Measurement of reduced backscattering noise in laser-driven fiber optic gyroscopes

Abstract

We report what we believe to be the first demonstration of a laser-driven fiber optic gyroscope (FOG) built with an air-core fiber. Its phase noise is measured to be 130 murad/ radicalHz. When the sensing fiber is replaced with a conventional fiber, this figure drops to 12 murad/ radicalHz. Comparison between these values suggests that the air-core fiber gyro is most likely not limited solely by backscattering noise but by reflections at the solid-core/air-core interface. By minimizing additional noise sources and reducing the air-core fiber loss to its theoretical limit (approximately 0.1 dB/km), we predict that the backscattering noise of the laser-driven air-core FOG will drop below the level of current FOGs. Compared with commercial FOGs, this FOG will exhibit a lower noise, improved thermal and mean-wavelength stability, and reduced magnetic-field sensitivity.

Performance analysis of an optical passive ring-resonator gyro with a hollow-core photonic bandgap fiber sensing coil

“…5 is made under the assumption that the operating point is at the resonance. By operating the Digonnet et al pointed out that in an IFOG, the actual effect of coherent backscatter could be significantly smaller than predicted by α B B S L [16,17], which only set an upper limit to the type of noise. We would expect a similar prediction for an OPRG.…”

“…(8) is noted that the error due to coherent scatter is several times larger for the HC-PBF OPRG than for the conventional SMF OPRG. This is due to the large scattering coefficient arisen from the surface fluctuation of the hollow-capillaries in the current commercial HC-PBF [16]. The surface scattering is expected to reduce with improved manufacturing techniques [10].…”

“…For an OPRG with a N-turn coil in a magnetic field H 0 , the variation of the phase difference between the cw and ccw beams in one round trip may be obtained by following a similar analysis and given by (16) where W is the power spectrum of the twist, and can be expressed as…”

Micro Sagnac Loop Beat Wave Interferometer Based on High-Order Modes Coupling in Tightly Twisted Micro Fiber Tapers

“…The optical path length difference (OPLD) between these counter-propagating lights is generated when the inertial frame is rotated [3] or when a birefringence is existed between the counter-propagating lights [4]. Usually, the SLI is capable of detecting very slowly varying motion since a sensing coil with a fiber length of more than 100 meters can offer an ultra-high phase-sensitive characteristic [5]. However, the SLI with a compact size is definitely required for a micro sensing system and the reduction of dimensions becomes unavoidable.…”

High sensitivity micro Sagnac loop interferometer based on tightly twisted micro fiber tapers

“…The optical path length difference (OPLD) between these counterpropagating lights is generated when the frame is rotated [3] or when a birefringence is existed between the counterpropagating lights [4]. Usually, the SLI is capable of detecting very slowly varying phenomena since a sensing coil with a fiber length of more than 100 meters can offer an ultra-high phase-sensitive characteristic [5]. However, the SLI with a compact size is definitely useful for a micro sensing system.…”