Elimination of Gray-Tracking Effects of KTiOPO4 Crystals Using a Strong Focusing Scheme

A simple method is presented to eliminate gray-tracking effects of KTP crystals using a strong focusing scheme. Experimental and theoretical studies on the gray-tracking effects are carried out. A 18 W green laser is demon-strated with a 9 kHz repetition rate, a beam quality factor of M^2 = 1.6 and a conversion efficiency of 44%.     

Monolithic LiF or MgF_2 lens-window-prism device for coherent 10.7 eV beam source with 1 MHz repetition rate

A monolithic lens-window-prism(LWP) device, made of lithium fluoride(LiF) or magnesium fluoride(MgF_2),was proposed. When either of the devices was fixed onto one end of a gas cell filled with Xe, it becomes a"wedge-crystal"-like device and was used to convert a 1 MHz femtosecond 347 nm laser to its third harmonic radiation at 10.7 eV. This led to an improved beam profile and a more compact and less lossy configuration.A stable output power of ～11 μW was demonstrated for 2 h using LiF-LWP. In addition, MgF_2-LWP was also verified for its practicability at 10.7 eV.     

用标准具测量微小频移的方法研究

针对光学系统表面反射激光和水中受激布里渊散射光通过F-P标准具后所形成的干涉环簇图样,提出了三种计算布里渊频移的方法,即小角度微分法、小角度差值法和环间距比例法。分别对其进行了理论推导,得出了相应的解析表达式,并通过实验进行了验证。使用这三种方法得出的结果分别为8.65GHz,8GHz和7.2GHz,其中由环间距比例法得出的结果与水中布里渊散射频移的理论值7.5GHz符合得最好。通过与已有方法进行比较,结果表明与环间距比例法相差1MHz。分析了各种方法的优缺点以及适用情况和条件。     

1.9-W flash-lamp-pumped solid-state 266-nm ultraviolet laser

Deep ultraviolet lasers have various applications in industries and scientific researches. For 266-nm ultra- violet （UV） laser generation, the good beam quality of 1064-nm laser and the elimination of gray-tracking effect of KTP crystal are two key factors. Using a dynamically stable resonator design, 1064-nm laser with an average power of 52 W is realized with repetition rate of 16 kHz. The measured M^2 factor characterizing the beam quality is 1.5. By the elimination of gray-tracking effect of KTP crystal, an 18-W green laser is realized with the M2 factor of 1.6. Using a BBO crystal for the fourth harmonic generation, a 1.9-W 266-nm UV laser is achieved.     

915 nm单频Nd∶YAG晶体衍生光纤激光器

报道了一种基于Nd∶YAG晶体衍生光纤(NYDF)的915 nm单频光纤激光器.使用掺杂原子数分数为2.5％的Nd∶ YAG晶体作为纤芯材料,高纯度石英管作为包层材料,利用熔芯法制备Nd∶ YAG晶体衍生光纤,其传输损耗为8 dB/m,在915 nm处其增益系数为1.16 dB/cm.基于Nd∶YAG晶体衍生光纤,实现了一个稳定的915 nm单频光纤激光器,信噪比大于50 dB.实验结果表明Nd∶ YAG晶体衍生光纤有潜力应用于890～920 nm单频激光器.     

晶体光纤及晶体衍生光纤制备与应用综述

晶体光纤是一种新型的高性能光纤材料,具有稀土离子掺杂浓度高、传光性好、耐高温、耐腐蚀等优点.晶体光纤在激光及传感方面具有巨大的应用潜力,然而至今还没有成功制备出真正意义上的同时具有晶体纤芯和晶体包层的小芯径晶体光纤.与传统的玻璃光纤相比,晶体光纤的制备工艺更加复杂,如何对晶体光纤制备工艺进行完善和创新是当前需要解决的重要问题.为了探索提高晶体光纤质量的途径,本文以晶体光纤的四种制备技术为主线,回顾了晶体光纤及其制备方法的发展历程,讨论了每种制备方法的局限性,对晶体光纤目前的应用状况进行了总结,并对其未来发展趋势进行了展望.     

Influence of spherical aberrations on fundamental mode beam quality under different laser resonators

Spherical aberrations of the thermal lens of the active media are severe when solid state lasers are strongly pumped. The fundamental mode profile deteriorates due to the aberrations. Self-consistent modes of a resonator with aberrations are calculated by using the Fox--Li diffraction iterative algorithm. Calculation results show that the aberration induced fundamental mode beam quality deterioration depends greatly on the resonator design. The tolerance of a flat--flat resonator to the aberration coefficient is about 30λ in the middle of stability, where λ is the wavelength of laser beam. But for a dynamically stable resonator, 2λ of spherical aberration will create diffraction loss of more than 40%, if inappropriate design criteria are used. A birefringence compensated laser resonator with two Nd:YAG rods is experimentally studied. The experimental data are in quite good agreement with simulation results.