Single Mode Fiber Optic Sagnac Interferometer with Wireless Data Collection

Since the introduction of fiber optic gyroscope in the late 1970’s 1, the need for accurate inertial navigational instruments has driven the evolution of the device into complex open or closed loop designs manufactured with expensive polarization maintaining fibers and fused fiber optic elements. Our goal herein is to describe a novel fiber optic Sagnac interferometer design made with readily available single mode (SM) components. The device utilizes a unique manual phase control method based on a single paddle fiber optic loop. This method allows the interferometer to be manually adjusted to the anti-phase condition prior to any measurements. Also described is the implementation of a wireless data logger whose output can be displayed in Excel. Since the output voltage verses rotation rate is not linear, we further develop an equation predicting the expected voltage output verses angular velocity which matches a physical model of the superimposition of the counter-propagating waves at the photo-detector. We demonstrate a lack of Doppler shift in the rotating frame consistent with a classical explanation of the Sagnac effect.