Research And Design Of Emitter And Receiver For Optical Fiber Sensing System

The transmitter and receiver for distributed optical fiber sensor system based on Raman scattering are studied in this paper. The temperature information is included in the Raman scattered signals, Stokes scattered light and anti-Stokes scattered light. An OTDR system is used to extract the distribution of temperature along the fiber. Compared to other methods, OTDR is simpler to be implemented, and can guarantee a certain spatial resolution.The system in the issue may mainly be divided into two parts, the transmitter which sends out optical pulses and the receiver which detects weak signal and process it. A low power optical pulse is created by the transmitter and then amplified by an EDFA to generate a high power pulse which is launched into a sensing fiber and stimulates the Raman scattered light. The scattered light is separated by a wavelength division multiplexer and is ready for weak signal detection by the receiver using PINFET and OPAMPs. Controlled by FPGA, a105MSPS,16bit ADC converts it into a digital signal, the AVG of which is buffed in a DDR II SDRAM and processed by a DSP that finally gives the temperature on the sensing fiber.In this issue the schematic and the PCB of the system is completed.