Nanophotonic antenna for optical trapping applications

By converting light from localized energy to freely propagating radiation, optical antennas are used for optical trapping and particle manipulation. Based on the optical antenna composed of etched trenches on a waveguide, we propose two integrated waveguide-based optical tweezers for the first time for trapping micro- and nano-particles. A quasi-Gaussian beam and a quasi-spherical-wave field well above the antenna are produced and the optical trapping of the microparticle and nanoparticle is demonstrated. The corresponding upward beams generate gradient forces up to hundreds of pN/W, which is enough to trap particles in microscale and nanoscale effectively. Particles well above the antennas, as high as about 18 μm, can be trapped. This new type of optical tweezers based on photonic antennas is believed to pave the way to build fully integrated photonic circuits with large-scale parallel particle manipulation.