D. Garbuzov

High-power (>10 W) continuous-wave operation from 100-μm-aperture 0.97-μm-emitting Al-free diode lasers

By incorporating a broad transverse waveguide (1.3 μm) in 0.97-μm-emitting InGaAs(P)/InGaP/GaAs separate-confinement-heterostructure quantum-well diode-laser structures we obtain record-high continuous-wave (cw) output powers for any type of InGaAs-active diode lasers: 10.6–11.0 W from 100-μm-wide-aperture devices at 10u2009°C heatsink temperature, mounted on either diamond or Cu heatsinks. Built-in discrimination against the second-order transverse mode allows pure fundamental-transverse-mode operation (θ⊥=36°) to at least 20-W-peak pulsed power, at 68×threshold. The internal optical power density at catastrophic optical mirror damage (COMD) PCOMD is found to be 18–18.5 MW/cm2 for these conventionally facet-passivated diodes. The lasers are 2-mm-long with 5%/95% reflectivity for front/back facet coating. A low internal loss coefficient (αi=1u2009cm−1) allows for high external differential quantum efficiency ηd (85%). The characteristic temperatures for the threshold current T0 and the differential quantum effic...

2.3-2.7-μm room temperature CW operation of InGaAsSb-AlGaAsSb broad waveguide SCH-QW diode lasers

A new approach in the design of (Al)InGaAsSb-GaSb quantum-well separate confinement heterostructure (QW-SCH) diode lasers has led to continuous-wave (CW) room-temperature lasing up to 2.7 /spl mu/m. This has been achieved by using quasiternary heavily strained InGaSb(As) QWs inside a broad-waveguide SCH laser structure. The QW compositions are chosen in the region outside the miscibility gap and, as a consequence, do not suffer from clustering and composition inhomogeneity normally found with quaternary InGaAsSb compounds of 2.3-2.7-/spl mu/m spectral range. Very low threshold current density (/spl sim/300 A/cm/sup 2/) and high CW output powers (>100 mW) were obtained from devices operating in the 2.3-2.6-/spl mu/m wavelength range.

4 W quasi-continuous-wave output power from 2 μm AlGaAsSb/InGaAsSb single-quantum-well broadened waveguide laser diodes

AlGaAsSb/InGaAsSb single-quantum-well (SQW) laser diodes emitting at 2 μm were fabricated and tested. At 10–15u2009°C, the uncoated SQW lasers with 2–3 mm cavity lengths exhibit a threshold current density of 115u2009A/cm2, a continuous-wave output power of 1.9 W, a differential efficiency of 53%, and a quasi-continuous-wave output power of 4 W. Their performance deteriorates rapidly as output losses increase beyond 10u2009cm−1.

14.3 W quasicontinuous wave front-facet power from broad-waveguide Al free 970 nm diode lasers

Wide-stripe, 0.97 μm emitting Al-free InGaAs(P)/InGaP/GaAs broad-waveguide separate confinement heterostructure quantum-well lasers demonstrate a record value for quasicontinuous wave (QCW) output power: 14.3 W (100-μm-wide stripe, 100 μs-wide pulses); and reach catastrophic optical mirror damage (COMD) in QCW operation at an optical power density of 22.5u2009MW/cm2; that is, 40% higher than COMD levels in cw operation. The devices have low internal losses (αi=1u2009cm−1) and high external differential quantum efficiency (86% for 2-mm-long lasers), and exhibit only 10–20u2009°C temperature rises in the active region at 10 W QCW power. We also show that long-cavity, large-contact-area devices exhibit relatively little spectral broadening with increased output power.

Temperature dependence of continuous wave threshold current for 2.3–2.6 μm InGaAsSb/AlGaAsSb separate confinement heterostructure quantum well semiconductor diode lasers

The dependence of spontaneous emission intensity on both current and temperature has been studied for 2.3–2.6 μm InGaAsSb/AlGaAsSb separate-confinement-heterostructure quantum well diode lasers operating in the continuous wave and pulsed regimes. We have used the temperature dependence of the nonradiative recombination processes in the active region to determine the dependence of threshold current on temperature for lasers operating in this wavelength range. The high T0 value (T0=110u200a°C) observed at T 65u200a°C and for 2.6 μm lasers in the whole temperature range studied has been identified with an enhancement of the Auger recombination process.

2.7‐μm InGaAsSb/AlGaAsSb laser diodes with continuous‐wave operation up to −39 °C

We have demonstrated continuous wave operation of 2.7‐μm InGaAsSb/AlGaAsSb multiquantum‐well diode lasers up to a temperature of 234 K (−39u2009°C). These devices were grown by molecular‐beam‐epitaxy. They have a tendency to operate in a dominant single mode over well‐defined temperature and current intervals. A comparison of spontaneous emission spectra shows that above threshold, the quasi‐Fermi level is pinned and that most of the carriers are injected into nonlasing states. This effect leads to a rapid decrease of differential efficiency with increasing temperature.

Effect of heterobarrier leakage on the performance of high-power 1.5 μm InGaAsP multiple-quantum-well lasers

Broad stripe 1.5 μm InGaAsP/InP multiple-quantum-well graded-index separate-confinement heterostructure lasers with different waveguide widths and doping profiles were designed, fabricated, and characterized. A record value of more than 16 W of pulsed optical power was obtained from lasers with a broadened waveguide design. Studies of the characteristics of lasers with different p-doping profiles as well as modeling data show that the heterobarrier electron leakage is responsible for the effect of the device optical power saturation with current.

Extraordinarily wide optical gain spectrum in 2.2–2.5 μm In(Al)GaAsSb/GaSb quantum-well ridge-waveguide lasers

A wide optical gain spectrum with full width at half maximum Δλ≈350 nm has been demonstrated in midinfrared (2.2–2.5 μm) room-temperature-operated InGa(As)Sb/GaSb quantum-well (QW) ridge-waveguide diode lasers. A QW width of 200 A ensured a small energy separation between the first and second quantized states in the QW. Transitions from both quantized states contributed equally to the overall gain spectrum when the optical loss was optimized.

11.5-W CW 1.83-μm diode laser array

We demonstrate high-power operation of both individual broad-waveguide separate-confinement-heterostructure quantum-well InGaAsP-InP laser diodes and 1-cm-wide arrays emitting at 1.83 /spl mu/m. Despite strong dependence of threshold current density and diode efficiency on operating temperature, a continuous-wave output power of 2.1 W has been obtained for 100-/spl mu/m-aperture lasers with 2-mm-long cavities. An output power of 11.5 W was reached for ten element 1-cm-wide array at a heatsink temperature of 16/spl deg/C.

Waveguide collapse In InGaAsP ridge-waveguide lasers with weak lateral optical confinement

Summary form only given. The maximum CW powers for single-mode diode lasers are limited by tolerable current and photon densities in their active regions. The maximum width of a single-mode laser active region is inversely proportional to /spl radic//spl Delta/n/sub B/, where /spl Delta/n/sub B/ is the built-in refractive index step at the active region boundary. In this paper, /spl lambda/=1.5 /spl mu/m InGaAsP/InP SCH 3QW broad-waveguide (600 nm) ridge waveguide lasers with low values of /spl Delta/n/sub B/ (5 - 7/spl times/10/sup -3/) have been investigated.