Nanomechanical displacement detection using fiber-optic interferometry

We describe a fiber-optic interferometer to detect the motion of nanomechanical resonators. In this system, the primary technical challenge of aligning the fiber-optic probe to nanometer-scale resonators is overcome by simply monitoring the scattered light from the devices. The system includes no free-space optical components, and is thus simple, stable, and compact with an estimated displacement sensitivity of ∼ 0.3 pm ∕ Hz at optical power levels of ∼ 0.75 mW .