Design of tunable GHz-frequency optomechanical crystal resonators (original) (raw)

GHz optomechanical resonators with high mechanical Q factor in air

We demonstrate wheel-shaped silicon optomechanical resonators for resonant operation in ambient air. The high finesse of optical whispering gallery modes (loaded optical Q factor above 500,000) allows for efficient transduction of the wheel resonator's mechanical radial contour modes of frequency up to 1.35 GHz with high mechanical Q factor around 4,000 in air.

Engineering Multiple GHz Mechanical Modes in Optomechanical Crystal Cavities

Physical Review Applied

Optomechanical crystal cavities (OMCCs) are fundamental nanostructures for a wide range of phenomena and applications. Usually, optomechanical interaction in such OMCCs is limited to a single optical mode and a unique mechanical mode. In this sense, eliminating the single-mode constraint-for instance, by adding more mechanical modes-should enable more complex physical phenomena, giving rise to a context of multimode optomechanical interaction. However, a general method to produce in a controlled way multiple mechanical modes with large coupling rates in OMCCs is still missing. In this work, we present a route to confine multiple GHz mechanical modes coupled to the same optical field with similar optomechanical coupling rates-up to 400 kHz-by OMCC engineering. In essence, we increase the number of unit cells (consisting of a silicon nanobrick perforated by circular holes with corrugations at both its sides) in the adiabatic transition between the cavity center and the mirror region. Remarkably, the mechanical modes in our cavities are located within a full phononic band gap, which is a key requirement to achieve ultrahigh mechanical Q factors at cryogenic temperatures. The multimode behavior in a full phononic band gap and the easiness of realization using standard silicon nanotechnology make our OMCCs highly appealing for applications in the classical and quantum realms.

Position-Squared Coupling in a Tunable Photonic Crystal Optomechanical Cavity

Physical Review X, 2015

We present the design, fabrication, and characterization of a planar silicon photonic crystal cavity in which large position-squared optomechanical coupling is realized. The device consists of a double-slotted photonic crystal structure in which motion of a central beam mode couples to two high-Q optical modes localized around each slot. Electrostatic tuning of the structure is used to controllably hybridize the optical modes into supermodes that couple in a quadratic fashion to the motion of the beam. From independent measurements of the anticrossing of the optical modes and of the dynamic optical spring effect, a positionsquared vacuum coupling rate as large asg 0 =2π ¼ 245 Hz is inferred between the optical supermodes and the fundamental in-plane mechanical resonance of the structure at ω m =2π ¼ 8.7 MHz, which in displacement units corresponds to a coupling coefficient of g 0 =2π ¼ 1 THz=nm 2. For larger supermode splittings, selective excitation of the individual optical supermodes is used to demonstrate optical trapping of the mechanical resonator with measuredg 0 =2π ¼ 46 Hz.

Ultralow-dissipation optomechanical resonators on a chip

Nature Photonics, 2008

Cavity-enhanced radiation-pressure coupling of optical and mechanical degrees of freedom gives rise to a range of optomechanical phenomena, in particular providing a route to the quantum regime of mesoscopic mechanical oscillators. A prime challenge in cavity optomechanics has however been to realize systems which simultaneously maximize optical finesse and mechanical quality. Here we demonstrate for the first time independent control over both mechanical and optical degree of freedom within one and the same on-chip resonator. The first direct observation of mechanical normal mode coupling in a micromechanical system allows for a quantitative understanding of mechanical dissipation. Subsequent optimization of the resonator geometry enables intrinsic material loss limited mechanical Q-factors, rivalling the best values reported in the high MHz frequency range, while simultaneously preserving the resonators' ultra-high optical finesse. Besides manifesting a complete understanding of mechanical dissipation in microresonator based optomechanical systems, our results provide an ideal setting for cavity optomechanics.

Demonstration of Ultra Low Dissipation Optomechanical Resonators on a Chip

2008

Cavity-enhanced radiation-pressure coupling of optical and mechanical degrees of freedom gives rise to a range of optomechanical phenomena, in particular providing a route to the quantum regime of mesoscopic mechanical oscillators. A prime challenge in cavity optomechanics has however been to realize systems which simultaneously maximize optical finesse and mechanical quality. Here we demonstrate for the first time independent control

Cavity optomechanics with ultrahigh-Q crystalline microresonators

Physical Review A, 2010

We present the first observation of optomechanical coupling in ultra-high Q crystalline whisperinggallery-mode (WGM) resonators. The high purity of the crystalline material enables optical quality factors in excess of 10 10 and finesse exceeding 10 6 . Simultaneously, mechanical quality factors greater than 10 5 are obtained, still limited by clamping losses. Compared to previously demonstrated cylindrical resonators, the effective mass of the mechanical modes can be dramatically reduced by the fabrication of CaF2 microdisc resonators. Optical displacement monitoring at the 10 −18 m/ √ Hzlevel reveals mechanical radial modes at frequencies up to 20 MHz, corresponding to unprecedented sideband factors (> 100). Together with the weak intrinsic mechanical damping in crystalline materials, such high sindeband factors render crystalline WGM micro-resonators promising for backaction evading measurements, resolved sideband cooling or optomechanical normal mode splitting. Moreover, these resonators can operate in a regime where optomechanical Brillouin lasing can become accessible. PACS numbers: 42.65.Sf, 42.50.Wk

Two-dimensional optomechanical crystal resonator in gallium arsenide

arXiv (Cornell University), 2023

In the field of quantum computation and communication there is a compelling need for quantumcoherent frequency conversion between microwave electronics and infra-red optics. A promising platform for this is an optomechanical crystal resonator that uses simultaneous photonic and phononic crystals to create a co-localized cavity coupling an electromagnetic mode to an acoustic mode, which then via electromechanical interactions can undergo direct transduction to electronics. The majority of work in this area has been on one-dimensional nanobeam resonators which provide strong optomechanical couplings but, due to their geometry, suffer from an inability to dissipate heat produced by the laser pumping required for operation. Recently, a quasi-two-dimensional optomechanical crystal cavity was developed in silicon exhibiting similarly strong coupling with better thermalization, but at a mechanical frequency above optimal qubit operating frequencies. Here we adapt this design to gallium arsenide, a natural thin-film single-crystal piezoelectric that can incorporate electromechanical interactions, obtaining a mechanical resonant mode at fm ≈ 4.5 GHz ideal for superconducting qubits, and demonstrating optomechanical coupling gom/(2 π) ≈ 650 kHz.

Integrated On-Chip Nano-Optomechanical Systems

International Journal of High Speed Electronics and Systems, 2017

Recent developments in integrated on-chip nano-optomechanical systems are reviewed. Silicon-based nano-optomechanical devices are fabricated by a two-step process, where the first step is a foundry-enabled photonic circuits patterning and the second step involves in-house mechanical device release. We show theoretically that the enhanced responsivity of near-field optical transduction of mechanical displacement in on-chip nano-optomechanical systems originates from the finesse of the optical cavity to which the mechanical device couples. An enhancement in responsivity of more than two orders of magnitude has been observed when compared side-by-side with free-space interferometry readout. We further demonstrate two approaches to facilitate large-scale device integration, namely, wavelength-division multiplexing and frequency-division multiplexing. They are capable of significantly simplifying the design complexity for addressing individual nano-optomechanical devices embedded in a la...

Eliminating Structural Loss in Optomechanical Resonators Using Elastic Wave Interference

CLEO: 2013, 2013

Optomechanical resonators suffer from the dissipation of mechanical energy through the necessary anchors enabling the suspension of the structure. Here we show that such structural loss in an optomechnaical oscillator can be almost completely eliminated through the destructive interference of elastic waves using dual-disk resonators. We also present both analytical and numerical model that predicts the observed interference of elastic waves. Our experimental data reveal unstressed Si3N4 devices with mechanical Q-factors up to 10 4 at mechanical frequencies of f = 102 MHz (f Q = 10 12) at room temperature.