Calculation of the matching of an injection laser to a dielectric waveguide

Calculations are reported of the parameters of a rectangular-core fiber waveguide needed to achieve an efficient matching to an injection laser which is in direct optical contact with the waveguide. Simple expressions are obtained for the relationships between the permittivity discontinuity at the core-cladding interface and the optimal thickness of the core on the one hand, and the laser parameters on the other. The requirements which the passband of the waveguide must satisfy impose restrictions on the laser-waveguide coupling coefficient. If the permissible distortion of a laser pulse is 30 nsec/km, about 65% of the injection laser radiation can be coupled into the waveguide.