Leon Shterengas

Continuous wave operation of diode lasers at 3.36μm at 12°C

GaSb-based type-I quantum-well diode lasers emitting at 3.36μm at 12°C with 15mW of continuous wave output power are reported. Devices with two or four InGaAsSb compressively strained quantum wells and AlInGaAsSb quinternary barriers were fabricated and characterized. It was shown that increase in the quantum-well number led to improved laser differential gain and reduced threshold current.

Room-temperature 2.5 μm InGaAsSb/AlGaAsSb diode lasers emitting 1 W continuous waves

We have characterized 2.5-μm-wavelength InGaAsSb/AlGaAsSb/GaSb two-quantum-well diode lasers that emit 1 W continuous waves from a 100-μm-wide aperture at a temperature of 12 °C. The threshold current density is 250 A/cm2, and the external quantum efficiency near threshold is 0.36. The wall–plug efficiency reaches a maximum of 12% at a current of 2 A. Operating in the pulsed-current mode, the devices output nearly 5 W at 20 °C. These lasers exhibit internal losses of about 4 cm−1 and differential series resistances of about 0.1 Ω. A broad-waveguide design lowers internal losses, and highly doped transition regions between the cladding layers and the GaSb reduces series resistance.

Design of high-power room-temperature continuous-wave GaSb-based type-I quantum-well lasers with λ > 2.5 µm

Measurements of gain, loss, threshold current, device efficiency and spontaneous emission of 2.5?2.82 ?m In(Al)GaAsSb/GaSb quantum-well diode lasers have been performed over a wide temperature range. The experimental results show that the thermal excitation of holes from the quantum wells into the waveguide where they recombine, but not Auger recombination, limits the continuous-wave room-temperature output power of these lasers, at least up to ? = 2.82 ?m. An approach to extend the wavelength of In(Al)GaAsSb/GaSb diode lasers beyond 3 ?m is discussed.

High-power room-temperature continuous wave operation of 2.7 and 2.8 μm In(Al)GaAsSb/GaSb diode lasers

We have fabricated and characterized 2.7 and 2.8 μm wavelength In(Al)GaAsSb/GaSb two-quantum-well diode lasers. All lasers have 2 mm cavity lengths and 100 μm apertures. Continuous wave operation up to 500 mW was recorded at 16 °C from 2.7 μm lasers, while 160 mW was obtained from 2.8 μm lasers. Threshold current densities as low as 350 A/cm2 were recorded from 2.7 μm lasers with external quantum efficiencies of 0.26 photon/electrons. The maximum wall-plug efficiency was 9.2% at a current of 2.4 A. A peak power of 2.5 W was recorded in pulsed-current mode operation at 20 °C at 2.7 μm and 2 W at 2.8 μm. Characteristic temperatures of T0=71 K and T1=86 K were measured from the 2.7 μm devices. T0=59 K and T1=72 K for the 2.8 μm lasers. The devices have differential series resistances of about 0.18 Ω with estimated thermal resistances of about 5 K/W.

High power 2.4μm heavily strained type-I quantum well GaSb-based diode lasers with more than 1W of continuous wave output power and a maximum power-conversion efficiency of 17.5%

The authors demonstrate a double quantum well GaSb-based diode laser operating at 2.4μm with a room-temperature cw output power of 1050mW and a maximum power-conversion efficiency of 17.5%. Laser differential gain with respect to current increases by a factor of 2 and laser threshold current is nearly halved when the compressive strain in the quantum wells is increased from 1.2% to 1.6%. This improvement is due to substantially improved hole confinement in the heavily compressively strained active region.

Type-I Diode Lasers for Spectral Region Above 3 μm

In this paper, we consider the role of carrier confinement in achieving high-power continuous wave (CW) room temperature operation of GaSb-based type-I quantum-well (QW) diode lasers at wavelengths above 3 μm. The use of compressive strain and quinternary barrier materials to confine holes in the active QWs allows the fabrication of 3-μm GaSb-based type-I QW diode lasers operating at 17 °C in the CW mode with output power of 360 mW. We will present the results of characterization of 2.2-μm diode lasers grown on metamorphic virtual substrates. The use of InGaSb virtual substrate makes it possible to fabricate devices with As free QWs. The prospects of using virtual substrates for development of GaSb-based type-I lasers will be discussed.

Continuous-wave room temperature operated 3.0μm type I GaSb-based lasers with quinternary AlInGaAsSb barriers

Diode lasers emitting at 3.0μm were designed and fabricated. Device active region contained two compressively strained InGaAsSb quantum wells incorporated in quinternary AlInGaAsSb barriers. Laser output power at room temperature was 130mW in continuous wave regime and more than 1W in pulse.

Room temperature operated 3.1μm type-I GaSb-based diode lasers with 80mW continuous-wave output power

High-power diode lasers with heavily-strained In(Al)GaAsSb type-I quantum-well active region emitting at 3.1 mum at room temperature are reported. Devices operate in continuous-wave regime with output power above 200 mW and 80 mW at 250 K and 285 K, correspondingly.

Nitrogen incorporation effects on gain properties of GaInNAs lasers: Experiment and theory

Gain properties of GaInNAs lasers with different nitrogen concentrations in the quantum wells are investigated experimentally and theoretically. Whereas nitrogen incorporation induces appreciable modifications in the spectral extension and the carrier density dependence of the gain, it is found that the linewidth enhancement factor is reduced by inclusion of nitrogen, but basically unaffected by different nitrogen content due to the balancing between gain and index changes.

Properties of unrelaxed InAs1−XSbX alloys grown on compositionally graded buffers

Unrelaxed InAs1−xSbx layers with lattice constants up to 2.1% larger than that of GaSb substrates were grown by molecular beam epitaxy on GaInSb and AlGaInSb compositionally graded buffer layers. The topmost section of the buffers was unrelaxed but strained. The in-plane lattice constant of the top buffer layer was grown to be equal to the lattice constant of unrelaxed and unstrained InAs1−xSbx with given X. The InAs0.56Sb0.44 layers demonstrate photoluminescence peak at 9.4 μm at 150 K. The minority carrier lifetime measured at 77 K for InAs0.8Sb0.2 was τ = 250 ns.