| 摘要 |
PURPOSE:To eliminate a polarization controller in each laser for transmission, to eliminate necessity to control a polarizing surface and to cause a transmitting device to be compact by providing a polarizing rotator to generate a time change for the polarizing surface in one part of the output light of a frequency variable laser. CONSTITUTION:The signal lights of a laser 200 for transmission to have mutually different oscillating frequencies are synthesized by a first synthesizer 500 and coupled to fiber for transmission. However, one part of the light is made incident to a second synthesizer 510. For an output light from a frequency variable lase 100, a frequency is periodically changed and the output light is divided into two lights by a divider 300. Then, one of the divided lights is synthesized with the signal light by the synthesizer 510. In such a case, a polarizing rotator 900, whose rotating speed is larger than the frequency change speed of the laser 100, is provided to rotate the polarizing surface of the output light from the laser 100 which is made incident to the synthesizer 510. Since the polarizing surface of the output light from the laser 100 is always rotated even when the signal light is made incident from the laser 200 to the synthesizer 510 and changed by the temperature change, etc., of synchronization, the control of the polarizing surface in the signal light is eliminated and the device is made compact. |
