【作者】 万顺平；

【导师】 田芊； 孙利群；

【作者基本信息】 清华大学 ， 光学工程， 2004， 博士

【摘要】 下一代光学陀螺的发展趋势将是高精度、全固态和小型化。作为一种具有诸多优点的固体激光陀螺(SSRLG)将是具有发展前途的新型陀螺仪之一。固体环形激光器是其核心部件。到目前为止还未见连续固体环形激光器用于陀螺仪的报道。本文以兵器科学研究院国防预研项目“小型固体激光陀螺的研究”的研制目标为背景,提出了LD泵浦连续波固体环形激光器的研究,以获得单频双向连续固体环形激光器。论文进行了系统方案的分析,建立了固体环形激光器实验装置,并进行了实验研究。论文提出了LD泵浦四镜8字形腔双向固体环形激光器方案,选择Nd:YVO4为工作物质,分析了其工作原理。使用ABCD矩阵理论分析了曲面镜焦距、放置距离以及环形腔边长变化时对谐振腔的稳定性和本征模的影响,得出了构成环形腔的稳定性条件,确定了环形腔的结构并计算了本征模分布。还分析了晶体热透镜效应对环形腔的影响,该环形腔结构热稳定很好,方案选择合理。对四镜8字形腔连续固体环形激光器进行了实验研究,泵浦源先后采用LD透镜耦合和LD光纤耦合。实验表明,对于使用均匀加宽增益的双向连续固体环形激光器,在未采取选模措施情况下模式一般为多模。采用腔内插入光阑实现了基横模多纵模运转,环形激光器双向输出功率基本相等,输出为垂直于环形腔平面的线偏振。使用F-P标准具选模,实现了单纵模运转,实验获得了LD泵浦单频双向连续固体环形激光器,并测量了其双向输出功率特性,单路输出功率稳定性100s内为0.4%。测量了单频环形激光器的线宽,在单模输出0.2mW时1.5秒内约为4kHz。实验表明使用均匀加宽增益的连续固体环形激光器能实现单频双向稳定运转,未出现反向行波模对因模竞争光强不稳而导致某一行波熄灭。实验还对因插入F-P标准具形成的折叠腔振荡输出特性进行了实验研究。论文最后进行了单频双向固体环形激光器的初步转动实验,没有观察到双向光干涉条纹的移动,实验表明固体环形激光器处于锁区。在转动实验中干涉<WP=5>条纹的强度和对比度不变,说明在具有转速输入的条件下,反向模对仍能稳定振荡。更多还原

【Abstract】 The next generation optical gyro will trend to high accuracy, all-solid-state and small size. As a novel concept optical gyro which has many advantages, solid-state ring laser gyro (SSRLG) must be one of promising alternatives. Continuous wave (CW) solid-state ring laser is the key part of SSRLG. To author’s knowledge, there is no CW solid-state ring laser used in optical gyro reported before in the world. Supported by Project “research on miniaturization of SSRLG”, this dissertation is involved in theoretical and experimental research on diode-pumped single-frequency bidirectional CW solid-state ring laser, attaining single-frequency, bidirectional, CW solid-state ring laser. The configuration of the ring laser is analyzed and the characteristic of bidirectional ring laser is studied in detail in this dissertation.Diode-Pumped 4-mirror 8-type cavity bidirectional solid-state ring laser is proposed, in which Nd:YVO4 is selected as laser media. Author investigates the laser’s operation principle and its potential accuracy. By exploiting ABCD transmission matrix theory, the influence on cavities’ stability and eigenmode by the ROC and separation distance of curved mirrors and cavities’ length is analyzed. The eigenmode and the stability condition of ring cavity is theoretically calculated deeply. Taken into the thermal lens effect of laser crystal, the cavities’ thermal stability also is researched, which indicates that stability and the configuration of the ring laser is perfect. The characteristic of the bidirectional output of the laser which is pumped by LD lens-coupled pump and LD fiber-coupled pump respectively is experimentally studied in this dissertation. The experimental result shows that the laser is operated in multimode state without mode selector in the cavity in which a homogenous-broaden gain laser media is exploited. By inserting a diagram in the ring cavity, multi-longitudinal mode and TEM00 mode outputs are realized. The laser output is linearly polarized in the direction perpendicular to the ring cavities’ plane. Single-longitudinal mode and TEM00 mode continuous wave outputs are obtained <WP=7>with an F-P etalon inserted in the ring cavity. Diode-pumped single-frequency bidirectional CW solid-state ring laser has been operated and its output powers are measured, the stability of which is 0.4% in 100s sampling time. The linewidth of the single-frequency was about 4 kHz in 1.5s sampling time when the output power is 0.2mW. Experimental results do prove that Diode-pumped solid-state ring laser which exploited a homogenous-broaden crystal as laser media can be operated in single-frequency, bidirectional output, stable state. And any traveling wave does not extinguish or be unstable for mode competition. Additionally the folded resonator laser composed by the inserted F-P etalon was experimentally studied.In the end of the dissertation, the rotation experiment of ring laser was experimentally investigated and the results show that the interfering fringe is stationary or randomly dithered when the stage is rotating, which indicates the bidirectional beam in the ring laser is lock-in. That the intension distribution and contrast of interfering fringe was stationary indicates that the bidirectional, single-frequency CW ring laser can be operated stably when the ring resonator is rotating.更多还原