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.
This paper describes a nano-scale tensile test to study the fatigue properties of LPCVD silicon nitride thin films using a novel electrostatic actuator design. Mechanical-amplifier devices made in silicon nitride thin films can apply controllable tensile stress (2.0-7.8 GPa) to test structures with relatively low actuation voltages (5.7-35.4 V RMS) at the resonant frequencies of the devices. The test devices are fabricated using a surface micromachining technique in combination with deep reactive ion etching and ion milling. With the recently developed experimental techniques inside a focused-ion-beam system, in situ fatigue measurements are performed on silicon nitride test structures with beam widths of 200 nm. The silicon nitride test structures are found to exhibit time-delayed failures with continuous increases in their compliance. By reducing the applied tensile stress to 3.8 GPa, the test structures can survive cyclic loadings up to 10 8 cycles.
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