METHOD AND APPARATUS FOR SUPPRESSION OF SPATIAL-HOLE BURNING IN SECOND OR HIGHER ORDER DFB LASERS

摘要

A surface emitting semiconductor laser is shown having a semiconductor laser structure (10) defining an intrinsic cavity having an active layer (22), opposed cladding layers contiguous to said active layer (22), a substrate (17) and electrodes (12, 14) by which current can be injected into said semiconductor laser structure (10) to cause said laser structure to emit an output signal in the form of at least a surface emission. The intrinsic cavity is configured to have a dominant mode on a longer wavelength side of a stop band. A structure such as a buried heterostructure for laterally confining an optical mode is included. A second order distributed diffraction grating (24) is associated with the intrinsic cavity, the diffraction grating (24) having a plurality of grating elements (27, 28) having periodically alternating optical properties when said current is injected into said laser structure. The grating is sized and shaped to generate counter-running guided modes within the intrinsic cavity wherein the grating (24) has a duty cycle of greater than 50% and less than 90%. Also provided is a means for shifting a phase (26) of said counter-running guided modes within the cavity to alter a mode profile to increase a near field intensity of said output signal.