主动相位偏置折叠型萨尼亚克光纤传感阵列时分复用技术

针对折叠结构萨尼亚克(Sagnac)光纤传感阵列存在噪声光与信号光混叠的问题,提出了一种主动相位偏置时分复用方案.在传统梯形结构传感阵列的基础上,通过调整总线光纤的长度关系和附加延迟光纤的方法,使噪声光和信号光依次交替返回而不会发生混叠.进一步分析表明,通过调整延迟光纤环的长度,可以使输入光脉冲的重复频率达到标准时分复用系统重复频率的二分之一.整个阵列的相位偏置由一个与输入光脉冲同步的相位调制信号驱动集成光学芯片实现.实验演示了一个两基元的传感阵列,最小时间间隔为331.25 ns,输入光脉冲重复频率可达754.727 kHz,在5 kHz处相位灵敏度为7.3μrad√(Hz),探头间串扰约为-51.75 dB.

Time-Division-Multiplexing Scheme of the Folded Sagnac Sensor Array with Active Phase Bias

To avoid the overlapping of signal and noise pulses in the folded Sagnac fiber sensor array (FSSA), a time-division-multiplexing (TDM) scheme with active phase bias is proposed. Noise pulses and signal pulses are controlled to return alternately, just by adjusting the length of the bus fiber of traditional sensor array with ladder structure and adding a section of delay fiber at one end of the Sagnac interferometer. Analysis shows the input pulse repetition rate can reach half of the standard TDM scheme when the length of the delay coil is appropriate. The phase bias of the sensor array is realized through an integrated optical chip (IOC) driven by a pulse signal synchronizing with the input optical pulse. A two-sensor-array with this structure is demonstrated experimentally, and the input optical pulse repetition is rate 754.727 kHz. The phase sensitivity is about 7.3 μrad/Hz at 5 kHz, and the crosstalk between two sensors is measured to be about -51.75 dB.