Hybrid Polymer Waveguide With Large Refractive Index Contrast for High-Density Optical Interconnects

We propose polymer waveguides with large refractive index contrast by adopting organic-inorganic hybrid resin and fluorinated acrylate resin as core and cladding materials, respectively. Both types of polymer materials are UV-curable and exhibit excellent compatibility throughout the fabrication process. The fabricated hybrid waveguides show good stabilities and the additional loss due to the adoption of two types of materials is negligible. In the experiment, we succeeded in the design and fabrication of hybrid polymer waveguides with a relative refractive index contrast (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Delta $ </tex-math></inline-formula>) as high as 7.7%. The measured bending loss of the waveguide is about 0.1 dB/90° turning under a bending radius of 1 mm at a wavelength of 1310 nm which is critical in realizing waveguide with complex topology and ultra-high density. The core dimension of the waveguide is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.5 \times \; 4.5 \; \mu $ </tex-math></inline-formula>m2 which guarantees low-loss interconnection with a typical silicon chip. The proposed method is useful in tuning the refractive index of waveguides in a wide range and the fabricated waveguide is promising for high-density optical interconnects application.