Analysis of Membrane Phononic Crystals with Wide Band Gaps and Low-Mass Defects

Reetz, Chris; Fischer, Ran; Assumpcao, Gabriel; McNally, Dylan P.; Burns, Peter; Sankey, J. C.; Regal, C. A.

doi:10.1103/physrevapplied.12.044027

Cited by 47 publications

(25 citation statements)

References 34 publications

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“…Although reaching the single-photon strong coupling regime of optomechanics is difficult, there is great experimental progress on reducing the mechanical dissipation rates in optomechanical systems. Quality factors Q m 10 8 have been reported for flexural modes in dielectric membranes [35][36][37][38] or nanobeams [39], and localized acoustic modes in suspended photonic crystals can have quality factors as large as Q m ∼ 10 10 [40]. In light of this, one may wonder whether any new phenomena can be realized in the regime where the single-photon optomechanical cooperativity…”

Section: Introductionmentioning

confidence: 99%

Critical quantum fluctuations and photon antibunching in optomechanical systems with large single-photon cooperativity

Børkje

2020

Phys. Rev. A

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A pertinent question in cavity optomechanics is whether reaching the regime of large single-photon cooperativity, where the single-photon coupling rate exceeds the geometric mean of the cavity and mechanical decay rates, can enable any new phenomena. We show that in some multimode optomechanical systems, the single-photon cooperativity can indeed be a figure of merit. We first study a system with one cavity mode and two mechanical oscillators, which combines the concepts of levitated optomechanics and coherent scattering with standard dispersive optomechanics. Later, we study a more complicated setup involving three cavity modes which does not rely on levitated optomechanics and only features dispersive optomechanical interactions with direct cavity driving. These systems can effectively realize the degenerate or the nondegenerate parametric oscillator models known from quantum optics, but in the unusual finite-size regime for the fundamental mode(s) when the single-photon cooperativity is large. We show that the response of these systems to a coherent optical probe can be highly nonlinear in probe power even for average photon occupation numbers below unity. The nonlinear optomechanical interaction has the peculiar consequence that the probe drive will effectively amplitude-squeeze itself. For large single-photon cooperativity, this occurs for small occupation numbers, which enables observation of nonclassical antibunching of the transmitted probe photons due to a destructive interference effect. Finally, we show that as the probe power is increased even further, the system enters a critical regime characterized by intrinsically nonlinear dynamics and non-Gaussian states.

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Section: Introductionmentioning

confidence: 99%

Critical quantum fluctuations and photon antibunching in optomechanical systems with large single-photon cooperativity

Børkje

2020

Phys. Rev. A

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“…Addition of a suitable absorbing layer on top of the PnC presents an additional path towards greater responsivities [28]. Even larger band gaps can be opened through variation of the PnC design, which might lead to modes with even higher localization [35]. Overall, the data presented FIG.…”

Section: Discussionmentioning

confidence: 83%

Thermal Transport and Frequency Response of Localized Modes on Low-Stress Nanomechanical Silicon Nitride Drums Featuring a Phononic-Band-Gap Structure

et al. 2020

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Development of broadband thermal sensors for the detection of, among others, radiation, single nanoparticles, or single molecules is of great interest. In recent years, photothermal spectroscopy based on the shift of the resonance frequency of stressed nanomechanical resonators has been successfully demonstrated. Here, we show the application of soft-clamped phononic crystal membranes made of silicon nitride as thermal sensors. It is experimentally demonstrated how a quasi-band-gap remains even at very low tensile stress, in agreement with finite-element-method simulations. An increase of the relative responsivity of the fundamental defect mode is found when compared to that of uniform square membranes of equal size, with enhancement factors as large as an order of magnitude. We then show phononic crystals engineered inside nanomechanical trampolines, which results in additional reduction of the tensile stress and increased thermal isolation, resulting in further enhancement of the responsivity. Finally, defect-mode and band-gap tuning is shown by laser heating of the defect to the point where the fundamental defect mode completely leaves the band gap.

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“…Instead, we used the opportunity to define the geometry of the device, its material properties and physical interactions into a multiphysics FEM model. In [12,29,34,43] FEM is successfully employed for the analysis of the properties of a vibrating fractal structures and phononic crystals. Thus, we use COMSOL FEM software to vary the stress in x-direction so the resulted eigenmodes fit with the experimental ones.…”

Section: Discussionmentioning

confidence: 99%

“…Secondly, as our fractal structure is clamped at all its vertices and the fabrication technology introduces high residual stress, we expect to some degree the effects of dissipation dilution and higher Q due to clamp-tapering [30,31]. In the recent studies of 1D and hexagonal phonon crystals (PnC) [32][33][34] these enhancing Q effects are combined with soft clamping which further reveals the importance of the lattice geometry for the amount of dissipated mechanical energy through the anchors.…”

Section: Introductionmentioning

confidence: 99%

Multi-Frequency Resonance Behaviour of a Si Fractal NEMS Resonator

et al. 2020

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Novel Si-based nanosize mechanical resonator has been top-down fabricated. The shape of the resonating body has been numerically derived and consists of seven star-polygons that form a fractal structure. The actual resonator is defined by focused ion-beam implantation on a SOI wafer where its 18 vertices are clamped to nanopillars. The structure is suspended over a 10 μm trench and has width of 12 μm. Its thickness of 0.040 μm is defined by the fabrication process and prescribes Young’s modulus of 76 GPa which is significantly lower than the value of the bulk material. The resonator is excited by the bottom Si-layer and the interferometric characterisation confirms broadband frequency response with quality factors of over 800 for several peaks between 2 MHz and 16 MHz. COMSOL FEM software has been used to vary material properties and residual stress in order to fit the eigenfrequencies of the model with the resonance peaks detected experimentally. Further use of the model shows how the symmetry of the device affects the frequency spectrum. Also, by using the FEM model, the possibility for an electrical read out of the device was tested. The experimental measurements and simulations proved that the device can resonate at many different excitation frequencies allowing multiple operational bands. The size, and the power needed for actuation are comparable with the ones of single beam resonator while the fractal structure allows much larger area for functionalisation.

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Analysis of Membrane Phononic Crystals with Wide Band Gaps and Low-Mass Defects

Cited by 47 publications

References 34 publications

Critical quantum fluctuations and photon antibunching in optomechanical systems with large single-photon cooperativity

Critical quantum fluctuations and photon antibunching in optomechanical systems with large single-photon cooperativity

Thermal Transport and Frequency Response of Localized Modes on Low-Stress Nanomechanical Silicon Nitride Drums Featuring a Phononic-Band-Gap Structure

Multi-Frequency Resonance Behaviour of a Si Fractal NEMS Resonator

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