Coherent mixing of mechanical excitations in nano-optomechanical structures
The combination of the large per-photon optical force and small motional mass achievable in nanocavity optomechanical systems results in strong dynamical back-action between mechanical motion and the cavity light field. In this Article, we study the optical control of mechanical motion within two different nanocavity structures, a zipper nanobeam photonic crystal cavity and a double-microdisk whispering-gallery resonator. The strong optical gradient force within these cavities is shown to introduce significant optical rigidity into the structure, with the dressed mechanical states renormalized into optically bright and optically dark modes of motion. With the addition of internal mechanical coupling between mechanical modes, a form of optically controlled mechanical transparency is demonstrated in analogy to electromagnetically induced transparency of three-level atomic media. Based upon these measurements, a proposal for coherently transferring radio-frequency/microwave signals between the optical field and a long-lived dark mechanical state is described.
Additional Information© 2010 Macmillan Publishers Limited. Received 12 October 2009; accepted 6 January 2010; published online 7 February 2010. The authors would like to thank T. Johnson and R. Perahia for their help with device processing, and T. Alegre for helpful discussions. This work was supported by the National Science Foundation (EMT grant no. 0622246 and CIAN grant no. EEC-0812072 through the University of Arizona) and through a seedling program from the Defense Advanced Research Projects Agency (grant no. HR0011-08-0002). Author Contributions: Q.L., J.R., R.C. and M.E. performed the majority of the fabrication and testing of devices. Q.L., J.R. and D.C. performed the bulk of the analysis, along with optical and mechanical modelling. O.P. and K.J.V. contributed to the planning of the measurements. All authors worked together to write the manuscript. The authors declare no competing financial interests.
Submitted - 0908.1128v1.pdf
Supplemental Material - nphoton.2010.5-s1.pdf