We report a miniature mechanical gyroscope that utilizes optical means to detect rotation-induced displacements in a
mechanical structure. It utilizes the Foucault pendulum principle used in some existing MEMS gyroscopes: a rotating
reference frame induces a Coriolis force that oscillates the structure about an axis orthogonal to the driving-mode axis.
The main difference with similar MEMS gyroscopes is that this rotation-induced oscillation is sensed using a pair of
high-finesse fiber Fabry-Perot displacement sensors instead of a capacitive device. The drive axis is also driven by
radiation pressure inside a set of auxiliary fiber Fabry-Perot cavities, making this device immune to electromagnetic
interference. Calculations predict that a rotation sensitivity on the order of 1°/h/Hz1/2 is achievable. We show that this
structure solves several problems associated with MEMS gyroscopes utilizing electrostatic sensing methods.
We report a miniature fiber hydrophone that consists of a Fabry-Perot interferometer made of a photonic-crystal reflector
embedded on a compliant silicon diaphragm placed at the tip of a single-mode fiber. A model was developed to show
that after proper optimization to ocean acoustics, this sensor has a minimum detectable pressure that follows the
minimum ambient noise of the ocean (reaching a minimum of ~10 μPa/Hz1/2 at ~30 kHz) in the bandwidth of 1 Hz-100
kHz. By placing several such sensors with different acoustic power ranges within a single hydrophone head, the
hydrophone is able of exhibiting a dynamic range in the excess of 200 dB. A prototype was fabricated, assembled, and
tested that confirmed this high sensitivity and bandwidth.