Patent ID: 8734011

Claim:
A distributed optical fiber temperature sensor based on optical fiber delay, comprising a tunable optical transmitter module, an optical receiver module, a signal processing and controlling module and multiple distributed sensing modules connected in series via transmission fibers, wherein multiple wavelengths optical signals transmitted from the tunable optical transmitter module respectively are transmitted into a first sensing module via a transmission fiber, and then transmitted out from a last sensing module; the output multiple wavelengths optical signals are transmitted into the optical receiver module via another transmission fiber; the optical receiver module converts optical signals of all wavelengths into electrical signals and transmits them into the signal processing and controlling module; the signal processing and controlling module measures transmission delay time of optical signal of each wavelength respectively, and calculates and obtains the temperature parameters of corresponding distributed testing positions based on the relative delay time, wherein the sensing module comprises a first optical circulator, a second optical circulator, transmission fibers, a sensing fiber and a wavelength selecting unit, wherein the multiple wavelengths optical signals arrive at the first optical circulator, pass through from port 1 to port 2 of the optical circulator, and then arrive at the wavelength selecting unit; the optical signal with a certain wavelength that is same with reflection wavelength of the wavelength selecting unit is reflected back to the port 2 of the first optical circulator; the reflected optical signal is output from port 3 of the first optical circulator, and enters into the sensing fiber via transmission fiber, so that the optical signal with additional delay caused by temperature variation is obtained; the optical signal is then transmitted to port 1 of the second optical circulator of the sensing module via transmission fiber, is output from port 2 of the second optical circulator, arrives at the wavelength selecting unit, then is reflected back to the port 2 of the second optical circulator, is output from port 3 of the second optical circulator, and is sent to the next sensing module via transmission fiber; the optical signals of other wavelengths arrive at port 2 of the second optical circulator directly through the wavelength selecting unit, then are output from port 3 of the second optical circulator, and are sent to the next sensing module via transmission fiber.