Observation of ultraslow and stored light pulses in a solid.

We report ultraslow group velocities of light in an optically dense crystal of Pr doped Y2SiO5. Light speeds as slow as 45 m/s were observed, corresponding to a group delay of 66 micros. Deceleration and "stopping" or trapping of the light pulse was also observed.

Turbulence-aberration correction with high-speed high-gain optical phase conjugation in sodium vapor.

Optical aberrations that are due to high-speed turbulence in the aero-optical regime are corrected with optical phase conjugation based on coherent population trapping in sodium vapor. Experimental measurements of an unheated, forced helium jet in air have demonstrated aberration correction by a factor of 7.8 at a forcing frequency of 18kHz with an optical power gain of 32.

Distortion-free gain and noise correlation in sodium vapor with four-wave mixing and coherent population trapping.

We observed optical gain as great as 30 with nearly distortion-free beam propagation in optically dense sodium vapor, using four-wave mixing. Moreover, 15-dB classical noise correlations were seen in the amplified probe and conjugate beams. To achieve this performance in such a strongly absorbing medium, one must suppress unwanted absorption and self-focusing effects.

Fiber-optic polarization and phase modulator utilizing transparent piezofilm with indium tin oxide electrodes.

A highly efficient optical polarization and phase modulator formed by the placement of a thin transparent piezofilm with indium tin oxide electrodes directly in the path of the output from an optical fiber is presented. Various configurations that differ in the clamping conditions, utilization of epoxy, and optical arrangement are presented. For a film thickness of 63.

Split-cavity cross-coupled extrinsic fiber-optic interferometric sensor.

A new configuration of the fiber-optic extrinsic Fabry-Perot interferometer is demonstrated. This configuration utilizes two sensor heads on a single directional coupler in a split-cavity cross-coupled extrinsic fiber interferometric (SCEFI) arrangement to provide a four-beam interference. The need for quadrature phase biasing is eliminated, with a new spectrum analysis detection scheme devised for the SCEFI in a no-feedback condition.

Minimum detectable phase shift in spectrum-analysis techniques of optical interferometric vibration detection.

The minimum detectable phase shift indicated in recent experimental reports of new linear spectrumanalysis techniques of optical interferometric vibration detection is established as the direct consequence of the 1/f noise voltage in the system components. The dynamic range and inaccuracy predicted by the simple theoretical model presented is in good agreement with experimental measurements. The conclusions of the analysis are compared with experimental reports of heterodyne shot-noise-limited optical systems.

Linear measurement of static phase change in optical homodyne interferometers: an analysis.

A new highly accurate linear method of dc phase-shift measurement based on spectrum analysis in a general optical homodyne interferometer is presented. The dc phase is superimposed onto a controllable ac phase modulation. The dc phase error is theoretically analyzed based on the excellently matching predicted and experimental reports of ac phase error.

Interferometric measurement of fiber strain hysteresis and nonlinearity for sensitivity optimization.

A simple and reliable fringe-counting method is used to determine the fiber static elastic response in fiber-optic sensors and modulators. Large strain hysteresis and nonlinearity have been observed in the commonly employed configuration of bonding a bare fiber onto a strain element. Jacketed fibers show reduced hysteresis and nonlinearity in their elastic response.

Static phase change in a fiber optic coil hydrophone.

For low acoustic frequencies, the acoustooptic interaction in a fiber optic interferometric coil hydrophone has been modeled on assumptions of hydrostatic and radial stress. However, an inherent ambiguity exists in the way by which the correct model has been chosen. It is established through unambiguous experimental determination of the sign of the induced static phase change that the hydrostatic model alone is valid.

Universal dynamic phase-calibration technique for fiber-optic interferometric sensors and phase modulators.

A new technique for dynamic phase calibration that utilizes only visual observation of the fringe pattern is demonstrated for use in fiber-optic interferometric sensors and phase modulators. The need for a photodetector and its associated electronic circuitry is completely eliminated. Observations show that random changes in phase, source intensity, and fringe visibility do not affect the phase calibration.

Linear readout of dynamic phase change in a fiber-optic homodyne interferometer.

A new technique that provides linear measurement of dynamic phase change in a no-feedback, no-phase-bias fiber-optic interferometer is described. The phase measurement is unaffected by random changes in phase, source intensity, and fringe visibility. A minimum detectable phase shift of 0.