基于3×3耦合器的光纤水听器时分复用系统的光强补偿方法  

Optical Intensity Compensating Method for Time Division Multiplexing of Fiber-Optic Hydrophone Using a 3×3 Coupler

作　　者：张华勇[1] 王东宁[2] 施清平[1] 田长栋[1] 王利威[1] 张敏[1] 廖延彪[1] 

机构地区：[1]清华大学电子工程系,北京100084 [2]香港理工大学电机工程学系

出　　处：《中国激光》2011年第11期174-181,共8页Chinese Journal of Lasers

基　　金：国家863计划(2006AA0AA102-03)资助课题

摘　　要：提出一种在光纤水听器时分复用系统中以3×3耦合器作为匹配干涉仪的光强补偿方案,光纤水听器仍为2×2耦合器结构。该方案以时分复用中的非干涉脉冲作参考光强,通过对3×3耦合器两路输出进行简单数学运算并结合数字反正切技术实现信号解调,光强波动和耦合器分光比变化导致的信号畸变得到有效抑制。算法不需要载波调制,可实现光纤水听器近似等臂干涉,有利于降低系统相位噪声。算法的运算量小且适用于一般的非对称3×3耦合器,解调动态范围大。利用该方案实现了8路光纤水听器时分复用实验系统,在光功率变化约10%时,光强补偿方法可将总谐波失真平均值降低30dB,系统噪声本底在信号频率为1kHz时小于30μrad/Hz1/2。An intensity compensating method for time division multiplexing （TDM） scheme of fiber-optic hydrophone using a 3 ×3 coupler as path-matched differential interferometer is proposed. The fiber-optic hydrophone is made by a 2 ×2 coupler. In this demodulation method, the non-interferential pulse is used as reference optical intensity. The signal is demodulated from two outputs by simple calculations and digital arctangent approach. The signal distortion caused by optical intensity fluctuation is suppressed efficiently. There is no carrier in this demodulation scheme. In addition, fiber-optic hydrophone can form a nearly zero path difference interferometer which is good for reducing system phase noise. The demodulation method is very simple and feasible for a general asymmetric 3 × 3 coupler. Correspondingly, it is easy to get a large dynamic range. A TDM experiment system composed of 8 sensors is set up. For a 10% intensity variation, the total harmonic distortion can be decreased by 30 dB by using the intensity compensating method. Noise floor of the TDM experiment system is less than 30 μrad/Hz1/2 at 1 kHz.

关 键 词：光纤光学 光纤水听器 信号解调 光强补偿 3×3耦合器 时分复用 匹配干涉仪 

分 类 号：TP212.14[自动化与计算机技术—检测技术与自动化装置]