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

An optical fibre is electrically poled by applying an intense external electric field across the fibre core and sustaining this field for a prolonged period of time. In this manner, a permanent linear electro-optic property is imparted to the fibre. Poling may be accelerated by performing this method at elevated temperature. Highest field intensities can be achieved using a fibre having one or two internal electrodes i.e. electrodes incorporated in the fibre cladding. Preferably the internal electrodes are of a metal or metal alloy that is liquid at poling temperature.

Method for the manufacture of an electro-optic device

We describe the fabrication, characterisation and applications of silica/air photonic crystal fibres with microscopic arrays of air capillaries running along their length.

https://iopscience.iop.org/article/10.7567/JJAPS.37S1.45/pdf

Silica/Air Photonic Crystal Fibres

The giant electro-optical response of Rydberg atoms manifests itself in the emergence of sidebands in the Rydberg excitation spectrum if the atom is exposed to a radio-frequency (RF) electric field. Here we report on the study of RF-dressed Rydberg atoms inside hollow-core photonic crystal fibres (HC-PCF), a system that enables the use of low modulation voltages and offers the prospect of miniaturised vapour-based electro-optical devices. Narrow spectroscopic features caused by the RF field are observed for modulation frequencies up to 500 MHz.

/pdf/rf-dressed-rydberg-atoms-in-hollow-core-fibres-2tyv2o0om3.pdf

RF-dressed Rydberg atoms in hollow-core fibres

Despite the fact that laser scanning confocal microscopy (LSCM) has become an important tool in modern biological laboratories, it is bulky, inflexible and has limited field of view, thus limiting its applications. To overcome these drawbacks, we report the development of a compact dual-clad photonic-crystal-fiber (DCPCF) based multiphoton scanning microscope. In this novel microscope, beam-scanning is achieved by directly scanning an optical fiber, in contrast to conventional beam scanning achieved by varying the incident angle of a laser beam at an objective entrance pupil. The fiber delivers femtosecond laser pulses for two-photon excitation and collects fluorescence back through the same fiber. Conventional fibers, either single-mode fiber (SMF) or multimode fiber (MMF), are not suitable for this detection configuration because of the low collection efficiency for a SMF and low excitation rate for a MMF. Our newly invented DCPCF allows one to optimize collection and excitation efficiency at the same time. In addition, when a gradient-index (GRIN) lens is used to focus the fiber output to a tight spot, the fluorescence signal collected back through the GRIN lens forms a large spot at the fiber tip because of the chromatic aberrations of the GRIN lens. This problem prevents a standard fiber from being applicable, but is completely overcome by the DCPCF. We demonstrate that this next generation scanning confocal microscope has an extremely simple structure and a number of unique features owing to its fundamentally different scanning mechanism: high flexibility, arbitrarily large scan range, aberration-free imaging, and low cost.

/pdf/development-of-a-double-clad-photonic-crystal-fiber-based-2c4lpz0nnm.pdf

Development of a double-clad photonic-crystal-fiber based scanning microscope

Coherent ultraviolet light has many uses, for example, in the study of molecular species relevant in biology and chemistry. Very few, if any, laser materials offer ultraviolet transparency along with damage-free operation at high-photon energies and laser power. Here we report efficient generation of narrowband deep and vacuum ultraviolet light using hydrogen-filled hollow-core photonic crystal fiber. Pumping above the stimulated Raman threshold at 532 nm, coherent molecular vibrations are excited in the gas, permitting thresholdless wavelength conversion in the ultraviolet with efficiencies close to 60%. The system is uniquely pressure tunable, allows spatial structuring of the out-coupled radiation, and shows excellent performance in the vacuum ultraviolet. As the underlying scattering process is effectively linear, our approach can also in principle operate at the single-photon level, when all other alternatives are extremely inefficient.

Philip St. J. Russell

Papers

Method for the manufacture of an electro-optic device

Silica/Air Photonic Crystal Fibres

RF-dressed Rydberg atoms in hollow-core fibres

Development of a double-clad photonic-crystal-fiber based scanning microscope

Thresholdless deep and vacuum ultraviolet Raman frequency conversion in hydrogen-filled photonic crystal fiber