Comparative study of the real-time optical trapping in the Rayleigh regime for continuous and femtosecond pulsed lasers

•First attempt to modeling femtosecond high repetition rate laser tweezer including cumulative thermal effect.•Modeling optical tweezers including optical nonlinearities.•Compared the real-time tweezing between continuous versus high repetition rate femtosecond laser pulses.•Competition between thermal effect versus nonlinearity. Simulating real-time scenarios to predict optical trapping behavior for continuous wave (CW) as well as femtosecond pulsed lasers is a challenging problem. The challenging nature of the problem arises from the fact that, for a tightly focused laser, one must also include the optical Kerr effect and the thermal nonlinearity. We show here the distinct differences between CW and femtosecond pulsed laser mediated optical trapping via their impact in scattering and gradient forces in the Rayleigh regime. In our newly developed model, it will be easier to predict the stability of the trap in real optical trapping scenarios, which would provide information regarding the choice of solvents, probes, and optical parameters, such as, the type of laser, power range, wavelength, etc.