【作者】 李琦；

【导师】 延凤平；

【作者基本信息】 北京交通大学 ， 通信与信息系统， 2013， 博士

【摘要】 单频窄线宽掺Er3+、掺Tm3+光纤激光器在军用、民用领域具有极大的应用价值。掺Er3+窄线宽光纤激光器在相干光通信、光载无线通信系统、长距离及超长距离光纤传感系统等领域有着广泛的应用,而掺Tm3+窄线宽光纤激光器则在激光医学、空间光通信、空间遥感、激光雷达以及光参量振荡放大等领域有着广泛的应用。本论文基于自制石英基稀土掺杂光纤与超窄带光纤光栅滤波器件,采用多种腔形结构对掺Er3+光纤激光器和掺Tm3+光纤激光器展开理论与实验研究,取得的主要研究成果与创新点为：1.提出并搭建了一种单偏振、单频线形腔石英基掺Er3+光纤激光器,利用自制布拉格光纤光栅(FBG)F-P窄带滤波器与饱和吸收体共同对激光纵模进行选择,通过在谐振腔内置入起偏器使得激光器在腔内无偏振保持器件条件下实现了稳定单偏振、单频输出。激光器在室温下的稳定输出波长为1544.45nm,输出激光信噪比为65dB,偏振度大于99%。通过延迟自外差法对输出激光进行测量得到Lorentz拟合线宽为6.95kHz。2.提出并搭建了一种用于光子微波生成的双波长单频环形腔石英基掺Er3+光纤激光器,利用自制双通道FBG F-P滤波器作为双波长振荡的选频器件,未泵浦的掺Er3+光纤作为可饱和吸收体结合高反FBG共同作用确保激光器两个波长均为单纵模运行,通过调节腔内的偏振控制器可以实现双波长激光的可切换输出。在室温条件下,激光器的两个稳定输出波长分别为1544.67nm和1544.73nm,其消光比均大于40dB,且均为单纵模运行。在稳定双波长激光输出时,经过光电转换可得7.129GHz的微波拍频信号,信号的信噪比(SNR)大于30dB,3dB带宽约为12kHz。3.利用相位掩膜法在自制的石英基高浓度掺杂Er3+光纤中写制长为13cm的相移光栅,以此构成DFB激光谐振腔。激光器在室温下的稳定输出波长为1544.77nm,最高输出功率达43.5mW,斜率效率为11.5%。通过延迟自外差法对输出激光进行测量得到Lorentz拟合线宽为9.39kHz。4.提出并搭建了一种石英基D型双包层掺Tm3+光纤DBR激光器,激光腔由直接写入自制掺Tm3+光纤纤芯中的一对FBG构成,通过控制写制FBG的曝光量实现激光腔两端FBG反射率R1和R2的调节。该激光腔内无熔接点,克服了D型有源光纤作为增益介质在光纤激光器搭建时容易引起巨大接续损耗的缺陷。激光输出中心波长为1946.4nm,光信噪比(OSNR)约为65dB,3dB带宽为0.16mn。最大输出功率为2.56W,斜率效率为38.4%,光光转换效率为36.2%。5.提出并搭建了线形腔和环形腔结构的单频石英基掺Tm3+光纤激光器,利用自制相移光纤光栅超窄带滤波器作为纵模选择器件,通过腔内偏振控制器抑制空间烧孔和偏振烧孔效应使得激光器在单纵模状态下稳定运行。这两种激光器的输出波长分别为1941.98nm和1941.61nm,在光谱仪分辨率为0.05nm时测得光信噪比分别为45dB和60dB,斜率效率分别为3%和30.5%,最高输出功率分别为65mW和385mW。通过自零差法验证,该两种激光器均为单频输出,且线宽分别小于6.4MHz和10MHz。6.基于自制啁啾莫尔FBG超窄带滤波器,提出并搭建了一种波长可调谐环形腔单频石英基掺Tm3+光纤激光器。通过应力对输出端选频器件FBG进行调节,当FBG的布拉格波长与啁啾莫尔FBG的谐振峰重叠时,激光器内的腔损达到最低,激光腔内即可实现激光振荡。激光器在室温下实现稳定的激光输出,其可调输出波长分别为1942.75nm,1943.28nm,1943.99nm,1944.35nm,1944.76nm,1945.08nm,1945.44nm,1945.83nm,此8个波长的光信噪比均大于40dB。通过零差法测量验证该激光器在每个波长输出时均为单纵模运转。更多还原

【Abstract】 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.更多还原