scholarly journals The photonic nanojets formation by two-dimensional microprisms

2020 ◽  
Vol 44 (6) ◽  
pp. 909-916
Author(s):  
V.D. Zaitsev ◽  
S.S. Stafeev
Keyword(s):  
Barium Titanate ◽  
Focal Spot ◽  
Incident Radiation ◽  
Maximum Intensity ◽  
Two Dimensional ◽  
Scalar Diffraction ◽  
Photonic Nanojet ◽  
Triangular Profile ◽  
Photonic Nanojets ◽  
Base Width

Using the finite difference method implemented in the COMSOL Multiphysics software package, the focusing of laser radiation by dielectric prisms with a triangular profile was numerically investigated. It was shown that two-dimensional triangular prisms make it possible to focus light in free space into spots with dimensions smaller than the scalar diffraction limit. In particular, a silica glass prism with a base width of 60 μm and a height of 28.5 μm forms a photonic nanojet with a maximum intensity of 6 times the intensity of the incident radiation and a width of FWHM=0.38λ. A prism from barium titanate with a base width of 60 μm and a height of 20 μm allows to obtain a photonic nanojet with the same width (0.38λ) and a maximum intensity 5 times the intensity of the incident radiation. The size of the focal spot can be reduced further if the height of the prism is selected so that the maximum intensity is located inside the material of the prism. For example, a barium titanate prism with a height of 21 μm and a base width of 60 μm forms a focal spot with a width of FWHM=0.25λ.

Optical properties of two-dimensional materials with tilted anisotropic Dirac cones: theoretical modelling with application to doped 8-Pmmn borophene

2021 ◽  
Author(s):  
Vl A Margulis ◽  
E E Muryumin
Keyword(s):  
Electronic Band Structure ◽  
Grazing Incidence ◽  
Dielectric Substrate ◽  
Incident Radiation ◽  
Brewster Angle ◽  
Theoretical Modelling ◽  
Two Dimensional ◽  
Electronic Band ◽  
A Value ◽  
Transmission And Absorption

Abstract The optical reflection, transmission and absorption properties of borophene, a newly discovered two-dimensional material with tilted anisotropic Dirac cones, are explored within a simple electronic band structure model of 8-Pmmn borophene, proposed by Zabolotskiy and Lozovik (2016 Phys. Rev. B 94 165403). It is assumed that the borophene layer is deposited on a dielectric substrate, such as Al2O3, and that the borophene's electron density is controlled by an external gate voltage. The reflectance, transmittance and absorbance of the borophene layer, the conduction band of which is filled with electrons up to the Fermi level, are calculated against the frequency of the incident radiation, as well as on the angle of its incidence on the layer. Considered are the two principal cases of the incident radiation polarization either parallel to or normal to the plane of incidence. We reveal that the optical characteristics of 8-Pmmn borophene are distinctly different for the above two cases at all angles of radiation incidence, excepting the grazing incidence, for which the borophene layer is found to behave like a mirror regardless of the wave polarization. The results obtained indicate the possibility of visualizing the borophene layer deposited on a dielectric substrate by observing the minimum reflectivity of this layer at a certain angle incidence (called the quasi-Brewster angle) of the p-polarized radiation, which may differ by a value of about ten degrees from the Brewster angle of the substrate.

scholarly journals Large-Scale Fabrication of Photonic Nanojet Array via Template-Assisted Self-Assembly

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 473 ◽  
Author(s):  
Pengcheng Zhang ◽  
Xi Chen ◽  
Hui Yang
Keyword(s):  
Self Assembly ◽  
Large Scale ◽  
Super Resolution ◽  
Light Signal ◽  
Practical Applications ◽  
Photonic Nanojet ◽  
Detection Technology ◽  
Size Uniformity ◽  
Resolution Imaging ◽  
Photonic Nanojets

A large-scale homogenized photonic nanojet array with defined pattern and spacing facilitates practical applications in super-resolution imaging, subwavelength-resolution nanopatterning, nano objects trapping and detection technology. In this paper, we present the fabrication of a large-scale photonic nanojet array via the template-assisted self-assembly (TASA) approach. Templates of two-dimensional (2D) large-scale microwell array with defined pattern and spacing are fabricated. Melamine microspheres with excellent size uniformity are utilized to pattern on the template. It is found that microwells can be filled at a yield up to 95%. These arrayed microspheres on the template serve as microlenses and can be excited to generate large-scale photonic nanojets. The uniformly-sized melamine spheres are beneficial for the generation of a homogenized photonic nanojet array. The intensity of the photonic nanojets in water is as high as ~2 fold the background light signal. Our work shows a simple, robust, and fast means for the fabrication of a large-scale homogenized photonic nanojet array.

scholarly journals Elongated Photonic Nanojet from Truncated Cylindrical Zone Plate

2012 ◽  
Vol 2012 ◽  
pp. 1-3 ◽  
Author(s):  
Sergey S. Stafeev ◽  
Victor V. Kotlyar
Keyword(s):  
Focal Spot ◽  
Zone Plate ◽  
Cylinder Surface ◽  
Dielectric Cylinder ◽  
Depth Of Focus ◽  
Photonic Nanojet

Previously (Chen et al., 2004), it was shown that dielectric cylinder can form focal spots with small diameters and long depth. This type of focal spot was called photonic nanojet. In this paper, it was shown that dielectric cylinder of radius 595 nm (1.12 of wavelength) forms near the surface a photonic nanojet with diameter equal to 0.31 of wavelength and depth of focus equal to 0.57 of wavelength. Adding truncated concentric rings with radiuses equal to radiuses of zone plate to the cylinder increases the depth of focus to 1.18 of the wavelength. The diameter and intensity of focal spot near the cylinder surface remain unchanged.

Photonic Nanojet Generation in Transmission and Reflection Mode

2020 ◽  
Vol 312 ◽  
pp. 213-220
Author(s):  
Alexander A. Sergeev ◽  
Ksenia A. Sergeeva ◽  
Aleksandr Vladimirovich Nepomniaschiy ◽  
Sergey S. Voznesenskiy
Keyword(s):  
Functional Performance ◽  
Gaseous Ammonia ◽  
The Novel ◽  
Reflection Mode ◽  
Sensitive Layer ◽  
Photonic Nanojet ◽  
Sensor Structure ◽  
Ammonia Detection ◽  
Photonic Nanojets ◽  
Transmission And Reflection

This paper is related to the problem of enhancing the optical and functional performance of luminescent gas sensors via its excitation by photonic nanojets. The novel sensor structure consisting of the array of alumina microparticles covered by optical sensitive layer was designed. The parameters of the photonic nanojets generated in both transmission and reflection modes has been numerically end experimentally studied. It was shown that PNJ in reflection mode demonstrates an unexpectedly high enhancement of photoluminescence. It was obtained that the excitation of the sensitive layer by photonic nanojets extends the limit of gaseous ammonia detection up to 0.1 ppm for reflection mode and up to 0.02 ppm for transmission mode.

Two-Dimensional Real-Time Interferometric Monitoring System for Exposure Controlled Projection Lithography

2012 ◽  
Author(s):  
Amit S. Jariwala ◽  
Robert E. Schwerzel ◽  
Michael Werve ◽  
David W. Rosen
Keyword(s):  
Real Time ◽  
Monitoring System ◽  
Substrate Surface ◽  
Three Dimensional ◽  
Incident Radiation ◽  
Solid Polymer ◽  
Two Dimensional ◽  
Projected Image ◽  
Transparent Substrate ◽  
Projection Lithography

Stereolithography is an additive manufacturing process in which liquid photopolymer resin is cross-linked and converted to solid polymer with an ultraviolet light source. Exposure Controlled Projection Lithography (ECPL) is a stereolithographic process in which incident radiation, patterned by a dynamic mask, passes through a transparent substrate to cure a photopolymer layer that grows progressively from the substrate surface. In contrast to existing stereolithography techniques, this technique uses a gray-scale projected image, or alternatively a series of binary bit-map images, to produce a three-dimensional polymer object with the desired shape, and it can be used on either flat or curved substrates. Like most stereolithographic technologies, ECPL works in a unidirectional fashion. Calibration constants derived experimentally are fed to the software used to control the system. This unidirectional fabrication method does not, by itself, allow the system to compensate for minor variations, thereby limiting the overall accuracy of the process. We present here a simple, real-time monitoring system based on interferometry, which can be used to provide feedback control to the ECPL process, thus making it more robust and increasing system accuracy. The results obtained from this monitoring system provide a means to better visualize and understand the various phenomena occurring during the photopolymerization of transparent photopolymers.

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