Waveguide-Based Photonic Antenna Tweezer for Optical Trapping

Optical antennas are promising for optical trapping and particle manipulation, when converting light between localized energy and freely propagating radiation. Here we propose an integrated waveguide-based optical tweezer for the first time for wavefront shaping to focus the upward radiation by the antenna, which is composed of etched trenches on a waveguide. The structural parameters of the antennas are optimized to produce a quasi-Gaussian field distribution above the antenna. Moreover, the gradient distribution of the electric field generates gradient force up to tens of pN/W, which is enough to enable effective optical trapping for particles a few micrometers in diameter and particles well above the antennas, as high as about 18 μm. We believe that as a new type of optical tweezer based on photonic antennas, the proposed devices pave the way to build fully integrated photonic circuits with large-scale parallel particle manipulation.