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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.

An optical waveguide MEMS switch fabricated on an indium phosphide (InP) substrate for operation at 1550 nm wavelength is presented. Compared to other MEMS optical switches, which typically use relatively large mirrors or long end-coupled waveguides, our device uses a parallel switching mechanism. The device utilizes evanescent coupling between two closely-spaced waveguides fabricated side by side. Coupling is controlled by changing the gap and the coupling length between the two waveguides via electrostatic pull-in. This enables both optical switching and variable optical coupling at voltages below 10 V. Channel isolation as high as 47 dB and coupling efficiencies of up to 66% were obtained with switching losses of less than 0.5 dB. We also demonstrate voltage-controlled variable optical coupling over a 17.4 dB dynamic range. The devices are compact with 2 m 2 m core cross section and active area as small as 500 m 5 m. Due to the small travel range of the waveguides, fast operation is obtained with switching times as short as 4 s. Future devices can be scaled down to less than 1 m 1 m waveguide cross-sectional area and device length less than 100 m without significant change in device design.[1372]Index Terms-Directional coupler, indium phosphide (InP), integrated waveguides, optical MEMS switches.

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