Silicon Photonic Paper-Clip Spiral Waveguides With Ultra-Low Propagation and Delay Loss

In this work, we demonstrate compact paper-clip spiral silicon photonic waveguides with ultra-low delay loss on a 300 mm-wafer foundry platform. We characterize the optical loss and group delay of single-mode and multi-mode silicon waveguides across the telecom O-, S-, C-, and L-bands. For spiral devices with 2.0-μm-wide waveguides, we measure propagation losses of 0.11 and 0.06 dB/cm at 1310 and 1550 nm, representing 10- and 20-times improvements, respectively, compared to the single-mode waveguides. Additionally, we observe a group delay of 1163 ps for a 9.5 cm-long waveguide with a device footprint of (0.3 × 3.0) mm2, yielding a delay loss of 0.5 dB/ns. These results establish a new benchmark for ultra-low-delay-loss silicon waveguides and open pathways for large-scale silicon photonic integration, delay lines, and on-chip programmable systems.