End-coupled optical waveguide MEMS devices in the indium phosphide material system

Abstract

We demonstrate electrostatically actuated end-coupled optical waveguide devices in the indium phosphide (InP) material system. The design of a suitable layer structure and fabrication process for actuated InP-based waveguide micro-electro-mechanical systems (MEMS) is reviewed. Critical issues for optical design, such as coupling losses, are discussed and their effect on device performance is evaluated. Several end-coupled waveguide devices are demonstrated, including 1 × 2 optical switches and resonant sensors with integrated optical readout. The 1 × 2 optical switches exhibit low-voltage operation (<7 V), low crosstalk (−26 dB), reasonable loss (3.2 dB) and switching speed suitable for network restoration applications (140 µs, 2 ms settling time). Experimental characterization of the integrated cantilever waveguide resonant sensors shows high repeatability and accuracy, with a standard deviation as low as σ = 50 Hz (0.027%) for f resonant = 184.969 kHz. By performing focused-ion beam (FIB) milling on a sensor, a mass sensitivity of m/ f = 5.3 × 10 −15 g Hz −1 was measured, which is competitive with other sensors. Resonant frequencies as high as f = 1.061 MHz (Q effective = 159.7) have been measured in air with calculated sensitivity m/ f = 1.1 × 10 −16 g Hz −1. Electrostatic tuning of the resonator sensors was also examined. The prospect of developing InP MEMS devices monolithically integrated with active optical components (lasers, LEDs, photodetectors) is discussed.

Optical design and performance of a novel multifunction optical device

“…The angular displacement of mirror can be equally converted to a lateral misalignment x and angular offset 2 between the two fibers, where x can be approximately represented as d ϫ 2. Accordingly, the insertion loss IL 2 can be calculated theoretically using the formula derive from [12][13][14] …”

Strong forces in optomechanically actuated resonant mass sensor

“…Pérez-Murano, Á. San Paulo and O. Gottlieb, " Top-down silicon microcantilever with coupled bottom-up silicon nanowire for enhanced mass resolution," Nanotechnology 26 (14), 145502 (2015).…”

“…The mechanical vibrations are imprinted on the optical signal by their perturbation of the mode coupling over the gap between the two SWG, [14]. The transmission can be described by,…”

“…The divergence of the light in the free space coupling gap is dependent on the dimensions of the SWG and particularly the width of the slot at the ends of the coupling section [14]. Simulations using Lumerical FDTD show that the sensitivity, om = δT tr a /δU increases for a decreasing gap d gap which therefore is chosen to be 100 nm, the minimal width that can be fabricated in our process (U is the displacement at the tip of the cantilever).…”

Detection of nanomechanical motion by evanescent light wave coupling

“…1,5 Recently, it was shown that motion of micron-scale devices can be monitored through changes in end-to-end alignment of optical waveguides. [9][10][11] In this letter, we propose an integrated and near-field optical motion detection technique that exploits near-field optical evanescent-wave coupling. We demonstrate that the technique works efficiently for nanoscale mechanical resonators, with greater sensitivity than conventional optical techniques.…”