Ultra-Long Compact Optical Polymeric Array Waveguide True-Time-Delay Line Devices

Abstract

New types of UV curable polymeric ultra-long array waveguide true-time-delay (TTD) lines for wideband phased array antennas (PAA) are designed and fabricated using direct UV photolithography process. The unique feature of the approach consists of different 1 × N waveguide splitters, low-loss S-bend cosine waveguide connectors, and 180° array bend waveguides with a constant spacing difference ¿R between adjacent waveguides. The delay time increments are measured from 1.4 ns to 6.6 ps. 1 × 2, 1 × 4, 1 × 8 polymeric star coupler devices are also successfully prepared. The bend loss of different curved waveguides is calculated and analyzed by the 3-D semivectorial beam propagation method (BPM). The optimized structural properties of the UV curable polymeric waveguides and fabrication procedures are demonstrated. The near-infrared field guided-mode patterns of the devices are obtained. The new technique can be well suited for realizing absence of "beam squint" in the antenna pattern as its frequency is switched from L(1-2.6 GHz) to X(8-12 GHz) band.