【作者】 蔡志强；

【导师】 姚建铨；

【作者基本信息】 天津大学 ， 物理电子学， 2007， 博士

【摘要】 二极管端面泵浦的全固态被动锁模激光器具有结构紧凑、效率高、可靠性好、寿命长等优点。随着激光技术的发展,全固态皮秒被动锁模激光器在工业加工,非线性频率变换,光生物学,光谱学,医疗诊断等领域具有广泛的应用。本论文的主要内容和创新之处可以概括为:1.双路输出SESAM锁模激光器。采用表面态SESAM,实现5.3W,83MHz的连续锁模（CWML）Nd:YVO₄激光器。在Nd:GdVO₄激光器中,实验验证了调制深度越小,脉宽越宽。在Nd:YLF激光器中加入布儒斯特片,分别实现了1047nm和1053nm的连续锁模,功率分别为1.1W和900mW。2.输出功率超过5W的单路输出SESAM连续锁模激光器。在激光腔内,插入KTP晶体,实现了激光器锁模泵浦阈值的减小,并首次观测到了双脉冲锁模现象。利用偏振旋转锁模和SESAM锁模相结合,实现了SESAM锁模激光器泵浦阈值的降低,增加了脉冲序列的稳定度。3.联合四分之一波片和薄膜偏振器（TFP）实现SESAM锁模激光器的单路输出且输出透过率可调。增益介质为Nd:YVO₄时,实现了4.8W的锁模输出,光-光转换效率34.3%,激光器最佳输出透过率约16.5%。采用Nd:YAG时,利用其退偏损耗作输出,获得2.3W的锁模输出。4.首次在国内实现了环行腔SESAM连续锁模激光器。激光器为六镜环行腔,具有较低的泵浦阈值,在3W的泵浦功率时,实现了2×200mW的锁模输出,脉冲重复频率117MHz,脉宽81ps（23ps）。5.首次提出一种新方法实现SESAM锁模激光器的频率翻倍。实现了3倍本征频率的输出,将本征频率83.8MHz提升到251.4MHz,激光器输出功率可达5W,光-光转换效率40%,激光器斜效率41%。6.设计了短腔和长腔两个非线性镜锁模（NLM）方案均实现CWML运转。在Nd:YVO₄晶体实现的NLM中,首次观测到双脉冲,多脉冲,四脉冲锁模现象。在9.3W注入泵浦功率时,输出功率4W,光-光效率43%,激光器斜效率52%。据我们所知,这是迄今为止在Nd掺杂的NLM激光器中,获得的最高光-光转换效率。首次研究了不同偏振入射角情况下的非线性镜锁模,偏振入射角在18 72之间均能实现连续锁模。7.利用Nd:YAG作增益介质,在注入泵浦功率15.9W时,获得2.6W1123nm连续输出。采用KTP腔内倍频,获得22.2mW 561nm黄光输出。更多还原

【Abstract】 Diode end-pumped all-solid-state passively mode-locked lasers have many advantages, such as compactness, high efficiency, robustness and long lifetime et al. As the development of laser technology, they have been widely used in the fields of industry machining, nonlinear frequency conversion, optical biology, laser spectroscopy and medical diagnostic purposes et al.The main contents and key creation points of this dissertation are as follows:1. Double output beams mode-locked lasers with semiconductor saturable absorber mirror （SESAM）. The continuous-wave mode-locked （CWML） Nd:YVO₄ used a surface-state SESAM as the self-starting device. The average output power was 5.3W and the pulses repetition rate was 83MHz. In Brewster-cut Nd:GdVO₄ laser, Experiment validated that the smaller the modulation depth of the SESAM, the broader the pulse width. Adding a Brewster plate to the Nd:YLF mode-locked lasers, the CWML pulses of 1047nm and 1053nm were obtained. And the average output power was 1.1W and 900mW, respectively.2. Output power >5W of single output beam CWML lasers with SESAM. Inserting a KTP crystal decreased the mode-locked incident pump power threshold. The double pulse splitting of the CWML pulses has been observed for the first time in the above laser. In addition, another laser by combining quadratic polarization switching and a SESAM was presented. The pump threshold was also decreased and the pulses trains stability was improved.3. The output transmission of the single beam SESAM laser could be adjusted by combining a quarter wave plate （QWP） and a thin-film polarizer （TFP）. When the gain medium was Nd:YVO₄, the output power was 4.8W, optical-optical conversion efficiency 34.3%, and the optimum output transmission was about 16.5%. Using the degraded polarization losses as useful output, the CWML Nd:YAG laser has an average output power of 2.3W.4. Demonstrated a bi-directional picosecnd pulsed ring Nd:YVO₄ laser for the first time in China. The six mirrors ring laser cavity has a low threshold of <0.3-W of pump power, due to the low intra-cavity losses. The bi-directional pulse train has a repetition rate of 117.5-MHz and a pulse width 81-ps （23-ps）. At the incident pump power of 3W, the output power was 2×200-mW and could be increased by increasing the transmission of the output mirror.5. By placing the SESAM in a special location in the laser cavity, we successfully demonstrated a mode-locking technique for multiplying the pulse repetition rate of a picosecond passively mode-locking Nd:YVO₄ laser for the first time. Optical pulses up to 250-MHz with average power 5-W were experimentally obtained with multiplying the fundamental mode-locking frequency, which is 3-times the fundamental mode-locked frequency determined by the master cavity length. The optical-optical conversion efficiency and the slope efficiency of the laser were 40% and 41%, respectively.6. Presented a short cavity and a long cavity CWML nonlinear mirror mode-locked laser. To the best of our knowledge, this is the first time that we observed double pulses splitting, multi-pulses and four pulses harmonic mode-locking in the nonlinear mirror mode-locked Nd:YVO₄ laser. At the incident pump power of 9.3W, the CWML laser average output power was 4W. The optical-optical conversion efficiency and the slope efficiency of the laser were 43% and 52%, respectively. So far, this is the highest conversion efficiency in the Nd doped NLM lasers to our knowledge. We researched the NLM laser operated in different polarization incident angles for the first time. When the polarization incident angle in the range of18 72 , the laser can be continuous-wave mode-locked.7. Presented a compact and high output power diode end-pumped Nd:YAG laser which operated at the wavelength of 1123nm. Continuous wave laser output power of 2.6W was achieved at the incident pump power of 15.9W. Intra-cavity doubled frequency by KTP, the output power of yellow laser at 561nm was 22.2mW.更多还原