Fabrication of polymer optical waveguides by digital ultraviolet lithography

Abstract

We present the design, fabrication and characterization of polymer optical waveguides using a digital ultraviolet (UV) lithography. Grayscale optical exposure with a nonlinear compensation in quadratic form is applied to minimize the stitching loss of the transition zone between two adjacent subpatterns. Proximity effects in lithography process are compensated based on an exposure dose-map that is calculated under the approximation of scattered light pixel with a Gaussian distribution. The bending loss and propagation loss of the fabricated polymer waveguides are experimentally characterized to be around 0.1 dB/90°-bend and 0.238 dB/mm, respectively. Moreover, 1 × 2 multimode-interference power splitter, 1 × 2 Y-branch power splitter and microring resonator are demonstrated to show the feasibility of the lithography technology on rapid fabrication of waveguides. Such a UV lithography technology flexibly manipulates huge-number light pixels for all-digital grayscale and dynamic optical exposure and thus can enable the fabrication of novel optical waveguide-based devices and sensors, such as 2.5D waveguides for multimode crossing and polymer waveguide devices for biosensing.