Nanophotonic detection of side-coupled nanomechanical cantilevers

Abstract

A silicon nanophotonic Mach-Zehnder interferometer (MZI) is used to detect the mechanical resonance of a cantilever external to a nanophotonic waveguide. Small cantilever devices, below the cut-off for waveguide supported modes, are fabricated ∼140 nm away from one MZI arm. Cantilever resonant frequencies up to 60 MHz are measured with mechanical quality factors around 20 000 and signal to noise ratios up to 1000. Phase-locked loop frequency stability measurements indicate a mass sensitivity of 2 zg in an example cantilever of 0.5 pg mass. An interferometric transduction mechanism is confirmed, and the system is shown to work effectively in all-optical operation.

Single laser modulated drive and detection of a nano-optomechanical cantilever

“…This is comparable to similar top-down devices driven and detected using more traditional methods. 10,30 In conclusion, a measurement scheme is described which uses only a single laser to coherently drive and detect a nano-optomechanical cantilever. The mathematical description fits closely with the measured data which confirms the signal mixing mechanism.…”

“…The general principles of NOMS detection involve an interaction between the mechanical resonator and a nanophotonic device such as a waveguide [8][9][10] or optical cavity. [11][12][13][14][15][16] The motion of the beam will modulate the optical properties of the nanophotonic structure which is detected as a power modulation at the device output.…”

Integrated On-Chip Nano-Optomechanical Systems

“…Alternatively, a timed wet etching process has also been developed to release nanomechanical devices with widths less than that of silicon photonic waveguides. 45 In Fig. 6, we present high-magnification SEM images of a number of completed NOMS devices.…”

“…41,43,45,51,52,61 Hence, NOMS is a perfect modern-day example where cutting-edge fundamental science meets innovative industry development. While we emphasize that the two aspects are both of paramount importance in the advancement of NOMS technology, in our current report, we will limit ourselves mostly to the later aspect.…”

“…65 The length of the cantilever is 4.4 µm and to excite the device. 45 The setup allows fast, and potentially fully-automated probe of a large number of NOMS devices in a single chamber pump-down cycle (provided that nanophotonic circuits connecting various NOMS devices have the same pitch size and the vacuum housing is fitted onto a computer-controlled, two-axis travel stage). Our measurement setup design represents a significant improvement when compared with previous optical-fiber-based measurement systems, in which only a single NOMS device may be tested during one pump-down cycle.…”