文献类型：期刊文献

中文题名：光诱导原子解吸附实验中的光热效应研究

英文题名：Photothermal Effect in Light-Induced Atomic Desorption

作者：高浩锋[1];李晓林[1];钮月萍[1];龚尚庆[1]

机构：[1]华东理工大学物理学院,上海200237

年份：2021

卷号：48

期号：23

起止页码：161

中文期刊名：中国激光

外文期刊名：Chinese Journal of Lasers

收录：CSTPCD;;EI(收录号：20220911713915);Scopus;WOS:【ESCI(收录号:WOS:000756529000018)】；北大核心:【北大核心2020】；CSCD:【CSCD2021_2022】；

基金：国家自然科学基金(11974109,12034007);上海市自然科学基金(20ZR1414300)。

语种：中文

中文关键词：量子光学;光诱导原子解吸附;光热效应;光学深度;原子浓度

外文关键词：quantum optics;light-induced atomic desorption;photothermal effect;optical depth;atomic concentration

摘要：利用光诱导原子解吸附效应,无需加热就可实现碱金属原子浓度的调控,简易有效,故常被应用于光纤内碱金属原子的充载和磁光阱内单原子的捕获等.在使用460nm的发光二极管阵列进行原子解吸附时,发现铷原子池的温度上升,说明光解吸效应受到了光热效应的影响,但目前关于光解吸附实验中的光热效应研究鲜有报道.当解吸光功率密度较小时,光热效应的影响几乎可忽略.当增大解吸光功率密度时,光解吸效应以及光热效应的影响不断增大且对原子浓度增长的贡献趋于接近,在两种效应的共同作用下,原子浓度的增长幅度得到进一步提高.研究结论对光子芯片研究具有参考意义.
Objective Recently,the study of integrated photonic devices is an important field of investigation,especially the photonic chip loaded with an atomic medium is one of the research hotspots.Based on the atomic medium,the integration of optical non-reciprocity,optical storage,and atomic clocks can be achieved.This requires an efficient interaction between light and atoms,which means that a certain optical depth is necessary and it is difficult to achieve at room temperature.The optical depth of an atomic medium can be increased by heating,but it is limited to the size of the photonic chip,which is not suitable in this scheme.Therefore,the use of light-induced atomic desorption(LIAD)is necessary,which does not require a heating system and it is beneficial to the integration of photonic chips.LIAD is an impressive phenomenon observed in a sodium-vapor glass cell,whose inner surface is coated with a thin siloxane film.It has been observed in experiments that an incoherent light illuminates a cell filled with alkali atoms and these atoms adsorbed on the inner surface fall off.Thus,LIAD can effectively increase the atomic concentration in the vapor cell,which is completely different from the thermal effect,and many parameters influence the effect of light-induced atomic desorption,such as the intensity and frequency of desorption light,the atom species,the geometry of the cell,and the inner surface morphology.In this paper,it is found that the atomic concentration increases due to the LIAD effect and photothermal effect.The influences of two mechanisms are experimentally studied,which is of great significance to the research of photonic chips.Methods A 150 mm diameter sphere with a highly reflective coating on the inner surface is used to enhance the LIAD effect,and a 460 nm light-emitting diode(LED)array mounted on the sphere is used as the illumination source.The power of the desorption light is changed by adjusting the driving current of the LED.When LIAD is carried out in a rubidium vapor cell,it is found that the temperature of the cell rises,which means that the atomic concentration increases due to the LIAD effect and the photothermal effect.By measuring the photothermal temperatures under different desorption light powers,the increase of atomic concentration caused by the photothermal effect is distinguished,and thus the relative influences of pure LIAD and photothermal effect are obtained.In order to verify whether the heat conduction caused by the LED array affects the cell or not,a water cooler is used to cool the LED array in the experiment.Besides,aglass plate is used to isolate the heat convection,which can reduce the effect of heat radiation on the cell.Results and Discussions With the increase of desorption light power,the effects of LIAD and photothermal effect are both increased(Fig.4).When the intensity of desorption light is 15 mW/cm^(2),the contribution of pure LIAD is close to 6 times that of the photothermal effect.In this case,the increase in atomic concentration caused by photothermal effect is basically negligible,and when the intensity reaches 80 mW/cm^(2),the ratio of atomic concentration increase caused by pure LIAD to that caused by photothermal effect is close to 6:4,which means that the effects of these two mechanisms are comparable(Fig.5).By cooling the LED array with a water cooler and isolating the heat convection,the temperature of the rubidium cell is 1--2℃ higher than that without water cooling(Fig.6),which means that the heat radiation caused by the LED array has little effect on the cell.Besides,the effect of heat convection is even negligible,which means that the increase of temperature in LIAD is mainly caused by the photothermal effect.Conclusions LIAD is a useful method to increase alkali atomic concentration without heating.In this paper,it is found that when using desorption light with high power density,the combined action of pure LIAD and photothermal effect further enhances the increase in atomic concentration.Besides,when increasing the wavelength of desorption light,the LIAD effect is reduced,while the photothermal effect is undoubtedly increased.Therefore,by changing the wavelength of desorption light,the contribution of these two mechanisms can be adjusted.In addition,since the desorption light with different power densities corresponds to different temperatures,the temperature of the atom cell can be controlled by adjusting the power density of the desorption light.These results have important reference value for the research of integrated photonic chips.