Long-Range Photonic Nanojet Formation via Superposition of Corner-Diffracted Waves

Microscale optical beams, or microbeams, are in high demand from many areas of optics but their realization remains challenging to date. This work aims to hybridize two types of optical beams, the quasi-non-diffracting (QND) and photonic nanojet (PNJ) beams, to facilely realize microbeams. QND optical beams are well-known for their long-range propagation. Shrinking their beam width down to the micrometric regime can lead to microbeam formation, but the process requires complex beam-forming platforms in general. On the other hand, the PNJ beams boast simple platforms and inherently small beam-size, but their short-ranged nature limited them primarily to near-field applications. In this work, the two beam concepts will be combined to realize microscale QND beams using a simple, PNJ-style platform. To that end, microscale cuboids made of low-index dielectric materials will be utilized dually, first to generate two corner-diffraction beams, and then to superpose them into a long-range microbeam. We will present the theoretical model of the beam formation process and validate it numerically and experimentally.