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.

Effect of the Multiple Cylinders Scattering of an Electromagnetic Plane Wave on the Formation of Whispering Gallery Modes

“…Since the coefficients aln varies inversely with R lj and become rapidly oscillating as R lj increase, we put p 2 =0 in (8) Figure 3 confirms the estimations (6) and (8).…”

“…[6] found and studied a narrow, high-intensity beam of light (photonic nanojet) generated at the shadow-side surface of dielectric cylinders illuminated by a plane wave. Photonic nanojet could be formed also by spheres [7], a two-layer dielectric microsphere cylinders [8], and discs [9]. The influence of incident light polarization was investigated in [10].…”

Process engineering study of photonic nanojet from highly intense to higher propagation using FDTD method

“…However the maximum dimension of this type of microstructures can be ten times that of the incident wave length. Currently various microstructures such as sphere [5], cylinder [6], ellipsoid [7,8], axicon [4,9], cuboids [10], microdisk [11] and there modified structures such as sections [12] , layer (graded [13], liquid immerged [14,15], metal coated [16]) or their chain [17] are also able to generate photonic nanojet. Out of these, sphere shaped micro structure has the ability to generate high intense nanojet however axicon shaped micro structure gives the highest propagation length in free space.…”

“…Theoretical investigations are mainly employed to know the behavior of change in light due to the desired structure. There are several methods employed to compute the solution of electromagnetic waves propagated from a finite structure such as transfer matrix method (TMM) [28], plane wave expansion (PWE) method [29], finite element method (FEM) [30], Boundary element method (BEM) [31], multiple multipole method (MMP) [7,8], finite difference time domain (FDTD) method [1][2][3][4][5][6][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] etc. Though there are several methods adopted for computation purpose, however FDTD method is frequently used because of user friendly simulation packages available in the market and to avoid empirical calculations [32].…”

Ultra-high ordered, centimeter scale preparation of microsphere Langmuir films

“…This technology relies on the principle of optical near-field enhancement underneath a monolayer of nano-or micro-spheres that can lead to laser spots with size well below the wavelength, while the structures thereby obtained have features at the nanometer scale. Thus, it is possible to micro-and/or nanostructure the substrates of choice using a sphere-assisted photonic nanojet lithography technique [26][27][28][29][30][31][32]. These sub-diffraction lithography techniques find applications in areas related to optical devices, spectroscopy, optical microscopy, data storage, and imaging [27][28][29]33].…”