Showing papers by "Amnon Yariv published in 1987"
TL;DR: In this article, a single quantum well laser with high reflectively coatings has been shown to achieve a threshold current of 0.95 mA for a buried graded-index separate-confinement heterostructure single QW laser with facet reflectivities of ∼70%, a cavity length of 250 μm and an active region stripe width of 1 μm.
Abstract: Unlike conventional semiconductor lasers, single quantum well lasers with high reflectively coatings have dramatically reduced threshold currents as a result of the smaller volume of the (active) quantum well region. A cw threshold current of 0.95 mA was obtained for a buried graded‐index separate‐confinement heterostructure single quantum well laser with facet reflectivities of ∼70%, a cavity length of 250 μm, and an active region stripe width of 1 μm.
109 citations
TL;DR: In this paper, the authors derived approximate analytical solutions for traveling wave fields within the broad area laser, where the field amplitude consists of a small ripple superimposed on a large dc value, and the matching fields at the boundary determined the modulation depth and imparts an overall phase curvature to the traveling wave mode.
Abstract: The lateral modes of broad area lasers are investigated theoretically. The nonlinear interaction between optical field and effective refractive index leads to a saturable nonlinearity in the governing field equation, so that self-modulated solutions are found to be stable with increased current injection above saturation intensity. We derive approximate analytical solutions for traveling wave fields within the broad area laser. The field amplitude consists of a small ripple superimposed on a large dc value. Matching fields at the boundary determines the modulation depth and imparts an overall phase curvature to the traveling wave mode. There are multiple lateral modes for a given set of operating conditions, and modes with successively more lobes in the ripple have greater overall phase curvature. In contrast to the linear problem, several lateral modes can achieve the same modal gain, for a given injected current density, by saturating the gain to different extent. Thus, these modes would exhibit slightly different optical powers.
67 citations
TL;DR: Room-temperature continuous-wave operation of large-area GaAs/AlGaAs graded-refractive-index separate-confinement heterostructure lasers on (100) Si substrates has been obtained under pulsed conditions.
Abstract: Room-temperature continuous-wave operation of large-area (120 μm X 980 μm) GaAs/AlGaAs graded-refractive-index separate-confinement heterostructure lasers on (100) Si substrates has been obtained. Minimum threshold-current densities of 214 A/cm2 (1900-μm cavity length), maximum slope efficiencies of about 0.8 W/A (600-μm cavity length), and optical power in excess of 270 mW/facet (900-μm cavity length) have been observed under pulsed conditions.
48 citations
TL;DR: In this article, the authors analyzed the threshold behavior of a pair of laterally coupled semiconductor lasers of different lengths and showed that they exhibit selectivity leading to single longitudinal mode operation with a periodicity determined by the length mismatch, and ripples in the equipower curves in the current plane due to carrier-induced index shifts.
Abstract: We analyze the threshold behavior of a pair of laterally coupled semiconductor lasers of different lengths. The predictions include longitudinal mode selectivity leading to single longitudinal mode operation with a periodicity determined by the length mismatch, and ripples in the equipower curves in the current plane due to carrier-induced index shifts. We present experimental measurements that confirm these predictions.
26 citations
TL;DR: In this article, a DH InGaAsP/InP mesa laser and an InGaP/INP mass-transport laser were successfully put together with a bipolar transistor in a vertical configuration, achieving a threshold current as low as 17 mA and output power of over 30 mW.
Abstract: A DH InGaAsP/InP mesa laser and a DH InGaAsP/InP mass-transport laser were successfully put together with an InGaAsP/InP heterojunction bipolar transistor in a vertical configuration. A laser threshold current as low as 17 mA and an output laser power of over 30 mW were achieved. Base injection current-controlled optical bistability and optical switching were demonstrated.
23 citations
TL;DR: In this paper, the field spectrum linewidth of a multiple quantum well laser immersed in a high magnetic field is measured at room temperature and at 165 K. The low-temperature measurements show a decrease of linwidth with increasing magnetic field.
Abstract: The field spectrum linewidth of a multiple quantum well laser immersed in a high magnetic field is measured at room temperature and at 165 K. The low-temperature measurements show a decrease of linewidth with increasing magnetic field. We believe this behavior results from the formation of a totally discrete electronic state space. Measurements of the low-temperature luminescence spectrum show that the emission is split into two peaks by the high field with the higher energy peak responsible for lasing action.
22 citations
TL;DR: A self-consistent formalism is developed for treating propagation of beams in situations which include phase conjugation and nonreciprocal elements.
Abstract: A self-consistent formalism is developed for treating propagation of beams in situations which include phase conjugation and nonreciprocal elements Two equivalent field representations, the rectangular polarization and the circular polarization representation, are considered, and the rules for transforming between them are derived An example involving a proposed new current fiber sensor is analyzed using the formalism
20 citations
TL;DR: A new generic architecture for realising the basic functions of neural networks is described, and the N × N interconnectivity problem is accomplished by a simultaneous combination of horizontal and vertical shifting of CCD arrays.
Abstract: A new generic architecture for realising the basic functions of neural networks is described. In the proposed configuration the N × N interconnectivity problem is accomplished by a simultaneous combination of horizontal and vertical shifting of CCD arrays. The proposed devices can be implemented with present-day technologies.
20 citations
TL;DR: In this article, a self-starting passive phase conjugate mirror using internal reflection was constructed using Ce-doped SrxBa1−xNb2O6, x=0.60 and 0.75, as the holographic four-wave mixing medium.
Abstract: We report the use of Ce-doped SrxBa1−xNb2O6, x=0.60 and 0.75, as the holographic four-wave mixing medium in the construction of a self-starting passive phase conjugate mirror using internal reflection. Without correcting for Fresnel reflections, a steady-state phase conjugate reflectivity of 25% was measured with Sr0.75Ba0.25Nb2O6:Ce. The distortion correcting property of such a mirror was demonstrated using an imaging experiment.
14 citations
Patent•
23 Nov 1987TL;DR: In this article, a method of providing an optoelectronic device is disclosed in which the spatial gain profile within the device is tailored by a predetermined pattern of injecting and noninjecting contacts over the surface of the device with variation in the fractional surface coverage per unit area of injecting to noninjection contact.
Abstract: A method of providing an optoelectronic device is disclosed in which the spatial gain profile within the device is tailored by a predetermined pattern of injecting and noninjecting contacts over the surface of the device with variation in the fractional surface coverage per unit area of injecting to noninjecting contact, thereby providing nearly arbitrary two-dimensional spatial gain profile within the optoelectronic device. A tailored gain broad area semiconductor laser fabricated by this method is capable of high power operation with very narrow, single lobed farfield patterns.
13 citations
01 Jan 1987
TL;DR: In this article, the authors describe semi-self-pumped photorefractive phase-conjugate mirrors based on the unidirectional ring resonator and the double phase conjugate mirror.
Abstract: We describe semi-self-pumped photorefractive phase-conjugate mirrors based on the unidirectional ring resonator and the double phase-conjugate mirror. Their applicability to thresholding phase conjugation and one-way imaging through distortions is discussed.
TL;DR: The investigation of polarization and spatial information recovery using a fiber-coupled phase-conjugate mirror and a theoretical model for these phenomena is discussed.
Abstract: We report the investigation of polarization and spatial information recovery using a fiber-coupled phase-conjugate mirror. A marked dependence of the phase-conjugate output on the input-beam conditions is experimentally observed. A theoretical model for these phenomena is also discussed.
TL;DR: In this article, the authors analyzed linear tailored gain waveguides with a linear gain gradient and obtained analytic approximations for their unsaturated optical eigenmodes, and used them to make a measurement of the anti-guiding parameter, and found b = 2.5 \pm 0.5, in agreement with previous results.
Abstract: Tailored gain semiconductor lasers capable of high-power operation with single-lobed, nearly diffraction limited beamwidths only a few degrees wide have been demonstrated in proton implanted chirped arrays and "halftone" broad area lasers. We analyze lasers with a linear gain gradient, and obtain analytic approximations for their unsaturated optical eigenmodes. Unlike a uniform array, the fundamental mode of a linear tailored gain laser is the lasing mode at threshold. Mode discrimination may be controlled by varying the spatial gain gradient. All modes of asymmetric tailored gain waveguides have single-lobed far-field patterns offset from 0°. Finally, we utilize tailored gain broad area lasers to make a measurement of the anti-guiding parameter, and find b = 2.5 \pm 0.5 , in agreement with previous results.
Patent•
08 May 1987
TL;DR: In this article, a coherent coupling of a plurality of reflection type optical gain elements with a seeding laser is provided by illuminating the optical gain element with fanned laser light scattered from a photorefractive medium.
Abstract: Coherent coupling of a plurality of reflection type optical gain elements with a seeding laser is provided by illuminating the optical gain elements with fanned laser light scattered from a photorefractive medium. The reflection type optical gain elements have an anti-reflective end nearer the photorefractive medium and a reflective opposite end. The optical gain elements also illuminate the photorefractive medium. The resultant amplified and coherent light beam has its wavefront cleaned up with a photorefractive oscillator to provide a diffraction limited or nearly diffraction limited beam.
TL;DR: This work demonstrates experimentally and explains theoretically polarization-preserving imaging through a lossy amplitude-distorting medium by propagating the beam, before its arrival at the lossy distorting medium, through a (multi) mode- and polarization-scrambling fiber and reflecting the signal, after it has passed the lossed medium, from a photorefractive phase-conjugate mirror.
Abstract: We demonstrate experimentally and explain theoretically polarization-preserving imaging through a lossy amplitude-distorting medium. This is accomplished by propagating the beam, before its arrival at the lossy distorting medium, through a (multi) mode- and polarization-scrambling fiber and reflecting the signal, after it has passed the lossy distorting medium, from a photorefractive phase-conjugate mirror.
TL;DR: In this article, a stripe-geometry InGaAsP/InP bipolar transistor (HBT) was fabricated for the first time, and the HBT was successfully integrated with a double-heterostructure (DH) laser, resulting in the first realization of laser operation in a vertical integration.
Abstract: A stripe-geometry InGaAsP/InP heterojunction bipolar transistor (HBT) was fabricated for the first time. High current gain (β > 500) and high collector current (I c > 200 mA) were obtained in devices with an emitter-down configuration. The HBT was successfully integrated with a double-heterostructure (DH) laser, resulting in the first realization of laser operation in a vertical integration.
TL;DR: In this article, the authors derive simple analytic formulas for the field coupling coefficients in a two-section coupled-cavity laser using a local field rate equation treatment, and show that there is a correction to the heuristic formulas based on power flow calculated by Marcuse.
Abstract: We derive simple, analytic formulas for the field coupling coefficients in a two-section coupled-cavity laser using a local field rate equation treatment. We show that there is a correction to the heuristic formulas based on power flow calculated by Marcuse; the correction is in agreement with numerical calculations from a coupled-mode approach.
TL;DR: It is demonstrated experimentally that the effects of nonreciprocal elements or media that would otherwise spoil phase conjugation can be neutralized by using a tandem combination of a modal- and polarization-scrambling fiber and a phase-conjugate mirror.
Abstract: We demonstrate experimentally that the effects of nonreciprocal elements or media that would otherwise spoil phase conjugation can be neutralized by using a tandem combination of a modal- and polarization-scrambling fiber and a phase-conjugate mirror. A theoretical model to explain the experimental results is presented.
TL;DR: In this paper, a double-heterostructure GaInAsP/InP unstable resonator was fabricated by a simple two-step chemical etching process and the required nearly vertical lateral curved cavity mirrors were achieved.
Abstract: Double-heterostructure GaInAsP/InP unstable resonator lasers have been fabricated for the first time. Both facets are made by a simple two-step chemical etching process. The required nearly vertical lateral curved cavity mirrors are achieved. The unstable resonator lasers exhibit an output power of 105 mW.
TL;DR: In this paper, a combination of a multimode fiber and a photorefractive passive phase conjugation mirror is used to demonstrate the coupling of temporal information between two beams.
Abstract: Coupling of temporal information between two beams is demonstrated using a combination of a multimode fiber and a photorefractive passive phase conjugation mirror. It is shown that the polarization and spatial properties are fully recovered but temporal information is exchanged. The theoretical explanation for these phenomena and possible applications are discussed.
08 Jan 1987
TL;DR: In this paper, the authors describe several ways to use photorefractive phase conjugators as thresholding elements for optical associative memories, such as background illumination of the crystal of a self-pumped conjugator, which increases reflectivity with increasing signal strength.
Abstract: We describe several ways to use photorefractive phase conjugators as thresholding elements for optical associative memories. The first involves background illumination of the crystal of a self-pumped phase conjugator. The second method uses a photorefractive phase conjugator designed so that its reflectivity increases with increasing signal strength. The third method uses semi-self-pumped phase conjugators in which one pump is externally provided as a thresholding reference and the other is self-induced as an oscillation beam. Two examples are the double phase conjugate mirror and a new type of phase conjugator based on injection of a counterpropagating pump beam into a unidirectional ring resonator.
01 Jan 1987
TL;DR: In this article, a non-phase conjugating ring resonator is introduced, and a discussion of photorefractive phase conjugation, phase-convugate resonators and self-pumped phase-conv conjugate mirrors are discussed.
Abstract: Ferroelectric crystals with large electrooptic coefficients such as BaTiO3and Sr1-xBaxNb2O6(SBN) are able to support photorefractive holographic gratings with large diffraction efficiencies. These gratings form even with low power (≈1W/cm2) beams in real time in such a way as to coherently amplify some of the writing beams at the expense of the others, making possible the construction of many kinds of optical parametric oscillators. Many of these devices are self-pumped phase conjugate mirrors and this accounts for much of the interest that they have generated in the optics community. The first part of this paper deals with a nonphase conjugating ring resonator. It is the simplest photorefractive oscillator and offers a good introduction to the more complex phase conjugating devices. We then proceed to a discussion of photorefractive phase conjugation, phase conjugate resonators and self-pumped phase conjugate mirrors.
01 Dec 1987
TL;DR: In this article, microwave modulation and CW operation of AlGaAs lasers grown by MBE on Si substrates have been obtained for the first time, and Ridge waveguide lasers(10µm×380µM) were modulated with a microwave signal up to 2.5GHz which is notable considering the structure used.
Abstract: Microwave modulation and CW operation of AlGaAs lasers grown by MBE on Si substrates have been obtained for the first time. Ridge waveguide lasers(10µm×380µm) were modulated with a microwave signal up to 2.5GHz which is notable considering the structure used. Near and far field measurements indicated a single transverse mode and a narrow beam angle (4.8°). Finally, polarization measurements appear to show the solely TE nature of the emission.
TL;DR: Self-focusing in a passive dielectric waveguide with a saturable nonlinearity with a good approximation to the lateral modes of broad-area semiconductor lasers under low-duty-cycle pulsed conditions is studied.
Abstract: Self-focusing in a passive dielectric waveguide with a saturable nonlinearity is studied. The eigensolutions constitute a good approximation to the lateral modes of broad-area semiconductor lasers under low-duty-cycle pulsed conditions. The laser modes are predicted to consist of adjacent filaments coupled in phase, leading to a single-lobed far field, and to be stable with increased current injection above saturation intensity. The ultimate filament spacing is inversely proportional to the threshold gain, and thus wider filaments are expected in low-threshold broad-area lasers.
01 Oct 1987
TL;DR: In this article, an experimental investigation of the frequency chirp in picosecond pulses from pulse modulated GaAs/AlGaAs with SQW active layers and the dependence on the lateral guiding mechanism is presented.
Abstract: The dynamic frequency shift, or frequency chirp, in pulse modulated semiconductor lasers has recently received great attention since it limits the bandwidth-distance product in high bit rate-dispersive optical communication systems emploing dynamic single mode lasers [1]. In the search for a laser structure that exhibits a small frequency chirp, the single quantum well (SQW) structure has been suggested [2–4]. In this paper, we report on an experimental investigation of the frequency chirp in picosecond pulses from pulse modulated GaAs/AlGaAs lasers with SQW active layers and the chirp dependence on the lateral guiding mechanism.