Sergey Suchalkin

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.

Optical gain and loss in 3 μm diode “W” quantum-well lasers

Gain in broad-area midinfrared diode “W” lasers (λ=3–3.1 μm) has been measured using lateral mode spatial filtering combined with the Hakki–Paoli approach. The internal optical loss of ≈19 cm−1 determined from the gain spectra was the same for devices with either ten or five period active regions and nearly constant in the temperature range between 80 and 160 K. Analysis of the differential gain and spontaneous emission spectra shows that the main contribution to the temperature dependence of the threshold current is Auger recombination, which dominates within almost the entire temperature range studied (80–160 K).

Widely tunable type-II interband cascade laser

We discuss an ultrawide, voltage-tunable type-II mid-IR interband cascade laser. Its design has a charge accumulation layers outside of the optically active quantum wells that unclamps the electron-hole concentrations and facilitates above-threshold Stark shifts. Our results demonstrate laser tuning of 120nm (120cm−1).

Experimental study of the optical gain and loss in InAs/GaInSb interband cascade lasers

Optical gain and loss have been measured in type II InAs/GaInSb interband cascade lasers operating in the 3.4–3.6 μm wavelength range. The maximum temperature of cw operation was found to be limited by strong gain saturation due to active region overheating, while the temperature increase of the total optical loss was relatively small. In devices with a longer lasing wavelength and a thinner substrate-side cladding layer, a strong periodic modulation of the optical gain spectra was observed. This effect is consistent with resonant optical leakage into the substrate.

GaSb based light emitting diodes with strained InGaAsSb type I quantum well active regions

Mid-IR (λ≈3–3.5 μm) light emitting diodes with quinternary AlInGaAsSb barriers and InGaAsSb strained quantum wells grown on GaSb substrates have been demonstrated. The devices produced a quasi-cw emission power of 0.7 mW at room temperature and 2.5 mW at T=80 K.

200 mW type I GaSb-based laser diodes operating at 3 μm: Role of waveguide width

Laser diodes based on AlInGaAsSb/InGaAsSb heterostructures with different waveguide widths were designed and fabricated. The decrease in the waveguide width from 1470 to 470 nm led to the improvement of the device performance. Lasers with 470 nm quinternary waveguides demonstrated 200 mW continuous wave output power at room temperature.

Different components of far-infrared photoresponse of quantum Hall detectors

We have performed time-resolved measurements of the far-infrared photoresponse of two-dimensional electron systems in the quantum Hall regime. The photoresponse consists of two equally important components: the longitudinal component, caused by the photoinduced change of the longitudinal resistance Rxx, and the transversal component, caused by the photoinduced Hall currents and by the photoinduced change of Rxy. Both these components are connected with two mechanisms of the photoresponse: a nonresonant bolometric, and a cyclotron-resonant contribution.

High performance interband cascade lasers at 3.8 microns

An interband cascade laser design has been grown by molecular beam epitaxy using uncracked arsenic and antimony sources. Lasers were fabricated into both broad-area and narrow-ridge devices, with cavity lengths ranging between 1 mm and 4 mm. At 300K, under low-duty-cycle pulsed conditions, threshold current densities for lasers with 2-mm cavity lengths are as low as 395 A/cm2, with optical emission centered at a wavelength of ~3.82 μm at 300 K. Continuous-wave (cw) performance of the narrow-ridge devices has been achieved for temperatures up to almost 60°C. We present results of both pulsed (broad-area and ridge) and cw (ridge only) measurements on these lasers, including L-I-V, spectral, cavity-length, and Hakki-Paoli analyses.

High dimensional addressable LED arrays based on type I GaInAsSb quantum wells with quinternary AlGaInAsSb barriers

GaSb-based type I InGaAsSb quantum well mid-infrared (mid-IR) light-emitting diodes (LEDs) operated at wavelengths up to 3.66 µm are demonstrated. The application of quinternary AlGaInAsSb barriers improved hole confinement in the quantum wells and enabled an LED radiant excitance of 1.3 W cm−2 (λ = 3.66 µm) at 100 K which corresponds to the emittance of a blackbody at 1350 K. High-contrast individually addressed 512 × 512 LED arrays were designed and fabricated using wet etching. An accurate characterization technique for mid-IR LEDs has been developed.

Dual wavelength GaSb based type I quantum well mid-infrared light emitting diodes

We have designed and developed dual wavelength type I quantum well light emitting diodes (LEDs) operating at 2 μm and 3–3.4 μm wavelengths with independently controlled intensities. The room temperature quasicontinuous wave output power was 2.8 mW at 2 μm and 0.14 mW at 3 μm. The design of the dual wavelength structure allows for monolithically integrating LED pixels with different wavelengths opening the way for the fabrication of multiwavelength LED arrays for multispectral and hyperspectral imaging applications.