FIG. 7.18 (a) Micromachined interferometric accelerometer showing the two optical beams, one from the diffraction grating and second from the mirror, which will interfere at the photodetector. (b) SiN nanobeam pair acting as “zipper” photonic crystal optomechanical cavity for accelerometry ( Krause et al., 2012 ). (c) Microdisk coupled to cantilever acting as a force sensor ( Doolin et al., 2014 ). The cantilever can deflect in both out-of-plane and in-plane mechanical modes. This results in the modulation of the disk's optical resonance frequency and is read out optically using a coupled fiber. (d) Split beam nano-cavity torque sensor ( Wu et al., 2014 ) showing the three degrees of freedom. One is out-of-plane rotation of the suspended mirror about the torsion beam, the second is in-plane bending about the torsion beam, and the third is out-of-plane bending of the cantilever mirror. More about this image found in (a) Micromachined interferometric accelerometer showing the two optical bea...