Determination of internal loss and quasi-Fermi level separation from the amplified spontaneous emission spectrum of Fabry-Pérot semiconductor lasers

The net modal gain and the un-amplified spontaneous emission (ASE) coupled into the laser waveguide mode are extracted from the ASE spectrum of Fabry-Pérot semiconductor lasers by the Fourier transform method with a deconvolution process. Highly accurate quasi-Fermi level separation and internal loss are then derived by a minimum search process from the relationship between the spontaneous emission and gain.