Si photonic crystal waveguide based delay lines

摘要

We report a four-channel on-chip true-time-delay (TTD) module based on a photonic crystal waveguide (PCW) array. By minimizing the coupling loss with a photonic crystal taper (PC taper), the delay lines with l-3mm long PCWs can operate up to a group index ng～23 without significant loss. The large group velocity dispersion enables continuous and wavelength-tunable time delays. Measurements show a highly linear phase-frequency relation, highest time delay up to 216.7 ps, and large tuning ranges of 58.28 ps, 115.74 ps, and 194.16 ps for l-3mm delay lines, respectively. The chip-scale TTD module can provide ±44.38° steering for an X-band phased array antenna (PAA), but occupies only 0.18 mm2 area.