MODE-LOCKED LASER SYSTEM

摘要

PURPOSE:To stabilize resonator length and thus improve the stability of mode locking operation by detecting fluctuations of resonator length due to those of the modulation frequency of probe light, and feeding them back to resonator length. CONSTITUTION:A low-frequency oscillator 11 oscillates at an oscillation frequency independent of the modulation frequency of mode-locked laser. A probe light source 12 produces probe light modulated to the output of the lowfrequency oscillator 11. The wavelength of the probe light is set so that it will be capable of permeating through a mode-locked laser 13 resonator. Light that permeated through the mode-locked laser 13 is converted by a light receiving circuit 14 into electrical signals, which are compared with the output of the low-frequency oscillator 11 by a phase comparator 15. The phase comparator 15 detects fluctuations of the modulation component contained in the output of the light receiving circuit 14. The output of the phase comparator 15 is fed back to the mode-locked laser 13 to provide control so that the fluctuations of resonator length will be set off. This makes it possible to stabilize resonator length and thus mode locking operation.