Determination of single-pass optical gain and internal loss using a multisection device

We describe a technique for the measurement of optical gain and loss in semiconductor lasers using a single, multisection device. The method provides a complete description of the gain spectrum in absolute units and over a wide current range. Comparison of the transverse electric and transverse magnetic polarized spectra also provides the quasi-Fermi-level energy separation. Measurements on AlGaInP quantum well laser structures with emission wavelengths close to 670 nm show an internal loss of 10 cm(-1) and peak gain values up to 4000 cm(-1) for current densities up to 4 kA cm(-2). (C) 1999 American Institute of Physics. [S0003-6951(99)04243-6].