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In this report, we present data on an InGaAs/GaAs strained single quantum well laser with the lowest reported threshold current density to date, namely 44 A cm−2 for a 3 mm cavity length. This was grown by solid-source molecular-beam epitaxy with the arsenic dimer, As2. The structure is that of a graded-index, separate-confinement heterostructure with a single strained InGaAs quantum well, sandwiched between GaAs barrier layers and AlGaAs cladding layers. The wavelength of the lasers was around 985 nm, and the internal efficiency and losses were 69% and 0.70 cm−1, respectively. In addition, data on the uniformity of our lasers, which are grown on rotating 2 in substrates (1 in = 2.54 cm), show drops in photoluminescence emission wavelength and layer thickness of less than 4 nm and 4%, respectively, from the centre to the edge of the wafer and very little compositional change.

An equivalent circuit model has been developed for quantum-well (QW) lasers from the electrical and optical rate equations and thermal conduction equation. This model and its SPICE implementation allow self-consistent calculation of the electrical, optical, and thermal interactions using lumped elements, and make possible the simulation of multiple components in optoelectronic integrated circuits in the presence of these interactions. Physical effects which are strongly temperature dependent, such as gain variation, leakage current, and Auger recombination, have been incorporated. The model has been validated with measured laser characteristics. >

The authors demonstrate the integration of a grating demultiplexer with curved output waveguides and a MSM photodetector array in InGaAs/AlGaAs/GaAs operating in the 1- mu m wavelength region. The structure provides 38 channels with 1-nm channel spacing. The total loss, including scattering from the unmetallized grating, is about 17 dB. A channel crosstalk of -11 dB is obtained. The FWHM of the channel pass band is 0.5 nm. >

We report on strained layer InGaAs/GaAs single quantum well (SQW) lasers with monolithically integrated nonlinear wave guides for surface-emitting sum-frequency generation. Broad-area, ridge wave-guide and segmented cavity lasers with uncoated facets were processed from a molecular beam epitaxy grown AlxGa1 − xAs multilayer embedded with an InGaAs SQW separate cofinement heterostructure and tested at room temperature. Broad-area threshold current density of 87.5 A cm−2 was obtained for a cavity length of 3.3 mm and ridge lasers had a minimum threshold current of ~8 mA. The differential internal quantum efficiency, wave-guide loss, and lasing wavelength variation with cavity length were investigated. The sum-frequency generation (SFG) was studied in an active/passive segmented cavity device by coupling 1.06 μm light into the cavity as the transverse magnetic guided wave to interact with the transverse electric SQW laser mode. The measured conversion efficiency in terms of the nonlinear cross section An1 is about 2 × 10−7 W−1, which agrees well with the calculated value. Applications of the integrated devices as WDM demultiplexers and spatially addressable coherent detectors were demonstrated.

Epitaxial growth and the crystal-orientation specific optical properties of InGaAs quantum wells and AlGaAs surface-emitting harmonic generation wave-guides on (111) substrates are discussed. The samples were grown by molecular beam epitaxy on misoriented (111)B GaAs substrates. Low As4 overpressure and a very high substrate temperature lead to excellent surface morphology for both types of structures, making their growth compatible for later monolithic integration. InGaAs quantum wells are shown to be strongly affected by the strained-induced electric field. We observe an important increase, with In content, of the resultant redshift between (111) and (100) layers; a luminescence redshift as large as 55 meV for an 18% In well is measured. We also demonstrate for the first time surface emission harmonic generation from an all-AlGaAs second harmonic generation wave-guide pumped with 1.06 μm transverse electric (TE) polarized light; as predicted theoretically, the emitted light is uniform along the guide, and as intense as on a (100) crystal for TE–TM (transverse magnetic) interaction.

We present a four-channel wavelength division demultiplexing detector using the principle of quantum confined Stark effect. This device is based on a ridge waveguide GaAs–AlGaAs single quantum well graded index separate confinement heterostructure. Four detectors are fabricated sequentially along the wave guide and their band gaps are tuned to progressively smaller values by applying progressively larger reverse bias voltages. Thus each detector responds preferably to one of the four input wavelengths. For transverse electric polarization, better than −10 dB crosstalk was achieved with a 14 nm wavelength separation. When operated as a three-channel device, better than −15 dB crosstalk was achieved with a 18 nm wavelength separation. For transverse magnetic polarization, better than −10 dB crosstalk was achieved with a 16 nm wavelength separation. We also present a theoretical study that leads to the optimization of the device.

We have performed a detailed series of photoconductivity (PC) and photoluminescence (PL) measurements on a reverse-biased GaAs/AlGaAs single quantum well graded index separate confinement heterostructure laser. The PC was performed, as a function of bias, at room temperature on a high-speed ridge waveguide structure. The PL was performed at low temperatures (20, 70, and, 150 K) on a ring mesa sample as a function of bias. The measurements show that this device behaves as an extremely efficient high-speed photodetector with an internal quantum efficiency of 100% and a FWHM response time of 35 ps. The data is fitted using a simple model based on electron recombination in the quantum well or escape out of the well. The escape occurs by one of three possible routes: direct tunnelling out of the lower electron level, thermally assisted tunnelling through the upper electron level, or thermionic emission over the barrier. Each of these three terms is calculated theoretically. A comparison of theory and experiment leads us to the conclusion that the theories explaining thermal emission of carriers from a quantum well underestimate the lifetimes.

An In/sub 0.22/Ga/sub 0.78/As/GaAs single quantum-well (SQW) laser integrated monolithically with a surface-emitting harmonic generator (SEHG) segment was fabricated and tested. By coupling a 1.06- mu m Nd:YAG laser output into the active device, the green surface-emitting light at 0.51 mu m was observed as the result of nonlinear interactions within the SEHG segment. The nonlinear interaction cross section A/sup nl/ of the device was found to be 2.3*10/sup -7/ W/sup -1/, which agrees well with theory. The application of the active devices as a dense wavelength-division-multiplexing (DWDM) demultiplexer was demonstrated with a tunable Ti:sapphire laser to simulate the multiwavelength signal source and a CCD detector array to record the spatially separated signals of different wavelength. System resolution better than 2 nm was obtained for the device, which was limited by the short length of the SEHG segment. Potential for a DWDM channel spacing of 10 GHz is discussed. >

The authors report a four-channel wavelength-division-demultiplexing detector based on a reverse-biased GaAs/AlGaAs single-quantum-well graded index separate confined heterostructure laser having segmented contacts. They achieve better than -15-dB channel crosstalk for three-wavelength operation, and better than -10-dB crosstalk for four-wavelength operation. The optimum wavelength separation is 18 nm for three channels and 14 nm for four channels. The authors show that by optimizing the segment lengths better performance can be obtained from the same layer structure. >

We investigate the limits of frequency resolution attainable in a nonlinear waveguide optical spectrometer, including the effects that are due to surface distortions and waveguide inhomogeneities, and demonstrate that the frequency-resolving capability is directly scalable with the radiating aperture length. The resolution of the waveguide is diffraction limited, and therefore the far-field radiation pattern can be used to characterize the phase variations along the waveguide that are due to surface distortions. The use of this device as a highly sensitive deformation sensor is demonstrated by application of a distortion to the waveguide and confirmation of the far-field diffraction pattern generated.

Optical second-harmonic generation of visible light in a superlattice of asymmetric coupled GaAs quantum wells has been measured for the first time to our knowledge. The orientation of the asymmetric quantum wells was periodically reversed such that the quantum-well contribution to the radiated second-harmonic signal was quasi-phase matched when it was excited by a λ = 1.319 μm fundamental in the reflection geometry. The second-harmonic intensity generated in this superlattice was approximately 3.6 times that generated in a homogeneous GaAs reference. The measured superlattice second-harmonic susceptibilities are ∣χyzy(2)∣=1.5×10-11 m V-1 and ∣χzyy(2)∣=1.3×10-11 m V-1.

A plurality of signals are mixed in a non-linear waveguide for generating a near field sum frequency output pattern. The near field output pattern is monitored for changes which correspond to changes in the phase relationship between the plurality of signals. A grating provides a mask through which the near field pattern may propagate. Detectors positioned above the grating at predetermined locations measure the intensity of the near field pattern and a change in the phase relationship between the input signals is determined from a change in the intensity of the near field output pattern.

InGaAs/GaAs circular-grating surface-emission DBR lasers with a pulsed external efficiency, over 11% (power>100 mW) and a divergence of 1° are obtained. We also demonstrate the first CW operation near room temperature, Semiconductor Laser Conference, 1994., 14th IEEE International, September 19-23, 1994, Maui, Hawaii, United States

Proof-of-concept devices to create surface-emitting visible lasers are described and demonstrated. A visible, surface-emitting, solid-state diode laser for InGaAs, InP, and GaAs geometries, as well as for several other devices, is discussed. The use of a multilayer system to enhance the waveguide harmonic mixing over a large bandwidth is demonstrated. The resulting surface-emitted light can then be used to measure frequency differences of multiple optical channels in a fiber communication system. It can also be used for nonblocking switching systems. Since phase is preserved by the harmonic mixing, the device is also usable in coherent communication schemes. Experimental measurements of harmonic generation coefficients for a large Al alloy content in AlGaAs are presented. >

Calculations of multiple-quantum-well laser threshold current show that a common minimum current value exists for each number of wells, at an appropriate cavity length. This optimum cavity length decreases rapidly with increasing number of wells, for instance from about 300 to 110 μm for one to three wells. Granded-index separate-confinement heterostructure (GRINSCH) lasers with 1–10 quantum wells, grown by molecular beam epitaxy, show consistently low threshold currents that agree well with theoretical predictions. Lasing is achieved at 160 A cm−2 and 4.6 mA for broad-area and ridge waveguide single-quantum-well devices, respectively. The field-dependent electroabsorption of these devices when operating as wave-guide modulators indicates good modulation properties for one and three quantum-well structures, with on:off ratios above 55 at lasing wavelength. The behavior becomes more complex with increasing number of wells. This systematic study of discrete multiple-quantum-well lasers and modulators demonstrates that GRINSCH structures with 1–3 wells are the most suitable for monolithic integration. Design rules for the laser cavity are also presented for numbers of wells ranging from 1 to 10.

We demonstrate efficient wave-guide quantum-well electroabsorption modulators that also show good performance as lasers, in GaAs–AlxGa1−xAs. Two structures, having one and three quantum wells in the wave-guide core, are considered. We show that, although the background-doping impurity level in the intrinsic region is high enough to quench the exciton absorption peaks, efficient electroabsorption can still be achieved. We obtain maximum changes in absorption of between 140 and 250 cm−1 for both samples, depending on the polarization. For the three-well sample we observe a dramatic reappearance of exciton-absorption peaks under an applied field that enhances the contrast ratio. For the single-well sample, however, no excitonic features are observed for any applied field. Finally, the wave-length dependent chirp parameters is calculated at various bias voltages via the Kramers–Kronig relations. Both samples show chirp parameters of less than unity throughout most of the wavelength region of interest.

It is found that an ordered and air-stable GaAs(111)A舑(1 × 1)舑Cl surface can be produced by chemical etching/passivation with dilute HCl solution. The synchrotron polarization-dependent Cl K-edge x-ray absorption near-edge structure and x-ray photoelectron spectroscopy studies showed that the surface is terminated with Ga舑Cl bonds oriented along the surface normal. Low-energy electron diffraction studies showed a bulklike (1 × 1) structure on the Cl-terminated GaAs(111)A surface. The Cl termination eliminates surface band-gap states caused by surface oxides. Photoluminescence measurements showed a dramatic increase in the near-band radiative emission rate corresponding to reduction in the occupied surface band-gap states. A reduction of surface gap states by Cl termination was confirmed by surface photovoltage measurements.

In this letter, we present the first room temperature continuous wave operation of circular-grating surface-emitting DBR lasers. The structure is an InGaAs/GaAs strained multiquantum-well. A modified fabrication process with a better control on the steps is used. A CW threshold current as low as 26 mA at a lasing wavelength of about 977 mm are reported. This is the first demonstration of CW operation for these lasers in any material system. >

Strained layer InGaAs/GaAs quantum wells have been grown by molecular‐beam epitaxy on patterned (100) GaAs substrates. Indium migration away from the facets of patterned mesas is shown to be strongly dependent upon the arsenic flux during growth. Based upon this effect we have grown structures in which the number of active quantum wells in adjacent areas of a segmented contact device can be varied.

The optical second‐harmonic (SH) response of GaAs and Al0.6Ga0.4As bombarded with 1.2‐MeV energy As+ ions has been measured for doses ranging from 5×1012 to 2×1014 ions cm−2. The measured SH response vanishes at an ion dose of 2×1014 ions cm−2 as a result of ion induced amorphization. Thermal annealing at 600 °C greatly reduced the damage induced optical absorption, for λ=1.06 μm light, but had no effect on the SH susceptibility.

The authors report the generation of tunable, CW, X-band microwave radiation using optical mixing in an Al/sub x/Ga/sub 1-x/As optical waveguide. Two optical frequencies from CW, Nd-YAG ring lasers are mixed to obtain microwave radiation between 7 and 13 GHz.

We recently demonstrated large second harmonic surface emission cross-sections in a nonlinear anti-resonant reflecting optical waveguide (NARROW). High efficiencies were obtained in thick films by simultaneously maintaining the anti-resonance conditions at the 1.06 /spl mu/m fundamental in the multilayer film and the harmonic 0.53 /spl mu/m resonance. Here we report on a full optimisation process, taking all material constants, linear and nonlinear, into account and optimising the thickness ratio and composition of each layer in the system. >

Summary form only given. As the size of OEICs and the number of components increase, the issue of thermal interaction becomes increasingly important. To analyze the thermal interactions between multiple devices and its effect on laser performance, we have developed a lumped element circuit model which includes the electrical, optical, and thermal interaction effects. This model supplements the two dimensional finite-element non-isothermal simulations which provide a detailed insight into the internal thermal effects for individual structures, but offers a more practical method for modelling multiple devices in integrated optoelectronic circuits. This new lumped element model of laser diodes is directly derived from the carrier and the photon rate equations and the thermal conduction equation. >

Sum-frequency mixing in a nonlinear waveguide using counter-propagating light beams was first demonstrated more than a decade ago. The subsequent development of quasi-phase matching (QPM) techniques in Al/sub x/Ga/sub 1-x/As heterostructure waveguides has improved the conversion efficiencies such that a variety of applications based on second-harmonic (SH) generation are now feasible. Difference-frequency mixing in an Al/sub x/Ga/sub 1-x/As waveguides can also be used to generate tunable CW microwave radiation. The optimization of devices based on QPM SH generation requires the capability to spatially modulate the second-order nonlinearity /spl chi//sup (2)/. Within the Al/sub x/Ga/sub 1-x/As material system, a number of approaches to controlling /spl chi//sup (2)/ have been explored. The simplest approach is to vary the concentration. Once appropriate materials have been found, the geometry of the heterostructure must be designed to optimize device operation.

Techniques for optical generation of microwave signals have recently received much attention. The generation of narrowband microwave signals from the mixing of two optical sources has been demonstrated using fast photodetectors. This paper describes the first generation of a tuneable, CW, narrowband microwave radiation by mixing two optical sources in a Al/sub x/Ga/sub 1-x/As waveguide, utilizing the inherent non-linear properties of the material. >

An equivalent circuit model has been developed to study the self-heating effects and the thermal crosstalk on lasers and other devices in optoelectronic integrated circuits (OEICs). We have applied this self consistent electro-opto-thermal lumped element model to a 1D laser array in order to predict how the L-I characteristics of a particular laser are affected by the thermal crosstalk from adjacent lasers operating under various bias conditions. We also performed experiments to validate the model. >

Although it has been known for many years that GaAs/AlGaAs quantum-well (QW) lasers exhibit low temperature sensitivity, or high characteristic temperatures, T/sub 0/, to our knowledge, optimization of the laser structure so as to maximize T/sub 0/ has never been shown. Previous work in GaAs/AlGaAs has been limited in scope, either only to Al content in the cladding layers and QW thickness, or to a small variety of numbers of quantum wells, n. There has also been work done on the influence of the number of wells in InP-based lasers at 1.3 /spl mu/m and 1.5 /spl mu/m wavelengths. In this paper, we present results of an experimental study on the variation of T/sub 0/ in graded-index, separate-confinement heterostructure GaAs/(Al,Ga)As QW lasers as a function of the Al content in the cladding layers at two different nominal values, and of the number of wells, ranging from n=l to 10.

Quasi-phase matched (QPM) second-harmonic (SH) generation in both insulator and semiconductor waveguides has applications ranging from the generation of coherent visible light to optical signal processing. QPM compensates the wavevector mismatch between the fundamental and SH light by periodically varying the SH susceptibility, /spl chi//sup (2)/, and refractive index, along the SH light propagation direction. It would be very useful if quantum wells could be used to engineer materials with a large /spl chi//sup (2)/ which can be easily varied. Large asymmetric quantum well SH susceptibilities have been measured for far infrared wavelengths, where the nonlinear response is dominated by intra-subband transitions. Although there have been several theoretical studies predicting a quantum well /spl chi//sup (2)/ comparable to that of LiNbO/sub 3/ or larger in the near infrared and visible wavelength range, there have been no experimental measurements of /spl chi//sup (2)/. The authors use reflection geometry QPM to selectively enhance the SH signal from an asymmetric coupled quantum well (ACQW) superlattice. In addition they present the first measurement, to the best of their knowledge, of /spl chi//sup (2)/ in the visible wavelength range for an ACQW. >

We demonstrate the use of a multilayer waveguide to enhance harmonic mixing over a large noncollinear angle and present first results for three‐dimensional nonlinear waveguide wave mixing. The resulting surface emission can be used to select any target coordinate within an output plane or half‐space with subpicosecond addressing speeds and large deflection angles. The electro‐optic version is limited only by device capacitance.

A multilayered core nonlinear antiresonant reflecting optical waveguide (NARROW) was used to generate surface emitted frequency doubled light. High efficiencies were obtained with the NARROW while simultaneously keeping optimum antiresonant conditions at the fundamental wavelength.

Un spectrometre a reseau integre avec des guides d'onde de sortie courbes a ete concu et fabrique dans une structure de guide d'onde GaAs-AlGaAs, pour utilisation a des longueurs d'onde micrometriques. L'incorporation de guides d'onde courbes permet d'obtenir une separation plus grande entre les facettes de sortie, ce qui est desirable pour integration future. Des patterns de haute qualite ont ete fabriques par lithographie FIB et RIE. On a obtenu huit sorties avec espacement des canaux de 2 nm, La possibilite d'integration de la structure avec des composants actifs est discutee

The authors demonstrate the fabrication and room temperature operation of an electrically pumped circular-grating surface-emitting distributed-Bragg-reflector laser. An InGaAs/GaAs single quantum well (SQW) graded-index separate confinement heterostructure (GRINSCH) structure was grown by one-step molecular beam epitaxy (MBE). Circular gratings were defined by focused ion beam lithography. The lasing wavelength was 942 nm, and the threshold current was 280 mA. This is the first demonstration of these lasers with no epitaxial regrowth. >

The authors report extremely efficient ( approximately 100% internal quantum efficiency) and high-speed ( approximately 25-pS FWHM) photodetection in a reverse-biased GaAs/AlGaAs ridge waveguide single-quantum-well (SQW) graded-index separate confinement heterostructure (GRINSCH) laser structure near lambda =830 nm. The impulse response is limited by device parasitics to 25 pS at large reverse bias voltages, and by photogenerated electron escape closer to flatband conditions. >

The authors demonstrate a SQW-GRINSCH ridge-waveguide electroabsorption modulator in GaAs/Al/sub x/Ga/sub 1-x/As that has a very high contrast ratio and low operating voltage and also acts as a laser with relatively low threshold current. They achieve contrast ratios of 10 dB/100 mu m of cavity length with an operating voltage of less than -4 V. In addition, when operated as laser, the device exhibits a threshold current of 25 mA. The active layer has a capacitance of 205 pF/mm/sup 2/ which would allow the fabrication of a device with a modulation bandwidth of over 20 GHz. The laser operated at a wavelength only 2-3 nm shorter than the optimum modulation wavelength. >

In this paper, we report on the design and fabrication of electrically-pumped circular-grating surface-emitting DBR lasers for operation in the 0.98-/spl mu/m wavelength range. The layer structure with InGaAs-GaAs-AlGaAs strained multiquantum-wells was obtained by one-step epitaxial growth. Circular gratings are defined by electron-beam lithography around circular gain sections of different diameters. Low threshold CW operation as low as 26 mA for a 60-/spl mu/m diameter gain section, and high-power pulsed operation of over 120 mW for a 100-/spl mu/m diameter gain region are demonstrated. A quasi-circular far-field pattern with a divergence of about 1/spl deg/ is obtained. >

The phenomenon of indium migration off the sidewalls of features on patterned GaAs substrates during MBE growth has been studied. The level of migration depends strongly on the arsenic flux and the growth temperature. Modulating the arsenic flux during the growth of multilayer structures allows the number of active quantum wells to vary from one region of a device to another.

In this paper, we report on the design and fabrication of electrically-pumped circular-grating surface-emitting DBR lasers for operation in 0.98 micrometers wavelength range. The layer structure consists of InGaAs/GaAs/AlGaAs strained multi-quantum-wells grown by one step epitaxial growth. Circular gratings are defined by electron-beam lithography around the circular gain sections. The effect of various parameters are discussed and the most recent results are presented.

Results will be presented on the variation of threshold current and emission wavelength with temperature of MQW InGaAs/GaAs circular-grating, surface-emitting, distributed Bragg reflector (CG-SE-DBR) lasers, in the range 10 - 90 degree(s)C. The structures were grown by one-step MBE and the circular gratings were defined by electron-beam lithography. Measurements were made pulsed and CW. The characteristic temperature ranged between 18 - 48 K. A wavelength variation with temperature of around 0.1 nm/ degree(s)C was obtained. The results are compared with those of linear, GaAs-based DBR lasers.

We report on the design, growth, fabrication and characterization of monolithic wavelength division multiplexed (WDM) laser array transmitter and receiver chips produced by the Canadian Solid State Optoelectronics Consortium. The transmitter chip includes multiple, discrete wavelength, distributed Bragg reflector (DBR) laser diodes monolithically integrated with waveguide combiners fabricated using an InGaAs/GaAs heterostructure. The corresponding wavelength demultiplexer unit is based on a Rowland circle grating spectrometer monolithically integrated with a metal-semiconductor-metal (MSM) detector array fabricated on an InGaAs/AlGaAs/GaAs heterostructure. The epitaxial layer wafers for both transmitter and receiver modules were grown in single molecular beam epitaxy (MBE) runs.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The inherent information bandwidth of optical fibers between the wavelengths 1.3 and 1.6 micrometers is in the terahertz range. One obvious way to exploit this bandwidth is to use wavelength-division multiplexing (WDM). The Canadian Solid State Optoelectronics Consortium (SSOC), an association of industry, university, and federal government research laboratories, has been developing the component technologies required to demonstrate the operation of an eight channel WDM system. This paper discusses the integration of the transmitter (Tx) and the receiver (Rx) modules using a thin film process on alumina substrates. The Tx module contains a fully integrated eight channel DBR laser array with two quad-laser driver circuits. The signal from the lasers is combined into a single waveguide and is then carried off-chip via a polarization maintaining optical fiber. The Rx module is made up of an integrated receiver circuit, and a series of amplifiers providing the gain required for signal and clock recovery. The receiver circuit consists of an echelle grating which disperses the eight distinct wavelengths into a bank of InGaAs metal-semiconductor-metal (MSM) detectors. Some of the performance parameters of the Tx and Rx modules are presented., Components for Wavelength Division Multiplexing, February 09, 1995, San Jose, CA, USA

We have measured the temperature sensitivity, T/sub 0/, of GaAs-(Al,Ga)As, GRINSCH, multiple quantum-well (MQW) lasers with different numbers of quantum wells ranging from one to ten. Our data suggests that there is an optimum number of wells, namely five, where T/sub 0/ is highest. Using a temperature-dependent model based on drift-diffusion equations, we have systematically analyzed the temperature sensitivity of a MQW GaAs-(Al, Ga)As laser. The T/sub 0/ versus well-number behavior observed experimentally is verified, and the important temperature-dependent factors are identified. >

We report on the design, growth, fabrication, and characterization of monolithic wavelength division multiplexed (WDM) modules produced within the Canadian Solid State Optoelectronics Consortium. The transmitter module includes multiple, discrete wavelength, distributed Bragg reflector (DBR) laser diodes monolithically integrated with waveguide combiners fabricated using an InGaAs/GaAs heterostructure. The wavelength demultiplexer unit is based on a Rowland circle grating spectrometer monolithically integrated with a metal- semiconductor-metal (MSM) detector array fabricated on an InGaAs/AlGaAs/GaAs heterostructure. The epitaxial layer wafers for both transmitter and receiver modules were grown in single molecular beam epitaxy (MBE) runs., Fiber Optic Network Components, Amsterdam, Netherlands, March 20-22, 1995, Series: Proceedings of SPIE

Wavelength‐division multiplexing with closely spaced multiple wavelengths is of great interest for high‐capacity data transmission. One major and very critical requirement of such a system is the fabrication of a laser array with very small wavelength separations (∼2 nm). In this paper, the design, fabrication, and performance of an integrated eight‐channel system is described. Focused ion beam lithography, with the beam deflection sensitivity modified from its calibrated value, is used to write the critical stepped‐period distributed‐Bragg‐reflector gratings required to provide the tightly controlled multiple laser frequencies. The outputs of the lasers are combined via curved waveguides into a single optical output.

In this article the fabrication of circular gratings by electron‐beam lithography (r‐θ coordinates) and by focused ion‐beam lithography (x‐y coordinate) is presented. The differences between the two techniques, relevant to the fabrication of circular patterns, are described. The optimum writing strategies and the quality of circular gratings are compared. Electrically pumped circular‐grating surface‐emitting distributed Bragg reflector (DBR) lasers were fabricated by the two techniques. Room temperature cw operation of a circular‐grating surface‐emitting DBR laser is demonstrated.

We review the progress in our physical understanding and modeling of integrated surface emitting harmonic generators and also present experimental results for the monolithic integration of active laser sources embedded with a quasi phased matched nonlinear heterostructure cavity for surface emission in the blue-green wavelength region.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Several years ago Stegeman and Normandin predicted, and subsequently demonstrated [1], the nonlinear mixing of oppositely propagating guided waves. The resultant second harmonic field was coupled to radiation modes and propagated in a direction perpendicular to the waveguide surface, in the case of equal fundamental frequencies. Its application to picosecond signal processing [2], the creation of all optical transient digitizers [3] and spectrometers [4] demonstrated the potential usefulness of this approach. Finally, the nonlinear cross section for uniform GaAs optical waveguides was calculated and published [5], and recently this GaAs prediction was verified [6] by Vakhsoori et al. In their geometry, the oppositely propagating beam was supplied by the reflection from the exit surface. Their use of picosecond pulses also demonstrated the potential for optical correlation in a geometry similar to references 2 and 3. However, the use of simple GaAs films results in low conversion efficiencies, due to difficult input coupling and absorption and phase cancellation effects at the harmonic wavelength.

High power operation of circular-grating surface-emitting distributed Bragg reflector lasers is demonstrated. The structure is a strained InGaAs/GaAs double quantum well grown by one step MBE. Circular gratings are defined by electron beam lithography. A surface emission power over 100mW is obtained.

We demonstrate high temperature operation of circular-grating surface-emitting distributed Bragg reflector lasers. The structure is a strained InGaAs/GaAs double quantum well. Circular gratings are defined by electron beam lithography. No epitaxial regrowth is used. A surface emission power of over 40 mW under pulsed operation at temperatures of up to 80/spl deg/C is obtained without saturation. A fixed single mode operation was achieved over a temperature range of 60 degrees. >