High-power, high-temperature operation of AlInGaAs-AlGaAs strained single-quantum-well diode lasers

Strained layer AlInGaAs-AlGaAs graded-index separate-confinement heterostructure single-quantum-well diode lasers with cavity width and length of 500 and 1000 mu m, respectively, have been operated continuous-wave (CW) at heatsink temperatures up to 125 degrees C, with output power up to 4.9 W per facet and power efficiency as high as 49% measured at 10 degrees C. Promising results have been obtained in initial reliability tests on uncoated devices at heatsink temperatures of 10 and 50 degrees C.<>     

Low-threshold 840-nm laterally oxidized vertical-cavity lasers using AlInGaAs-AlGaAs strained active layers

We explore the use of a novel strained AlInGaAs-AlGaAs material system to achieve low-threshold current in oxide-apertured vertical-cavity lasers (VCLs) emitting near 850 nm. We report a low continuous-wave (CW) room-temperature threshold current of 290 /spl mu/A from top-emitting, 840-nm VCLs with a 5-/spl mu/m-wide thin-oxide aperture. The low-threshold current has been attributed to the use of strained active layers, which increase the gain and reduce the transparency current. We also studied the effects of post-growth rapid thermal annealing (RTA) on the characteristics of AlInGaAs-AlGaAs VCLs and found that RTA improves the material quality and significantly enhances VCL performance.     

One watt CW visible single-quantum-well lasers

We report room-temperature CW high output power (1 W) at ~ 7770 ? from OM-VPE-grown ultra-thin single-quantum (~60 ?)-well lasers. The devices are broad-area (250 × 210 ?m) lasers with a quantum-well GaAlAs active region doped with Mg, and with applied high reflective and low reflective mirror facets. For an output power of 1 W from the emitting facet, the DC-to-light conversion efficiency is as high as 21%.     

2μm InGaSb/AlGaAsSb应变量子阱激光器的MBE生长研究

摘要：对InGaSb/AlGaAsSb应变量子阱和GaSb接触层掺Te的MBE生长进行了研究。通过原子力显微镜(AFM)、X射线衍射(XRD)设备、光致发光谱(PL)测试,对应变量子阱的生长参数进行了优化。量子阱室温PL测试,发光波长为1.98 μm,半峰宽为115nm。通过Hall测试优化了GaSb外延掺Te的生长参数,最优的掺杂浓度为1.1271018 cm-3,电阻率为5.29510-3Ω?cm。     

Molecular beam epitaxy growth of InGaSb/AlGaAsSb strained quantum well diode lasers

2μm InGaSb/AlGaAsSb strained quantum wells and a tellurium-doped GaSb buffer layer were grown by molecular beam epitaxy（MBE）.The growth parameters of strained quantum wells were optimized by AFM, XRD and PL at 77 K.The optimal growth temperature of quantum wells is 440℃.The PL peak wavelength of quantum wells at 300 K is 1.98μm,and the FWHM is 115 nm.Tellurium-doped GaSb buffer layers were optimized by Hall measurement.The optimal doping concentration is 1.127×10¹⁸ cm^-3 and the resistivity is 5.295×10^-3Ω·cm.     

Characterization of thin p-clad InGaAs single-quantum-well lasers

Low-ridge, thin p-clad InGaAs single-quantum-well (SQW) lasers with shiny Au contacts have been fabricated using a pulsed anodic oxidation technique. Although the ridge is very low (130 nm), the lateral refractive index step is sufficiently large to provide strong lateral waveguiding. Pulsed current measurements of threshold current, operating wavelength, and lateral far field as a function of ridge width are presented and compared with measured values reported for low-ridge and oxide-defined lasers fabricated from conventional thick p-clad material. The CW performance characteristics of five-micron-wide, low-ridge, thin p-clad lasers are shown to be comparable to those of conventional InGaAs SQW high-ridge waveguide lasers     

Electrically pumped circular-grating surface-emitting DBR laser onInGaAs strained single-quantum-well structure

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     

High-speed operation of single-quantum-well lasers with large gaincompression

It is shown that the overdamped response of single-quantum-well lasers due to a large gain compression can be countered by the destabilizing effect of an intracavity saturable absorber. Modulation bandwidths (3 dB) of up to 13 GHz for single-quantum well lasers were obtained using this technique     

High-brightness, high-efficiency, single-quantum-well laser diode array

Single-quantum-well, separate-confinement double-heterostructure laser diode arrays which exhibit a high power conversion efficiency of greater than 54% have been demonstrated. The high efficiency results from a low internal loss of 3cm1 and high internal conversion efficiency. The maximum output power for a 100?m emitting aperture is 2 W CW and is independent of the cavity length.     

Operating characteristics of single-quantum-well AlGaAs/GaAshigh-power lasers

The operating characteristics of six types of graded-index separate confinement heterostructure single-quantum-well wide-stripe lasers grown by metalorganic chemical vapor deposition are reported. The lasers exhibited intrinsic mode losses as low as 3 cm^-1 and internal quantum efficiencies near unity. Measured differential gain coefficients range from 3.7 to 6.5 cm/A, and extrapolated transparency current densities range from 54 to 145 A/cm². These wide-stripe lasers are typically multilongitudinal mode and exhibit narrowing of the gain envelope and lateral far-field pattern as the cavity length increases. The high value of T₀(>200 K) at long cavity lengths in conjunction with the low current density permits junction-side-up operation to CW optical powers of 0.5-0.7 W/facet, at which level catastrophic facet damage occurs on the uncoated devices. A maximum power conversion efficiency of 57% was measured on the laser structure exhibiting the lowest threshold current     

Self-defined AlAs oxide-current-aperture buried-heterostructureridge waveguide InGaAs single-quantum-well diode laser

Techniques for fabricating a self-defined AlAs oxide-current-aperture that is applicable to very small stripe width edge emitting devices and small aperture vertical-cavity surface-emitting lasers are reported. InGaAs single-quantum-well buried-heterostructure edge-emitting lasers with a self-defined AlAs oxide-current-aperture were fabricated by a three-step metal-organic chemical vapor deposition growth to demonstrate the validity of the process. The AlAs layer for the AlAs oxide was grown by selective area growth techniques. The threshold current and differential quantum efficiency of 3-μm stripe width, 446-μm-long laser were 2 mA and 91%, respectively. The leakage current at -15 V was less than 20 nA     

1.5< lambda <1.7 mu m strained multiquantum well InGaAs/InGaAsP diode lasers

The long wavelength limitations of strained In/sub 0.7/Ga/sub 0.3/As/InGaAsP four-quantum well (QW) lasers are investigated. For this confining structure and QW composition, wavelengths range from 1.52 to 1.72 mu m for QW thicknesses between 33 and 70 AA, and there is an optimum QW thickness of approximately 40 AA.<>     

Very low threshold current ridge-waveguide AlGaAs/GaAs single-quantum-well lasers

Ridged-waveguide AlGaAs/GaAs single-quantum-well lasers were fabricated from a molecular-beam-grown GRIN-SCH wafer in which a superlattice buffer layer was introduced. Fabricated diodes exhibited excellent lasing characteristics including a very low threshold current of 5 mA with a T0 value as high as 160 K.     

High-efficiency AlGaAs/GaAs single-quantum-well semiconductor laser with strained superlattice buffer layer

The use of a strained superlattice buffer (SSLB) layer composed of a short-period (InGaAs)(GaAs) superlattice in a lattice-matched AlGaAs/GaAs system in order to reduce the internal stress is discussed. A five-times-higher photoluminescence peak intensity has been observed from a single quantum well (SQW) with the SSLB than without the SSLB. A high-quantum efficiency, a small cavity loss, and high-output power operation have been achieved in a narrow ridge-waveguide 770-nm graded-index-separate confinement heterostructure SQW laser diode with the SSLB.<>     

Band-structure engineering in strained semiconductor lasers

The influence of both compressive and tensile strain on semiconductor lasers and optical amplifiers is reevaluated in the light of recent experimental and theoretical work. Strain reduces the three-dimensional symmetry of the lattice and helps match the wave functions of the holes to the one-dimensional symmetry of the laser beam. It can also decrease the density of states at the valence band maximum and so reduce the carrier density required to reach threshold. These two effects appear to adequately explain the TE and TM gain in compressive and tensile structures, including polarization-independent amplifiers, the behavior of visible lasers and the improved frequency characteristics of InGaAs/GaAs lasers. In 1.5 μm InGaAsP/InP lasers phonon-assisted Auger recombination appears to remain the dominant current path and can explain why the temperature sensitivity parameter to remains <100 K at room temperature     

Single-lobe phased-array diode lasers

We show mathematically that the lowest-order supermode of a real-refractive-index phase-locked semiconductor diode laser array, which radiates into a single narrow far-field lobe, is favoured by its lower threshold when the gain in the interspaces between the waveguides exceeds that of the waveguides themselves.     

Q-switched semiconductor diode lasers

Diode lasers with an intracavity electroabsorption modulator have been operated with full on/off modulation at rates of 3 GHz. In addition, modulation of the lasers has been shown up to a detector-limited frequency of 6 GHz. A new model of these devices, which includes amplified spontaneous emission and high gain is developed in this paper. A quasi-static gain approximation is introduced and the dynamics of the electron and photon population are modeled by three coupled nonlinear difference equations which can be numerically solved with very little computation time. The model predicts the possibility of a new mode ofQ-switched operation with the capacity for repetition rates of tens of gigahertz and binary pulse position modulation at rates of the order of 10 Gbits/s.     

Improved performance of long-wavelength strained bulk-likesemiconductor lasers

The authors show that the incorporation of either tensile or compressive strain can have significant advantages for long-wavelength bulk-like lasers, with greater advantage being achieved in tensile-strained structures. The differential gain is enhanced compared to unstrained structures and a larger peak gain can be achieved than in comparable structures under biaxial compression. The effect of the spin-orbit interaction on the polarized gain and character of the valence states is calculated as a function of built-in strain. The spin-split-off band is included in the calculations and it is shown that the strain-induced interaction with this band has a significant influence on laser characteristics. The effect of biaxial strain on the major intrinsic loss mechanism of Auger recombination in long-wavelength 1.55-μm lasers is investigated     

High-temperature operation of InGaAs strained quantum-well lasers

Strained-layer quantum-well (SQW) laser structures have been investigated for avionics applications requiring high-temperature performance. The authors have successfully demonstrated InGaAs-GaAs SQW lasers capable of CW operation up to 200 degrees C with more than 5 mW single-mode optical power. These lasers have an emission wavelength of approximately=980 nm, threshold current density of 200 A/cm/sup 2/, differential quantum efficiency of 60%, high output power of approximately=1 W with 50 mu m stripe, and characteristic temperature of 130-140 K.<>     

Very low threshold graded-indexseparate-confinement-heterostructure strained InGaAsPsingle-quantum-well lasers

A low threshold current density of ~100 A/cm² has been obtained at 1.55 μm using a graded-index separate-confinement-heterostructure strained InGaAsP single-quantum-well laser. The design of the laser structure is based on results calculated from the viewpoint of effective carrier injection into the well