Nanoscale mechanical actuation and near-field read-out of photonic crystal molecules

Abstract

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Multimode photonic molecules for advanced force sensing

“…While, for evaluating the sensitivity of the system we stress that by increasing ∆d we find two actuation regimes, related to two different sensitivity parameters. The first regime is the force sensing regime, in which the S (AS) modes rigidly red (blue) shift, accordingly with the previous experimental results [19]. Here we can quantify the minimum detectable force (MDF) of the device, by evaluating the minimum detectable rigid shift of the modes, to be compared with a spectral resolution of the order of γ/1000 (where γ is the FWHM of a single peak with Q = 10 4 ) which can be detected by resonant detection methods [21].…”

“…Specifically, leveraging on the spectral features detection from a single optical channel, the system is able to identify the position where the force is applied, with a sub-micrometer in-plane spatial resolution. It was experimentally proven that by reducing the intermembrane distance d, the molecular modes spectrally shift [19]. In particular the S modes shift to longer wavelengths, while the AS modes shift to shorter wavelengths.…”

“…3(b) shows a horizontal cut of the FEM displacement map. This value of the force was chosen as it reproduces a maximum displacement of the upper membrane (the elastic constant of the dielectric membrane is k≈10 N/m) which is similar to the one obtained in the case of near-field mechanical actuation experiments on single cavities [19]. Using the deformation map we can determine the dependence of the out-of-plane coupling factors on the relative cavities z-coordinates by performing FDTD simulations on DM structures at different inter-membrane distances (from 240 nm to 80 nm in steps of 40 nm).…”

“…Large mode tuning with minor reduction of quality factor Q has been recently demonstrated by the electromechanical control of the distance between two PhCCs realized on two closely spaced parallel membranes [16][17][18]. Specifically, the effects of a local force exerted by nanoscale mechanical and electro-mechanical actuation on reconfigurable bilayer photonic crystal resonators have been studied [19][20]. These actuation methods allow the control of the spectral properties of coupled cavities in an ultrawide spectral range, demonstrating a fine and reversible mode shift.…”

Nano-opto-electro-mechanical switch based on a four-waveguide directional coupler

“…The initial zero-bias gap between suspended waveguides and bottom ones is 220 nm, which is relatively small compared to most MEMS switches in the literature. However, we have demonstrated experimentally several generations of devices based on similar gap scale, which work successfully and reproducibly [26,29,30]. In the symmetric case, the structure is symmetric and works in the cross-state.…”