| 摘要 |
PROBLEM TO BE SOLVED: To enable accurate calibration of a high frequency superposition amount even when I-L (driving current - optical output) characteristics change due to a temperature of a semiconductor laser and a secular change thereof.SOLUTION: A base current generation unit for controlling base current supplied to a semiconductor laser, includes an APC (Automatic Power Control) circuit that performs control so that a light emission amount detected by a light emission amount detection unit is kept at a target light emission amount, and control is performed so that a base driving current gets near to a light emission threshold Ith of the laser source, and on the basis of the information on a light emission amount detected by the light emission amount detection unit, a high frequency current superposition unit is controlled. |
