An integrated piezo-resistive sensor for determining mirror position in an optical
switch. One or more piezo-resistive layers may be formed in silicon springs supporting
a movable mirror in the switch. Change in resistivity of those layers due to spring
deformation during mirror motion is measured and related to the mirror deflection
angle. Information about the angle may be used to provide feedback to the motion
actuator, which then may be operated to orient the mirror more accurately. A sensor's
sensitivity may be increased by appropriately orienting the springs with respect
to the crystallographic axes of the silicon.
