Spectral composition of radiation from microlaser coupled to waveguide

We investigate the mode composition of a microdisk laser coupled with an optical waveguide. The output spectra of emission and light-current characteristic of the microlaser obtained from the output edge of the waveguide are studied. The microlaser demonstrates single-mode emission in consecutive ranges of injection currents, that are alternated with pronounced mode hoping. The intensity of the modes changes non-monotonically with the growth of the pump current. Such a behavior, which we attribute to the laser self-heating, results in numerous kinks in the light-current curve. The kink-free current range in which single-mode lasing is maintained reaches 25 mA.