Frequency-switched heterodyne cavity ringdown spectroscopy.

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.

Continuous-wave frequency tripling and quadrupling by simultaneous three-wave mixings in periodically poled crystals: application to a two-step 1.19-10.71-microm frequency bridge.

We observed cw third-harmonic generation in a periodically poled LiNbO(3) crystal by cascading optimally phase-matched second-harmonic and sum-frequency generation. Other processes, such as fourth-harmonic generation, are allowed by the flexibility of quasi-phase matching. We demonstrate a divide-by-nine (1.

Free-induction decay in molecular iodine measured with an extended-cavity diode laser.

The free-induction decay (FID) technique combined with broadly tunable lasers offers a convenient way to survey molecular dephasing times. We measured FID's in molecular iodine by frequency switching an extended-cavity diode laser with a small current modulation. These decay times provide valuable information on the Doppler-free linewidths for frequency-standard applications.

Edge detection for magnetooptical data storage.

The polarization sensitive optical heterodyne methods used to detect polarization rotations in conventional magnetooptic data storage systems can be altered to produce nonzero electronic signals only when the polarization rotation changes. Such systems detect the edges of the magnetic domains optically and produce signals similar to conventional inductive magnetic recording channels. Both theoretical and experimental results indicate that optimized edge detection systems can have a performance comparable with present level detection systems but with less complexity.

Stochastic noise in TEM(00) laser beam position.

The centroid of a single-transverse-mode laser beam fluctuates in position because of spontaneous emission of the laser medium into higher transverse cavity modes.

Squeezing of classical noise by nondegenerate four-wave mixing in an optical fiber.

Nondegenerate four-wave mixing in an optical fiber is shown to attenuate one quadrature of random sideband fluctuations created by external modulators. A theory of the nonlinear interaction that includes nonlinear dispersion fits the results. Analogous experiments on quantum noise inputs should prove successful.

Frequency-modulation-polarization spectroscopy.

We have combined frequency-modulation and polarization spectroscopy to detect anisotropic spectral features with high sensitivity. The many line shapes possible with this technique and the potential for laser noise suppression were demonstrated by using saturation holes in iodine vapor.

FM spectroscopy detection of stimulated Raman gain.

We have used FM spectroscopy to detect the stimulated Raman gain effect in deuterium, demonstrating for the first reported time the quantum-noise-limited performance of this technique.

Continuous-wave Doppler-free two-photon frequency-modulation spectroscopy in Rb vapor.

Frequency-modulation spectroscopy was employed successfully to measure the Doppler-free absorption and dispersion signals originating from several two-photon transitions in (85)Rb and (87)Rb. The two-photon cross section of the hyperfine transition 5S(1/2) (F = 2) ? 5D(5/2) (F = 4) in (87)Rb was determined to be sigma((2)) asymptotically equal to 4 x 10(-20) cm(4)/W. The transition isotope shift (TIS) of the transition 5S(1/2) ? 5D(5/2) between (87)Rb and (85)Rb was found to be Deltanu(TIS) = +166 +/- 2 MHz.