Laser-frequency stabilizer and laser-frequency stabilization method

A laser-frequency stabilizer configured to change a resonator length based on a saturated absorption line included in an optical output signal obtained by irradiating an absorption cell with a laser beam to stabilize an oscillation frequency of the laser beam to a specific saturated absorption line, the laser-frequency stabilizer comprising:

• a converter configured to convert the laser beam having passed through the absorption cell into the optical output signal;
• an actuator configured to change the resonator length in accordance with a voltage applied to the actuator;
• and
• a control unit configured to control the voltage applied to the actuator, wherein
• the control unit is configured to search for a target saturated absorption line based on the optical output signal and when the voltage applied to the actuator when the target saturated absorption line is found is within a predetermined range defined corresponding to the target saturated absorption line, lock the oscillation frequency of the laser beam at the target saturated absorption line.