Low-Loss Singlemode PECVD Silicon Nitride Photonic Wire Waveguides for 532–900 nm Wavelength Window Fabricated Within a CMOS Pilot Line

TLDR

The study investigates how silicon nitride waveguide loss depends on wire width, wavelength, and cladding. Losses were measured on both clad and unclad single‑mode PECVD silicon nitride waveguides at 532, 780, and 900 nm. Clad single‑mode waveguides exhibited losses below 1 dB cm⁻¹ across 532–900 nm, while unclad waveguides had 1 dB cm⁻¹ at 900 nm and 1–3 dB cm⁻¹ at 780 and 532 nm, confirming low‑loss operation in the visible–near‑IR window.

Abstract

PECVD silicon nitride photonic wire waveguides have been fabricated in a CMOS pilot line. Both clad and unclad single mode wire waveguides were measured at λ = 532, 780, and 900 nm, respectively. The dependence of loss on wire width, wavelength, and cladding is discussed in detail. Cladded multimode and singlemode waveguides show a loss well below 1 dB/cm in the 532-900 nm wavelength range. For singlemode unclad waveguides, losses 1 dB/cm were achieved at λ = 900 nm, whereas losses were measured in the range of 1-3 dB/cm for λ = 780 and 532 nm, respectively.