We consider the problem of measurement of optical transverse profile parameters and their conjugate variable. Using multimode analysis, we introduce the concept of detection noise modes. For Gaussian beams, displacement and tilt are a pair of transverse-profile conjugate variables. We experimentally demonstrate the optimal encoding and detection of these variables with a spatial homodyning scheme. Using higher-order spatial mode squeezing, we show the sub-shot-noise measurements for the displacement and tilt of a Gaussian beam.
© 2006 Optical Society of America
(270.6570) Quantum optics : Squeezed states
Original Manuscript: November 28, 2005
Revised Manuscript: February 23, 2006
Manuscript Accepted: March 6, 2006
Vincent Delaubert, Nicolas Treps, Charles C. Harb, Ping Koy Lam, and Hans-A. Bachor, "Quantum measurements of spatial conjugate variables: displacement and tilt of a Gaussian beam," Opt. Lett. 31, 1537-1539 (2006)