Alan R. Sugg

Continuous-wave operation of λ=3.25 μm broadened-waveguide W quantum-well diode lasers up to T=195 K

Mid-infrared (λ=3.25 μm) broadened-waveguide diode lasers with active regions consisting of 5 type-II “W” quantum wells operated in continuous-wave (cw) mode up to 195 K. At 78 K, the threshold current density was 63 A/cm2, and up to 140 mW of cw output power was generated. A second structure with ten quantum wells operated up to 310 K in pulsed mode.

High-temperature continuous-wave 3–6.1 μm “W” lasers with diamond-pressure-bond heat sinking

Optically pumped type-II W lasers emitting in the mid-infrared exhibited continuous-wave (cw) operating temperatures of 290 K at λ=3.0 μm and 210 K at λ=6.1 μm. Maximum cw output powers for 78 K were 260 mW at λ=3.1 μm and nearly 50 mW at λ=5.4 μm. These high maximum temperatures were achieved through the use of a diamond-pressure-bonding technique for heat sinking the semiconductor lasers. The thermal bond, which is accomplished through pressure alone, permits topside optical pumping through the diamond at wavelengths that would be absorbed by the substrate.

Mid-infrared W quantum-well lasers for noncryogenic continuous-wave operation

We review the recent progress of electrically injected and optically pumped mid-IR lasers based on antimonide quantum wells with the type II W configuration. W quantum-well diodes have achieved cw operation up to 195 K at lambda = 3.25 mum. Optically pumped devices that employ the diamond pressure bond heat sink have reached 290 K at 3 mum and 210 K at 6 mum. Pulsed power conversion efficiencies of up to 7% at 220 K have been attained by use of an optical pumping injection cavity approach, in which an etalon cavity for the pump beam significantly enhances its absorptance. The angled-grating distributed-feedback configuration has been used to obtain near-diffraction-limited output for an optical pumping stripe width of 50 mum.

High power linear arrays of 1.9 /spl mu/m laser diodes

We describe the development of high-power single-aperture InGaAsP-InP laser diodes at 1.9 /spl mu/m emitting 1 W CW and 2.2 W pulsed optical power. Linear arrays of 10 of these diodes gave 5 W CW and 11 W pulsed optical power. The InGaAs-InGaAsP-InP broadened waveguide (BW) lasers were grown by using a Riber gas-source molecular beam epitaxy (GSMBE) reactor. The structure consists of a two-step undoped confinement heterostructure or waveguide sandwiched between highly doped InP cladding regions. The QWs are composed of compressively strained InGaAs layers.

Optically pumped mid-infrared type-II lasers: advances in high-temperature performance

Optically-pumped type-II W lasers have exhibited improved high-temperature performance throughout the wavelength range of 2.7 micrometer to 7.3 micrometer. Low duty cycle pumping at 2.1 micrometer yielded maximum operating temperatures as high as 360 K at (lambda) less than or equal to 4 micrometer for 3 devices, with peak output powers exceeding 1.5 W at ambient temperature. Internal losses of 90 cm-1 at 300 K were seen for one device and suppressed Auger recombination coefficients were observed for all three. Pulsed operation at wavelengths as long as 7.3 micrometer was seen in another device which had a maximum operating temperature of 220 K. For 1.064 micrometer optical pumping, the same laser was able to operate in continuous-wave (cw) mode to 130 K. Cw operation was also observed at temperatures as high as 290 K for lambda approximately equals 3.0 micrometer. Maximum cw output powers (per uncoated facet) of 260 mW at (lambda) equals 3.1 micrometer and 50 mW at (lambda) equals 5.4 micrometer were observed at T equals 77 K. With further improvements in the design and growth quality of these W laser structures, it is projected the cw output powers of 0.5 W or more should be achievable at thermoelectric cooler temperatures.

High-temperature CW operation of optically-pumped W-lasers

We report the high-temperature cw operation of optically-pumped W-lasers (so named because of the shape of the conduction band minimum). The active region of the MBE-grown structure consists of 80 periods of 16/25/40 /spl Aring/ InAs-GaInSb-AlAs-AlAsSb clad on top and bottom. The cladding and active regions are lattice matched to the GaSb substrate.