Photonic crystal waveguide intersection design based on Maxwell's fish-eye lens

TL;DR

This paper introduces a compact photonic crystal waveguide intersection design using Maxwell's fish-eye lens, enabling multiband operation with reduced footprint and low crosstalk for complex photonic circuits.

Contribution

It presents a novel intersection design integrating the lens into the waveguide crossing, covering multiple optical bands with optimized crosstalk and insertion loss performance.

Findings

Crosstalk below -24dB for 4x4 GPC-MFE intersections.

Covers entire C-band with optimized GPC-MFE lens.

Reduced footprint by integrating bends into the intersection.

Abstract

The number of waveguides crossing an intersection increases with the development of complex photonic integrated circuits. Numerical simulations are presented to demonstrate that Maxwell's fish-eye (MFE) lens can be used as a multiband crossing medium. In previous designs of waveguide intersection, bends are needed before and after the intersection to adjust the crossing angle resulting in a larger footprint. The presented design incorporates the waveguide bends into the intersection which saves footprint. In this paper, 4x4 and 6x6 intersections based on ideal and graded photonic crystal (GPC) MFE lenses are investigated, where 4 and 6 waveguides intersect, respectively. The intersection based on ideal MFE lens partially covers the O, E, S, C, L, and U bands of optical communication, while the intersection based on GPC-MFE lens is optimized to cover the entire C-band. For 4x4 and 6x6 intersections based on GPC-MFE lens, crosstalk levels are below -24dB and -18dB, and the average insertion losses are 0.60dB and 0.85dB in the C-band with lenses' radii of 7xa and 10xa, respectively, where a is the lattice constant of the photonic crystal.