激发态质子转移分子2-(2′-羟基苯基)苯并噻唑溶液的全光开关效应

All-optical switching effect of the excited state proton transfer molecule 2-(2′-hydroxyphenyl) benzothiazole in different polar solvents

研究了激发态质子转移(ESPT)分子2-(2′-羟基苯基)苯并噻唑(HBT)在不同极性溶剂中的光开关行为,探讨了溶剂极性对HBT分子光开光效应的影响.揭示了光开关脉冲信号的形成原因,建立了基于光诱导HBT分子激发态非线性折射效应的皮秒全光开关的理论模型.根据对时间响应函数的理论计算和实验结果分析,确定了光开关脉冲信号下降前沿和上升后沿的形成机理以及影响因素,并提出了增强光开关信号下降前沿的关断深度,提升上升后沿的恢复速度的有效途径和方法.本文工作为制成皮秒量级关断,微秒甚至纳秒量级重新打开的快速全光开关器件提供了理论和实验依据,表明ESPT分子HBT有望成为超快全光开关器件的优选介质.

An all-optical switching model system comprising a single pulsed pump beam at 355 nm and a cw He-Ne signal beam at 632. 8 nm was demonstrated with 2-（2′-hydroxyphenyl） benzothiazole（HBT） in five different polar solvents. The origin of the optical switching effect was discussed,and it was verified that fast excited state intramolecular proton transfer （ESIPT） of HBT and the slow thermal effect of solvent together induced the change of the refractive index of HBT solutions,which lead to the signal beam deflection and dominated the optical switching ＂off ＂ and ＂on ＂ states, respectively. The slow thermal effect of solvent results in the＂tail＂phenomenon of the optical switching recovery,and reducing the signal beam waist radius is a viable means for accelerating the recovery of the optical switching. The results indicated that the HBT molecule could be an excellent candidate for high-speed and high-sensitivity optical switching devices. This work provides a theoretical as well as experimental basis for the production of ultra-fast all-optical switching device.