Graded-index Waveguide Separate-confinement Heterostructure Research Articles

850 nm高亮度锥形半导体激光器的光电特性

High-brightness tapered laser diode at 850 nm was fabricated based on the AlGaInAs/A1GaAs chip with graded-index waveguide separate confinement hetero-structure.The tapered laser has better performance than the broad laser under the same condition.The lateral divergence angles of the tapered laser and the broad laser were 4° and 6° at the output power of 1 W,while the beam propagation factor M2 were 2.8 and 9.2,respectively.The slope efficiency of the tapered laser had a high value of 0.58 W/A and the conversion efficiency reached 30% in the output power 1.40 W under the injection current of 3 A.The facts indicated the tape-red laser would be an ideal choice for high brightness high power laser diodes.

Interface Recombination and Threshold Current in Grinsch-QW ALGaAs/GaAs Laser Diodes

ABSTRACTA series of Graded-Index Waveguide Separate-Confinement Heterostructure Quantum Well (GRINSCH-QW) laser diodes were grown by MBE at the systematically varied substrate temperatures. The threshold current of laser diodes were found to depend strongly on the growth temperature. The structure and electrical characteristics of the laser diodes were studied by double-crystal x-ray diffraction, I-V-T, C-V and deep level transient spectroscopy (DLTS). The interface recombination is found to be the dominant carrier transport process in the high threshold current laser diodes and is closely related to the presence of the high concentration of deep traps and interface states. In the low threshold current laser diodes, diffusion process is found to be the dominant carrier transport process.

Broad area phase-locked superlattice barrier quantum well laser diode

The lateral coherence of an extremely broad-area laser diode is examined. The device was fabricated using molecular-beam epitaxy (MBE). For a 350- mu m-wide mesa laser, a single-lobed phase-locked narrow beam was obtained owing to the use of a high-uniformity quantum well graded-index waveguide separate confinement heterostructure (GRIN-SCH) with a short-period (AlGaAs)(GaAs) superlattice MBE-fabricated barrier layer.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Very low threshold current density GaInAs/AlGaInAs MQW lasers made by phosphorus-free MBE and operating in 1.5–1.6 μm range

Multiquantum-well lasers have been fabricated by molecular beam epitaxy (MBE) in the ‘phosphorus-free’ AlGaInAs/GaInAs system. For the first time, very low current densities were obtained: 940 A/cm2 for a 800 μm-long device at 1.58 μm. The structures used a quaternary alloy for the buffer layer and the quantum well barriers; the best result was obtained from a graded-index waveguide separateconfinement heterostructure.

Four-channel AlGaAs/GaAs optoelectronic integrated transmitter array

A monolithic four-channel optical transmitter at 0.8 μm wavelength has been fabricated. This has been achieved by using AlGaAs/GaAs optoelectronic integrated circuit (OEIC) approach. The OEIC chip contains four transmitter channels and each channel is composed of a graded-index waveguide separate-confinement heterostructure single quantum well laser, a monitor photodiode, and a laser driver circuit. The characteristics have been shown to be very uniform over four channels and pulse modulation responses over 1 Gb/s have been achieved.

An Improved Technique for Fabricating High Quantum Efficiency Ridge Waveguide AlGaAs/GaAs Quantum Well Lasers

A technique has been developed for improving the quantum efficiency and the temperature stability of ridge waveguide AlGaAs/GaAs quantum well lasers. Excellent lasing characteristics, including a differential quantum efficiency of 75%, have been achieved in graded-index waveguide separate-confinement heterostructure single quantum well lasers fabricated by this technique.

High-efficiency broad-area single-quantum-well lasers with narrow single-lobed far-field patterns prepared by molecular beam epitaxy

Broad-area single-quantum-well graded-index waveguide separate-confinement heterostructure lasers were fabricated by molecular beam epitaxy. A high external quantum efficiency of 79 percent and stable, single-lobed far-field patterns with a beam divergence as narrow as 0.8 deg (1.9 times diffraction limit) for a 100 micron-wide laser were obtained under pulsed conditions.

Monolithic integration of a low threshold current quantum well laser and a driver circuit on a GaAs substrate

An AlGaAs/GaAs graded-index waveguide separate-confinement heterostructure (GRIN SCH) laser and a laser driver circuit composed of four GaAs metal-semiconductor field-effect transistors have been monolithically integrated on a semi-insulating GaAs substrate. By introducing the GRIN SCH single quantum well (6 nm thick) structure, the integrated laser has exhibited room-temperature cw operation characteristics with an extremely low threshold current of 15 mA as well as a high quantum efficiency of 50%. Measurements have also shown the conversion ratio of laser output power to input gate voltage of 4.3 mW/V, and the turn-on and turn-off times of the light output of 400 and 900 ps, respectively, demonstrating high sensitivity and fast response performance of the present monolithic laser/driver.

Improving performance of AlGaAs/GaAs monolithic laser/FET by GRIN-SCH quantum-well laser

An AlGaAs/GaAs graded-index-waveguide separate-confinement-heterostructure (GRIN-SCH) single-quantum-well (SQW) laser has been monolithically integrated with a couple of field-effect-transistor drivers on a semi-insulating GaAs substrate. The adoption of the GRIN-SCH SQW laser has enabled an improvement in the laser/FET performance, exhibiting a low laser threshold current (12 mA) and a high sensitivity of the output light power to the input gate voltage (7.5 mW/facet/V).

Cw electro-optical characteristics of graded-index waveguide separate-confinement heterostructure lasers with proton-delineated stripe

Shallow proton-bombarded stripe-geometry (5 μm wide, 380 μm long) lasers were fabricated from graded-index waveguide separate-confinement heterostructure (GRIN-SCH) laser wafers grown by molecular beam epitaxy (MBE). Low median cw threshold currents of ∼50 mA were obtained for this stripe-geometry gain-guided structure. Such threshold currents represent a reduction by 25% from those of similar geometry lasers fabricated under the same technologies from the lowest threshold regular double heterostructure (DH) lasers wafers grown by MBE or liquid phase epitaxy (LPE). Up to the maximum measured output power of 10 mW/mirror (cw) the linearity is good and the symmetry of the output powers from both mirrors of these GRIN-SCH (gain guided) lasers compares well to those lasers of the buried heterostructure type (index guided). The average intrawafer variation in the symmetry of the two end mirror outputs can be characterized by the average of the quantity 〈α〉, which is the deviations from unity of the A/B power output ratio measured at 3 mW. For three LPE grown DH wafers 〈α〉 is about ±20%, and varies from ±5% to ±8% for three MBE grown DH wafers. For three GRIN-SCH wafers, 〈α〉 between ±3% and ±0.8% was obtained. The standard deviations of the cw threshold current distributions for MBE grown lasers (σ≂4 mA dc) are one-half that for LPE grown lasers. This documents the improved layer thickness and composition control achievable with the MBE growth procedure.

Ultra-low threshold, graded-index waveguide, separate confinement, CW buried-heterostructure lasers

Ultra-low-threshold semiconductor diode lasers were fabricated by forming buried heterostructures from MBE-grown graded-index waveguide, separate-confinement heterostructure (GRIN-SCH) wafers. CW threshold currents as low as 2.5 mA for 250 μm cavity length, output power as high as 20 mW/mirror and external quantum efficiency as high as 80% were obtained.