Resonant Stimulated Photorefractive Scattering.

We present the first observations, and a complete theoretical explanation, of stimulated photorefractive scattering in a high- Q crystalline cavity. The standing-wave light field in the cavity induces an ultranarrow and long-lived Bragg grating through the photorefractive effect. The spatial phase of the grating is automatically matched to that of the standing wave.

Test of Special Relativity Using a Fiber Network of Optical Clocks.

Phase compensated optical fiber links enable high accuracy atomic clocks separated by thousands of kilometers to be compared with unprecedented statistical resolution. By searching for a daily variation of the frequency difference between four strontium optical lattice clocks in different locations throughout Europe connected by such links, we improve upon previous tests of time dilation predicted by special relativity. We obtain a constraint on the Robertson-Mansouri-Sexl parameter |α|≲1.

Compact, thermal-noise-limited reference cavity for ultra-low-noise microwave generation.

We demonstrate an easy-to-manufacture 25-mm-long ultra-stable optical reference cavity for transportable photonic microwave generation systems. Employing a rigid holding geometry that is first-order insensitive to the squeezing force and a cavity geometry that improves the thermal noise limit at room temperature, we observe a laser phase noise that is nearly thermal noise limited for three frequency decades (1 Hz to 1 kHz offset) and supports 10 GHz generation with phase noise near -100  dBc/Hz at 1 Hz offset and <-173  dBc/Hz for all offsets >600  Hz. The fractional frequency stability reaches 2×10 at 0.

Nano-Kelvin thermometry and temperature control: beyond the thermal noise limit.

We demonstrate thermometry with a resolution of 80  nK/Hz using an isotropic crystalline whispering-gallery mode resonator based on a dichroic dual-mode technique. We simultaneously excite two modes that have a mode frequency ratio that is very close to two (±0.3  ppm).

Optical amplification and pulse interleaving for low-noise photonic microwave generation.

We investigate the impact of pulse interleaving and optical amplification on the spectral purity of microwave signals generated by photodetecting the pulsed output of an Er:fiber-based optical frequency comb. It is shown that the microwave phase noise floor can be extremely sensitive to delay length errors in the interleaver, and the contribution of the quantum noise from optical amplification to the phase noise can be reduced ∼10  dB for short pulse detection. We exploit optical amplification, in conjunction with high power handling modified unitraveling carrier photodetectors, to generate a phase noise floor on a 10 GHz carrier of -175  dBc/Hz, the lowest ever demonstrated in the photodetection of a mode-locked fiber laser.

Two-color rubidium fiber frequency standard.

We demonstrate an optical frequency standard based on rubidium vapor loaded within a hollow-core photonic crystal fiber. We use the 5S(1/2)→5D(5/2) two-photon transition, excited with two lasers at 780 and 776 nm. The sum-frequency of these lasers is stabilized to this transition using modulation transfer spectroscopy, demonstrating a fractional frequency stability of 9.

Oscillating test of the isotropic shift of the speed of light.

In this Letter, we present an improved constraint on possible isotropic variations of the speed of light. Within the framework of the standard model extension, we provide a limit on the isotropic, scalar parameter κ̃(tr) of 3±11×10({-10), an improvement by a factor of 6 over previous constraints. This was primarily achieved by modulating the orientation of the experimental apparatus with respect to the velocity of Earth.

High-performance iodine fiber frequency standard.

We have constructed a compact and robust optical frequency standard based around iodine vapor loaded into the core of a hollow-core photonic crystal fiber (HC-PCF). A 532 nm laser was frequency locked to one hyperfine component of the R(56) 32-0 (127)I(2) transition using modulation transfer spectroscopy. The stabilized laser demonstrated a frequency stability of 2.

Effects of the neuroprobe in the treatment of second-degree ankle inversion sprains.

This study compared the effects of standard physical therapy plus Neuroprobe Systems II NP 200 treatments with the effects of standard physical therapy treatments alone on second-degree ankle inversion sprains of 16 patients. The following data were collected: release day from treatment and measurements for both ankles over a 17-day period for plantar flexion-dorsiflexion and inversion-eversion range of motion, edema, and pain. When compared with the standard physical therapy treatments, the group that underwent Neuroprobe treatments showed significant differences in release day from treatment, range of motion for plantar flexion-dorsiflexion and inversion-eversion.