Method of characterizing the multicomponent spectrum of a VCSEL in devices based on the CPT effect

We propose and experimentally demonstrate a method of spectral measurement of multicomponent radiation emitted by a modulated vertical cavity surface-emitting laser (VCSEL) relying on peculiarities of absorption in alkali metal vapor. The method consists in determination of the radiation spectrum (which is formed due to RF modulation of the injection current of a diode laser) fromthe dependence of transmittance of rubidium vapor upon the radiation wavelength.We show that the proposed method allows fairly precise measurement of the spectrum of multicomponent radiation used in devices based on the coherent population trapping (CPT) effect when the frequency difference between the radiation components matches that between absorption lines of an alkali metal.