Based on insights from a new model of scattering in FOGs for high-coherence sources, we demonstrate experimentally
that a fiber optic gyroscope (FOG) can be driven with a laser of suitable linewidth and exhibit short and long-term
performance matching that of a FOG driven by a broadband source. This innovation can be combined with the use of
hollow-core fiber in the sensor coil to produce new FOGs exceeding current standards.
We report for the first time experimental evidence of near shot-noise limited performance for an open loop
interferometric fiber optic gyroscope interrogated with a narrowband laser instead of a broadband source. Using a highly
coherent laser source (▵f = 2.2 kHz), the measured gyroscope noise is 350 nrad/Hz for an average returning power of
20 μW, while the measured noise for the same gyro operated with a broadband source (▵λ ≈ 30 nm) was 850 nrad/√Hz.
This measured noise is only ~2 dB above the calculated shot noise for this power. This result was made possible by using
a very narrow linewidth, which greatly reduces the laser phase noise and thus the phase-noise-mitigated coherent
backscattering. This excellent noise performance has applications for future fiber gyroscope technologies as well as other
sensors utilizing a Sagnac interferometer. The bias drift of the laser-driven gyroscope was higher than anticipated but
could be reduced to roughly Earth-rate using a frequency sweeping technique. In addition to improved sensitivity, the
benefits of using a laser include much higher scale factor stability, lower power consumption, and lower component cost.
We report for the first time a tactical-grade fiber optic gyroscope interrogated with a laser instead of a broadband
source. The measured bias drift is 2.5 °/h and the random walk 0.016 °/√
h. This random walk is lower than
when the same gyroscope is interrogated with a broadband source, while the drift is only ~3 times higher.
This significant development was enabled by an appropriate choice of laser linewidth to mitigate backscattering
effects, and careful control of spurious reflections. The benefits of using a laser include a much higher scale factor
stability, lower power consumption, and lower component cost.
Numerical simulations predict that the coherent backscattering noise of a fiber optic gyroscope (FOG) interrogated with
a laser decreases when the laser's coherence length exceeds the length of the fiber loop. With a sufficiently coherent
laser, this noise drops below the excess noise of the same FOG probed with broadband light. This new principle is
paramount for the air-core FOG, which has a low sensitivity to the Kerr effect but exhibits stronger backscattering. It is
also applicable to a conventional FOG. We provide evidence of this effect in an experimental FOG.
A new fiber sensor integrated monitor to be used in an embedded instrumentation system is proposed and its operating features are examined. The system integrates a fiber sensor together with a tunable MEMS filter, superluminescent light emitting diode and microcontroller creating a high-speed, low cost, low power smart sensor. The device has applications to a variety of fiber sensing technologies and, as an example, is integrated with a fiber Bragg grating for temperature sensing.