Classical and fluctuation-induced electromagnetic interactions in micronscale systems: designer bonding, antibonding, and Casimir forces

Whether intentionally introduced to exert control over particles and macroscopic objects, such as for trapping or cooling, or whether arising from the quantum and thermal fluctuations of charges in otherwise neutral bodies, leading to unwanted stiction between nearby mechanical parts, electromagnetic interactions play a fundamental role in many naturally occurring processes and technologies. In this review, we survey recent progress in the understanding and experimental observation of optomechanical and quantum-fluctuation forces. Although both of these effects arise from exchange of electromagnetic momentum, their dramatically different origins, involving either real or virtual photons, lead to different physical manifestations and design principles. Specifically, we describe recent predictions and measurements of attractive and repulsive optomechanical forces, based on the bonding and antibonding interactions of evanescent waves, as well as predictions of modified and even repulsive Casimir forces between nanostructured bodies. Finally, we discuss the potential impact and interplay of these forces in emerging experimental regimes of micromechanical devices.Comment: Review to appear on the topical issue "Quantum and Hybrid Mechanical Systems" in Annalen der Physi

Frontiers in Guided Wave Optics and Optoelectronics

Non

A full degree-of-freedom photonic crystal spatial light modulator

Harnessing the full complexity of optical fields requires complete control of all degrees-of-freedom within a region of space and time -- an open goal for present-day spatial light modulators (SLMs), active metasurfaces, and optical phased arrays. Here, we solve this challenge with a programmable photonic crystal cavity array enabled by four key advances: (i) near-unity vertical coupling to high-finesse microcavities through inverse design, (ii) scalable fabrication by optimized, 300 mm full-wafer processing, (iii) picometer-precision resonance alignment using automated, closed-loop "holographic trimming", and (iv) out-of-plane cavity control via a high-speed micro-LED array. Combining each, we demonstrate near-complete spatiotemporal control of a 64-resonator, two-dimensional SLM with nanosecond- and femtojoule-order switching. Simultaneously operating wavelength-scale modes near the space- and time-bandwidth limits, this work opens a new regime of programmability at the fundamental limits of multimode optical control.Comment: 25 pages, 20 figure

Dynamic bandgap tuning of solid thin film photonic crystal structures

Nanophotonics, specifically photonic crystals (PhCs), offer unique optical bandgap engineering possibilities that has driven the emergence of a variety of device platforms, including: beam splitters, nano-cavity resonators, lasers, fibers, waveguides and highly sensitive optofluidic biosensor devices. The design and fabrication of accurate lattice parameters for a PhC is very important to achieving the desired operating bandgap. The inclusion of tunability in thin film PhCs not only offers a means of adjusting for fabrication errors but also a mechanism to increase device functionality as well as providing a wider range of operating wavelengths. Nitride thin films, specifically Aluminum Nitride (AlN) and Gallium Nitride (GaN), are being used as PhC slab materials by our group due to their desirable optical properties at visible wavelengths and high chemical and thermal stability under harsh conditions. The inherent piezoelectric properties of these materials offer a means of direct tuning of PhC lattice parameters through piezoelectric deformation.;This thesis presents the results of research aimed at actively tuning the bandgap of PhCs fabricated in piezoelectric AlN thin films. Theoretical investigations of the bandgap tuning of =as-drawn\u27 and deformed 1- and 2-D PhC lattice structures using coupled results from PhC optical behavioral modeling and finite element mechanical simulations are discussed. The results of experimental characterization of the optical and mechanical (i.e. tuning) properties of micro to nanoscale PhC lattice structures fabricated in Si and AlN using e-beam and optical lithography and reactive ion etching are presented. Experimental data is then used to explore the bandwidth tuning capability of large-area periodic nanophotonic structures

TUNING AND OPTOMECHANICS OF COUPLED PHOTONIC CRYSTAL NANOBEAM CAVITIES

Ph.DDOCTOR OF PHILOSOPH

Infrared optical filters based in macroporous silicon for espectroscopic gas detection

Aplicat embargament des de la data de defensa fins el 31 de desembre de 2021Gas detection is of great importance in areas as diverse as industry, health or safety in domestic environments or public spaces, among others, and it is highly specific to each application. The detection method depends on factors such as the species of gas to be detected, concentration range, required resolution, sensitivity, specificity, response time, operating environment (temperature, humidity, interfering species, etc.), size and cost, among other considerations. Optical gas sensors are an attractive solution for gas detection. Most of them rely on molecular absorption and offer fast responses, minimal drift and are intrinsically reliable thanks to perform self-referenced measurements. Sensitivity and selectivity depend on the characteristics of the device. For example, laser-based gas sensors are highly selective with zero cross response to other gases and also with first-in-class sensitivity. The downside is that they are expensive. Non-dispersive infra-red (NDIR) sensors are a widespread alternative for cost-effective optical detection. They have inferior performances in terms of sensitivity and selectivity than laser-based sensors, but are two or three orders of magnitude less expensive. This thesis is dedicated to improving the selectivity and sensitivity of NDIR devices through the use of macroporous silicon technology. More specifically, it studies how photonic crystals manufactured by electrochemical etching can be used as narrow mid-infrared filters for gas detection purposes. That is, the photonic crystals are designed in such a way that only a small range of frequencies from an external source are transmitted while the surroundings are blocked. These filters are narrower than those available on the market and can be used to improve the selectivity and the sensitivity of NDIR devices as well as to reduce cross detection with other gases. In addition, the study shows how macroporous silicon photonic crystals can be heated to work as selective emitters. This can be used to reduce the complexity of the NDIR device while maintaining similar optical characteristics. Furthermore, it is proven that photonic molecules can be employed to perform dual detection in both transmission and emission, giving a new approach to self-referenced measurements. Conclusions of the work show that macroporous silicon technology is a versatile platform to provide solutions in the mid-infrared range for developing compact, sensitive and selective optical gas sensing.La detecció de gasos és de gran importància en àrees tan diverses com la indústria, la salut o la seguretat en entorns domèstics o espais públics, entre d'altres, i és altament específica per a cada aplicació. El mètode de detecció a utilitzar depèn de factors com ara el gas a detectar, el rang de concentració, la resolució requerida, la sensibilitat, l'especificitat, el temps de resposta, l'entorn operatiu (temperatura, humitat, espècies interferents, etc. .), la mida i el cost, entre altres consideracions. Els sensors òptics de gas són una solució atractiva per a la detecció de gas. La majoria d'ells es basen en l'absorció molecular i ofereixen respostes ràpides, deriva mínima i són intrínsecament fiables gràcies a la realització de mesures auto-referenciades. La sensibilitat i la selectivitat depenen de les característiques del dispositiu. Per exemple, els sensors de gas basats en tecnologia làser són altament selectius, no presenten resposta creuada a altres gasos i són altament sensibles. El desavantatge és que són cars. Els sensors d'infrarojos no dispersius (NDIR) són una alternativa molt estesa per a la detecció òptica de baix cost. Tenen un rendiment inferior en termes de sensibilitat i selectivitat que els sensors basats en làser, però són dos o tres ordres de magnitud més barats. Aquesta tesi està dedicada a millorar la selectivitat i la sensibilitat dels dispositius NDIR mitjançant la tecnologia de silici macroporós. Més específicament, estudia com els cristalls fotònics fabricats mitjançant el gravat electroquímic poden ser usats com a filtres estrets d'infraroig mitjà per a la detecció de gasos. És a dir, els cristalls fotònics estan dissenyats de tal manera que només un petit rang de freqüències d'una font externa es transmet mentre que els voltants estan bloquejats. Aquests filtres són més estrets que els disponibles en el mercat i poden utilitzar-se per millorar la selectivitat i la sensibilitat dels dispositius NDIR, així com per reduir la detecció creuada amb altres gasos. A més, l'estudi mostra com els cristalls fotònics de silici macroporós poden funcionar com a emissors selectius si són escalfats. Això pot ser usat per reduir la complexitat dels dispositius NDIR alhora que es mantenen característiques òptiques similars. A més, s'ha demostrat que les molècules fotòniques poden emprar-se per realitzar una detecció dual tant en la transmissió com en l'emissió, donant un nou enfocament a les mesures auto-referenciades. Les conclusions del treball mostren que la tecnologia de silici macroporós és una plataforma versàtil que proporciona solucions en el rang d'infraroig mitjà per al desenvolupament de sensors de gas òptics compactes, sensibles i selectius.Postprint (published version

Optical studies of photonic crystals and high index-contrast microphotonic circuits

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.Includes bibliographical references (p. 137-143).Both high index-contrast (HIC) photonic crystals and HIC microphotonic circuits are presented in this thesis. Studies of macro-scale 2D photonic crystal meta-materials are first described. Through comparison of experimental and theoretical beam evolution about the super-collimation frequencies, the effects of disorder on beam evolution are pinpointed. Despite the effects of disorder, super-collimation is found to be robust, producing stationary beam-widths over 600 isotropic diffraction-lengths. In addition, nano-scale photonic crystal defect modes are studied over large optical bandwidths through newly developed supercontinuum based techniques. Novel all-fiber supercontinuum sources facilitate the generation of unpolarized supercontinuum light over 1.2-2.0 micron wavelengths. Broadband experimental methods make possible the application of these sources to the study of 1D and 3D photonic crystals with defect states. Studies of both static and dynamic microring resonator based HIC filters are described. Numerous microring based studies are reported which lead to frequency-compensated multi-ring filters, permitting the first high-fidelity microring filters in HIC microphotonics.(cont.) Though telecom-grade performance achieved via frequency compensation, the aforementioned filters exhibit severe polarization sensitivities, making them incompatible for real-world applications. Through integration of identical sets of these filters in a generalized polarization diversity scheme, polarization insensitive HIC filters are demonstrated for the first time, yielding a maximum polarization dependant loss of 2.2 dB over broad bandwidths. Finally, evanescent field-perturbation is investigated as a means of tuning microcavities over ultrawide wavelength ranges. Through nano-metric control of a silica perturbing body in the near-field of a microring waveguide, a 27 nm (or 1.7%) reversible tuning of its cavity mode is achieved.by Peter Thomas Rakich.Ph.D