TECHNIQUES FOR SUPER-MODE OSCILLATION.
Interim engineering rept. no. 5, 1 Jul-30 Sep 66,
ELECTRONIC DEFENSE LABS SYLVANIA ELECTRONIC SYSTEMS-WEST MOUNTAIN VIEW CALIF
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Construction of an automatic frequency control system for the absolute frequency stabilization of our 2-meter long, 50 mw FM laser was completed. The FM laser produces an error signal which increases as the laser frequency drifts with respect to the center of the Doppler-broadened fluorescence line. The electrical phase of the error signal changes by 180 degrees as the laser drifts from one side of line center to the other. The servo-system generates a control signal of the appropriate magnitude and sign to move a laser mirror attached to a piezoelectric crystal, and cancels any tendency of the laser frequency to drift from line center. The discontinuous 180-degree change of phase in the error signal at line center was measured. The profile of the extremely sharp discriminant was measured and shown to agree satisfactorily with that predicted by theory. The FM laser controlled by this servo-system was demodulated by means of optical heterodyne detection by photomixing with a laser of known stability. This photomixing experiment showed that the FM laser is, at present, absolutely stabilized to within 1.5 MHz of line center. Work is now under way to improve this preliminary figure.
- Lasers and Masers