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

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 fresonant = 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 (Qeffective = 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. (Some figures in this article are in colour only in the electronic version)