Digital Interferometric Open Loop Phase Recovery in a Fiber Optic Gyroscope

We present the first use of a Digitally Enhanced Homodyne readout on a Sagnac interferometer, demonstrating the technique's capability as a readout method for high dynamic range, open loop interferometric fiber optic gyroscopes. We achieve an optical phase noise floor of 0.7 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula>rad/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sqrt{\text{Hz}}$</tex-math></inline-formula>, and phase linearity of 8 ppm demonstrated over a phase dynamic range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$16\pi$</tex-math></inline-formula>. We rotation calibrate the system using a rate table, confirming an angular random walk (ARW) of 0.0014 deg/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sqrt{\text{hr}}$</tex-math></inline-formula>, bias instability of 0.012 deg/hr.