Dynamically tunable ultralong photonic nanojets by a curved surface truncated dielectric microcylinder

As for microparticles (microspheres or microcylinders) that form photonic nanojets (PNJs) in the near field, a curved truncated dielectric microcylinder structure (CSTDM) is investigated by the finite element method which can form ultralong PNJs with the longest effective length: 209.49 lambda. Changing parameter h of the structure can realize long dynamic range tuning of the effective length of the PNJ. The effective length varies quasi-periodically with h; the law of the variation of main indicators of the microcylinder is further discussed, such as the effective length, the working distance, peak electric field intensity, and full width at half height. (C) 2022 The Japan Society of Applied Physics