A picogram- and nanometre-scale photonic-crystal optomechanical cavity
The dynamic back-action caused by electromagnetic forces (radiation pressure) in optical and microwave cavities is of growing interest. Back-action cooling, for example, is being pursued as a means of achieving the quantum ground state of macroscopic mechanical oscillators. Work in the optical domain has revolved around millimetre- or micrometre-scale structures using the radiation pressure force. By comparison, in microwave devices, low-loss superconducting structures have been used for gradient-force-mediated coupling to a nanomechanical oscillator of picogram mass. Here we describe measurements of an optical system consisting of a pair of specially patterned nanoscale beams in which optical and mechanical energies are simultaneously localized to a cubic-micron-scale volume, and for which large per-photon optical gradient forces are realized. The resulting scale of the per-photon force and the mass of the structure enable the exploration of cavity optomechanical regimes in which, for example, the mechanical rigidity of the structure is dominantly provided by the internal light field itself. In addition to precision measurement and sensitive force detection, nano-optomechanics may find application in reconfigurable and tunable photonic systems, light-based radio-frequency communication and the generation of giant optical nonlinearities for wavelength conversion and optical buffering.
Additional Information© 2009 Macmillan Publishers Limited. Received 15 December 2008; accepted 8 April 2009. Published online 13 May 2009. The authors would like to thank Q. Lin for extensive discussions regarding this work, and for pointing out the origin of the mechanical resonance interference. Funding for this work was provided by a US Defense Advanced Research Projects Agency seedling effort managed by H. Temkin, and through an Emerging Models and Technologies grant from the US National Science Foundation. Author Contributions: M.E. and R.C. performed the majority of the fabrication and testing of devices and J.C. performed the optical and mechanical simulations. O.P., along with M.E. and K.J.V., developed the device concept. O.P., K.J.V., M.E. and R.C. all contributed to planning the measurements. All authors worked together to write the manuscript.
Submitted - 0812.2953v1.pdf
Supplemental Material - Eichenfield2009p4481Nature_supp.pdf