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Optics Letters

Phase-sensitive frequency-modulation noise spectroscopy with a diode laser

Seema Lathi, Steven Kasapi, Y. Yamamoto

Published Oct 1, 1996• 5 citations
Publisher

Abstract

We have demonstrated phase-sensitive FM noise spectroscopy, using the frequency noise of a diode laser. We obtained the reference signal for this experiment by sending part of the diode-laser beam through a Mach-Zehnder interferometer, which acted as a frequency discriminator. Both the reference beam (prepared with an interferometer) and the probe beam (which probed a Fabry-Perot cavity) carried amplitude noise converted from the intrinsic frequency noise. Mixing the two noise signals allowed us to measure the absorptive and dispersive responses of the sample. This method may provide a simple and sensitive spectroscopic tool.

DOI
10.1364/ol.21.001600

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We have developed a sub-shot-noise diode laser system and used it to perform sub-shot-noise FM spectroscopy. By inducing FM sidebands on a direct-current modulated external-cavity diode laser and injection locking a slave laser, we have suppressed the residual AM in the master by 50 dB and achieved a noise level of 0.8 dB below the shot-noise level. We expect that such techniques will provide useful and practical tools for future precision measurements and novel atom-photon interaction experiments.
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