Influence of the operation regime of an injection laser on the efficiency of coupling of its radiation into an optical waveguide

A study was made of the efficiency of coupling of radiation emitted by heterolasers (including lasers made of new multicomponent compounds and emitting at 1.08 μ) into a multimode fiber by direct contact or by matching with a microlens at the fiber end. A coupling efficiency up to 0.9 was obtained using a strip heterolaser and an SiO₂ fiber (light losses ~25 dB/Km). An increase in the pump current lowered the coupling efficiency. Experiments on a single-mode heterolaser with an external selective resonator showed that one of the reasons for the nonmonotonic dependence of the coupling efficiency on the pump current was the mode deformation as a result of self-focusing effects.