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Geometry-Dependent Photonic Nanojet Formation and Arrays Coupling
Zehua Sun1, Shaobo Ge1, Lujun Shen1
1Shaanxi Province Key Laboratory of Thin Films Technology and Optical Test, School of Optoelectronic Engineering, Institute for Interdisciplinary and Innovation Research, Xi'an Technological University, Xi'an 710021, China.
Nanomaterials (Basel, Switzerland)
|January 27, 2026
Summary
This study explores how different shapes in photonic nanojet (PNJ) arrays affect light focusing. Cone and pyramid shapes offer stronger, more stable focusing compared to cylinders and truncated pyramids.
Area of Science:
- Photonics
- Optical Engineering
- Materials Science
Background:
- Photonic nanojets (PNJs) are highly localized optical fields generated by subwavelength dielectric structures.
- Understanding PNJ behavior in arrays is crucial for applications like optical sensing and micro-manipulation.
- The influence of geometric configuration on PNJ planar arrays requires systematic investigation.
Purpose of the Study:
- To systematically investigate photonic nanojet (PNJ) planar arrays formed by dielectric microstructures.
- To analyze the effects of geometry, array arrangement, and sparsity on PNJ formation and coupling.
- To determine the optimal geometric configurations for enhanced PNJ properties.
Main Methods:
- Utilized full-wave finite-difference time-domain (FDTD) simulations.
- Analyzed optical field distributions for various array configurations (cylinders, cones, truncated pyramids, pyramids).
- Investigated the impact of inter-element spacing and array sparsity on coupling behavior.
Main Results:
- Different geometries exhibit distinct coupling responses and PNJ intensities.
- Pyramid and cone structures show higher spatial stability and significantly greater PNJ intensity (up to 93 a.u.) compared to cylinders and truncated pyramids.
- Full Width at Half Maximum (FWHM) remains consistent across geometries, indicating geometry dictates lateral focusing.
- Array sparsity can be tuned to control inter-element coupling, with different geometries requiring specific sparsity levels.
Conclusions:
- Geometric configuration is the dominant factor in PNJ planar array performance.
- Cone and pyramid structures are superior for achieving high-intensity, stable PNJs.
- The findings provide essential guidance for the predictable design of PNJ planar arrays for various applications.
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