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In the development of topological photonics, achieving three-dimensional topological insulators is of notable interest since it enables the exploration of new topological physics with photons and promises novel photonic devices that are robust against disorders in three dimensions. Previous theoretical proposals toward three-dimensional topological insulators use complex geometries that are challenging to implement. On the basis of the concept of synthetic dimension, we show that a two-dimensional array of ring resonators, which was previously demonstrated to exhibit a two-dimensional topological insulator phase, automatically becomes a three-dimensional topological insulator when the frequency dimension is taken into account. Moreover, by modulating a few of the resonators, a screw dislocation along the frequency axis can be created, which provides robust one-way transport of photons along the frequency axis. Demonstrating the physics of screw dislocation in a topological system has been a substantial challenge in solid-state systems. Our work indicates that the physics of three-dimensional topological insulators can be explored in standard integrated photonic platforms, leading to opportunities for novel devices that control the frequency of light.
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Coupling-Controlled Photonic Topological Ring Array
Photonic topological insulators with boundary states present a robust solution to mitigate structure imperfections. By alteration of the virtual boundary between trivial and topological insulators, it is possible to bypass such defects. Coupled resonator optical waveguides (CROWs) have demonstrated their utility in realizing photonic topological insulators, as they exhibit distinct topological phases and band structures. With this characteristic, we designed and experimentally validated a CROW array capable of altering its topological phase by adjusting the coupling strength. This array functions partially as a topological insulator and partially as a topologically trivial array, guiding light along the virtuous boundary between these two regions. By altering the shape of the topological insulator, we can effectively control the optical path. This approach promises practical applications, such as optical switches, dynamic light steering, optical sensing, and optical computing.
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- Award ID(s):
- 2340060
- PAR ID:
- 10559360
- Publisher / Repository:
- ACS Photonics
- Date Published:
- Journal Name:
- ACS Photonics
- ISSN:
- 2330-4022
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.1021/acsphotonics.4c01502
