Broadband resonant optical gyroscope using dual acousto-optic frequency modulation and closed-loop interrogation

Broadband-source-driven resonant fiber-optic gyroscopes provide a promising route to suppress coherence-related parasitic effects while retaining a resonator-based differential-frequency discriminator. However, existing interrogation schemes still rely heavily on phase-modulator-based frequency shifting, which can introduce reset transients, half-wave-voltage drift, residual intensity modulation and harmonic distortion. Here, we demonstrate a broadband resonant optical gyroscope based on dual acousto-optic frequency modulation and closed-loop resonance interrogation. A broadband ASE source interrogates a fiber ring resonator, while two acousto-optic modulators independently control the counter-propagating optical frequencies. One AOM applies dual-frequency frequency-shift modulation to sample the resonator response on both sides of the resonance, converting the symmetric resonance envelope into an antisymmetric error signal. The second AOM applies an RF-defined feedback frequency that compensates the Sagnac-induced frequency detuning, allowing the angular rate to be recovered directly from the closed-loop feedback signal. With a 500 m fiber ring resonator, a 70 mm mean diameter and a 30 nm-bandwidth ASE source centered near 1550 nm, the system shows stable closed-loop operation under zero-rate conditions. A 5 h continuous data segment selected from a continuous acquisition gives an angle-random-walk estimate of 0.00163 ∘ /h from the one-second Allan-deviation level and a minimum Allan deviation of 0.00172 ∘ /h. The results establish dual-AOM frequency control as a flexible interrogation strategy for broadband resonant optical gyroscopes and provide a practical route to reducing phase-modulator-induced errors in low-coherence resonant inertial sensing.