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 report the use of photonic crystal fibres (PCF) as spectrofluorimetric systems in which sample solutions are excited within the microstructure of the fibre. The use of intra-fibre excitation has several advantages that combine to enable highly sensitive measurements of fluorescence spectra and lifetimes: long path-lengths are achieved by the efficient guidance of the fundamental mode; sample volumes contained within the micron-scale structure are very small, only a few nanolitres per cm of path; collection and guidance of the emitted fluorescence is efficient and the fluorescence lifetime is unperturbed. Fluorophores in bulk solution can be studied in hollow core PCF, whereas the use of PCF with a suspended, solid core enables selective excitation of molecules in close proximity to the silica surface, through interaction with the evanescent field. We demonstrate the measurement of fluorescence spectra and fluorescence lifetimes in each of these excitation regimes and report the detection of attomole quantities of fluorescein.

/pdf/spectrofluorimetry-with-attomole-sensitivity-in-photonic-3gr4na6ol7.pdf

Spectrofluorimetry with attomole sensitivity in photonic crystal fibres

Supercontinuum generation in a regime where the self-phase-modulation of the pump wave gives a negligible contribution to the spectral broadening reveals the importance of parametric and Raman effects in photonic crystal fibers.

Single-mode white-light supercontinuum with 60 ps pump pulses in a photonic crystal fiber

Second harmonic (SH) generation with 300 fs pump pulses is reported in a xenon-filled hollow-core photonic crystal fiber (PCF) across which an external bias voltage is applied. Phase-matched intermodal conversion from a pump light in the LP01 mode to SH light in the LP02 mode is achieved at a particular gas pressure. Using periodic electrodes, quasi-phase-matched SH generation into the low-loss LP01 mode is achieved at a different pressure. The low linear dispersion of the gas enables phase-matching over a broad spectral window, resulting in a measured bandwidth of ∼10  nm at high pump energies. A conversion efficiency of ∼18%/mJ is obtained. Gas-filled anti-resonant-reflecting hollow-core PCF uniquely offers pressure-tunable phase-matching, ultra-broadband guidance, and a very high optical damage threshold, which hold great promise for efficient three-wave mixing, especially in difficult-to-access regions of the electromagnetic spectrum.

Broadband electric-field-induced LP 01 and LP 02 second harmonic generation in Xe-filled hollow-core PCF.

Summary form only given. Multicore fibers are optical fibers with two or more cores. The cores can be coupled or uncoupled depending on the properties of the fiber. Photonic crystal fiber (PCF) is an undoped all silica fiber with an array of air holes that run along its length. This novel type of optical fiber has some remarkable waveguiding properties that can be characterized by the size of the air holes and the distance between them. PCF is fabricated using a proven stack and draw technique, due to this unique fabrication process the inclusion of multiple cores, anywhere within the two-dimensional hexagonal lattice is significantly simpler than the fabrication of conventional step index fibers. In this paper we demonstrate an evanescent field coupler by selective heat-treating a region of a previously uncoupled twin core PCF.

Directional coupling in a twin core photonic crystal fiber using heat treatment

We report on a highly efficient experimental scheme for the generation of deep-ultraviolet (UV) ultrashort light pulses using four-wave mixing in gas-filled kagome-style photonic crystal fiber. By pumping with ultrashort, few microjoule pulses centered at 400 nm, we generate an idler pulse at 266 nm and amplify a seeded signal at 800 nm. We achieve remarkably high pump-to-idler energy conversion efficiencies of up to 38%. Although the pump and seed pulse durations are ∼100  fs, the generated UV spectral bandwidths support sub-15 fs pulses. These can be further extended to support few-cycle pulses. Four-wave mixing in gas-filled hollow-core fibers can be scaled to high average powers and different spectral regions such as the vacuum UV (100–200 nm).

/pdf/highly-efficient-deep-uv-generation-by-four-wave-mixing-in-29lhhug0au.pdf

Philip St. J. Russell

Papers

Spectrofluorimetry with attomole sensitivity in photonic crystal fibres

Single-mode white-light supercontinuum with 60 ps pump pulses in a photonic crystal fiber

Broadband electric-field-induced LP 01 and LP 02 second harmonic generation in Xe-filled hollow-core PCF.

Directional coupling in a twin core photonic crystal fiber using heat treatment

Highly efficient deep UV generation by four-wave mixing in gas-filled hollow-core photonic crystal fiber.