Optical limiting using Laguerre-Gaussian beams

We demonstrate optical limiting using the self-lensing effect of a higher-order Laguerre-Gaussian beam in a thin dye-doped polymer sample, which we find is consistent with our model using Gaussian decomposition. The peak phase shift in the sample required for limiting is smaller than for a fundamental Gaussian beam with the added flexibility that the nonlinear medium can be placed either in front of or behind the beam focus.Comment: 3 pages, 4 figure

Numerical investigation of the boundary layer separation in chemical oxygen iodine laser

Large eddy simulation is carried out to model the flow process in a supersonic chemical oxygen iodine laser. Unlike the common approaches relying on the tensor representation theory only, the model in the present work is an explicit anisotropy-resolving algebraic Subgrid-scale scalar flux formulation. With an accuracy in capturing the unsteady flow behaviours in the laser. Boundary layer separation initiated by the adverse pressure gradient is identified using Large Eddy Simulation. To quantify the influences of flow boundary layer on the laser performance, the fluid computations coupled with a physical optics loaded cavity model is developed. It has been found that boundary layer separation has a profound effect on the laser outputs due to the introduced shock waves. The F factor of the output beam decreases to 10% of the original one when the boundary transit into turbulence for the setup depicted in the paper. Because the pressure is always greater on the downstream of the boundary layer, there will always be a tendency of boundary separation in the laser. The results inspire designs of the laser to apply positive/-passive control methods avoiding the boundary layer perturbation. (C) 2017 Elsevier Ltd. All rights reserved

increasingchemicalefficiencybymixingdifferentbuffergasesoncoil

为进一步提高氧碘化学激光器效率,提出一种不改变激光器结构,仅变换主副载气的方法。在增益区长度为11.7 cm的激光器上进行实验,以N2,Ar和CO2做为氧碘化学激光器的主载气或副载气,对激光器的输出功率和化学效率进行了研究。实验结果表明,平均分子质量改变对主副气流的混合是有利的,因而可以提高激光器的输出效率。当N2为主载气,Ar为副载气时,激光器输出功率和化学效率最高,分别达到3.09 kW,30.2%

increasingchemicalefficiencybymixingdifferentbuffergasesoncoil

为进一步提高氧碘化学激光器效率,提出一种不改变激光器结构,仅变换主副载气的方法。在增益区长度为11.7 cm的激光器上进行实验,以N2,Ar和CO2做为氧碘化学激光器的主载气或副载气,对激光器的输出功率和化学效率进行了研究。实验结果表明,平均分子质量改变对主副气流的混合是有利的,因而可以提高激光器的输出效率。当N2为主载气,Ar为副载气时,激光器输出功率和化学效率最高,分别达到3.09 kW,30.2%

The response speed and fatigue characteristics of a pulsed 778 nm -> 420 nm conversion in rubidium vapor

A strong 778 nm -> 420 nm conversion was realized in Rb vapor. With the help of the multi-spike structure of the 778 nm pumping laser, the response speed of the 778 nm -> 420 nm conversion was successfully measured. Experimental results showed that the conversion was a high-speed process, with a response bandwidth of 1 GHz. In addition, fatigue phenomenon of the 778 nm -> 420 nm conversion under strong pumping was observed, and the recovery time of such fatigue was measured with a dual pump method. (C) 2016 Elsevier B.V. All rights reserved

Combustion Parametric Optimization for All Gas-Phase Iodine Laser Driven by D-2/NF3/DCI Combustion and Self-Pooling of NCI(a) Catalyzed by NF(a)/NF(b)

Combustion parametric optimization for all gas-phase iodine laser driven by D-2/NF3/DCI combustion was performed, and an energy transfer channel called self-pooling of NCI(a) catalyzed by NF(a)/NF(b) was presented. The results show that a flow rate ratio of NF3 and D-2 of 0.8 to 1.5 and DCI and D-2 of > 1.5 is necessary for high efficiency of CI atoms generation. The results also show that NF(a) and NF(b) from the reaction of HN3 and residual F atoms or from the D-2/NF3 combustion have a serious effect on the generation and transport of NCI(a) via the NF(a) direct quenching of NCI(a) or via the catalysis of NF(a)/NF(b) on NCI(a) self-pooling. The generation of NF can be avoided if sufficient DCI was used and the NF3/D-2 flow rate ratio was properly controlled

Influence of pumping power density on output intensities and stabilities of competitive multi-line frequency up-conversions in cesium vapor

Multi-line frequency up-conversions are realized in Cs vapor using 718.8 nm pumping laser resonating with the two-photon transition 6(2)S(1/2) -> 8(2)D(5/2) of Cs atom. The pumping beam is converted into a beam including wavelengths of 361.2, 387.7, 455.7 and 621.5 nm. Experiments with collimated and focused pumping configurations are carried out and compared. Spectrum peak at 361.2 nm is strongest under collimated pumping condition, while 387.7 nm is strongest under focused pumping beam. The output beam under focused pumping is more stable than that under collimated pumping. Results in this work may be useful in laser frequency standard, beacon light, laser measuring and optics communications, etc. (C) 2017 Elsevier Ltd. All rights reserved