Mode Behavior Improvement in DFB LDs by Light Phase Control at the Facet

Abstract
Lasing characteristics of InP/InGaAsP DFB-BH LDs, which show a two longitudinal mode operation on both sides of the stop band in as-fabricated state, have been remarkably improved and made into a single longitudinal mode operation by shifting the light phase about π/4 at the facet. The light phase was shifted by changing the relative position of the cleaved facet and the grating. Ion beam etching and dielectric film coating were successfully applied for this purpose.
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