Laser trapping dynamics of L-alanine depending on the laser polarization

摘要

We successfully demonstrate crystallization and crystal rotation of L-alanine in D2O solution using a focused laser beamof 1064 nm with right- or left-handed circularly polarization. Upon focusing each laser beam into a solution/air interfaceof the solution thin film, one single crystal is generally formed from the focal spot. The necessary time for thecrystallization is systematically examined against polarization and power of the trapping laser. The significant differencein the average time is observed between two polarization directions at a relatively high laser power, where the left-handedcircularly polarized laser takes 3 times longer than the right-handed one. On the other hand, the prepared crystalis stably trapped and rotated at the focal point by circularly polarized lasers after the crystallization, and the rotationdirection is completely controlled by the polarization of the trapping laser. The mechanisms for the crystallization andthe crystal rotation are discussed in terms of trapping force and rotation torque of circularly polarized lasers acting on theliquid-like clusters and its bulk crystal, respectively.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.