PHASE SHIFTED SURFACE EMITTING DFB LASER STRUCTURES WITH GAIN OR ABSORPTIVE GRATINGS

摘要

A surface emitting semiconductor laser is shown having a semiconductor lasing structure having an active layer, opposed cladding layers contiguous to said active layer, a substrate, and electrodes by which current can be injected into the semiconductor lasing structure. Also included is a distributed diffraction grating having periodically alternating elements, each of the elements being characterized as being either a high gain element or a low gain element. Each of the elements has a length, the length of the high gain element and the length of the low gain element together defining a grating period, where the grating period is in the range required to produce an optical signal in the optical telecommunications signal band. A phase shifting structure is provided in the center of the grating to cause a peak intensity to occur over the center of the cavity by altering a mode profile of the output signal, while spatial hole burning arising from said altered mode profile is ameliorated.