Signal Transmission of Multichannel Fiber-optic Sensors in Wavelength-division Multiplexing Technology

The article proves the possibility of signal transmission of multichannel fiber-optic polarization sensors via an optical single-mode route, with using polarization-division and wavelength-division multiplexing techniques. Fiber-optic polarization sensors can be placed in dangerous environments with the high possibility of explosion, with chemical vapours and at all places where it is necessary to have lightweight, inertness and non-electric elements for monitoring temperature changes. Polarization-division multiplexing, operating at one wavelength, multiplies the volume of transmitted data due to the orthogonality of signals. This technique allows transmission of the sensor's reaction, but single-mode optical route negatively affects these signals by its polarization non-maintaining properties. Signal polarization is randomly changed in the end, which causes incorrect polarization demultiplexing. This article solves the problem by connecting a polarization controller at the end and deals with the influence of wavelength-division multiplexing techniques for future utilization. Wavelength 1550.12 nm was used for power-supply of the sensor and wavelengths 1556.56 nm, 1555.75 nm and 1554.94 nm were used for proof of independence of wavelength-division multiplexing. The circuit was tested in a laboratory with a constant temperature of 24 °C by using a container of water at 0 °C, 48 °C, and pendulum swinging with a bob cooled to 0 °C.