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ABSTRACT Spatiotemporal modulation approaches have been often employed as alternatives for producing optical nonreciprocity without magneto‐optic materials. Unidirectional inter‐modal scattering, enabled by either acousto‐optic or electro‐optic (EO) modulation, is a promising method in this category as it can directly modify optical dispersions and even enables linear nonreciprocal photonic devices in the strong coupling limit. Although EO approaches are often preferred for their practicality, it is challenging to generate the large spatiotemporal momentum required for inter‐modal phase matching without EO drive schemes involving multiple drive stimuli. Here, we demonstrate highly selective nonreciprocal inter‐modal EO scattering enabled by a single high‐index radiofrequency (RF) traveling wave stimulus. Our experimental demonstration is performed on a thin‐film lithium niobate‐integrated photonics platform in which we engineer a slow‐wave radiofrequency (SWRF) transmission line with an effective RF index that natively generates the required RF momentum while simultaneously maintaining strong RF‐optical mode overlap. By additionally engineering the interaction length, we achieve a directional dB nonreciprocal scattering contrast. The SWRF architecture provides a scalable route to magnetic‐free nonreciprocity and establishes momentum‐engineered RF waves as a powerful tool for next‐generation, fully integrated nonreciprocal photonic systems.
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This content will become publicly available on November 6, 2026
Full-core antimony sulfide platform for reconfigurable on-chip photonics
Chalcogenide phase-change materials exhibit large, reversible index shifts that promise nonvolatile, energy-efficient photonic technologies. Yet, current implementations either rely on ultrathin, lossy films integrated with passive Si/SiN waveguides, limiting index modulation, or exploit direct laser writing for localized switching, at the expense of strong optical confinement. Here we demonstrate an antimony trisulfide (Sb2S3) waveguide platform where the material itself forms the guiding core. The proposed architecture theoretically supports substantial modulation of both effective index and absorption, thereby providing a robust platform for the realization of reconfigurable and densely integrated photonic devices.
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- Award ID(s):
- 2217453
- PAR ID:
- 10679097
- Publisher / Repository:
- OPTICA
- Date Published:
- Journal Name:
- Optics Letters
- Volume:
- 50
- Issue:
- 22
- ISSN:
- 0146-9592
- Page Range / eLocation ID:
- 7011
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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