title: Fiber-coupled, Littrow-grating cavity displacement sensor.
abstract: We have demonstrated a compact, optical-fiber-fed, optical displacement sensor utilizing a Littrow-mounted diffraction grating to form a low-finesse Fabry-Perot cavity. Length changes of the cavity are read out via the Pound-Drever-Hall rf modulation technique at 925 MHz. The sensor has a nominal working distance of 2 cm and a total dynamic range of 160 nm. The displacement noise floor was less than 3x10(-10) m/sqrt[Hz] above 10(-2) Hz, limited by the frequency drift of the reference laser. A frequency-stabilized laser would reduce the noise floor to below 10(-12) m/sqrt[Hz]. The use of a 925 MHz modulation frequency demonstrates high-precision readout of a low-finesse compact resonant cavity.
authors.affiliation: Hansen Experimental Physics Laboratory, Stanford University, Stanford, California 94305-4085, USA. gsallen@stanfordalumni.org
authors.forename: Graham
authors.initials: G
authors.lastname: Allen
authors.forename: Ke-Xun
authors.initials: KX
authors.lastname: Sun
authors.forename: Robert
authors.initials: R
authors.lastname: Byer