Femtometer displacement resolution with phase-insensitive Doppler sensing

Bethany J. Little*, Julián Martínez-Rincón, Umberto Bortolozzo, Stefania Residori, John C. Howell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


The measurement of extremely small displacements is of utmost importance for fundamental studies and practical applications. One way to estimate a small displacement is to measure the Doppler shift generated in light reflected off a moving object, converting a displacement measurement into a frequency measurement. Here we show a sensitive device capable of measuring μHz∕ p Hz Doppler frequency shifts corresponding to tens of femtometer displacements for a mirror oscillating at 2 Hz. While the Doppler shift measured is comparable to other techniques, the position sensitivity is orders of magnitude better, and operates over several orders of magnitude of Doppler frequency range. In addition, unlike other interferometric techniques, our device is phase insensitive, making it unusually robust to noise.

Original languageAmerican English
Pages (from-to)355-358
Number of pages4
JournalOptics Letters
Issue number2
StatePublished - 15 Jan 2019

Bibliographical note

Publisher Copyright:
© 2019 Optical Society of America.


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