Ultralow-loss compact silicon photonic waveguide spirals and delay lines

Low-loss and compact optical waveguides are key for realizing various photonic integrated circuits with long on-chip delay lines, such as tunable coherence tomography, gyroscopes. In this paper, a low-loss silicon waveguide spiral is proposed by introducing broadened Archimedean tapered Euler S-bend. A 100-cm-long realized minimal bending radius small 10 ?m using standard 220-nm-thick silicon-on-insulator foundry process, the measured propagation loss low 0.28 dB/cm. Furthermore, present spirals used to realize 10-bit line, which has footprint 2.2 mm × 5.9 dynamic range of 5120 ps fine resolution ps.