两级溴化锂气泡泵的泵起时间及其影响因素的实验研究

为了进一步提高能源利用效率和实现其空冷化,在双效溴化锂吸收式制冷系统中利用两级气泡泵代替溴化锂吸收制冷系统中传统的机械溶液泵。本文重点对两级溴化锂气泡泵的泵起时间及其影响因素做相关的实验研究,并得出以下的主要研究结果:1)对于不同的管径,两级气泡泵的泵起时间随着加热功率、浸没高度、工质浓度的变化趋势是基本一致的;2)加热功率越大越有利于气泡泵的泵起;3)随着浸没高度的增大气泡泵的泵起时间逐渐减小;4)工质浓度的增大也会使气泡泵的泵起时间增大,但当溴化锂溶液浓度大于54%后影响不明显;5)一级气泡泵的气液成分及中间溶液的闪发一定程度上影响两级气泡泵的泵起时间,因而造成局部区域与上述规律的偏离。     

Lasing properties of a Yb ion in tetragonal LuPO_4 and LuVO_4 isomorphic crystals: A comparative study

A comprehensive investigation is carried out to compare the spectroscopic properties, absorption saturation behaviors and lasing properties of a Yb ion in tetragonal LuPO_4 and LuVO_4 isomorphic crystals. Significant distinctions are revealed in many aspects of the lasing behavior for the Yb ion doped in the two crystal hosts, and Yb:LuPO_4 proves to be superior to Yb:LuVO_4 since it enables efficient laser action to be much more easily achieved. With a 0.6 mm thick crystal plate of Yb:LuPO_4, an output power of 3.30 W can be generated with an optical–optical conversion efficiency of 50.8%; whereas with a 2 mm long miniature crystal rod, the output power produced can reach 8.35 W with an optical–optical conversion efficiency of 46.7%.     

Passive Q-Switching of a Yb:LuVO_4 Laser with Cr~(4+):YAG:Approaching the Intrinsic Upper Limit of Repetition Rate

We demonstrate a diode pumped Yb:LuVO_4 laser that can be passively Q-switched by a Cr~(4+):YAG saturable absorber having an initial transmission as high as 99.3%.A maximum pulsed output power of 2.35 W is generated at a repetition rate of 285.7 kHz,approaching or very near the intrinsic upper limit imposed by the recovery time of the Cr~(4+):YAG saturable absorber,and the resulting pulse energy,duration and peak power are,respectively,8.2μJ,39.2ns and 0.209kW.     

Graphene Q-switched 0.9-μm Nd:La_(0.11)Y_(0.89)VO_4 laser

Graphene saturable absorber(SA) is used as the passive Q-switcher of a 0.9-μm solid-state laser.When the laser medium is a Nd:La0.11Y0.89VO4 crystal,the initial transmittance of the graphene SA is 78%;at an absorbed pump power of 7.62 W,the maximum average output power,largest pulse energy,and minimum pulse width are 0.62 W,2.58μJ,and 84 ns,respectively.This study shows that graphene is a promising and cost-saving SA for 0.9-μm pulse generation.