Pulse light source, and method for stably controlling phase difference between pulse laser lights

摘要

A pulse light source includes: a master laser that outputs a master laser light pulse whose repetition frequency is controlled to a predetermined value; a slave laser that outputs a slave laser light pulse; a phase comparator that detects a phase difference between an electric signal having a frequency of the predetermined value, and an electric signal based on a light intensity of the slave laser light pulse; a loop filter; an adder that adds a repetition frequency control signal having a certain repetition cycle, to an output from the loop filter; and a phase comparator that measures a pulse phase difference which is a phase difference between the master laser light pulse and the slave laser light pulse. A magnitude of the repetition frequency control signal is controlled such that the measured pulse phase difference matches with a target value of the pulse phase difference.

主权项

1. A pulse light source that is adapted to feed-back control a repetition frequency control signal from a repetition frequency control signal source in accordance with a phase difference between two pulse laser lights, wherein lasers that output the two pulse laser lights comprise:
a master laser that outputs a master laser light pulse whose repetition frequency is controlled to a predetermined value; and a slave laser that outputs a slave laser light pulse, wherein the pulse light source comprises: a phase difference detector that detects a phase difference between an electric signal having a frequency of the predetermined value, and an electric signal based on a light intensity of the slave laser light pulse; a loop filter that removes a high-frequency wave component of an output from the phase difference detector; an adder that adds a repetition frequency control signal output from the repetition frequency control signal source and having a certain repetition cycle, to an output from the loop filter; and a pulse phase difference detector that measures a pulse phase difference which is a phase difference between the master laser light pulse and the slave laser light pulse, wherein the repetition frequency of the slave laser light pulse varies depending on an output from the adder, and a magnitude of the repetition frequency control signal is controlled such that the measured pulse phase difference matches with a target value of the pulse phase difference.