| 摘要 |
PURPOSE:To detect quantity of light without deteriorating optical signals propagating in an optical fiber, by controlling the output light of a semiconductor laser, according to signals converted by a first photodetector which is adjacent to the semiconductor laser and monitors the quantity of light, and a second photodetector which detects light signals scattered from a core of the optical fiber. CONSTITUTION:In a second photodetector 10, a hollow part 15 is formed for detecting a part of incident light propagating in a clad 9, and a first optical fiber 6 and a second optical fiber 7 are in physical contact. In the vicinity of the contact part, the tip is sphered, and the clad 9 is extremely thinned. As a result, the greater part of incident light 16 propagating in the clad 9 is apt to be scattered outword. The scattered light illuminates the light receiving surface of the photodetector 10 and is absorbed. Since a backward bias is applied across a P-electrode 18 and an N-electrode 19 of the second photodetector 10, the absorbed light is converted into a photocurrent. |
