Optical method for determining the amplitude of microwave current modulation in vertical-cavity surface emitting lasers

A method is described for optically measuring the amplitude of microwave current modulation in a vertical-cavity surface emitting laser (VCSEL). The method is based on comparing the laser-frequency variation induced by a change in the dc current component and the frequency variation resulting from the microwave current modulation. The shift is due to the heating of the laser cavity. Knowing the amplitude of the current modulation is important in the analysis of the modulation spectra of VCSELs, taking into account the dynamics of the interaction of the spectrum components with each other and with inversion.