在经典理论框架下，相干探测性能受限于散粒噪声对应的标准量子极限，而量子增强接收技术通过引入位移算子，采用关联的方式将经典的平衡零拍/零差探测转化为光子数态的测量，理论上可以突破标准量子极限并不断逼近Helstrom极限。无歧义量子态识别(Unambiguous State Discrimina-tion, USD)是量子增强接收常用的识别判决策略之一。然而，由于微弱光信号的能量有限，传统的USD量子增强接收方法的适用微弱信号范围较小，微弱信号识别的错误率较高。提出了一种QPSK调制量子增强接收的混合测量优化方案，该方案首先通过二态零差测量将QPSK相干态的区分转化为BPSK相干态的区分，然后通过BPSK量子增强接收测量实现相干态的无歧义识别。仿真表明，混合测量方案在平均光子数在3.2~11.3之间优于经典的外差测量方案，而且比传统QPSK量子增强接收方案具有更大的适用信号范围。

详细调研了近年来基于光纤激光倍频的高功率绿光光源的研究进展，绿光激光功率从百瓦到千瓦，光束质量近衍射极限，而且输出功率有望进一步提升。采用光纤激光倍频技术得到高功率绿光光源的技术路线大致分为两条：一条是用高功率单子束光纤激光器作为基频光源，然后级联单程非临界相位匹配LBO晶体作为倍频；另一条是用多子束光纤激光器作为基频光源，然后合成与倍频分别实现，或者合成与倍频一体实现。对比两条技术路线，前者相对后者简单，后者具有更高输出功率的潜力，但是倍频晶体的弱吸收是两条技术路线共同面临的问题。

航天发动机供油装置的喷油流量均匀性是决定其性能质量的关键技术指标，其中供油孔的形状尺寸、内表面状态是喷油流量的重要影响因素。传统的供油孔加工方法以电火花加工为主，存在较厚的重铸层，且加工效率低。而激光制孔为典型的非接触式制孔方法，具有加工效率高、质量好，重铸层少的显著优势。为满足某型号航天发动机供油装置的高效高质量制造要求，采用脉宽为200 fs的超短脉冲飞秒激光螺旋制孔工艺，针对1.5 mm厚的GH3044镍基合金材料开展了以0.39 mm孔径为加工基准的流量数值模拟及工艺试验研究。首先通过数值模拟手段，研究了孔径、圆度、锥度以及内壁粗糙度对供油孔流量的影响规律和控制手段，之后根据模拟所获得的理论结果，通过飞秒激光制孔试验对制孔工艺进行了优化。研究发现，出入口孔径是决定流量大小最重要的因素，在单脉冲能量140 μJ，单层扫描时间1200 ms，单层进给量0.02 mm，重复频率100 kHz，旋转速度2400 r/min的工艺下，将孔径偏差控制在±5 μm以内，最终成功实现了供油孔流量偏差1.8%的制孔效果。

飞秒激光平面螺旋钻孔策略在灵活性、精度和工艺效率方面具有许多优势，可满足某型号航天发动机供油喷嘴直通孔的加工精度需求。因此，本研究采用飞秒激光平面螺旋钻孔方式，系统研究了激光功率、单层进给量、单层扫描时间、离焦量以及脉冲重复率之间的作用关系及对钻孔质量的影响。结果表明，离焦量对入口孔径的影响最为明显；对出口孔径和锥度影响较大的参数为功率以及进给量；对加工效率影响最大的参数为功率。根据上述影响规律进行调整，本实验成功在厚度为1.5 mm的GH3044板材上制备出孔径为390 μm的通孔，出口入口孔径误差小于0.6 μm、锥度小于0.5°。通过统计不同参数下微孔内壁粗糙度变化规律并以此对参数进行调整，有效地将孔壁粗糙度降低至Sa 0.6μm，满足工艺要求。孔壁形貌分析表明钻孔质量优良，随激光脉冲重复频率增加，孔壁附近组织逐渐粗化，但均无明显重铸层或热影响区，能够实现高精度微孔的相对“冷加工”。本研究为后续追求高雾化效果的异形孔的制备提供了理论依据。

Fifth harmonic generation (5th HG) of a Nd:glass laser is an effective way to acquire high-energy coherent deep-ultraviolet radiation near 200 nm. In this work, cascade generation of the fifth harmonic of a Nd:glass laser in a 5 mm ammonium dihydrogen phosphate (ADP) crystal was investigated, and maximum conversion efficiency of 14% and large angular acceptance of 45 mrad were demonstrated at a noncritical phase-matching temperature of 75.1°C. However, as the results reveal, the temperature sensitivity and nonlinear absorption would hinder its high-energy application. As for that, based on the complementary relationship of the angle and temperature in the phase-matching condition, an upgraded focusing 5th HG design coupled with the cylindrical temperature distribution scheme was proposed. By this upgraded focusing design, more than the improvement of the conversion efficiency, the output 5ω near-field intensity distribution turns out to be insensitive to the temperature gradient. Potentially, this idea can be applied for many other frequency conversion schemes such as high-repetition frequency lasers, which have similar temperature gradient problems.

A fourth harmonic generation (FHG) scheme in focusing beams is proposed and demonstrated for large aperture Nd:glass laser facilities. By placing the focusing lens before the FHG crystal, the problem of ultraviolet damage can be overcome, largely without affecting FHG conversion efficiency owing to the large angular acceptance of the non-critical phase matching technique. A numerical simulation of the FHG process indicates that angular acceptance can be appropriately increased by lowering the working temperature and jointing the two adjacent compensating angles, so that FHG in focusing beams with relatively small F numbers becomes feasible. With a 170 mm × 170 mm × 7 mm and 65% deuterated potassium dihydrogen phosphate crystal mounted in a high-precision, temperature-controlled system, high-efficiency FHG has been demonstrated in the focusing beam with a full beam convergence angle of 36 mrad. When driven with a 223 J, second harmonic radiation (2ω), 1 ns flat-top pulse with a beam area of 130 cm², corresponding to 1.7 GW/cm² 2ω input intensity, 182 J of fourth harmonic radiation (4ω) were generated.

In indirect drive, reducing peak intensity of a single beam and controlling overlap of multi-beams are two opposite requirements for laser focal spot design. In this paper, an improved laser spot design technique for indirect drive built upon the geometric structures of laser propagation into hohlraum has been introduced. The proposed technique is able to generate appropriate continuous phase plate (CPP) producing a special shaped spot that can balance the opposite requirements. The corresponding CPP does not bring difficulties to the design and fabrication. Phase aberrations are more sensitive to the special shaped spot; however, it can be tolerable for the current beam control level.