Abstract
A new concept of inertial force sensor, which uses a Mach-Zehnder Interferometer (MZI) type optical waveguide made of crystal silicon, is proposed in this paper. In this sensor, one waveguide of branched two waveguides in the MZI has floating beam structure (air-bridge type). Additionally, the cantilever supporting a proof mass intersects with the floating optical waveguide. When inertial force is applied to the proof mass, the floating waveguide is expanded and the output of the MZI is modulated.
An optical optimization of the inertial force sensor is carried out by using a simulation, of which a solver is 2-dimentional beam-propagation method (2D BPM). As a result, optical loss at the intersection of the floating waveguide and the cantilever is improved by using multi-mode interference (MMI) waveguide as an intersected waveguide.
Structure of the sensor is also optimized by a simulation which uses 3-dimentical finite element method (3D FEM). Especially, deflection at the intersection of the sensor is focused on. As results of the simulation, it is found that the sensitivity of the sensor can be controlled by changing in the width and length of the cantilever. Additionally, it is also found that the using of MMI waveguide as interconnecting waveguide dose not decay the sensitivity of sensor. As the results of above simulation, it is expected that an inertial force sensor, which have both high sensitivity and good mechanical strength properties, can be fabricated by using the structure in which multiple cantilevers crosses with the MMI waveguide.
