Mode-division (de)multiplexing using adiabatic passage and supersymmetric waveguides

TL;DR

This paper presents a robust and efficient integrated mode-division (de)multiplexer design using adiabatic passage and supersymmetric waveguides, achieving high fidelity in mode separation for optical communications.

Contribution

It introduces a novel combination of spatial adiabatic passage and supersymmetric techniques for mode-division multiplexing, enhancing robustness and efficiency.

Findings

Output fidelity exceeds 0.90 for various parameters

Fidelity reaches 0.99 with optimization

Design is robust across broad wavelength range

Abstract

The development of mode-division multiplexing techniques is an important step to increase the information processing capacity. In this context, we design an efficient and robust mode-division (de)multiplexing integrated device based on the combination of spatial adiabatic passage and supersymmetric techniques. It consists of two identical step-index external waveguides coupled to a supersymmetric central one with a specific modal content that prevents the transfer of the fundamental transverse electric spatial mode. The separation between waveguides is engineered along the propagation direction to optimize spatial adiabatic passage for the first excited transverse electric spatial mode of the step-index waveguides. Thus, by injecting a superposition of the two lowest spatial modes into the step-index left waveguide, the fundamental mode remains in the left waveguide while the first excited mode is fully transmitted to the right waveguide. Output fidelities $\mathcal{F}>0.90$ are obtained for a broad range of geometrical parameter values and light's wavelengths, reaching $\mathcal{F}=0.99$ for optimized values.