High-power diode lasers between 1.8µm and 3.0µm

Abstract

High-power diode lasers in the mid-infrared wavelength range between 1.8μm and 3.0μm have emerged new possibilities for solid-state pumping and direct material applications based on water absorption with favoured wavelengths at 1.94μm and 2.9μm. GaSb based diode lasers are naturally predestined for this wavelength range. We will present results on MBE grown (AlGaIn)(AsSb) quantum-well diode laser single emitters and laser arrays at different wavelengths between 1.8μm and 3.0μm. At 1.94μm different epitaxial designs have been investigated in order to optimize the GaSb based diode lasers for higher wall-plug efficiency and higher brightness. More than 30% maximum wall-plug efficiency in cw operation for single emitters could be demonstrated for resonator lengths of 1mm. At 2.25μm a high wall-plug efficiency of 24% has been measured. For 2mm resonator length by using asymmetric waveguide structures the wall-plug efficiency could be doubled. Fast axis far field widths of 70 degree (95% power included) have been demonstrated. At 2.9μm emitting wavelength broad-area lasers with 2mm resonator length with 360mW at 10°C heat sink temperature are presented. We have also started to transfer the concepts for higher brightness to this wavelength regime. 19-emitter laser arrays emitting at 1.94μm have been packaged on actively cooled heat sinks. Comparable high wallplug efficiencies have been measured with p-side down and p-side up packaging. In all configurations far field widths are well below 90 degree (95% power included). Finally a record value of 140W have been measured for a stack built of 10x 20% fill factor bars emitting at 1.91μm.