Ultrasensitive inverse weak-value tilt meter

Julián Martínez-Rincón*, Christopher A. Mullarkey, Gerardo I. Viza, Wei Tao Liu, John C. Howell

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


We present an interferometric technique for measuring ultrasmall tilts. The information of a tilt in one of the mirrors of a modified Sagnac interferometer is carried by the phase difference between the counter-propagating laser beams. Using a small misalignment of the interferometer, orthogonal to the plane of the tilt, a bimodal (or two-fringe) pattern is induced in the beam’s transverse power distribution. By tracking the mean of such a distribution, using a split detector, a sensitive measurement of the phase is performed. With 1.2 mW of continuous-wave laser power, the technique has a shot noise limited sensitivity of 56 frad/√Hz and a measured noise floor of 200 frad/√Hz for tilt frequencies above 2 Hz. A tilt of 200 frad corresponds to a differential displacement of 4.0 fm in our setup. The novelty of the protocol relies on signal amplification due to the misalignment and on good performance at low frequencies. A noise floor of about 70 prad∕/√Hz is observed between 2 and 100 mHz.

Original languageAmerican English
Pages (from-to)2479-2482
Number of pages4
JournalOptics Letters
Issue number13
StatePublished - 1 Jul 2017
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2017 Optical Society of America.


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