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The optimization of MBE growth conditions and layer structures for room temperature operation of 2.26mm AlGaAsSb/GaInAsSb laser structures is investigated. Index guided triple quantum well large optical cavity diode lasers with 64mm � 1000mm cavities and high reflection/antireflection coated facets reveal a cw output power of 350 mW at T ¼ 280 K. An internal quantum efficiency Zi of 69%, internal losses ai of 7.7 cm � 1 and a threshold current density for infinite cavity length of j1 ¼ 144 A/cm 2 are obtained for this structure. # 2001 Elsevier Science B.V. All rights reserved.

The influence of strain in Ga 0.7 In 0.3 As y Sb 1− y quantum wells (QWs) embedded in Al 0.24 Ga 0.76 As y Sb 1− y barriers on the photoluminescence (PL) emission wavelength and intensity has been investigated. The strain was adjusted by varying the As content in the QW and barrier layers. For As mole fractions in the (GaIn)(AsSb) QW layers between y =0.25 and 0.05, the average strain perpendicular to the growth plane changes from (Δ a / a ) ⊥ =2.0×10 −3 to 10.4×10 −3 for lattice matched (AlGa)(AsSb) barriers. At room temperature, highest PL intensities are obtained for QW structures with a net compressive strain of (Δ a / a ) ⊥ =8.7×10 −3 . In order to compensate the compressive strain in the QWs, strain-balanced laser core structures with barriers under tensile strain have been investigated. This was found to allow a reduction of the average strain in the laser core without shifting its emission wavelength. Ridge waveguide large optical cavity (LOC) laser diodes containing three compressively strained (GaIn)(AsSb) QWs embedded between lattice matched (AlGa)(AsSb) barriers show room temperature cw laser emission at a wavelength of 2.26 μm. For 64 μm wide and 600 μm long devices, a differential quantum efficiency of 43% and a threshold current density of 395 A/cm 2 with a characteristic temperature of T 0 =110 K are obtained.

The incorporation of As and In during MBE growth in (AlGaIn)/(AsSb) layers used for the fabrication of diode lasers in the 2.0–2.5 μm wavelength range has been investigated. The As content was found to depend linearly on the beam equivalent pressure for As mole fractions between y=0.05 and y=0.20. Broad area AlGaAsSb/GaInAsSb single-quantum well laser diodes with quasi-cw output at room temperature at an emission wavelength of 2.03 μm and a threshold current density of 515 A/cm2 for 1370 μm long and 70 μm wide devices have been fabricated. In order to shift the emission wavelength of the laser structures to longer wavelengths, the growth of lattice matched AlGaAsSb/GaInAsSb laser core structures with different In and As mole fractions in the quantum wells has been investigated.

Strained single- and triple-quantum-well (SQW and TQW), large optical cavity GaInAsSb/AlGaAsSb/GaSb laser diodes emitting at 2.26 μm are investigated. Internal loss coefficients as low as 5 and 7.7 cm−1 for the SQW and TQW, respectively, and relatively high internal quantum efficiencies of 65% (SQW) and 69% (TQW) were obtained. Extrapolated threshold current densities for infinite cavity lengths of 55 and 150 A/cm2 have been deduced for the SQW and TQW, respectively. These values scale very well with the number of QWs and are among the lowest reported for diode lasers in this wavelength range. A differential quantum efficiency as high as 50% and a total power efficiency of 23% were achieved at 280 K. The temperature dependence of the threshold current density revealed a high characteristic temperature of 110 K. Single-ended output powers of 240 mW in continuous-wave mode and exceeding 0.5 W in pulsed operation were obtained for a TQW laser with high-reflection/antireflection coated facets at 280 K, mounte...

In this paper we review recent progress achieved in our development of type-I GaInAsSb/AlGaAsSb quantum-well (QW) lasers with emission wavelength in the 1.74–2.34 μm range. Triple-QW (3-QW) and single-QW (SQW) diode lasers having broadened waveguide design emitting around 2.26 μm have been studied in particular. Comparing the two designs we have find that the threshold current density at infinite cavity length as well as the transparency current density scale with the number of QWs. Maximum cw operating temperature exceeding 50°C and 90°C has been obtained for ridge waveguide lasers emitting above and below 2 μm, respectively. Ridge waveguide diode lasers emitting at 1.94 μm exhibited internal quantum efficiencies in excess of 77%, internal losses of 6 cm−1, and threshold current density at infinite cavity length as low as 121 A/cm2 reflecting the superior quality of our diode lasers, all values recorded at 280 K. A high characteristic temperature TOof 179 K for the threshold current along with a value of T1 = 433 K for the characteristic temperature of the external efficiency have been attained for the 240–280 K temperature interval. Room temperature cw output powers exceeding 1.7 W have been demonstrated for broad area single element devices with highreflection/ antireflection coated mirror facets, mounted epi-side down. The latter result is a proof for the high power capabilities of these GaSb-based mid-ir diode lasers.

We report on the temperature dependence of threshold current for ridge waveguide Ga/sub 1-x/In/sub x/As/sub y/Sb/sub 1$/ -/sub y//Al/sub 0.29/Ga/sub 0.71/As/sub 0.02/Sb/sub 0.98/ triple-QW diode lasers grown by MBE on GaSb. In and As contents in the QWs were in the 0.16/spl les/x/spl les/0.30 and 0/spl les/y/spl les/0.15 range, respectively, resulting in different strain states, band gap energies and band offsets. Devices with lasing wavelengths extending from 1.8 to 2.3 /spl mu/m at room-temperature were tested in cw mode. Characteristic temperatures for the threshold current ranged from T/sub 0/=172 K at 1.94 /spl mu/m to T/sub 0/=93 K at 2.23 /spl mu/m and T/sub 0/=52 K at 2.34 /spl mu/m for the 200 to 280 K temperature interval. The pronounced drop in T/sub 0/ is associated with a significant decrease in the valence band offset from 0.27 eV to 0.22 eV and 0.14.

Summary form only given. We have demonstrated room-temperature CW operation of large optical cavity GaInAsSb-AlGaAsSb type-I QW lasers emitting at 2.25 /spl mu/m, lasing up to at least 320 K. A maximum current efficiency of 0.16 W/A and power efficiency of 17% has been achieved.

We report on room temperature cw operation of type-I semiconductor quantum well (QW) laser diodes based on the GaInAsSb/AIGaAsSb/GaSb material system emitting beyond 2.2 µm. Lasing is observed in cw mode up to at least 320 K. A high internal quantum efficiency of 65% and a low internal loss coefficient of 5 cm1have been achieved for a single QW (SQW)large optical cavity laser at 280 K. An extrapolated threshold current density for infinite cavity length of 144 A/cm2and 55 A/cm2has been deduced for the 3 QW and SQW lasers, respectively, which scales with the number of QWs. A maximum cw light output power of 230 mW at 280 K heatsink temperature was obtained for a 3 QW large optical cavity laser with HR/AR coated mirror facets, mounted substrate-side down.