When the frequency of light coupled into a cavity is suddenly shifted, the radiation emanating from the input port of the previously excited cavity can beat with the reflection of the frequency-shifted input on the surface of a photodetector. When the beat frequency is stable, the time decay of the resulting optical heterodyne signal can be used to measure intracavity absorption spectra with near quantum-limited sensitivity.
© 2000 Optical Society of America
(040.2840) Detectors : Heterodyne
(120.6200) Instrumentation, measurement, and metrology : Spectrometers and spectroscopic instrumentation
(300.6310) Spectroscopy : Spectroscopy, heterodyne
(300.6360) Spectroscopy : Spectroscopy, laser
M. D. Levenson, B. A. Paldus, T. G. Spence, C. C. Harb, R. N. Zare, M. J. Lawrence, and R. L. Byer, "Frequency-switched heterodyne cavity ringdown spectroscopy," Opt. Lett. 25, 920-922 (2000)