Slot Waveguides With Silicon-Rich Materials for Nonlinear Applications

• Main Authors: Meicheng Fu, Xiaoyan Wang, Wenjun Yi, Xiujian Li, Lars Frandsen, Xiaowei Guan
• Format: Article
• Language: English
• Published: IEEE 2021-01-01
• Series: IEEE Photonics Journal
• Subjects: Integrated optics; nonlinear photonics; supercontinuum generation; four-wave mixing
• Online Access: https://ieeexplore.ieee.org/document/9399784/
• ISSN: 1943-0655

Slot waveguides based on silicon-rich materials are proposed and experimentally demonstrated, which consist of a silicon-rich oxide (SRO) slot layer sandwiched by two silicon-rich nitride (SRN) layers. Measurements show the waveguides have a low propagation loss of <inline-formula><tex-math notation="LaTeX">$\sim$</tex-math></inline-formula>2.2&#x00A0;dB/cm and a 50-<inline-formula><tex-math notation="LaTeX">$\mu \text{m}$</tex-math></inline-formula>-radius micro-ring resonator can achieve a loaded quality factor (<inline-formula><tex-math notation="LaTeX">$Q_{load}$</tex-math></inline-formula>) of <inline-formula><tex-math notation="LaTeX">$\sim 10^5$</tex-math></inline-formula>. Four-wave mixing experiments in the slot waveguides reveal a high nonlinearity <inline-formula><tex-math notation="LaTeX">$\gamma$</tex-math></inline-formula> of 16&#x00A0;W<inline-formula><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula>m<inline-formula><tex-math notation="LaTeX">$^{-1}$</tex-math></inline-formula> of the waveguide and an averaged nonlinear index <inline-formula><tex-math notation="LaTeX">$n_2$</tex-math></inline-formula> of 2.5 x 10<inline-formula><tex-math notation="LaTeX">$^{-18}$</tex-math></inline-formula> m <inline-formula><tex-math notation="LaTeX">$^2$</tex-math></inline-formula>/W of the silicon-rich materials, 10 times larger than that of stoichiometric silicon nitride (Si<inline-formula><tex-math notation="LaTeX">$_3$</tex-math></inline-formula>N<inline-formula><tex-math notation="LaTeX">$_4$</tex-math></inline-formula>). Supercontinuum generation (SCG) experiments have shown a large fabrication tolerance of such slot waveguides that 1.2 octave spectral broadening in a 1510-nm-wide slot waveguide can be achieved while that is 0.9 octave in a slot waveguide with a width shrinking as large as 220&#x00A0;nm.