A Fiber-Optic Interferometer with Sub-Picometer Resolution for DC and Low-Frequency Displacement Measurement

Published

March 13, 2009

Author(s)

Douglas T. Smith, Jon R. Pratt, L Howard

Abstract

We have developed a fiber-optic interferometer optimized for best performance in the frequency range from DC to 1 kHz, with displacement linearity of 1 % over a range of ± 25 nm, and noise-limited resolution of 2 pm. The interferometer uses a tunable IR laser source (nominal 1550 nm wavelength) with high amplitude and wavelength stability, low spontaneous self-emission noise, high sideband suppression and a coherence control feature. The amplitude stability of the source, combined with the use of specially manufactured “bend-insensitive” fiber and all-spliced fiber construction, result in a robust homodyne interferometer system which achieves resolution of 40 fm•Hz-1/2 above 20 Hz and approaches the shot-noise-limit of 22 fm•Hz-1/2 at 1 kHz, without the need for differential detection, and at working distances as large as a millimeter from a suitably reflecting surface. Here we describe the design and construction of the interferometer, and demonstrate its use in the measurement of picometer-scale motions in atomic-scale mechanics studies.

Citation

Review of Scientific Instruments

Volume

80

Pub Type

Journals

Download Paper

DOI Link

Keywords

interferometry, fiber optics, length metrology

Citation

Smith, D. , Pratt, J. and Howard, L. (2009), A Fiber-Optic Interferometer with Sub-Picometer Resolution for DC and Low-Frequency Displacement Measurement, Review of Scientific Instruments, [online], https://doi.org/10.1063/1.3097187 (Accessed October 17, 2025)