Topological Rainbow Trapping with Expanded Bandwidth in Valley Photonic Crystals
We introduce a novel approach to achieve broadband rainbow trapping in a 2D photonic crystal (PC) platform. By exploiting the concept of valley PCs, we engineer a structure that supports robust topological edge states. A carefully designed rotational angle gradient along the edge state path induces...
Saved in:
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-05-01
|
| Series: | Photonics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-6732/12/5/487 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | We introduce a novel approach to achieve broadband rainbow trapping in a 2D photonic crystal (PC) platform. By exploiting the concept of valley PCs, we engineer a structure that supports robust topological edge states. A carefully designed rotational angle gradient along the edge state path induces frequency-dependent light localization, forming a topological rainbow with a significantly expanded bandwidth. This phenomenon of topological rainbow trapping is attributed to the interplay between valley-dependent topological edge states and the engineered rotational angle gradient. To further enhance light localization and broaden the trapping spectrum, we incorporate a graded radius profile in the bottom row of dielectric columns. Through a combination of rotational angle modulation and radius grading, we successfully realize broadband rainbow trapping with enhanced light localization. Our findings reveal a broad trapping bandwidth spanning from <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.8314</mn><mi>c</mi><mo>/</mo><mi>a</mi></mrow></semantics></math></inline-formula> to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.9205</mn><mi>c</mi><mo>/</mo><mi>a</mi></mrow></semantics></math></inline-formula>, showcasing the potential of this approach for applications in optical frequency filtering, sensing, and information processing. |
|---|---|
| ISSN: | 2304-6732 |