The advantages of optical time-domain reflectometer (OTDR) using spread spectrum technology are analyzed briefly. For the shortcomings of spread spectrum OTDR in traditional despreading method, the concept of optical domain multiplier is first proposed, i.e., the most important multiplication operation in despreading is realized by modulating the phase of Mach–Zehnder modulator before photoelectric conversion. The proposed two methods of despreading in optical domain overcome the electronic bottleneck of correlative despreading in electrical domain, and solve the various restrictions on the application of high-speed spreading code in OTDR. Simulations verify the correctness and feasibility of the two methods.

中文翻译：

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利用扩频技术的光时域反射仪的光域解扩方法

简要分析了使用扩频技术的光学时域反射仪（OTDR）的优势。针对传统解扩方法中扩频OTDR的缺点，首先提出了光域倍增器的概念，即在解扩中最重要的乘法运算是在光电转换之前通过调制Mach-Zehnder调制器的相位来实现的。所提出的两种在光域中解扩的方法克服了在电域中相关解扩的电子瓶颈，并解决了在OTDR中应用高速扩展码的各种限制。仿真验证了两种方法的正确性和可行性。