MEMS accelerometer with all-optical readout based on twin-defect photonic crystal waveguide

A novel design is proposed for a Si accelerometer sensor chip where a stress-tunable photonic crystal is used as the sensitive element to optically measure the deflection of a bulk-micromachined diaphragm with a boss. The photonic crystal may be 1D stack, 2D channel type, microbridge, etc. The photoelasticity effect is used instead of customarily utilized piezoresistivity and thus an all-optical readout is obtained. A feasibility analysis of the proposed structure is performed. 3D finite element modeling is used to determine the mechanical properties of the structure and the transfer matrix method to calculate its electromagnetic behavior. The advantages of the proposed concept are its simplicity, all-optical operation, monolithic integration with the sensor chip and compatibility with contemporary fiber-optic and integrated optics systems and devices.