Parasitic element influence on the wide-band electrical noise and modulation response of semiconductor lasers

The influence of parasitic elements on the wide-band electrical noise in GaAlAs BH-BOG lasers is investigated theoretically and experimentally. The results show that the maximum small-signal modulation bandwidth can be determined from measurements of the electrical noise spectrum. A small difference of the peak frequency in the optical intensity noise and the peak frequency in the electrical noise spectra is observed (about 200 MHz), and it is explained by introducing the nonlinear intrinsic diode impedance in the parasitic element model. However, the peak frequency in the small-signal modulation response spectrum coincides with the peak frequency in the electrical noise spectrum. It is also shown that the spectral line width, calculated from electrical noise measurements, is not significantly affected by the parasitic element filtering. The electrical noise level is observed to approach an inverse output power dependence at high pumping rates, in good agreement with theoretical calculations.