A He–Ne ring laser has given the Earth-rotation-induced Sagnac frequency to a precision of 1 μHz, or 2 parts in 108, 2 × 10−21 of the laser frequency. Because the beat frequency in a ring laser originates in either time-reversal or (with a more complicated polarization geometry) parity-violating effects, such systems have the potential of detecting ultrasmall symmetry violations.
© 1995 Optical Society of America
Original Manuscript: August 1, 1994
Published: February 1, 1995
G. E. Stedman, H. R. Bilger, M. T. Johnsson, Z. Li, and C. H. Rowe, "T violation and microhertz resolution in a ring laser," Opt. Lett. 20, 324-326 (1995)