Long-range coupling of silicon photonic waveguides using lateral leakage and adiabatic passage

Abstract

We present a new approach to long range coupling based on a combination of adiabatic passage and lateral leakage in thin shallow ridge waveguides on a silicon photonic platform. The approach enables transport of light between two isolated waveguides through a mode of the silicon slab that acts as an optical bus. Due to the nature of the adiabatic protocol, the bus mode has minimal population and the transport is highly robust. We prove the concept and examine the robustness of this approach using rigorous modelling. We further demonstrate the utility of the approach by coupling power between two waveguides whilst bypassing an intermediate waveguide. This concept could form the basis of a new interconnect technology for silicon integrated photonic chips.

Quantitative Analysis of TM Lateral Leakage in Foundry Fabricated Silicon Rib Waveguides

“…This mechanism is useful in the development of integrated sensors [1], [2], polarizers [3], liquid crystal platforms [4] and a recently proposed waveguide switching network [5].…”

Experimental demonstration of TM lateral leakage in a standard SOI photonics platform

“…Our fabricated devices show low loss propagation at 720 nm with the loss dramatically increasing away from this resonance, in close agreement with predictions. These results demonstrate that a standard silicon photonic platform can achieve controllable coupling between guided and radiative modes, which can potentially provide a routing pathway between two spatially separated waveguides, no longer relying on evanescent interactions [3].…”

“…Instead of viewing this lateral leakage as loss, it can be engineered for new photonic device topologies [3]. Previous demonstrations of lateral leakage waveguides rely on exotic and potentially non-CMOS compatible fabrication processes [1].…”

Lateral Leakage in Silicon Photonics: Theory, Applications, and Future Directions

“…Therefore, it is desirable to suppress the power existing in this common TE slab mode while using this TE slab mode as a bus for long-range coupling. It is possible to achieve long-range coupling in thin-ridge SOI waveguides using a common TE slab bus mode without exciting this bus as well as bypassing intermediate waveguides by combining the lateral leakage behaviour and an adiabatic technique called Coherent Tunnelling Adiabatic Passage (CTAP) [49] or photonic quantum gate design [50].…”