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Updated: May 18, 2026

Fabrication And Characterization Of Photonic Crystal Slow Light Waveguides And Cavities
Published on: November 30, 2012
Oscillating test of the isotropic shift of the speed of light
Fred N Baynes1, Michael E Tobar, Andre N Luiten
1Frequency Standards and Metrology, The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia. fred@physics.uwa.edu.au
Abstract:
In this Letter, we present an improved constraint on possible isotropic variations of the speed of light. Within the framework of the standard model extension, we provide a limit on the isotropic, scalar parameter κ̃(tr) of 3±11×10({-10), an improvement by a factor of 6 over previous constraints. This was primarily achieved by modulating the orientation of the experimental apparatus with respect to the velocity of Earth. This orientation modulation shifts the signal for Lorentz invariance to higher frequencies, and we have taken advantage of the higher stability of the resonator at shorter time scales, together with better rejection of systematic effects, to provide a new constraint.
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