Modulation of phased-array semiconductor lasers at K-band frequencies

The possibility of phase locking the lateral modes of a multiple-emitter semiconductor-laser phased array by modulating at the beat frequency of the lateral modes is presented. A rate equation model of a twin-emitter array is introduced and used to find the response of the optical output of the array to small sinusoidal modulations of the injection current. In-phase modulation of the emitters is found to be ineffectual, while modulating the emitters 180° out of phase extended the responsivity well beyond the relaxation oscillation frequency to approximately the frequency associated with the rate of photon exchange between the coupled emitters. The rate equations were numerically integrated for several cases of interest to evaluate the stabilizing effect of strong modulation (entrainment)