| 摘要 |
PURPOSE:To optically and efficiently couple a semiconductor laser with a photodetector by forming a semiconductor for electrically separating both a laser oscillation gain region and an absorbing region for converting to an electric signal on the same optical axis inside a resonator, and forming a high reflecting film at the absorbing region side. CONSTITUTION:A current blocking layer 30, a stripe groove 31, the first clad layer 3, an active layer 4, the second clad layer 5, and an ohmic layer 6 are sequentially grown on a substrate 2. An Si3N4 film 20 is formed on the multilayer film, the film 20 and the layer 6 directly on the region 9 are removed, with the film 20 as a mask an impurity for converting to a P-type semiconductor is diffused to arrive at the layer 3, the region 9 is formed, and the film 20 is removed, thereby forming a P-type side electrode 1, a gain region electrode 8 and an absorbing region electrode 7. Further, a high reflecting film 50 is formed on a resonator face (f) of the absorbing region side. Thus, the laser oscillation light emitted from the layer 4a passes a waveguide 4c to be fully coupled with the active layer 4b, not emitted externally, but returned to the resonator. Accordingly, the laser and the photodetector are coupled in optically high efficiency. |
