Etch Rate Dependence of Optical Loss in Silicon Photonics

Quantum photonic integrated circuits are emerging as a prominent research area due to their potential in quantum communications and quantum computing. In these systems, minimizing optical loss is critical as photon loss directly results in irreversible degradation of encoded quantum information, which cannot be restored by amplification due to the no-cloning theorem. Here, we introduce a straightforward yet effective optimization strategy for reducing the propagation loss of silicon waveguides by controlling the etching rate during fabrication. Systematic experimental results demonstrate a clear inverse correlation between etching rate and propagation loss. Specifically, we successfully reduced the propagation loss from 3.2 dB/cm to 1.55 dB/cm in a 500-nm-wide, half-etched silicon waveguide. This simple optimization technique provides a practical and scalable solution for fabricating low-loss quantum photonic integrated circuits.