Temperature Feedback Control for Long-Term Carrier-Envelope Phase Locking

A feedback control module for stabilizing a carrier-envelope phase of an output of a laser oscillator system, the feedback control module comprising:

• a first photodetector configured to generate an electrical first feedback signal corresponding to a first portion of a laser beam from an oscillator;
• a second photodetector configured to generate an electrical second feedback signal corresponding to a second portion of the laser beam filtered by a low-pass filter;
• a phase stabilizer configured to divide the frequency of the first feedback signal by a factor and generate an error signal corresponding to the difference between the frequency-divided first feedback signal and the second feedback signal;
• an optical modulator configured to modulate the laser beam within the oscillator corresponding to the error signal;
• and
• a thermal control element configured to change the temperature of the oscillator corresponding to a signal operable to control the optical modulator.

A method for stabilizing the carrier-envelope phase of a laser oscillator system, the method comprising the steps of:

• a) generating an electrical first feedback signal corresponding to a first portion of a laser beam from an oscillator;
• b) filtering a second portion of the laser beam using a low-pass filter;
• c) generating an electrical second feedback signal corresponding to the filtered second portion of the laser beam;
• d) dividing the frequency of the first feedback signal by a factor;
• c) generating an error signal corresponding to the difference between the frequency-divided first feedback signal and the second feedback signal;
• and
• changing the temperature of the oscillator corresponding to an optical modulator signal.