| AVS 60th International Symposium and Exhibition | |
| MEMS and NEMS | Monday Sessions |
| Session MN+NS-MoA |
| Session: | Optomechanics, Photonics, and Quantum Nanosystems |
| Presenter: | Z. Diao, National Institute for Nanotechnology and University of Alberta, Canada |
| Authors: | Z. Diao, National Institute for Nanotechnology and University of Alberta, Canada V.T.K. Sauer, National Institute for Nanotechnology and University of Alberta, Canada J.E. Losby, National Institute for Nanotechnology and University of Alberta, Canada M.R. Freeman, University of Alberta and The National Institute for Nanotechnology, Canada W.K. Hiebert, National Institute for Nanotechnology and University of Alberta, Canada |
| Correspondent: | Click to Email |
In the past few years nanophotonic transduction, in which a nanomechanical resonator is coupled to a high finesse optical cavity and its displacement is monitored through the cavity near-field has been demonstrated as a highly flexible, ultra-sensitive, wide bandwidth scheme for nanomechanical resonator displacement readout. A common design of the so-called nano-optomechanical devices (NOMS) involves either releasing a part of a nanophotonic waveguide in a race-track optical cavity, so the evanescent field of the guided mode is coupling to the remaining substrate [1], or laterally coupling a doubly clamped mechanical beam to an optical cavity [2]. In both cases, only the fundamental flexural mode is usually investigated [3].
The quest for large bandwidth mass sensors draws attention to higher flexural modes of nanomechanical resonators. Compared to the fundamental flexural mode, higher modes of a mechanical beam offer much higher operating bandwidth while incurring only a modest (or no) increase in its effective mass, depending on the boundary conditions. Higher modes of nanomechanical devices are also of interest for realizing cavity-optomechanics in the resolved-sideband limit [4], and nonlinear modal coupling among different mechanical modes has recently attracted renewed attention [5]. Hence, there is a demand to fully understand the behaviour of higher flexural modes in NOMS devices.
In this work, we fabricate NOMS devices by releasing parts of a nanophotonic waveguide in a race-track optical cavity. Sensitive photonic transduction allows thermomechanical noise of odd flexural modes (up to 50 MHz limited by our measurement electronics) to be observed. However, the transduction responsivity diminishes for even modes, due to the geometrical symmetry of the device design. We show that breaking this symmetry can increase the transduction responsivity for even flexural modes. The nanophotonically transduced displacement responsivity for different modes is also compared to that measured using a free-space interferometry setup. We further discuss the internal stress of the devices and its influence on the mode frequency, shape and transduction responsivity.
[1] W. H. P. Pernice et al.,Opt. Express17, 12424 (2009).
[2] O. Basarir et al.,Opt. Express20, 4272 (2012).
[3] M. Li et al.,Appl. Phys. Lett.97, 183110 (2010).
[4] G. Anetsberger et al.,Nature Physics5, 909 (2009).
[5] M. H. Matheny et al.,Nano Lett.13, 1622 (2013).