Based On The New Type Of Optical Fiber Filter Of Tunable Laser And Temperature Sensor

With rapid development of optical fiber technology and optical fiber device, optical fiber systems have been gradually took the place of the optic-electric systems in many fields, such as communication, sensing, medical industry, industrial processing and et. al.. Fiber filters as one of the key components in these systems have played increasing important roles.Helped by the fiber optical technology, fiber laser technology has been rapidly developed. The lasing wavelength of tunable fiber laser can be flexibly tuned, which could meet the demand of multiple wavelengths by the Dense Wavelength Division Multiplexing (DWDM) system. High performance tunable filters are indispensable in these lasers for achieving tunable lasing operation, thus designing and fabricating qualified fiber filters with practicability, stability and good tunability is of great significance. For the case of fiber sensing, fiber filters with specific optimization can be used as sensors for detecting different parameters. Meanwhile, the sensitivity can be greatly improved and the applied range can be widened as well by designing special configuration or by adopting optical fiber with specific properties.In this thesis, we theoretically analyzed some typical fiber filters, based on which we developed a hybrid fiber filter formed by combining an Mach-Zehnder (MZI) and a Birefringence Fiber Filter (BFF). Theoretical analysis of the filtering function based on Jones matrix has been performed. In our work, we have experimentally demonstrated a tunable fiber laser based on this proposed hybrid filter. The tuning range achieves30nm with power uniformity of less than2dB, and Side Mode Suppression Ratio (SMSR) of～40dB. The power fluctuation and wavelength variation at1556.26nm are observed to be less than0.5dB and0.04nm in30minutes, respectively. What’s more, the tuning step was changed from2.83nm into1.5nm by adjusting the optical path difference of the MZI.We designed two fiber filters aiming to temperature sensing, the filtering characteristics of which were theoretically analyzed. One of the filters is so called Reflected Birefringence Fiber Filter (RBFF). Benefited from high thermal-optic effect of the Hi-Bi fiber, the temperature sensor based on this RBFF exhibits an extremely high sensitivity up to-1.46nm/ ℃with perfect linearity. On the other hand, an FP cavity that serves as high temperature sensor is formed by splicing a short section of Polarization Maintaining Photonic Crystal Fiber (PM-PCF) to an end cleaved single mode fiber with controllable offset. The temperature sensitivity within a range of33℃to nearly600℃was measured to be13.8pm/℃, agreeing well with the theoretical result.