Highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles

Yuewang Huang; Qiancheng Zhao; Nicholas Sharac; Regina Ragan; Ozdal Boyraz

doi:10.1117/12.2182290

18 May 2015 Highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles

Yuewang Huang, Qiancheng Zhao, Nicholas Sharac, Regina Ragan, Ozdal Boyraz

Proceedings Volume 9503, Nonlinear Optics and Applications IX; 95030H (2015) https://doi.org/10.1117/12.2182290
Event: SPIE Optics + Optoelectronics, 2015, Prague, Czech Republic

Abstract

We demonstrate the fabrication of a highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles for plasmonic enhancement. The average enhancement effect is evaluated by measuring the spectral broadening effect caused by self-phase-modulation. The nonlinear refractive index n₂ was measured to be 7.0917×10^-19 m²/W for a waveguide whose W_open is 5 μm. Several waveguides at different locations on one wafer were measured in order to take the randomness of the nanoparticle distribution into consideration. The largest enhancement is measured to be as high as 10 times. Fabrication of this waveguide started with a MEMS grade photomask. By using conventional optical lithography, the wide linewidth was transferred to a <100> wafer. Then the wafer was etched anisotropically by potassium hydroxide (KOH) to engrave trapezoidal trenches with an angle of 54.7º. Side wall roughness was mitigated by KOH etching and thermal oxidation that was used to generate a buffer layer for silicon nitride waveguide. The guiding material silicon nitride was then deposited by low pressure chemical vapor deposition. The waveguide was then patterned with a chemical template, with 20 nm gold particles being chemically attached to the functionalized poly(methyl methacrylate) domains. Since the particles attached only to the PMMA domains, they were confined to localized regions, therefore forcing the nanoparticles into clusters of various numbers and geometries. Experiments reveal that the waveguide has negligible nonlinear absorption loss, and its nonlinear refractive index can be greatly enhanced by gold nano clusters. The silicon nitride trench waveguide has large nonlinear refractive index, rendering itself promising for nonlinear applications.

Citation Download Citation

Yuewang Huang, Qiancheng Zhao, Nicholas Sharac, Regina Ragan, and Ozdal Boyraz "Highly nonlinear sub-micron silicon nitride trench waveguide coated with gold nanoparticles", Proc. SPIE 9503, Nonlinear Optics and Applications IX, 95030H (18 May 2015); https://doi.org/10.1117/12.2182290

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