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

摘要

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 1x2 optical switches and resonant sensors with integrated optical readout. The 1x2 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 mu s, 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 sigma=50 Hz (0.027%) for f(resonant)=184.969 kHz. By performing focused-ion beam (FIB) milling on a sensor, a mass sensitivity of Delta m/Delta f=5.3x10(-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 Delta m/Delta f=1.1x10(-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.