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

Two schemes for multi-μJ pulse compression in noble-gas-filled hollow-core kagome-PCF are demonstrated and compared. A fiber-plus-chirped-mirror combination compresses 150 fs, 9.5 μJ pulses to 26 fs, and soliton-effect compression produces sub 7 fs pulses.

Two schemes for pulse compression in gas-filled kagomé-PCF

Using a polarization-spectroscopy technique, we observe spontaneous forward Brillouin scattering of light in birefringent lead-silicate PCF. The higher stress-optical coefficient of the glass means that signals can be detected even in short lengths of fiber.

Forward-Brillouin Scattering of Light at Acoustic Resonances in SF6 Glass PCF

Low-noise trains of few-fs pulses are widely used for studying and controlling ultrafast dynamics in matter. Microjoule-level pulse energies are often more than sufficient to trigger and observe these dynamics, and repetition rates in the few MHz range allow reduced acquisition times and improved signal-to-noise ratios—crucial for studies of processes with low-interaction cross-sections. The latest generation of fibre lasers can provide ultrashort pulses with stable carrier-envelope phase (CEP) at unprecedented energies and hundreds of kHz repetition rates [1] , [2] . However, because the generated pulses are hundreds of fs long, multiple compression stages are required to reach the few fs regime, thus increasing the system complexity and reducing the throughput efficiency.

Towards CEP-stable single-cycle pulses with microjoule-level energy at 8 MHz repetition rate

We discuss four-wave mixing and resonant radiation in photonic crystal fibers with three zero dispersion wavelengths. We find a complex phase-matching landscape that allows multiple frequencies to be generated by both continuous waves and solitons.

Topology of four-wave mixing and resonant radiation in PCFs with three zero-dispersion wavelengths

Short laser pulses undergoing soliton self-compression in gas-filled hollow-core photonic crystal fibre (HC-PCF) can reach intensities sufficient to significantly ionise the gas under many experimental conditions. Due to the long-lived nature of the plasma, this may affect the propagation dynamics of subsequent pulses and thus limit scaling to higher repetition rates [1, 2]. Here we report experimental measurements and a numerical study of the free electron density distribution along the length of a gas-filled HC-PCF including its temporal evolution (with a few fs resolution) over 1 ns after the ionisation event. The plasma causes the effective refractive index of the modes to decrease which, in turns, alters the phase-matching conditions for dispersive wave (DW) generation from counter-propagating probe pulse, which shifts to higher frequencies in the ultraviolet. By measuring this shift we can detect free electron densities as low as ∼1016 cm−3, corresponding to a drop of refractive index of only ∼10−6.

Philip St. J. Russell

Papers

Two schemes for pulse compression in gas-filled kagomé-PCF

Forward-Brillouin Scattering of Light at Acoustic Resonances in SF6 Glass PCF

Towards CEP-stable single-cycle pulses with microjoule-level energy at 8 MHz repetition rate

Topology of four-wave mixing and resonant radiation in PCFs with three zero-dispersion wavelengths

Plasma Profile along a Hollow-Core Photonic Crystal Fibre Measured with Counter-Propagating Probe Solitons