Resonator fiber-optic gyro with intensity error suppression using a bias-sampling compensation technique.

Resonator fiber-optic gyros (RFOGs) are one of the most promising candidates for next-generation inertial rotation sensors. The frequency servo loop is used to lock the laser frequency to the resonance frequency of fiber ring resonator via adjusting the laser diode current, which increases accompanying intensity variation and induces RFOG drift. RFOG output compensation using a bias-sampling technique is proposed to suppress intensity error.

Frequency tuning ratio testing of a laser via a hollow photonic crystal fiber resonator.

In order to satisfy the requirements of laser frequency tuning ratio (FTR) measurement, experimental equipment based on a hollow photonic crystal fiber resonator (HPCFR) is proposed in this paper. First, the principle scheme of the equipment consisting of HPCFR is designed, and the resonance curves of the HPCFR are theoretically analyzed, calculated, and simulated; second, the transmissive HPCFR sample is fabricated and the resonance curve is obtained; eventually, the experimental results from the established laser FTR experimental setup demonstrate that the FTRs of a narrow-linewidth fiber laser and semiconductor laser are 17.6 MHz/V and 30.

Frequency tracking out-of-lock control in a resonator fiber-optic gyro.

A resonator fiber-optic gyro (RFOG) is being pursued because of its theoretical potential to meet navigation-grade performance with small size, high precision, and lower cost. The stability of the RFOG operation is based on the synchronization of laser frequency to the fiber ring resonator (FRR) resonance frequency. Frequency tracking out-of-lock will lead to peak pulse and zero-bias change at the output of the RFOG, which seriously degrades the performance.

Embedded reservoir and constructed wetland for drinking water source protection: Effects on nutrient removal and phytoplankton succession.

An embedded reservoir that provides an efficient nutrient removal system protects drinking water. However, embedded reservoirs are rarely used in eutrophic shallow lakes because of their undetermined nutrient retention efficiency and unknown effects by the phytoplankton community. In this study, we aim to investigate the nutrient retention and algae succession in an embedded reservoir and adjacent wetland from April 2017 to September 2018 in the eastern part of Lake Taihu, China.