A Closer Look at Photonic Nanojets in Reflection Mode: Control of Standing Wave Modulation

Effective method for photonic jet shaping in reflection mode

We report an effective method to shape a photonic jet (PJ) generated by a dielectric cuboid scatterer on a hollow reflection screen. The study focuses on the shaping of PJ by hollow and cuboid geometries, including side length, depth, and position. The results show that all the geometric parameters can effectively shape the PJ in characteristic parameters of intensity, focal length (FL), and lateral size. The comparison shows that the present shaping method is much superior to the previously reported one based on a change of cuboid height, characterized by three times larger of the varying ranges of the PJ characteristic parameters. The shaping by the side length and depth of hollow and cuboid is explained from viewpoints of ray optics and electromagnetic field theory in terms of hollow-induced phase singularity in Poynting vector distribution. The hollow position mainly shapes the propagation trajectory of PJ. The deviation of the hollow position results in the curvature of the propagation trajectory of PJ, and the curvature is correlated with the asymmetric extent of the scattering system.

Generation of Photonic Nanojet Using Gold Film Dielectric Microdisk Structure

Due to their narrow beam waist size, high intensity, and long propagation distance, photonic nanojets (PNJs) can be used in various fields such as nanoparticle sensing, optical subwavelength detection, and optical data storage. In this paper, we report a strategy to realize an SPP-PNJ by exciting a surface plasmon polariton (SPP) on a gold-film dielectric microdisk. In detail, an SPP is excited by the grating-coupling method, then it irradiates the dielectric microdisk to form an SPP-PNJ. The characteristics of the SPP-PNJ, including maximum intensity, full width at half maximum (FWHM), and propagation distance, are studied by using finite difference time domain (FDTD) numerical solutions. The results demonstrate that the proposed structure can produce a high-quality SPP-PNJ, the maximum quality factor of which is 62.20, and the propagation distance of the SPP-PNJ is 3.08 λ. Furthermore, the properties of the SPP-PNJ can be modified flexibly by changing the thickness and refractive index of the dielectric microdisk.

Special Issue on Photonic Jet: Science and Application

Photonic jets (PJs) are important mesoscale optical phenomena arising from electromagnetic waves interacting with dielectric particles with sizes around several to several tens wavelengths (~2–40 λ) [...]

Optical Phenomena in Mesoscale Dielectric Particles

During the last decade, new unusual physical phenomena have been discovered in studying the optics of dielectric mesoscale particles of an arbitrary three-dimensional shape with the Mie size parameter near 10 (q~10). The paper provides a brief overview of these phenomena from optics to terahertz, plasmonic and acoustic ranges. The different particle configurations (isolated, regular or Janus) are discussed, and the possible applications of such mesoscale structures are briefly reviewed herein in relation to the field enhancement, nanoparticle manipulation and super-resolution imaging. The number of interesting applications indicates the appearance of a new promising scientific direction in optics, terahertz and acoustic ranges, and plasmonics. This paper presents the authors’ approach to these problems.