Alignment tolerances of short-external-cavity InGaAsP diode lasers for use as tunable single-mode sources.

The side-mode suppression ratio (SMSR) and single-mode continuous tuning range were measured for planar short-external-cavity semiconductor diode lasers to examine the positional and angular alignment tolerances of the external cavity mirror relative to the laser facet. For inverted rib waveguide lasers, the SMSR was found to be