GaSb-based narrow ridge waveguide laser diode with single transverse mode operation

We have fabricated and characterized a narrow ridge waveguide InGaSb/AlGaAsSb type-I separate-confinementheterostructure (SCH) multi-quantum-well (MQW) laser diode emitting near 2.0μm. The broadened vertical waveguide laser structure is grown by the solid-state molecular beam epitaxy. The 4.5μm lateral ridge waveguide results in a single transverse mode operation of the laser with an injunction current below 200mA at a heat sink temperature of 293K. This laser diode provides a room temperature continuous-wave output power of 40mW at a driving current of 200mA with a 1mm cavity length and 97/5% high-reflection/anti-reflection coatings, mounted epi-side down. The far-field beam intensity distribution on the fast and slow axis of the laser diode demonstrates a TE₀₀ fundamental transverse mode laser beam with the fast and slow axis beam divergence of 58°*23° full width at half maximum (FWHM). The diode lasers operating on fundamental spatial mode are efficiently coupling into optical fibers or collimating for free-space applications. The midinfrared region single transverse mode GaSb-based laser is hence an ideal light source for spectroscopic sensing and diodepumping pumping fiber amplifiers and solid-state lasers systems.