| 摘要 |
PURPOSE:To remarkably relax the request condition to a semiconductor laser and to reduce the cost by providing a converting part to low frequency, an electro/optical conversion transmitting part, an onto/electric conversion receiving part and a converting part to a high frequency band. CONSTITUTION:An electric signal of a high frequency band inputted to a terminal 1 is converted to a signal of a low frequency band by a frequency converting part 6, and inputted to an electro/optical conversion transmitting part 2 by a semiconductor laser. An optical signal of the transmitting part is transmitted to an opto/electric conversion receiving part 4 through an optical fiber 3 and converted into a high frequency band by a frequency converting part 7, and outputted from a terminal 5. Accordingly, a high frequency distortion Dn characteristic of a laser itself by the transmitting part 2 is improved. Since the modulation amplitude can be taken large within a range in which the Dn characteristic is satisfied, C/N can be improved, and a desired characteristic can be secured by smaller receiving photoelectric power. Accordingly, the request condition to a semiconductor laser is relaxed. |
