二极管侧泵浦板条固体激光器的热效应研究

 用有限差分法对二极管侧泵浦板条激光介质的温度分布作了数值计算。在此基础上, 对不同条件下二极管侧泵浦激光器的最佳冷却方案进行了研究。用峰值功率为100W, 工作频率为100Hz的二极管泵浦Nd:YAG板条作了实验研究, 所得结果与计算符合较好。     

Bit-rate Flexible Picosecond Pulse Width Conversion with All-optical Mono-stable Multivibrator Laser Diode

An optical mono-stable multivibrator laser diode (MM-LD) is realized by using a multi-electrode distributed feedback laser diode. All-optical pulse-width conversion of ultra-short pulses to non-return-to-zero (NRZ) is achieved using an MM-LD. The MM-LD is adopted for a wide range of bit-rates between 2-10 Gbit/s by tuning the DC bias. Data format transformation from 10-Gbit/s return-to-zero optical signals to NRZ optical-signals is achieved with error free operation. Converted optical signals, which have a narrower spectral bandwidth and lower peak power than when input, are transmitted using a 1.3-μm zero dispersion fiber (1.3Aλ₀-SMF).     

Optical resonator for high-power transverse flow CO2 lasers

A new design of the U-type resonator is described. In this way, a laser beam with symmetrical intensity profile (regarding to a symmetry plane) can be extracted from an active medium that exhibits gain asymmetry along one of the transverse directions. The whole area of the active medium cross-section can be used, and consequently the laser efficiency will be increased. This resonator structure was applied for efficiency power extraction (as a low order TEM modes laser beam) from a DC excited transverse flow CO₂ laser with cylindrical geometry. Although the cross-section area of the discharge was entirely used (including the cathode fall region), a symmetrical intensity profile of the laser beam (regarding to the two orthogonal symmetry planes) was obtained in the near field as well as in the far field; the gain asymmetry along the flow direction was compensated by the gas circulation fluidodynamical circuit with two counterflowing discharge channels. A double-U optical resonator was introduced in order to provide a laser beam with axial symmetry.For the practical construction of these two types of optical resonators we have developed two new types of 90° deflection elements: the first one, which does not reverse the image (and which has the properties of the pentaprism), and the second one, which rotates the image with 90° angle. Both elements exhibit good focusability if they are equipped with two concave mirrors.     

后腔镜对掺Yb3+双包层光纤激光器性能影响的研究

采用自行研制的内包层为矩形的掺Yb^3 双包层石英光纤，以透射率不同的一组二向色镜为后腔镜构成了双包层光纤激光器。实验证明：后腔镜具有较高透射率为佳；后腔镜可以实现对激光波长的控制；激光斜率效率与后腔镜透射率之间的关系符合指数变化规律，在本实验的条件下，斜率效率的最大值约60％。     

High power 1341.4 nmNd:YAlO3 CW laser and its performances

A lamp pumped high power 1341.4 nmNd:YAlO₃CW laser and its performances have been described. As high as 188 W of CW output power has been obtained at 1341.4 nm alone line with a overall efficiency of 1.37% and a slope efficiency of 2.14%. The divergence (FWHM) and instability (RMS) of this laser at output power of 155 W are 15 mrad and 1.19%, respectively.     

Electron paramagnetic resonance studies of photorefractive crystals II: Fe3+ doped Bi12SiO20 with copper vapour laser illumination in 10–100 K range

Photo-induced charge transfer and its kinetics were investigated in Bi₁₂SiO₂₀ in 10–300 K temperature range, using EPR of Fe³⁺ centre, underin situ illumination with copper vapour laser (CVL). The decay kinetics was found to follow double exponential behaviour. Relaxation of the photo-induced electron transfer to the preillumination condition occurred even at 10 K. Shallow traps were, therefore, associated with the electron trapping, leading to a better understanding of the fast photorefractive response of BSO.     

亚皮秒太瓦脉冲激光与物质相互作用研究进展

当前亚皮称太瓦超短冲激光技术的发展为激光与物质相互作用领域提供了许劝人心的研究机会，从激光与单个原子的相互作用到激光等离子体中的集体效应，如原子的高度离化、Ｘ射线激光、等离子体波导，等离子体粒子加速器，快速点火方案等等，文章评述了最近几年这方面的研究进展。     

激光雷达对中层顶大气密度起伏的探测

利用钠荧光散射激光雷达对中层顶（７５～１０５ｋｍ）高度的钠原子层进行探测，以钠原子作为示踪物，通过反演得到了该区域大气密度起伏随高度分布和随时间变化关系．结果表明，中层顶附近大气密度起伏远大于平流层和对流层，在２ｈ内，密度起伏可达５％，３日平均Ｒｉｃｈｏｒｄｓｏｎ数为０．４６．     

内腔级联拉曼光纤激光器输出特性的实验研究

采用标准单模石英光纤作为拉曼增益介质，光纤布拉格光栅作为谐振腔镜，研制了一台内腔级联拉曼光纤激光器。利用掺Yb双包层光纤激光器作为抽运源，实现了二级拉曼转换，在波长1176.8nm获得了309mW的最大输出功率，斜率效率接近51.5％。在小抽运功率下，发现拉曼光纤激光器的输出中存在重复周期约为2.9μs的脉冲序列；当抽运功率大于某一值时，上述脉冲消失，获得了十分稳定的连续输出。     

Taking into account scattering of polarized laser radiation by cuvet walls when probing blood

We have studied the ratio of the intensities of radiation scattered by a layer of blood in a cuvet and by the cuvet walls for normal incidence or incidence at the Brewster angle for probing radiation from a He-Ne laser, linearly polarized in the plane of incidence (plane of observation) or orthogonal to that plane. We have compared it with the intensity of the radiation reflected by the surface of the cuvet wall, as estimated based on the geometric approximation. We have found the optimal conditions for probing and observing scattering for the layer in a cuvet, where such conditions are characterized by a minimal effect from the cuvet walls and the maximum ratio of useful signal to background. Report given at the Fifth International Scientific and Technical Conference on Quantum Electronics, 22–25 November 2004, Minsk, Belarus. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 2, pp. 270–272, March–April, 2006.