authors, and a discussion of film growth and etching shows that the laser is capable of performing all of the basic processing steps required in device fabrication without the need for photolithographic techniques.
Abstract: A wide variety of semiconductor and metal films have recently been grown, doped, or etched by laser photochemical processes. While still early in its development, laser-driven processing of semiconductor devices appears promising as a supplement to existing processing techniques and particularly in the fabrication of III-V compound and custom devices. A discussion of film growth and etching shows that the laser is capable of performing all of the basic processing steps required in device fabrication without the need for photolithographic techniques. The boundaries of the field are set only by the number of semiconductor and metal-containing compounds having reasonable vapor pressure (~1 torr) at several hundred degrees centigrade or less.
01 Jan 1986
TL;DR: Optical computing was first discussed seriously in the 1960's as mentioned in this paper, however, it was concluded that digital optical computational techniques could not hope to compete with electronics and the possibility of developing viable optical computing systems returned to prominence in the early 1980's.
Abstract: Optical computing was first discussed seriously in the 1960’s. In the context of the nonlinear optical devices available at that time, however, it was concluded that digital optical computational techniques could not hope to compete with electronics. Since that time there have of course been great advances in electronic machines. Nevertheless the possibility of developing viable optical computing systems returned to prominence in the early 1980’s.
TL;DR: In this article, a formalism for calculating the output power of high-magnification curved-mirror semiconductor lasers is described, which allows arbitrary single-pass gain and includes thez-dependent saturation by the expanding or contracting mode fields.
Abstract: A formalism is described for calculating the output power of high-magnification curved-mirror semiconductor lasers. This model allows arbitrary single-pass gain and includes thez-dependent saturation by the expanding or contracting mode fields. The results are in agreement with recently published experimental data and the same techniques will apply to other types of high-loss resonators.
TL;DR: InGaAsP/InP buried heterostructure (BH) lasers emitting at 1.3 μm have continued to operate stably for more than 3.3 \times 10^{4} h (3.8 years) at 50-60°C and at an output power of 5 mW/facet and are subjected to accelerated aging at 60°C with EL-mode aging.
Abstract: InGaAsP/InP buried heterostructure (BH) lasers emitting at 1.3 μm have continued to operate stably for more than 3.3 \times 10^{4} h (3.8 years) at 50-60°C and at an output power of 5 mW/facet. A statistically estimated median lifetime exceeds 106at 50°C. A relatively low activation energy of 0.32 eV is obtained for slow degradation. The saturable behavior of the aging characteristics is observed in many of the lasers. This mode is explained by the increased leakage current through the buried regions, and can be eliminated by electroluminescence (EL) mode aging at high temperature and current. Distributed feedback (DFB) lasers emitting at 1.55 μm are also subjected to accelerated aging at 60°C with a 3 mW/facet output after EL-mode aging. These DFB lasers demonstrate stable aging characteristics, for more than 2000 h of operating time being currently achieved.
CNET1
TL;DR: In this paper, the authors theoretically analyzed QWS-DFB semiconductor laser with asymmetric structure in terms of wavelength selectivity, differential efficiency, linewidth and sensitivity to external optical feedback.
Abstract: Quarter-wave-shifted distributed-feedback (QWS-DFB) semiconductor lasers with asymmetric structure are theoretically analysed in terms of wavelength selectivity, differential efficiency, linewidth and sensitivity to external optical feedback. The analysis is used to design narrow-linewidth lasers with low sensitivity to optical feedback for coherent transmission.
Patent•
01 Oct 1986
TL;DR: In this paper, the authors proposed a method to obtain a semiconductor integrated light source which does not take much time to assemble its system, nor cause deviation of the alignment of an optical system, is not bulky in the system, has no delay of phase due to the length of a feedback system and can stabilize the frequency of light by integrally manufacturing semiconductor laser, an optical fiber and an optical detector close to one another on the same substrate.
Abstract: PURPOSE:To obtain a semiconductor integrated light source which does not take much time to assemble its system, nor cause deviation of the alignment of an optical system, is not bulky in the system, has no delay of phase due to the length of a feedback system and can stabilize the frequency of light by integrally manufacturing a semiconductor laser, an optical fiber and an optical detector close to one another on the same substrate. CONSTITUTION:A semiconductor laser 10, an optical filter 20 having a semiconductor waveguide, and a photodetector 30 like a semiconductor photodetector are all manufactured in a series of semiconductor light source manufacturing process on the same substrate 40. That is, the filter 20 is formed of a pair of high reflecting films 24 formed oppositely to the laser 10 and the photodetector 30 at both sides of a semiconductor waveguide 22 so that the film 24 forms a pair of Fabry-Perot etalons. The laser 10 and the filter 30, and the filter 20 and the photodetector 30 are manufactured therebetween at intervals of several mum.
09 Jun 1986
01 Jan 1986
TL;DR: In this paper, the authors have developed the high switching speed optical RS flip-flop which is fabricated on a single chip of semiconductor laser, and the injected light signal consists of the modulated TM wave, and is superposed on a dc TM wave of l.OmW.
Abstract: We have developed the high switching-speed optical RS flip-flop which is fabricated on a single chip of semiconductor laser. The optical polarization bistability, which occurs by injection of light signal into the semiconductor laser, has been developed to obtain high-speed switching performance. The bistability is caused by the interaction of the gain between the transverse electric mode and the transverse magnetic mode in the laser, and the switching speeds are higher by one order than those of the bistability caused by the saturable absorption. The injected light signal consists of the modulated TM wave, and is superposed on a dc TM wave of l.OmW. We have adopted our low threshold current InGaAsP buried heterostructure laser, for which the bias current of only 1.05 times threshold current is needed. The turn-on and turn-off times are 340psec and 430psec, respectively.
TL;DR: In this paper, the authors describe methods by which this may be achieved using passive optical feedback from an array of mirrors or optical fibres, and active control of the laser drive current from the output of an interferometer monitoring the laser emission.
Abstract: Semiconductor lasers are particularly attractive as sources for optical sensors. However, if they are to be incorporated in unbalanced interferometric sensors their phase noise must be reduced. This paper describes methods by which this may be achieved using (a) passive optical feedback from an array of mirrors or optical fibres, and (b) active control of the laser drive current from the output of an interferometer monitoring the laser emission.
CNET1
TL;DR: In this paper, the effect of weak external feedback on the threshold gain and resonant frequency of DFB semiconductor lasers is theoretically analyzed, and simple formulas are derived which allow comparison of the sensitivity to optical feedback for DFB lasers and Fabry-Perot lasers.
Abstract: The effect of weak external feedback on the threshold gain and resonant frequency of DFB semiconductor lasers is theoretically analysed. Simple formulas are derived which allow comparison of the sensitivity to optical feedback for DFB lasers and Fabry-Perot lasers.
01 Jan 1986
TL;DR: In this article, measured switching power of 1µW and predicted response time of 1ns for 1.55µm optical amplifiers are reviewed in the context of other bistable optical devices.
Abstract: Measured switching power of 1µW and predicted response time of 1ns for 1.55µm optical amplifiers are reviewed in the context of other bistable optical devices.
01 Jan 1986
TL;DR: In this article, the operation of an optical switch requiring less than one femtojoule (10−15 J) of incident optical energy was reported, and the measured switching time was about 0.5 ns.
Abstract: We report the operation of an optical switch requiring less than one femtojoule (10−15 J) of incident optical energy. It is a bistable Fabry-Perot laser amplifier that operates at room-temperature, at 1.3 um wavelength, and is cascadable because of its large gain. The measured switching time is about 0.5 ns.
01 Jan 1986
TL;DR: In this article, the authors have made ZnSe laser with room temperature threshold of 15 A/cm2 at 30 kV and CdS laser with threshold of 2.0 A/ cm2 at 28 kV.
Abstract: Electron-beam-pumped lasers (EBL) are small-target CRT's which are useful for projection displays, optical printing and PROMs, and optical mass-memory devices. Despite the obvious practical utility of a laser source with simple electronic scanning, applications of these devices have been held up by the high currents and, more importantly, high voltages necessary to achieve laser threshold. We have made ZnSe lasers (blue) with room temperature thresholds of 15 A/cm2at 30 kV and CdS lasers (green) with thresholds of 2.0 A/cm2at 28 kV.
TL;DR: It is shown that if two light beams intersect in a medium containing the appropriate molecule, one beam can modulate the other by making use of the differences in the absorption spectra of the ground and excited molecular states.
Abstract: It is shown that if two light beams intersect in a medium containing the appropriate molecule, one beam can modulate the other by making use of the differences in the absorption spectra of the ground and excited molecular states. This is possible even with the power of semiconductor lasers. From this, an opto–optical modulating device can be conceived which would have micrometer dimensions, potentially fast response time, and significant quantum gain. Such a device could find use in optical communications and optical computing.
25 Nov 1986
TL;DR: In this article, a semiconductor diode laser array model is applied to the case of the optimization of a twin channel laser (TCL) design, and results substantially in agreement with experiment are obtained as to optimum general geometry, active layer thickness, cladding layer thickness to either side of the coupled channels (wing region), and threshold current.
Abstract: A semiconductor diode laser array model is applied to the case of the optimization of a twin channel laser (TCL) design. Results substantially in agreement with experiment are obtained as to optimum general geometry, active layer thickness, cladding layer thickness to either side of the coupled channels (wing region), and threshold current. Differential efficiency predictions are too high relative to experiment, probably due to leakage currents in the experimental device. A current-induced mode instability at high current is predicted.
02 Jun 1986
TL;DR: In this article, an experimental and theoretical study of large-signal switching transients in directly modulated semiconductor lasers is presented, where the main parameters affecting high-speed switching are identified and device-dependent limitations on modulation at multi-gigabit per second data rates are described.
Abstract: An experimental and theoretical study of large-signal switching transients in directly modulated semiconductor lasers is reported. The main parameters affecting high-speed switching are identified and device-dependent limitations on modulation at multi-gigabit per second data rates are described.
TL;DR: In this article, an analysis of the laws governing the propagation of optical radiation in a semiconductor heterostructure with coupled waveguides in the presence of amplification or absorption is made.
Abstract: An analysis is made of the laws governing the propagation of optical radiation in a semiconductor heterostructure with coupled waveguides in the presence of amplification or absorption. A method is developed for the calculation of the transfer functions describing the operation of various systems (optical amplifier, photodetector, laser) using similar structures. The influence of the spread of the parameters of the waveguide layers on the operating characteristics of these systems is assessed.
25 Nov 1986
TL;DR: In this article, a wave optics model is developed for predicting the performance of high-energy laser systems, with particular emphasis on its application to the cylindrical, source-flow HF chemical laser.
Abstract: In this paper, we describe a wave optics model we have developed for predicting the performance of high-energy laser systems, with particular emphasis on its application to the cylindrical, source-flow HF chemical laser. The structure of the code is based on the 'lumped equivalent optical train' concept, in which any continuous spatial effect on the optical field, such as mirrors, apertures, and gain medium, is approximated numerically by a finite number of transfer functions on the field. Free space propagation between elements is achieved by using Fast Fourier Transforms. The gain is modeled as a series of gain sheets, where the spatial dependence of the gain is calculated from a detailed aerokinetic treatment of the interaction of the intensity field with the flow in the laser cavity. Resonator calculations will be described for two different gain models. In the rotational nonequilibrium (RNE) model, the effects of disequilibrium in the rotational distribution of the individual vibrational levels are accounted for explicitly by solving an evolution equation for each vibro-rotational state of the lasing molecule. The second gain model, referred to as the single line (SL) model, is based on two assumptions, namely that the rotational levels in each vibrational level are in thermal equilibrium, and that the gain on the lasing lines is identical.