title: A grating-assisted resonant-cavity-enhanced optical displacement detection method for micromachined sensors.
abstract: We present an integrated optical displacement sensing method for microscale sensors which is based on an asymmetric Fabry-Perot etalon structure with an embedded phase-sensitive diffraction grating. Analytical modeling of the structure shows that the etalon significantly improves the detection sensitivity as compared to a regular optical interferometer and the embedded diffraction grating enables integration of optoelectronics in a small volume. The efficacy of the method is experimentally validated on a surface micromachined diffraction-based opto-acoustic sensor fabricated on a quartz wafer. A 15 nm silver layer is used to form the bottom mirror of the etalon structure with a sensor membrane and embedded diffraction grating made of aluminum. Comparison of the results with and without the etalon shows an 8 dB increase in detection sensitivity with the etalon structure, which should be further enhanced with the use of low-loss dielectric mirrors.
authors.affiliation: G. W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332.
authors.forename: Wook
authors.initials: W
authors.lastname: Lee
authors.forename: Neal A
authors.initials: NA
authors.lastname: Hall
authors.forename: F Levent
authors.initials: FL
authors.lastname: Degertekin