Measurement of semiconductor laser gain and dispersion curves utilizing Fourier transforms of the emission spectra

A new technique for the measurement of semiconductor laser gain and dispers ion spectra is presented. The technique is based on an analysis of the subt hreshold emission spectrum by Fourier transforms. Applications of this meth od to AlGaInP-based interband laser diodes and mid-infrared intersubband qu antum cascade lasers are discussed. A good agreement between the measured d ispersion of the refractive index and tabulated values in the literature wa s found.