Improved Design of Two-Wave Interferometers for High-Precision Sensors

Researchers at Stanford have modified the spatial construction of two-wave interferometers to enable high-precision acoustic sensors and accelerometers produced at scale. This is realized with the principle of near-zero-order interferometry using a spring-loaded Si MEMS diaphragm wherein sensitivity is set precisely during micro-fabrication of the diaphragm structure and weakly dependent on wavelength and temperature. The novel, interdigitated configuration developed at Stanford facilitates large-scale, mass production of such high-precision sensors with uniform sensitivity. This solution provides two main advantages: (1) misalignments between the fiber and the chip, which are inevitable during assembly, will have negligible impact on the optical sensitivity of the two-wave interferometer. (2) The design ensures that the sensitivity across many sensors will remain within a tight margin of the optimal sensitivity of the two-wave interferometer.

Stage of Development
The best performance of the sensors are 2 µPa/?Hz as microphones and 550 ng/?Hz as accelerometers.