Specific features of the VCSEL spectra under microwave current modulation

Abstract

The optical spectrum of a vertical-cavity surface-emitting laser under microwave frequency current modulation is asymmetric in most cases, i.e., sidebands equidistant from the carrier have unequal powers. Spectra asymmetry is conventionally explained as a result of amplitude modulation affecting a phase-modulated field, but this approach does not give a comprehensive description of the asymmetry. We performed a sequential analysis based on Maxwell’s equations accounting for the nonlinear interaction of five spectral components of the laser field. This approach predicted a non-global asymmetry of the spectrum and a new resonant feature in the dependence of the second sidebands’ power ratio on the injection current, which we demonstrate experimentally.