PROGRESS TOWARD PHASE-STABLE OPTICAL FREQUENCY STANDARDS

The sensitivity of laser spectroscopy is usually limited by laser amplitude noise of a technical nature. We describe a new and very sensitive detection technique which basically eliminates this source of noise by encoding the resonance information into RF frequencies using FM modulation followed by optical heterodyne and RF phase-sensitive detection. The method is applied to laser stabilization and sub-Doppler spectroscopy. Calculation shows the method provides an available sensitivity within 3.4 dB of the theoretical limit for ideal absorption spectroscopy