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Whispering Gallery Microcavity Sensing
Published in Kevin Yallup, Krzysztof Iniewski, Technologies for Smart Sensors and Sensor Fusion, 2017
Serge Vincent, Xuan Du, Tao Lu
Microtoroids are frequently fabricated by reflowing a microdisk with a CO2 laser source to boost quality factors by an order of magnitude, to 5 × 108 [14]. As one of the only on-chip ultrahigh-Q microcavities demonstrated by the time of its invention, silica microtoroids have been extensively used in the study of nonlinear optics [15], frequency microcomb generation [16], cavity optomechanics [17], cavity quantum electrodynamics [18], low threshold power, narrow-linewidth laser sources [19], as well as ultrasensitive biosensors [20].
Controllable optical bistability and Fano line shape in a hybrid optomechanical system assisted by kerr medium: possibility of all optical switching
Published in Journal of Modern Optics, 2018
Aranya B. Bhattacherjee, Muhammad S. Hasan
Cavity optomechanics is a rapidly growing field of research in which a coherent coupling between the cavity optical modes and the mechanical modes of the oscillator can be achieved via the radiation pressure exerted by the trapped cavity photons [15–19]. Rapid technological advancements in this field has led to marked achievements such as ultrahigh-precision measurements [20], gravitational wave detectors [21], quantum information processing [22,23], quantum entanglement [24–26] and optomechanically induced transparency (OMIT) [27–35]. In optomechanical systems, a high degree of nonlinearity exists between the optical field and mechanical mode, which gives rise to optical bistability and multistability [34,36–38]. This optical phenomena has practical applications in all optical switching [39,40] and memory storage [41,42]. Optomechanical systems also exhibits an interesting optical phenomena called Fano resonance [43] which is based on quantum coherence and interference. Fano resonance is characterized by a sharp asymmetric line profile. Fano resonance is different from electromagnetically induced transparency (EIT) and OMIT, both of which have symmetric line profile. The asymmetry of the Fano line shape and enhanced interference effect has attracted many theoretical [44–47] as well as experimental investigations [48–51]. EIT is a quantum interference effect arising from different transition pathways of optical fields [35]. In the EIT effect, an abnormal dispersion occurs with the opening of a transparency window, resulting in slow light i.e reduction of light group velocity [52,53]. This phenomenon implies that light can be stored in atomic ensembles [54,55]. Slow light has important applications in optical networks [56], quantum networks [57] and quantum memory [58,59].
Rigorous simulation of nonlinear optomechanical coupling in micro- and nano-structured resonant cavities
Published in International Journal of Optomechatronics, 2018
Matteo Stocchi, Davide Mencarelli, Yan Pennec, Bahram Djafari-Rouhani, Luca Pierantoni
In the recent past, the interlacing between optical cavities and mechanical systems has given rise to a rapid development of the research branch called cavity optomechanics which aims, by the means of a high-Q resonant recirculation, to confine light into small volumes.[1–4] The intent of an optomechanical system is to investigate the interaction of light with a mechanical oscillator, and its highly interdisciplinary nature leads to several potential applications in various fields of research, especially in quantum processing.[5–9] It has been shown that the combination of both optical and mechanical interactions guarantees the most successful exploitation of mechanical vibrations for the managing of quantum phenomena through phonon-assisted optical or sideband transitions, as demonstrated in trapped ions[10,11] and, more recently, in cavity optomechanics.[12–19] Focusing on the latter, optomechanical micro-cavities can also serve as a possible concept to provide new functionalities, applications and opportunities beyond standard technology, owing to phonon propagation, generation and processing.[20,21] In this contribution, we present a fully coupled numerical approach which, combining the two exerted physics of mechanics and optics, accurately predicts the optomechanical dynamics in micro-structured resonant cavities.[22] The rigorousness of such analysis is ensured by considering all the four main energy-transduction contributions.[23] Referring to the two inserts of Figure 1, the radiation pressure and the electrostriction constitutes the forces wielded by the E-field on the matter, whereas the photoelasticity describes the perturbation of the electromagnetic radiation caused by the presence of the mechanical wave. Special considerations are then required for what concerns the so called moving boundary effect, i.e. the boundary deformation caused by the space–time varying pressure field that perturbates the electromagnetic boundary conditions. Specifically, the Eulerian coordinates in which the Maxwell equations are solved are not able to take into account for the mechanical displacement, defined, in turn, in Lagrangian coordinates. As a matter of fact, the just reported limitation can be numerically significant in case of nano-scale cavities. The transformation optics (TO)[24,25] method represents an elegant and efficient solution to the addressed problem. According to its original concept, TO is an analytical tool that facilitates the design of a variety of optical devices (lenses, phase shifters, deflectors, etc.) by deforming the coordinate system, warping space to control the trajectories of the electromagnetic radiation. Such alteration then turns into a change of the electromagnetic material parameters such as the permittivity and the permeability μ. For the special case of optomechanics, TO is used to take into account for the time-varying boundaries of the domain under investigation,[26] making then possible to consider the moving boundary effect by means of a modified version of the standard Helmholtz equation.