Design and analysis of an ARROW-waveguide-based silicon pressure transducer

We present the design and analysis of a microfabricated silicon pressure transducer. The operating principle for this device is based on the evanescent modulation of power in an integrated optical waveguide. A silicon diaphragm attenuator is initially separated from the waveguide by a precise microfabricated gap spacing. When external pressure is applied to the sensor, the silicon attenuator is moved into closer proximity with the waveguide, and light is coupled out of the waveguide into the attenuator. Thus, by monitoring the light intensity at the output of the waveguide, one can deduce the pressure applied to the silicon diaphragm. Packaging considerations have played an important role in the development of the device and have led to the use of anti-resonant reflecting optical waveguides (ARROWs), which are etched down to form a rib in order to provide confinement in the lateral direction. These waveguides provide good spatial and index matches to single-mode optical fibers. Numerical simulations of device performance have provided information critical to the design of the sensor.