Photonic Nanojet Beam Shaping by Illumination Polarization Engineering

This study investigates the application of photonic nanojets (PNJs) in particle manipulation, focusing on single, dual, and two-layer microsphere models. The single microsphere model demonstrates the generation of PNJs capable of trapping nanoparticles; however, its manipulation efficacy is directionally limited due to structural asymmetry. To address this limitation, a dual-microsphere configuration is introduced, enhancing manipulation precision and enabling multi-channel control through phase modulation. Further improvement is achieved with a two-layer microsphere structure, which increases channel width, thereby enhancing particle trapping efficiency and manipulation flexibility. These advancements offer novel strategies for particle manipulation and provide reliable methods for micromanipulation and biological sample analysis in biomedical applications.