Fresnel-focusing and bessel-beam integrated optical phased arrays for optical trapping applications

Abstract

Optical trapping and tweezing - the manipulation of particles using optical forces - enables direct interaction with biological samples and non-invasive monitoring of their properties. As such, optical trapping has become a common tool in biology with applications ranging from better understanding of DNA mechanics to non-invasive manipulation of red blood cells in vivo. While optical trapping using bulk optics is a well established technique, recent work has turned towards chip-based optical trapping using integrated devices. However, many of these integrated systems are fundamentally limited to passive demonstrations within microns of the chip surface. Integrated optical phased arrays, which manipulate and dynamically steer light, provide one possible approach to scaling and arbitrary tweezing of optical traps. However, current on-chip optical phased array demonstrations have focused on systems which form and steer beams or project arbitrary radiation patterns in the far field. In this thesis, Fresnel-lens-inspired focusing integrated optical phased arrays are demonstrated for the first time and proposed as a method for chip-based optical trapping. These systems focus radiated light to tightly-confined spots in the near field above the chip to enable applications in wide-angle trapping at millimeter scales. Furthermore, integrated optical phased arrays are proposed and demonstrated for the first time as a method for generating quasi-Bessel beams in a fully-integrated, compact-form-factor system. Through generation of quasi-Bessel beams with elongated properties, these devices have potential for applications in multi-particle, multi-plane optical trapping. To enable these phased array systems, a suite of integrated nanophotonic architectures and devices for waveguiding, coupling, routing, phase control, and radiation are developed, simulated, fabricated, and tested and a CMOS-compatible foundry platform is leveraged for natural scaling to active demonstrations.