Patterned Optical Trapping with Two-Dimensional Photonic Crystals

We demonstrate an approach to achieve patterned optical trapping with two-dimensional photonic crystals (2D PC). A Gaussian beam infrared laser is guided and loosely focused by a simple optical system onto the surface of the 2D PC, which generates an enhanced diffraction field for optical trapping of microbeads with high efficiency. The diffraction patterns are determined by the structures of the 2D PC, and the experimental results match well with the modeling results using the finite-difference time-domain method. Polarization control is demonstrated as one way to achieve reconfigurability. Using this approach, we demonstrate high design flexibility for patterned optical trapping as determined by the 2D PC structure with low laser intensity.