本文利用飞秒激光频谱相位整形技术和偏振调制技术, 对罗丹明B溶液中双光子荧光的相干控制进行了研究。通过对飞秒激光脉冲进行π相位扫描和余弦相位调制, 实现了罗丹明B溶液中双光子荧光的相干控制, 荧光强度能够被有效操控。经过理论模拟与分析, 证实罗丹明B溶液中双光子荧光强度的变化由双光子跃迁过程中不同量子路径之间的干涉相长和干涉相消引起的。对激光脉冲进行偏振调制的实验, 罗丹明B溶液中双光子荧光强度呈现出周期性变化; 经过理论模拟计算, 发现这种变化是受激光偏振的影响产生的。

With femtosecond laser spectral phase shaping technique and polarization modulation technique, the coherent control of two-photon fluorescence (TPF) in Rhodamine B solution is studied. By shaping the femtosecond pulse with simple phase patterns (cosinusoidal and π phase step-function shape), two-photon fluorescence intensity of Rhodamine B can be controlled effectively. Theoretical simulation and calculation show that the variation of two-photon fluorescence intensity for Rhodamine B solution is ascribed to the constructive and destructive interference of various quantum paths in two-photon transitions. TPF of Rhodamine B solution displays periodical change by polarization modulation. TPF decreases when the laser polarization changes from linear through elliptical to circular. These experimental results are theoretically confirmed to be caused by the variation of laser polarization.