# Maxwell's fisheye lens as efficient power coupler between dissimilar photonic crystal waveguides

## TL;DR

This paper presents a novel Maxwell's fisheye lens-based coupler that efficiently connects dissimilar photonic crystal waveguides, demonstrating superior performance in the C-band with low insertion loss and broad bandwidth coverage.

## Contribution

It introduces a ring-based multilayer Maxwell's fisheye lens design for efficient power coupling between different photonic crystal waveguides, outperforming GPC-based designs.

## Key findings

- Achieves an average insertion loss of 0.1dB in the C-band.
- Covers the entire C and U bands with the proposed design.
- Maximum return loss of -11dB in the C-band.

## Abstract

The imaging properties of the Maxwell's fisheye (MFE) lens makes it a viable candidate to implement power coupling between different types of waveguides. A coupler based on the MFE lens is designed to couple a square lattice photonic crystal to a triangular lattice one. The MFE lens is implemented as ring-based multilayer and graded photonic crystal (GPC) structures. The performance of the ring-based MFE lens is better than the GPC-based one in the C-band of optical communication. The proposed ring-based MFE coupler has a footprint of $3.62\times 3.62\mu m$ and covers the entire C and U bands. The S and L bands are partially covered. The average insertion loss of 0.1dB and the maximum return loss of -11dB in the C-band is achieved.

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Source: https://tomesphere.com/paper/1904.01242