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Research On Single Frequency Narrow Linewidth Rare-earth-doped Silica Fiber Laser And Its Key Technologies

Posted on:2014-02-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q LiFull Text:PDF
GTID:1268330425970467Subject:Communication and Information System
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Single frequency, narrow linewidth Er3+/Tm3+-doped fiber laser has great applications in millitary-civil fields. The mainly applications of the Er3+-doped narrow linewidth fiber laser are in the fields of coherent optical communication, radio over fiber and ultra-long range optical fiber sensors. What’s more, the Tm3+-doped fiber laser is mainly used in the fields of laser medicine, space optical communication, space remote sensing, lidar and optcial parametric oscillator. This thesis is mainly devoted to the detailed theoretical and expterimental researches on fabrication of rare-earth-doped silca fiber, fabrication of ultra-narrow bandwidth fiber filters, and design of laser cavity. The main achievements of this thesis are listed as follows:1. A stable single polarization, single frequency linear cavity silica based Er3+-doped fiber laser using a saturable absorber is proposed and demonstrated. The F-P filter, polarizer, and saturable absorber are used together to ensure stable single frequency, single polarization operation, and the linewidth of the laser has been measured by the delayed self-heterodyne method. The optical signal to noise rate of the lasing is approximately65dB, and the Lorentz fitting3dB linewidth is6.95kHz.2. A switchable dual-wavelength ring cavity silica based Er3+-doped fiber laser is proposed and demonstrated. When the laser operates with single wavelength, the optical signal to noise rate of each wavelength will be larger than40dB, and each wavelength is certified as single frequency operation. Stable dual-wavelength SLM fiber laser operation is obtained with a wavelength seperation of approximately0.057nm, which is good agreement with the detected generated microwave frequency of7.129GHz. The3dB bandwidth and signal-to-noise rate of the generated microwave signal are approximately12kHz and more than30dB, respectively.3. A π phase shifted distributed feedback laser based on single mode large effective area heavy concentration silica based Er3+-doped fiber is proposed and demonstrated. The homemade Er3+-doped fiber was fabrecated by the MCVD technique, and the13cm long phase shifted fiber grating was written in the intracore of the Er3+-doped fiber. The measured maximum output power is43.5mW, the slope efficiency is11.5%, and the Lorentz fitting3dB linewidth is9.8kHz.4. A fiber laser with central wavelength of1946.4nm based on homemade D-shape single-transverse-mode double-cladding silica based Tm3+-doped fiber is proposed and demonstrated. The distributed-Bragg reflector laser was fabricated by a pair of fiber Bragg gratings, which is directly writting in the intracore of this fiber. The threshold of the laser is1.15W, and a stable maximum output power of2.56W is chieved while pumping with input launched power of6.9W, corresponding to a slope efficiency of38.4%and light-to-light conversion efficiency of36.2%. When operating at the maximum output power, the laser has a3dB bandwidth of0.16nm, and a signal-to-noise of approximately65dB.5. A ring cavity and a linear cavity silica based Tm3+-doped fiber laser based on phase shifted grating filter are proposed and demonstrated. The single longitude mode operation of the proposed lasers is confirmed by method of self-homodyne, and the linewidth of each laser was narrower than10MHz. The central wavelength of the two laser are1941.98nm and1941.61nm, and the optical signal-to-noise rate are45dB and60dB, the slope efficiency are3%and30.5%, the maximum output are65mW and385mW, respectively.6. A tunable ring cavity silica based Tm3+-doped fiber laser based on chirped moire fiber grating filter is proposed and demonstrated. As the central wavelength of the tunable fiber Bragg grating matches with each resonance peak of the chirped moire fiber grating, the Q-value of the laser reaches a maximum and single frequency laser oscillation could be realized. Ultimately, the eight wavelengths of the laser are1942.75nm,1943.28nm,1943.99nm,1944.35nm,1944.76nm,1945.08nm,1945.44nm,1945.83nm, respectively. What’s more, the optical signal-to-noise rate of the each output lasing wavelength is larger than40dB.
Keywords/Search Tags:Single frequency narrow linewidth, Er3+-doped fiber laser, Tm3+-dopedfiber laser, Narrow bandwidth fiber grating filter, Silica
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