Stabilization of single frequency operation of coupled-cavity lasers

We present a theoretical analysis of cleaved coupled-cavity lasers. Mode selectivity arises from two mechanisms. The first is diffraction loss in the gap between the cleaved sections. The second is based on one section acting as a resonant reflector. Our analysis includes the change of refractive index with carrier density which shifts the cavity resonances and causes mode switching. Above threshold the gains g1and g2of the two cavities are not pinned, but are related for each mode in the form of a curve in the ( ) plane. The separation of mode curves along a 45° line determines the ratio of mode intensities. Single mode operation above threshold is described by zones in the ( ) plane where C1and C2are the currents driving the two cavities. Cases of stable, unstable, and bistable operation are discussed.