Influence of injection-current noise on the spectral characteristics of semiconductor lasers

The spectral characteristics of a semiconductor laser are altered by injecting additional noise current into its current-drive port. A continuously varying spectral linewidth from about 5 MHz to above 100 MHz is achieved experimentally in this semiconductor laser. The conditions under which the line shape changes from a standard Lorentzian shape to a Gaussian shape as functions of laser power and noise current are investigated and compared with an existing theoretical treatment.