FREQUENCY-STABILIZED RING LASER

摘要

PURPOSE:To prevent the oscillation frequency of an optical ring laser from being fluctuated by an external disturbance and to stably oscillate the optical ring laser when the optical ring laser is oscillated in a single longitudinal mode at a narrow spectral-line width. CONSTITUTION:One part of the laser oscillation output of a ring laser is injected into a ring in a direction opposite to that of its laser oscillation; a laser oscillator is utilized as a resonator in a light path in the opposite direction. A circulator 4 is installed in the ring; a difference is formed in a light-path length in a direction opposite to the positive direction; an-attenuator 5 is installed in the light path in the opposite direction; a slight difference is formed in an optical loss. A beam of light in the opposite direction is detected; an error signal is obtained by means of a comparator 14; a laser-resonator length is fixed by using a phase modulator 15 by means of a feedback by the error signal. By its result, a laser-oscillation wavelength is stabilized without a need for the absolute standard of a wavelength. Consequently, an oscillation frequency is stabilized with reference to an external disturbance.