Design and performance of a composite Tm:YAG laser pumped by VBG-stabilized narrow-band laser diode

A 2-μm composite Tm:YAG laser pumped with a narrow-band laser diode was presented. The temperature distribution and thermal lens in the Tm:YAG were numerically simulated by a finite element method and the results were used to design the special cavity, in order to achieve a high efficiency and stable output. With a 25-W incident pump power, we obtained a maximum output power of 11 W at 2018.5 nm, corresponding to a slope efficiency of 51.3% and an optical-to-optical efficiency of 44.5%, respectively. The beam quality was measured to be M_x~2= 1.8 and M_y~2= 1.6.     

Energy reduction:a technique for seed-injection locking of single-axial-mode Q-switched Nd:YAG laser

A new technique for seed-injection locking of single-axial-mode (SAM) Q-switched Nd:YAG laser is re- ported.The technique called energy reduction (ER) is utilized when SAM operation is locked to design its feedback scheme.This method ensures long-term 100% seed-injection locking performance and the pulsed SAM output energy can reach as high as 200 mJ.Both temporal and spatial interferometric experiments have been executed to confirm the SAM oscillation.     

High peak power first,second, and third order Stokes pulses based on intracavity self-stimulated Raman scattering lasers

<正>We obtain high peak power pulses in megawatt range of the first(1181 nm),second(1321 nm),and third order(1500 nm) Stokes radiation from self-conversion of the 1067-nm laser radiation based on Nd:KGW laser.The maximum output energy of the first order Stokes laser is 35.3 mJ,which is to our knowledge, the highest reported energy in an intracavity Q-switched laser.The third order Stokes pulse is obtained in an intracavity Q-switched laser.     

高功率全正色散锁模掺Yb3+双包层光纤飞秒激光器

以芯径为30 μm的掺Yb³⁺双包层光纤为增益介质, 利用非线性偏振旋转技术以及光栅-小孔结构组成的光谱滤波器提供有效的振幅调制, 实现了稳定的全正色散耗散孤子锁模运转. 激光器直接输出重复频率为76.6 MHz、平均功率达6.3 W的超短脉冲, 单脉冲能量可达82 nJ. 直接输出脉冲宽度为1.33 ps, 经腔外压缩后的宽度为377 fs. 通过调节光栅角度还实现了输出脉冲中心波长在1025—1078 nm范围内的调谐.     

Ba1-xB2-y-zO4SixAlyGaz晶体和频可调谐深紫外飞秒激光器

介绍了一种基于新型非线性晶体Ba_1-xB_2-y-zO₄Si_xAl_yGa_z 的可调谐深紫外飞秒激光光源. 从理论上分析了基频光和倍频光在通过非线性晶体时所造成的空间走离和群速度失配, 为了补偿空间走离以及波长调谐过程中晶体折射造成的光束偏离现象, 将两块相同的倍频晶体成镜像放置来产生二次谐波. 并调节延迟线的长度来补偿基频光和倍频光之间的群速度失配, 从而提高和频转换效率. 然后通过和频方式进行三倍频和四倍频来突破晶体相位匹配条件的限制, 产生了波长低于200 nm的深紫外飞秒激光. 利用钛宝石激光器提供基频光光源, 最终在250–300 nm, 192.5–210 nm 范围内获得了高重频、可调谐超短脉冲紫外和深紫外激光. 并在基频光波长为800 nm时, 得到的二倍频、三倍频和四倍频的功率分别为1.28 W, 194 mW和5.8 mW, 相对于前一级的转换效率依次为46.14%, 15.16%和3%. 采用互相关法测量得到266.7 nm紫外激光的脉冲宽度约为640.4 fs.     

用直接法测量血液的衰减系数μt存在的问题

用直接测量法测量人全血的衰减系数μ_t时,发现血液的衰减系数μ_t随样品厚度的增大而减小,随样品到探测器的距离增大而增大.因而用此测量方法测量衰减系数μ_t存在一些问题.本文通过研究光在血液中的散射,发现:采用足够薄的血样、适当减小限光光阑孔径、增大光探测器离样品的距离L_sd可减小轴向散射光的影响.并提出一种近似扣除轴向散射光的措施,能较准确地测量血液的衰减系数μ_t.