Rohit Kumar Yadav

Education / Work History

• R&D Member, TVS Motors (present)
• M.Tech, Center for Lasers and Photonics (CELP), IIT Kanpur (2016-2018)

Thesis Abstract

Discerning the Effects of Thermal Nonlinearity in Optical Trapping

In a typical optical trap, light pressure from a tightly focused laser beam is used to trap nano-sized & microscopic particles. It has found a large number of applications in biology, physics and other fields. Typical single beam optical tweezers use CW lasers. Here we present the principles of optical tweezers using a high repetition rate Femtosecond laser beam. We use the principle that the high peak power of each laser pulse is enough to provide an instantaneous trapping potential while the high repetition rate ensures the sustained stable trapping from the successive pulses. Since high peak powers are involved, the nonlinear optical effect becomes much more significant for femtosecond optical trapping. Consequently, trapping of spherical beads is analysed using the additional nonlinear effect for the femtosecond laser case and is compared with CW trapping. Numerical modelling is used to find the feasibility of femtosecond laser tweezers and calculating the induced forces on the nanometer size spherical particle. This model can be used to evaluate the stability of optical traps under a variety of different conditions like power, beam parameters, Wavelength, beam waist etc. for the particles in Rayleigh Regime, Lorenz Mie Regime, And the Ray Optics Regime so that the simulated results can be correlated to the experimental results.

Research Topic / Interest

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