设计了基于倾斜光栅和InGaAs光电二极管阵列的两级解调系统。利用倾斜光栅的包层耦合模,实现了一种以倾斜光栅为分光器件的FBG波长解调技术。只对传感信息发生变化的通道进行解调,优化系统的采集规则;两个解调设备同时对传感通路进行扫描解调进一步提高系统的解调响应速度。测试和实验结果表明,系统的平均解调时间为40 ms,平均信号频率为15 Hz,解调带宽为40 nm,波长解调精度为20 pm。该系统具有较短的平均等待时间、解调时间与光栅通道数无关等优点。此外,能够满足一些复杂系统和大型分布式智能系统信号解调的要求。
A dual FBG demodulation technique based on tilted grating and InGaAs photodiode array is proposed. Using the coupling modes of the cladding, a demodulation method with the tilted grating as the spectroscopic device is achieved. The system only demodulates FBG sensors whose peak wavelengths are shifting, so that the demodulation rule is more rational. Two tunable F-P filters scan and demodulate the sensing path at the same time to further improve the system response speed. Simulation analysis and experiment work demonstrate that the average delay time is 40 ms and the average singal rate can reach 15 Hz, the demodulation bandwidth is 40 nm, its resolution of wavelength demod- ulation can reach 20 pm. The system has a few advantages:the shorter delay time, the average delay time immuning to the scale size, etc. Therefore, this technique is able to meet the smart requirement of some complex system and large scale distributed system.