|
In this work, we demonstrated a new method for coupling light, using prism with a small index of refraction and surface plasmon polaritons (SPP), into a crystalline silicon (Si) waveguides and performed simulation work using Lumerical FDTD Solutions. The designed structure is comprised of a dielectric prism, air-gap, metal (Ag) film, Si and silicon dioxide (SiO2). The system follows the Otto configuration for the excitation of SPP which includes a fused silica prism and a 100 nm layer of silver metal sputtered on top of SiO2 with an air-gap between the prism and the metal film. A 0.75×100 μm (height×width) silicon waveguide with tapered coupler is located on the same buried oxide along the silver layer for optical input channel. A p-polarized (TM mode) light with an incident angle of 44° at the wavelength of 1550 nm is incident at the interface of the fused silica/air-gap to excite the SPP. The 2D simulation shows a coupling efficiency of 54% which reveals the potential for application of this I/O coupling method in silicon photonics. For proof of concept, we fabricated and characterized the materials layout described above on an SOI substrate. For the Si structure, a tapered coupler and waveguide is fabricated using a XeF2 dry-etch and lift-off for the metal structure. Also, the experimental setup is suggested to locate the prism on the right position of the wafer and measure the output light from the waveguide by butt coupling.
|
