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

Laser cooling of mechanical degrees of freedom is one of the most significant achievements in the field of optomechanics. Here, we report, for the first time to the best of our knowledge, efficient passive optomechanical cooling of the motion of a freestanding waveguide coupled to a whispering-gallery-mode (WGM) resonator. The waveguide is an 8 mm long glass-fiber nanospike, which has a fundamental flexural resonance at Ω/2π=2.5  kHz and a Q-factor of 1.2×105. Upon launching ∼250  μW laser power at an optical frequency close to the WGM resonant frequency, we observed cooling of the nanospike resonance from room temperature down to 1.8 K. Simultaneous cooling of the first higher-order mechanical mode is also observed. The strong suppression of the overall Brownian motion of the nanospike, observed as an 11.6 dB reduction in its mean square displacement, indicates strong optomechanical stabilization of linear coupling between the nanospike and the cavity mode. The cooling is caused predominantly by a combination of photothermal effects and optical forces between nanospike and WGM resonator. The results are of direct relevance in the many applications of WGM resonators, including atom physics, optomechanics, and sensing.

/pdf/optomechanical-cooling-and-self-stabilization-of-a-waveguide-1g9iiu8vat.pdf

Optomechanical cooling and self-stabilization of a waveguide coupled to a whispering-gallery-mode resonator

Vector coupled-mode (VCM) theory, applied to helical Bloch waves [1], was recently introduced to clarify the origins of circular dichroism in twisted single-ring hollow-core photonic crystal fibres [2]. Here we show it can also be used to calculate, rapidly and precisely, the photonic band structure of regular lattices of coupled anisotropic waveguides, offering considerable advantages over the plane-wave expansion method and finite element modelling (FEM). As an example, we treat a graphene-like lattice of coupled cores (Fig. 1a), which represents the type of mode seen in coreless twisted PCF [3]. The VCM approach itself is illustrated in Fig. 1b.

Rapid and Accurate Calculation of Vector Photonic Band-Structure in Regular Arrays of Coupled Waveguides

We report new nonlinear features observed in an adiabatically tapered photonic crystal fiber. When using femtosecond pulses, the soliton self-frequency shift and generation of nonsolitonic radiation result in a dasiashark-finpsila-shaped feature in the power-dependent spectrum.

Evolution of soliton behavior in adiabatically tapered photonic crystal fiber

Untersuchungen zum Einsatz photonischer Kristallfasern in der Katalyse

We report light-driven instability and optomechanical self-oscillation of a fused silica “nanospike” at low gas pressures.
The nanospike (tip diameter 400 nm), fabricated by thermally tapering and HF-etching a single mode fiber (SMF), was
set pointing at the endface of a hollow-core photonic crystal fiber (HC-PCF) into the field created by the fundamental
optical mode emerging from the HC-PCF. At low pressures, the nanospike became unstable and began to self-oscillate
for optical powers above a certain threshold, acting like a phonon laser or "phaser". Because the nanospike is robustly
connected to the base, direct measurement of the temporal dynamics of the instability is possible. The experiment sheds
light on why particles escape from optical traps at low pressures.

Philip St. J. Russell

Papers

Optomechanical cooling and self-stabilization of a waveguide coupled to a whispering-gallery-mode resonator

Rapid and Accurate Calculation of Vector Photonic Band-Structure in Regular Arrays of Coupled Waveguides

Evolution of soliton behavior in adiabatically tapered photonic crystal fiber

Untersuchungen zum Einsatz photonischer Kristallfasern in der Katalyse

Optically Driven Self-Oscillations of a Silica Nanospike at Low Gas Pressures