Oriented Basic Research, Distributed Vibration Sensing And Signal Transmission In The Intelligent Optical Network

Intelligent optical network is a developing trend and an important research direction of the optical network, it will be more widely used in the next generation of "Internet of things". Sensing and transmission are two important parts of the intelligent optical network. The scope of this paper covers these two parts, including distributed optical fiber vibration sensors as well as the alarm control circuits in the Multi-Service Transfer Platform (MSTP) based optical transmission network. Distributed optical fiber vibration sensors can monitor vibration occurred in the circumstances where the sensing fiber is installed,such as communications cable, high-voltage power lines, oil pipelines, power generators, etc. The MSTP-based optical transmission system is a mainstream in optical Metropolitan Area Network. Network element is a core part of MSTP system, and the alarm control card is the equipment which manages and controls the working states of network element, ensuring the system operating stably and intelligently.In the optical sensing part, we analyze the basic principles of distributed optical fiber sensing system based on Sagnac structure, design a new optical sensing scheme, and build up an experimental sensing system. The sensing system consists of a single-mode optical sensing fiber, an optical coupler, a laser diode impulse source, a optical detector, a piezoelectric ceramics vibration source, and so on. The specialty of this scheme is that we construct a nonlinear optical loop mirror to enhance the optical power that reflected into the optical detector, thus increasing the detection distance of sensors. The nonlinear optical loop mirror consists of a conventional 2×2 optical coupler. The experimental results prove the feasibility of the optical sensing system, demonstrating that our scheme can improve the detection distance.In the MSTP-based optical transmission network part, we design and make an alarm control card that is used in the network elements of MSTP system. We firstly analyze the system requirements for the alarm control card, design the required functions, including slow-switching, under-voltage protecting, voltage converting, voltage monitoring, input/output isolating, etc. After the designed card is fabricated, we debug the alarm control card, and conduct the necessary testing work, e. g., power supply test, signal quality test, function test, microcontroller programming test and extreme condition test. The card is re-designed and fabricated after finding the leakages in the testing work. The final card passes through all the tests, and meets the requirement of the MSTP system.