We review the field of cavity optomechanics, which explores the interaction between electromagnetic radiation and nano- or micromechanical motion This review covers the basics of optical cavities and mechanical resonators, their mutual optomechanical interaction mediated by the radiation pressure force, the large variety of experimental systems which exhibit this interaction, optical measurements of mechanical motion, dynamical backaction amplification and cooling, nonlinear dynamics, multimode optomechanics, and proposals for future cavity quantum optomechanics experiments In addition, we describe the perspectives for fundamental quantum physics and for possible applications of optomechanical devices

Cavity Optomechanics

Photonic crystal fibers guide light by corralling it within a periodic array of microscopic air holes that run along the entire fiber length Largely through their ability to overcome the limitations of conventional fiber optics—for example, by permitting low-loss guidance of light in a hollow core—these fibers are proving to have a multitude of important technological and scientific applications spanning many disciplines The result has been a renaissance of interest in optical fibers and their uses

https://science.sciencemag.org/content/sci/299/5605/358.full.pdf

Photonic crystal fibers

A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

We review the recent developments in the area of optical fiber grating sensors, including quasi-distributed strain sensing using Bragg gratings, systems based on chirped gratings, intragrating sensing concepts, long period-based grating sensors, fiber grating laser-based systems, and interferometric sensor systems based on grating reflectors.

Fiber grating sensors

A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Supercontinuum generation in photonic crystal fiber

We present a technique that uses noisy broadband pulse bursts generated by modulational instability to probe nonlinear processes, including infrared-inactive Raman transitions, in molecular gases. These processes imprint correlations between different regions of the noisy spectrum, which can be detected by acquiring single shot spectra and calculating the Pearson correlation coefficient between the different frequency components. Numerical simulations verify the experimental measurements and are used to further understand the system and discuss methods to improve the signal strength and the spectral resolution of the technique.

Covariance spectroscopy of molecular gases using fs pulse bursts created by modulational instability in gas-filled hollow-core fiber

In straight single-ring hollow-core PCFs, dramatic higher-order-mode suppression occurs for a strict geometrical condition. Twisting permits this condition to be relaxed, reducing fabrication tolerances. The twisted fiber also exhibits weak circular birefringence.

Twist-tuning of higher-order mode suppression in single-ring hollow-core photonic crystal fibers

A broad-band in-fiber polarizer with suppression >25 dB over 300 nm bandwidth is reported. It is made by introducing a high quality Ge nanowire into one of the hollow channels of a photonic crystal fiber.

Polarization properties of PCF with Ge-nanowire

We present a localization technique for an optically trapped microparticle inside hollow-core photonic crystal fibers which is the basis of a new generation of fiber optical sensors. A polystyrene particle of diameter ~15 µm is optically trapped and moved inside the hollow-core fiber by optical forces while its position is tracked using coherent optical frequency domain reflectometry. We demonstrate that this technique can locate the particle position with a standard deviation of ~10 µm. By applying a time-apertured Fourier transform, the dynamics of particle motion can be resolved with millisecond temporal resolution.

High-Precision Localization of Trapped Microparticles inside Hollow-Core Photonic Crystal Fibers using Coherent Optical Frequency Domain Reflectometry

A method of forming electrets in optical fibres, which method comprises thermally poling the optical fibres in order to provide the optical fibres with a built-in electret, the method being such that the optical fibres are thermally poled in the absence of air. Optical fibres devices when produced by the method of the invention, include: frequency converters, linear electro-optic modulators, linear electro-optic switches, electric field sensors, second order non-linear mirrors, electrically controllable Bragg gratings, and transducers for exciting surface acoustic waves on glass substrates.

Philip St. J. Russell

Papers

Covariance spectroscopy of molecular gases using fs pulse bursts created by modulational instability in gas-filled hollow-core fiber

Twist-tuning of higher-order mode suppression in single-ring hollow-core photonic crystal fibers

Polarization properties of PCF with Ge-nanowire

High-Precision Localization of Trapped Microparticles inside Hollow-Core Photonic Crystal Fibers using Coherent Optical Frequency Domain Reflectometry

A method of forming electrets in optical fibres