| 摘要 |
PROBLEM TO BE SOLVED: To provide a light transmission circuit which can obtain a high quality optical signal at a low cost in an analog optical transmission or the like, by reducing nonlinear distortion of an optical signal for communication itself. SOLUTION: In an optical signal generating part 1, the difference between a modulated electrical signal 11 and a feedback electric signal 12 is detected by a drive circuit 5, and a drive current proportional to the difference is injected into an LD 6, thereby generating an optical signal, which is transmitted as the optical signal 13 for transmission by an optical transmission line 2. A part of the optical signal 13 is branched as an optical signal 14 for monitoring and inputted in a monitoring part 4, in which the optical signal 14 is subjected to photoelectric conversion by a PD 7, amplified by an amplifier 8 and outputted as an output electric signal 15. A part of the electrical signal 15 is branched by a branching circuit 9, and inputted in the driving circuit 5 as the feedback electrical signal 12, and as a result, by making negative feedback applies to the circuit as a whole, the linearity of an output light of the LD 6 is improved and nonlinear distortion is reduced. |
