DISTRIBUTED FEEDBACK SEMICONDUCTOR LASER WITH MONITOR

PURPOSE:To improve the characteristics of a DFB laser itself by burying the isolating region between a monitor region and a laser region with semiconductor which has forbidden band width larger than that of the light emitting layer of a laser region, thereby integrating the laser and the monitor on the same substrate and readily manufacturing and reducing the DFB laser itself. CONSTITUTION:After a wafer which has a layer structure similar to the DFB laser is produced, the isolating region between a laser region and a monitor region is uniformly buried with semiconductor 12 which has a forbidden band width larger than that of a light emitting layer 3 such as a high resistance InP, electrodes 8, 8a are individually led with lead wirings 10, 10a, thereby disposing the DFB laser region and the monitor region on the same substrate 1. According to this structure, the part of the buried semiconductor 12 becomes larger than the forbidden band width of the layer 3. Accordingly, the output light from the laser region is not absorbed but becomes a transparent window. In this manner, the output light can readily reach the monitor region, and reflection in the contacting surface of the layer 3 with the buried part 12 can be extremely reduced, thereby obtaining stable laser oscillation.