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

Photonische Kristallfasern sind Glasfasern, deren Mantel in Langsrichtung von Kanalen mit mikroskopischem Querschnitt durchzogen ist. Uber den Faserquerschnitt betrachtet bilden diese ein periodisches Lochmuster. Sie wirken auf das transportierte Licht wie ein zweidimensionaler photonischer Kristall. Im Kern sind die Fasern entweder hohl oder mit Glas gefullt. Solche Fasern konnen zum Beispiel Laserlicht selektiv in der Grundschwingungsmode transportieren. Mit ihnen lassen sich auch extrem lange Fokustiefen erzielen. Das Licht leiten sie so gut, dass sie bei den internen Reflexionen zu den weltbesten Spiegeln gehoren. Gasgefullte Kanale machen sie zu empfindlichen Gassensoren und hocheffizienten Frequenzvervielfachern. Letztere lassen sich einfach in optische Bauelemente der Telekommunikation integrieren. Hohlkernfasern konnen sogar als lasergetriebene Teilchenbeschleuniger funktionieren. Nicht zuletzt stellen die Fasern ein wichtiges Bauteil im nobelpreisgekronten optischen Frequenzkamm dar. Sie eroffnen noch viele weitere Anwendungsfelder.

Eingesperrtes Licht. Photonische Kristallfasern

Optical fiber modes carrying orbital angular momentum (OAM) have many applications, for example in mode-division-multiplexing for optical communications. The natural guided modes of N -fold rotationally symmetric optical fibers, such as most photonic crystal fibers, are helical Bloch modes (HBMs). HBMs consist of a superposition of azimuthal harmonics (order m ) of order $\ell _{\rm{A}}^{(m)} = \ell _{\rm{A}}^{(0)} + mN$ . When such fibers are twisted, these modes become circularly and azimuthally birefringent, that is to say HBMs with equal and opposite values of $\ell _{\rm{A}}^{(0)}$ and spin s are non-degenerate. In this article we report the use of Bragg mirrors to reflect and convert HBMs in a twisted three-core photonic crystal fiber, and show that by writing a tilted fiber Bragg grating (FBG), reflection between HBMs of different orders becomes possible, with high wavelength-selectivity. We measure the near-field phase and amplitude distribution of the reflected HBMs interferometrically, and demonstrate good agreement with theory. This new type of FBG has potential applications in fiber lasers, sensing, quantum optics, and in any situation where creation, conversion, and reflection of OAM-carrying modes is required.

/pdf/bragg-reflection-and-conversion-between-helical-bloch-modes-2if6adfu63.pdf

Bragg Reflection and Conversion Between Helical Bloch Modes in Chiral Three-Core Photonic Crystal Fiber

We report the successful fabrication of a ZBLAN photonic crystal fiber with sub-micron features and large air-filling fraction and use it to generate a 10dB-flat supercontinuum (350 to 2500nm) from 140fs, 1nJ pulses at 1042nm.

Close to three-octave-spanning supercontinuum generated in ZBLAN photonic crystal fiber

A continuously twisted PCF can be viewed as a one-dimensional metamaterial in which both ϵ and μ tensors develop off-diagonal elements. Finite-element calculations confirm the appearance of unique loss peaks in the experimental transmission spectrum.

Strongly Twisted Solid-Core PCF: A One-Dimensional Chiral Metamaterial

We use Raman amplification in hydrogen-filled hollow-core kagome photonic crystal fiber to generate high energy pulses in pure single higher-order modes. The desired higher-order mode at the Stokes frequency is precisely seeded by injecting a pulse of light from the side, using a prism to select the required modal propagation constant. An intense pump pulse in the fundamental mode transfers its energy to the Stokes seed pulse with measured gains exceeding 60 dB and output pulse energies as high as 8 µJ. A pressure gradient is used to suppress stimulated Raman scattering into the fundamental mode at the Stokes frequency. The growth of the Stokes pulse energy is experimentally and theoretically investigated for six different higher-order modes. The technique has significant advantages over the use of spatial light modulators to synthesize higher-order mode patterns, since it is very difficult to perfectly match the actual eigenmode of the fiber core, especially for higher-order modes with complex multi-lobed transverse field profiles.

Philip St. J. Russell

Papers

Eingesperrtes Licht. Photonische Kristallfasern

Bragg Reflection and Conversion Between Helical Bloch Modes in Chiral Three-Core Photonic Crystal Fiber

Close to three-octave-spanning supercontinuum generated in ZBLAN photonic crystal fiber

Strongly Twisted Solid-Core PCF: A One-Dimensional Chiral Metamaterial

Raman amplification of pure side-seeded higher-order modes in hydrogen-filled hollow-core PCF