title: Ultralong photonic nanojet formed by a two-layer dielectric microsphere.
abstract: A photonic nanojet is a highly focused optical beam with a subwavelength waist on the shadow side of the sphere. Successful far-field applications require long nanojets that extend afar. Using the exact Mie theory, we show that ultralong nanojets can be generated using a simple two-layer microsphere structure, using conventional optical materials that are readily available. In particular, we show that for a glass-based two-layer microsphere, the nanojet has an extension of 22 wavelengths. We also show that long nanojets can be formed using semiconductors at infrared frequencies in free space.
authors.forename: Yuecheng
authors.initials: Y
authors.lastname: Shen
authors.forename: Lihong V
authors.initials: LV
authors.lastname: Wang
authors.forename: Jung-Tsung
authors.initials: JT
authors.lastname: Shen
mesh_terms: D017076:Computer-Aided Design; D017097:Electric Impedance; D008027:Light; D008029:Lighting / Q000295:instrumentation*; D008863:Microspheres; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D017785:Photons; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D012666:Semiconductors; D020349:Surface Plasmon Resonance / Q000295:instrumentation*