Measurement of Gain Spectra of Semiconductor Lasers Using Least Squares Fitting Method

A new technique for the measurement of net modal gain spectra of semiconductor lasers is presented. The technique is based on a least squares curve fitting to each longitudinal mode of amplified spontaneous emission spectrum. The errors of measurement over a wide wavelength range because of the asymmetric shape of individual mode and the limit resolution of the optical spectrum analyzer are greatly reduced, compared with those of conventional methods.