Tuesday, May 30, 2017

Evanescent field interferometric optical tweezers with rotational symmetric patterns

Mohammadbagher Mohammadnezhad and Abdollah Hassanzadeh

A simple configuration to create optical lattices with 𝑁N-fold rotational symmetry using the interference of 𝑁N evanescent fields is proposed. The potential energy of a Rayleigh particle in the generated patterns (optical lattices) is investigated. The results show that by adjusting the relative phases and polarization states of the incident beams, an enormous range of optical lattices can be obtained. When the number of interfering beams is increased, circular spots beyond the diffraction limit can be created. For 𝑠s-polarization, the intensity landscape has a dark-centered distribution at the origin encircled by a very small bright circular ring whose radius is 120 nm. This intensity distribution acts as a hollow beam and can be used for efficient trapping of low-index particles. We believe that the resulting lattices can find applications in the arrangement of particles, creation of optical lattices, and efficient trapping of very small Rayleigh particles.

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