Resolving the Puzzling Observations in Trapping Dynamics of Polystyrene and Silica Microparticles Under Femtosecond...

We set out to resolve a long-standing dilemma regarding the contradictory claims for the less or equal effectiveness of high-repetition-rate ultrashort pulsed excitation compared with continuous-wave (CW) excitation in optical trapping of dielectric microparticles. We present a comparative analysis of the trap stiffness of polystyrene and silica microparticles under CW and femtosecond pulsed excitation. We investigate how optical nonlinearity influences trap stiffness and highlight the distinct responses exhibited by polystyrene and silica particles under different excitations. Our results explain previous confounding results of trap stiffness under pulsed excitation compared to CW excitation in optical trapping of microscopic particles.