An external cavity laser diode, which includes a $LiNbO_3$ phase modulator, was frequency-stablized to a resonance frequency of a Fabry-Perot etalon. The Fabry-Perot etalon was temperature-controlled within 2.5℃ in 24 hours. The rear facet of the electro-optic phase modulator was coated with gold and used as an external mirror. The optical frequency fluctuation was detected through a Fabry-Perot etalon and the detected signal was fed back to the temperature control loop of the laser diode. The detected signal was commonly used to control the optical phase of the phase modulator for the frequency stabilization of the external cavity laser diode.
At feedback-off state the peak-to-peak frequency fluctuation of the external cavity laser diode was 10 MHz. At feedback-on state the peak-to-peak frequency fluctuation was reduced to 1 MHz in 1 hour.
