Generalized Sagnac Effect

• Also called the "Wang experiment."
• Sagnac effect discusses how light takes longer to travel if flung clockwise than counterclockwise.
• Fiber Optic Gyroscopes (FOG.)
• Winding single mode fiber in a coil with N turns, the Sagnac effect is multiplied N times.

any moving path contributes to the total phase difference between two counterpropagating light beams in the loop

• Generalizes the Sagnac effect to cover linear motion, enabling fiber optic based detection of linear motion (FOLMS.)