Silicon nitride CMOS-compatible platform for integrated photonics applications at visible wavelengths

Fluorescence image of light propagati ng inside an MMI. Water with fluorescent dies was used as a top cladding.

Fluorescence image of light propagati ng inside an MMI. Water with fluorescent dies was used as a top cladding.

Abstract:
Silicon nitride is demonstrated as a high performance and cost-effective solution for dense integrated photonic circuits in the visible spectrum. Experimental results for nanophotonic waveguides fabricated in a standard CMOS pilot line with losses below 0.71dB/cm in an aqueous environment and 0.51dB/cm with silicon dioxide cladding are reported. Design and characterization of waveguide bends, grating couplers and multimode interference couplers (MMI) at a wavelength of 660 nm are presented. The index contrast of this technology enables high integration densities with insertion losses below 0.05 dB per 90° bend for radii as small as 35 µm. By a proper design of the buried oxide layer thickness, grating couplers with efficiencies above 38% for the TE polarization have been obtained.
S. Romero-García, F. Merget, F. Zhong, H. Finkelstein, J. Witzens, “Silicon Nitride CMOS-compatible platform for integrated photonics applications at visible wavelengths”, Opt. Express 21, 14036-14046 (2013).