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Photoreflectance (PR) and photoluminescence (PL) have been applied to study the band structure and PL thermal quenching for Ga0.24In0.76Sb/GaSb quantum wells (QWs) of the widths varying from 10 to 21 nm. In the case of PR spectra, a strong GaSb-related resonance followed by Franz–Keldysh oscillations and PR resonances associated with optical transitions between the QW ground and the excited states have been clearly observed. The QW transitions have been identified on the basis of theoretical calculations which were performed in the framework of the effective mass model. Satisfactory agreement between theoretical calculations and experimental data has been found for the conduction band offset of ∼80%–85% that is consistent with the theoretical predictions, which were obtained within the “model-solid” theory. In the case of PL measurements, a very efficient QW emission without any localization features has been observed in the temperature range of 10–280 K. It has been concluded that the thermal quenching of PL can be described by a standard expression with two characteristic activation energies, which can be attributed to an electron escape and a heavy-hole escape to the conduction and valence continua in GaSb barriers, respectively. The obtained activation energies are in the range of 20–30 and 80–100 meV for the first and the second quenching mechanism, respectively. The Varshni parameters for the QW ground state transition have been determined to be α=0.36–0.39 meV/K and β=155–175 K. [ABSTRACT FROM AUTHOR]

Photoreflectance (PR) and photoluminescence (PL) are applied to study the band structure and PL thermal quenching for [Ga.sub.0.24][In.sub.0.76]Sb/GaSb quantum wells (QWs) of the varying widths. The thermal quenching of PL is described by a standard expression with two characteristic activation energies, which is attributed to an electron escape and a heavy-hole escape to the conductance and valence continua in GaSb barriers.

GaSb-based diode lasers emitting at a wavelength of 2.8 \mum have been grown. The devices feature GaSb or Al0.21Ga0.58In0.21As0.20Sb0.80 barrier layers for the quantum wells, respectively. The transparency current density, modal gain, internal absorption, and characteristic temperature have been investigated on both devices. Since the barrier layers serve at the same time as waveguide for the laser light, the optical properties and the impact on device performance have been determined. The refractive index for Al0.21Ga0.58In0.21As0.20Sb0.80 has been estimated to be 3.26. [ABSTRACT FROM PUBLISHER]

We report a mode-locked antimonide-based semiconductor disk laser operating at 2 mum, synchronously pumped with a pulsed source incorporating a 1.57-mum diode laser, a lithium niobate intensity modulator, and an erbium-doped fiber amplifier. The method for producing the pump signal utilizes commercially available telecom components and allows for convenient selection of the mode-locking harmonics. When compared with configurations based on mode-locked pump sources, the generation of pump pulses using amplitude modulation and digital data technology is simple and offers the possibility to actively lock the optical pulses to a stable clock. [ABSTRACT FROM PUBLISHER]

The authors present coupled cavity lasers on the AlGaIn-AsSb material system embedded in a matrix of two-dimensional photonic crystals serving both as interruption between the cavities and as highly reflecting micro-scaled-back mirrors. These widely tunable lasers emit single-mode with sidemode suppression ratios up to 40 dB over a wavelength range of 47 nm from 1965 up to 2012 nm and exhibit output powers up to 13.5 mW. [ABSTRACT FROM PUBLISHER]

The optical transitions in Ga0.76In0.24As0.08Sb0.92/GaSb quantum wells with the width varying from 10 to 21 nm were studied by room temperature contactless electroreflectance (CER). In addition to the quantum well (QW) ground state transition (11H), the 22H and 33H transitions (where klH denotes transition between the kth heavy hole and the lth electron subbands) have been clearly observed in CER spectra. The experimental QW transition energies were compared with theoretical predictions based on an effective mass formalism model. It has been concluded that this QW is type I for both electron and holes and the conduction band offset for the unstrained Ga0.76In0.24As0.08Sb0.92/GaSb interface equals ∼90%. [ABSTRACT FROM AUTHOR]

Wide range tunable lasers based on the coupling of two Fabry-Peacuterot resonators have been realized in the (AlGaIn)(AsSb) material system. The laser consists of two longitudinally oriented ridge waveguide cavities coupled through an etched gap. By carefully controlling the injection current of each resonator and, therefore, varying the corresponding resonator temperature, a single-mode tuning range of 45 nm is achieved [ABSTRACT FROM PUBLISHER]

A 2 µm semiconductor disk laser with a tuning range of 35 nm and output power exceeding 500 mW is reported. The method for generating wavelength-tunable radiation is based on self-seeding the disk laser using optical feedback from a diffraction grating. [ABSTRACT FROM AUTHOR]

Room-temperature continuous-wave operation of a singlemode GaInAsSb/GaSb/AlGaAsSb distributed feedback (DFB) laser is presented at a record long emission wavelength for this material system of 2.843 µm. The threshold current at 20°C is 75 mA. Mode selection was realised by metal gratings laterally patterned to a ridge waveguide. By varying the grating period, DFB emission from 2.738 up to 2.843 µm is obtained. [ABSTRACT FROM AUTHOR]

We present the realization of two-dimensional (2D) photonic crystals (PhCs) on the GaSb material system. An electron cyclotron resonance reactive ion etch process using Cl(2)/Ar allows the fabrication of PhCs covering air fill factors of f = 20%-50%, lattice periods of a = 400-500 nm and aspect ratios of 5:1. Quality and reflectivity of these structures are evaluated by incorporating the PhCs as high reflective back mirrors in GaSb-based ridge waveguide lasers with cavity lengths between 200 and 1100 µm with the front facet as cleaved. The shortest devices show remarkable threshold currents below 12 mA and efficiencies of 0.23 W A(-1), yielding a maximum output power of almost 19 mW, proving the applicability of the chosen approach to numerous further concepts based on 2D PhCs on the GaSb material system.

For the first time, lasers with short period superlattice based quantum wells have successfully been fabricated and characterized on the (AlGaIn)(AsSb) material system. These new quantum wells are composed of alternating InSb/Ga(x)In(1-x)Sb layers with submonolayer thickness. Distributed-feedback lasers fabricated from the epitaxial layers emit in the wavelength range around 1.9 µm. Side mode suppression ratios over 35 dB and very low threshold currents of 23 mA were realized. The laser emission wavelength can be varied from 1.844 to 1.902 µm using grating periods between 255.0 and 263.8 nm.

We report a high-power optically pumped semiconductor vertical external cavity surface emitting laser operating at 2-mum wavelength. The gain material consisted of 15 GaInSb quantum-wells placed within a three-lambda GaSb cavity and grown on the top of an 18-pairs AlAsSb/GaSb Bragg reflector. For thermal management we have used a transparent diamond heat spreader bonded on the top of the structure. When cooled down to 5 degrees C, the laser emitted up to 1 W of optical power in a nearly diffraction-limited Gaussian beam demonstrating the high potential of antimonide material for VECSEL fabrication.