Injection Laser for High Data Rate Communications.

Injection lasers of AlGaAs (Lambda(L) approximately 800 nm) have been permanently bonded to single-mode fibers, with power levels up to 600 microwatts being coupled into the fibers. Values over 150 microwatts were consistently obtained under cw operation at room temperature. Very close mechanical alignment tolerances are required to achieve good coupling, with positioning to + or - 1 micrometer being required. This necessitates the use of bonding materials for attaching the fiber to the laser mount that have a high dimensional stability over long time periods, and lasers whose modal patterns do not change with time or operating conditions. An epoxy provided the best bonding material that we found, although there are indications that suitable low-melting solders can also be used. Laser mode changes with drive current level can alter the observed coupling efficiency significantly.