A gallium indium arsenide antimonide (GaInAsSb)-based quantum-well laser designed and fabricated by researchers at the Universität Würzburg (Würzburg, Germany) operates at room temperature, emitting a single-mode continuous-wave beam at a record-long wavelength of 3019 nm, with a side-mode suppression ratio of greater than 30 dB. The development will enable high-sensitivity molecular spectroscopy in this wavelength range, for example in the form of relatively inexpensive but high-performance trace-gas analyzers.
A separate-confinement heterostructure and a buffer layer were grown on a GaSb substrate; claddings were tellurium- and beryllium-doped aluminum gallium arsenide antimonide (AlGaAsSb), and a contact layer was highly p-doped GaSb. Two GaInAsSb quantum wells were separated by a GaSb barrier. The distributed-feedback (DFB) laser contained a chromium grating as a wavelength selector. The maximum output power of the DFB laser was 3.6 mW at 20ºC, at a slope efficiency of 0.026 W/A at room temperature (threshold current was 195 mA). By changing the period of the grating, the laser’s output wavelength could be varied from 2970 to 3019 nm. The wavelength shift with temperature was 0.264 nm/K toward longer wavelengths. Contact Thomas Lehnhardt at [email protected].