| 摘要 |
PURPOSE:To attain excellent signal transmission by setting temperature around a semiconductor laser to be lower as a transmission distance of a transmission station up to a reception station is longer in the optical transmission method receiving simultaneously plural optical signals by one reception station and demodulating the signals. CONSTITUTION:Video signals from transmission stations 11, 12,... are modulated on a carrier whose frequency is a specific frequency fn by a modulator and an optical signal generated from each semiconductor laser 3 of the transmission stations 11, 12,... are modulated by the resulting signal. The optical signals from the transmission stations 11, 12,... are led to an optical fiber main line 15 via an optical multiplexer 14, in which multiplexed and the resulting signal is received by a light receiving device 16 of the reception station 2 altogether. The temperature is easily adjusted by using a Peltier cooler integrated in the inside of a module of a distribution feedback type DFB laser 3. A wavelength is selected to be, e.g. 0.1nm or over by using the temperature dependency so as to revise the wavelength. Then the temperature of the laser is selected to be lower for a transmission station at a remoter location so as to compensate an optical transmission loss thereby almost uniformizing the reception power level. |
