Angular Velocity Measurement with Improved Scale Factor Based on a Wideband-Tunable Optoelectronic Oscillator

Optoelectronic oscillator (OEO) has received growing attentions from researchers in the field of demodulations for optical sensors because of its excellent performance of combining optics and electronics in signal processing. In this article, we present a wideband-tunable OEO for angular velocity measurement. The OEO consists of two cascaded microwave photonic filters (MPFs), namely, a dispersion-induced MPF for mainly determining the OEO's oscillating frequency and a two-tap MPF for the fine selection of the oscillating frequency. With proper control of polarization of the optical signal, the angular velocity is first mapped into the central frequency shift of the dispersion-induced MPF, which will then cause an oscillating frequency shift of the OEO. This approach ensures a large-scale factor for the angular velocity measurement due to the fact that a small phase change in the optical domain causes a large frequency shift in the electrical domain. An experiment is conducted to validate the scheme. The experimental results show that the oscillating frequency shift can reach nearly 700 MHz when the system rotates at about 1 rad/s by using a 560-m Sagnac loop. In addition, the measurement range can be achieved to 5.24 rad/s with a 2.5-GHz oscillating frequency tuning range and the maximum measurement error is 0.06 rad/s.