Single-Crystal Diamond Nanobeam Waveguide Optomechanics

Abstract

Optomechanical devices sensitively transduce and actuate motion of nanomechanical structures using light. Single-crystal diamond promises to improve the performance of optomechanical devices, while also providing opportunities to interface nanomechanics with diamond color center spins and related quantum technologies. Here we demonstrate dissipative waveguide-optomechanical coupling exceeding 35 GHz/nm to diamond nanobeams supporting both optical waveguide modes and mechanical resonances, and use this optomechanical coupling to measure nanobeam displacement with a sensitivity of 9.5 fm/ √ Hz and optical bandwidth > 150nm. The nanobeams are fabricated from bulk optical grade single-crystal diamond using a scalable undercut etching process, and support mechanical resonances with quality factor 2.5 × 10 5 at room temperature, and 7.2 × 10 5 in cryogenic conditions (5K). Mechanical self-oscillations, resulting from interplay between photothermal and optomechanical effects, are observed with amplitude exceeding 200 nm for sub-µW absorbed optical power, demonstrating the potential for optomechanical excitation and manipulation of diamond nanomechanical structures.

High-Q/V Monolithic Diamond Microdisks Fabricated with Quasi-isotropic Etching

“…This scalable technique relies upon undercutting of diamond with inductively coupled plasma reactive-ion etching (ICPRIE) along diamond crystal planes using a zero bias oxygen plasma. 36 This approach, which was also recently used to create diamond nanobeams, 36 shares the low material damage characteristics of the Faraday cage ICPRIE process of Burek et al 33 while providing an undercut profile intrinsic to the device geometry and etching parameters. It is fully compatible with standard nanofabrication tools and does not require modification to the etching tool setup.…”

“…31,44 Smaller pedestals are also desirable for reducing the dissipation of microdisk mechanical resonances used in optomechanics experiments. 45,46 Although this fabrication process has been shown to allow creation of high mechanical quality factor nanobeam structures, 36 it is expected that the relatively large pedestal diameter will limit the mechanical dissipation properties of the microdisk mechanical resonances. 47 Reducing the relative pedestal size to minimize mechanical dissipation 26 can be achieved through longer undercut etch times or by studying smaller microdisks operating at shorter wavelengths.…”

Inscription of 3D waveguides in diamond using an ultrafast laser

“…Elegant nanobeam waveguides have recently been demonstrated through either angled 15 or undercut RIE etching 16 . Alternatively, direct ion microbeam writing has been used to create shallow subsurface multimode waveguides 17 .…”

Advances in diamond nanofabrication for ultrasensitive devices

“…It is important to note that a figure of merit which should be considered to enhance sensitivity in nanomechanical resonators is based on the f c · Q m product. In this respect, in single crystal diamond nanomechanical resonators, the present record achieved is of f c · Q m = 2.2 THz at 5 K in doubly clamped nano-beam waveguides 32 , while for diamond nanocantilevers f c · Q m = 48.3 GHz at 3 K (Ref. 27).…”

“…32). The tunable coupling of single NV-center spins to external electromagnetic fields for quantum information applications was recently demonstrated in a hybrid spin-electro-mechanical device, where, by integrating a NV-embedded diamond beam with a superconducting coplanar waveguide cavity, a single NV-center spin is coupled to the single microwave cavity photons, enabling the mediation of coherent information transfer by mechanically dark polaritons 96 .…”