共享激光器的分布式光纤气体传感系统

Distributed optical fiber gas sensing system with shared laser

为了实现远端多节点的高效检测并降低成本,设计了一种新颖的分布式光纤气体传感系统。该系统采用共享一个工作于特种波长的分布反馈半导体激光器,将其置于一个本地控制节点内并通过双向光纤链路串联各远端检测节点,同时使用特殊设计的远端节点结构和光纤段,在每个检测节点,用两个Y型耦合器接入气室,将系统中信号分为上行流和下行流,避免来自其它节点信号影响并直接实现时分复用;并以三节点系统的瓦斯体积分数检测为例进行数值计算和实验。结果表明,激光二极管占总成本比重可由约60%降至约38%,且增加循环检测次数能使各节点测定气体体积分数的相对误差降低,首个节点的相对误差可降至0.2%以下,甚至更低,该方案能够精简高效地实现共享光源的分布检测。

In order to realize the efficient detection of remote multiple nodes and reduce the cost , a distributed feedback semiconductor laser working at special central wavelength was shared and placed at a local control node being connected to each remote detection node with bi-directional fiber links in series .Furthermore , a novel distributed optical fiber gas sensor system was designed by using the special structure of remote nodes and fiber segments .At each detection node, the gas cell was added between two Y-couplers.There were the upstream signal and the downstream signal in the system, which could avoid the influences of the signals from other nodes and implement time division multiplexing directly . The numerical calculation and experiments were carried out in a 3-node methane detection system .The results show that the proportion of the laser diode in the total cost drops from about 60%to about 38%.When the loop number is increased , the relative error of the measured gas density at each node can be reduced , and particularly the relative error at the first node can be reduced to below 0.2%or even lower .Distributed sensing with a shared light source can be achieved efficiently .