Generation of Photonic Hooks under Point-Source Illumination from Patchy Microcylinders

Abstract

Photonic hook (PH) is a new type of non-evanescent light beam with subwavelength curved structures. It has shown promising applications in super-resolution imaging and has the potential to be used in micromachining, optical trapping, etc. PHs are generally produced by illuminating mesoscale asymmetric particles with optical plane waves. In this work, we used the finite-difference time-domain (FDTD) method to investigate the PH phenomenon under point-source illumination. We found that the PHs can be effectively generated from point-source illuminated patchy particles. By changing the background refractive index, particle diameters and the position and coverage ratio of Ag patches, the characteristics of the PHs can be effectively tuned. Moreover, the structure of the intensity distribution of the light field generated from small and large particles can have an opposite bending direction due to the near-field light-matter interaction.

Photonic-hook enhanced microsphere-assisted label-free super-resolution imaging

“…4 Point source illumination can also be used to produce photonic hooks from patchy particles. 5 Here we reported the progress of using patchy particles for super-resolution imaging, and we showed that the performance of the imaging system can also be enhanced by coating microspheres with Al films. Using Al instead of Ag can significantly reduce the cost of fabrication, and facilities the commercialization of this technique.…”

Photonic hook propagation from eccentric microcylinder

“…There are different methods used to achieve a particle structure with broken symmetry. One approach involves designing a structure with a fixed refractive index distribution but an asymmetrical geometry, such as adding a triangular prism to the front of a cuboid [21,22] or coating a metal film onto part of a microcylinder [23]. The other method entails designing a structure with a symmetrical geometry but an inhomogeneous refractive index distribution, exemplified by Janus particles, cuboids cladded with cylinders, or hexagonal prisms [24][25][26][27].…”

Photonic Hook-Assisted Contrast-Enhanced Super-Resolution Imaging Using Janus Microspheres

“…For instance, patchy microspheres with metallic surface coatings can block a portion of incoming light, resulting in an asymmetric illumination effect. Their capacity of PH generation has been theoretically and experimentally demonstrated [15], [16], [17]. One of the most important applications of PHs is in super-resolution imaging [18], [19].…”