Measurements of optical losses in mid-infrared semiconductor lasers using Fabry-Perot transmission oscillations

We present a Fabry-Perot resonator technique for room temperature optical loss measurements on mid-infrared (lambdasimilar to2-4 mum) lasers. The quality of optical waveguides for lambdaapproximate to2.3 mum InGaAsSb/AlGaAsSb/GaSb interband lasers and a lambdaapproximate to3.7 mum strain-compensated InGaAs/InAlAs/InP quantum cascade laser have been estimated using this method. The optical losses for these lasers lie in the range 15-25 cm(-1) for interband lasers and 4-5 cm(-1) (transverse electric polarization) and 21-23 cm(-1) [transverse magnetic (TM) polarization] for the quantum cascade laser. The considerably higher losses for TM polarization in the case of quantum cascade laser are explained by intersubband absorption in the active layers. The method may be applied to structures with only a minimum amount of device processing, facilitating rapid progress in development of mid infrared laser designs in new materials systems. (C) 2004 American Institute of Physics.