| 摘要 |
PURPOSE:To control and stabilize laser electric current, by feeding back output lights outputted from light-emitting faces of a laser to light-emitting faces each other, and controlling the phase change of the light passing on optical paths such that a mean power of AC components of the light is minimized and a DC output is maximized or minimized. CONSTITUTION:A phase modulator 27 and a phase changer 26 are connected in a feed back path of a laser 21. The modulator 27 modulates the phase of light passing there, in accordance with an AC output signal from a signal source 28. A detector 29 photoelectrically converts light transmitted by a half mirror 24 and a phase detector 31 comparates its phase with that of the output from the signal source 28 so that a signal is generated in accordance with a difference in phase. A servo signal is generated by a servo circuit 32 in accordance with this signal and driving current is outputted by a drive circuit 33 to drive the laser 21. On the other hand, an AC component of the detector 29 is taken out by means of a low- pass filter 34 and a servo signal is generated by a servo circuit 35, so that a phase changer 26 performs DC phase change in the light passing there. A temperature controller 36 is caused to drive a Peltier element 37 by a servo signal from the servo circuit 35 and the laser 21 oscillates as determined by the driving current from the drive circuit 33. An operating temperature during the oscillation is determined by the operation of the Peltier element 37, and an optical frequency can be stabilized when there is no phase shift between the lights in both directions that are coupled within the laser. |
