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Optomechanical Design Principles
Published in Anees Ahmad, Handbook of Optomechanical Engineering, 2018
Vibration is a source of performance degradation in optomechanical systems. Very low levels of vibration induce a blur in the focus. This vibration-induced blur is sometimes mistaken for blur due to a system misalignment, or an out-of-focus condition. Higher levels of vibration create a time-variant blur, which is at least easy to diagnose. Very high levels of vibration carry the potential for structural failure of the system. In general, operation is not expected at such levels, only survival.
Progress of optomechanical micro/nano sensors: a review
Published in International Journal of Optomechatronics, 2021
Xinmiao Liu, Weixin Liu, Zhihao Ren, Yiming Ma, Bowei Dong, Guangya Zhou, Chengkuo Lee
In summary, a comprehensive review of micro/nano optomechanical sensors development has been presented. In general, it can be categorized into three major fields of development according to their configurations. First is the most developed current passive optomechanical sensors with applications in physical sensing, second is the electrically modulated optomechanical sensing platforms with huge potential, while third is the nanoantenna-assisted molecular vibration level sensing and all-optical photothermal sensing. The current passive optomechanical sensors started with cantilever configurations in the early years, then extended to other configurations such as membranes and coupled nanocavities. The main applications of these optomechanical sensors are found in physical sensing, including force, displacement, inertia, and acoustic, etc.[267] Then, to add the tunability to the whole optomechanical systems, tuning mechanisms such as acousto-optical tuning through piezoelectric effect and electrostatic effect have been proposed, providing an extra degree of freedom for the sensing systems. Lastly, leveraging the interactions between molecular bonds vibrations and optical resonance, molecular vibrational sensing with nanoantenna assistance has been proven as an emerging field for chemical and biological sensing due to excellence in low detection limit, enhanced sensitivity, and compact footprint. The photothermal effect, a novel strategy to improving the sensing signal readout, is introduced as well.
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.