Advanced materials, process, and designs for silicon photonic integration

[摘要] (cont.) It is capable of transforming single mode light between single mode fiber and waveguides with minimal coupling loss of 0.45 dB between 1520 nm and 1630 nm. We have also demonstrated a vertical waveguide-to-waveguide coupler that is based on complementary inverse tapers. This design is tolerant of large refractive index mismatch between the two waveguides and also of any fabrication variation that would affect the effective indices of the two waveguides. We have achieved a minimal coupling loss of 0.25 dB per coupler and excellent broadband behavior is also demonstrated. Slot waveguides are a newly developed class of waveguides with unique optical properties. Slot waveguides can achieve exceptional high optical field in nanometer sized low index regions. In this thesis, we have demonstrated low loss transmission of 6 dB/cm for the fundamental slot mode in horizontal slot waveguides at 1550 nm. The horizontal slot configuration removes the constraints of thin slot definition by lithography and allows an arbitrarily thin slot to be fabricated via deposition or oxidation. Because the resulting interface is much smoother than the etched interface, the transmission loss in horizontal slot waveguides is much lower than in vertical slot waveguides. We also demonstrated that multiple slot configurations result in higher optical confinement compared to single slot configurations with the same slot thickness. The low loss and high optical confinement in the low index slot region realized in horizontal slot waveguides promises many useful applications, such as Er-doped silicon-based light emitters. For integration of slot waveguides with conventional channel waveguides, we have designed and simulated mode couplers and polarization rotators for slot-slot, slot-channel waveguide mode transformations.Athermal operation is important for realizing stable passive, WDM optical network on silicon. Athermal design of silicon waveguide systems uses advanced polymer cladding of large negative TO coefficient to provide compensation for the large positive TO coefficient in silicon. The reduced thermo-optic (TO) effect is experimentally demonstrated by reducing TO coefficient from 85 pm/K to 11 pm/K using polymer films.

[发布机构] Massachusetts Institute of Technology