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.

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.

scholarly journals Inverse-phase composite zone plate providing deeper focus than the normal diffraction-limited depth of X-ray microbeams

2019 ◽  
Vol 26 (1) ◽  
pp. 52-58
Author(s):  
Yasushi Kagoshima ◽  
Yuki Takayama
Keyword(s):  
Spatial Resolution ◽  
Optical Axis ◽  
Focal Point ◽  
Zone Plate ◽  
One Dimension ◽  
Depth Of Focus ◽  
Third Order ◽  
X Ray ◽  
Limited Depth ◽  
Focusing Properties

A novel type of zone plate (ZP), termed an inverse-phase composite ZP, is proposed to gain a deeper focus than the standard diffraction-limited depth of focus, with little reduction in spatial resolution. The structure is a combination of an inner ZP functioning as a conventional phase ZP and an outer ZP functioning with third-order diffraction with opposite phase to the inner ZP. Two-dimensional complex amplitude distributions neighboring the focal point were calculated using a wave-optical approach of diffraction integration with a monochromatic plane-wave illumination, where one dimension is the radial direction and the other dimension is the optical-axis direction. The depth of focus and the spatial resolution were examined as the main focusing properties. Two characteristic promising cases regarding the depth of focus were found: a pit-intensity focus with the deepest depth of focus, and a flat-intensity focus with deeper depth of focus than usual ZPs. It was found that twice the depth of focus could be expected with little reduction in the spatial resolution for 10 keV X-ray energy, tantalum zone material, 84 nm minimum fabrication zone width, and zone thickness of 2.645 µm. It was also found that the depth of focus and the spatial resolution were almost unchanged in the photon energy range from 8 to 12 keV. The inverse-phase composite ZP has high potential for use in analysis of practical thick samples in X-ray microbeam applications.

Sub-Micrometer Scale Laser Machining Using Position Controlled Photonic Nanojet

2020 ◽  
Author(s):  
Tsutomu Uenohara ◽  
Yasuhiro Mizutani ◽  
Yasuhiro Takaya
Keyword(s):  
High Intensity ◽  
Hole Diameter ◽  
Beam Diameter ◽  
Micro Machining ◽  
Depth Of Focus ◽  
Electromagnetic Simulations ◽  
Photonic Nanojet ◽  
Laser Micro Machining ◽  
Micrometer Scale ◽  
Machining Characteristics

Abstract A photonic nanojet (PNJ) is a fine and high intensity light beam that is generated from a dielectric microsphere irradiated by a laser. A PNJ has a smaller beam diameter than the wavelength of the incident laser and can propagate for longer than 1 μm with high intensity and minimal divergence. In other words, a PNJ has a long depth of focus. Due to its outstanding optical properties, PNJ is suitable for laser micro machining. In this paper, we theoretically and experimentally investigated machining characteristics of laser micro machining using a PNJ. First, electromagnetic simulations were conducted to estimate hole diameter when PNJ is irradiated to a sample by changing a distance from the microsphere to the sample. The simulation demonstrated that sub-micrometer scale hole diameter could be obtained even when PNJ is defocused by 1 μm due to the long depth of focus. Next, machining experiments were also conducted on a silicon substrate. A femtosecond laser was used as the machining laser. By holding the microsphere with a micropipette and controlling its position, the position of the PNJ can be controlled in the z direction. Micrometer and sub-micrometer scale hole diameters were obtained even when the position of PNJ in the z direction was changed by 1 μm. The hole diameters obtained in the experiment were consistent with the hole diameter estimated by the simulation. In conclusion, the long depth of focus of a photonic nanojet enable to create sub-micrometer scale structure.

Laser Micro Machining Using a Photonic Nanojet in Water Medium

2021 ◽  
Author(s):  
Tsutomu Uenohara ◽  
Reza Aulia Rahman ◽  
Yasuhiro Mizutani ◽  
Yasuhiro Takaya
Keyword(s):  
High Intensity ◽  
Propagation Direction ◽  
Water Medium ◽  
Beam Diameter ◽  
Micro Machining ◽  
Depth Of Focus ◽  
Photonic Nanojet ◽  
Laser Micro Machining ◽  
Scale Structures ◽  
Micrometer Scale

Abstract A photonic nanojet (PNJ) is a fine and high intensity light beam that is generated from a dielectric microsphere irradiated by a laser. A PNJ has a smaller beam diameter than the wavelength of the incident laser and can propagate for longer than 1 μm with high intensity and minimal divergence. In other words, a PNJ has a long depth of focus. Due to its outstanding optical properties, a PNJ is suitable for laser micro machining to create sub-micrometer scale structures. Depth of focus of a PNJ generated in water is longer than in air. In this paper, we experimentally investigated machining characteristics of laser micro machining using a PNJ in water medium. First, electromagnetic simulation was conducted to know the intensity distribution of PNJ in water medium. The simulation demonstrated that PNJ in water mdium has beam diameter of sub-micrometer scale and micrometer scale depth of focus. Next, machining experiments were also conducted on a silicon substrate. A femtosecond laser was used as the machining laser. By controlling the microsphere position, the PNJ position can be controlled in the propagation direction. Sub-micrometer scale hole diameters were obtained even when the PNJ position in the propagation direction was changed by 3 μm. In conclusion, the long depth of focus of a photonic nanojet in water medium enable to create sub-micrometer scale structures.

scholarly journals Tunable depth of focus of acoustical pupil masked Soret Zone Plate

2019 ◽  
Vol 286 ◽  
pp. 183-187 ◽  
Author(s):  
Sergio Castiñeira-Ibáñez ◽  
Daniel Tarrazó-Serrano ◽  
Oleg V. Minin ◽  
Constanza Rubio ◽  
Igor V. Minin
Keyword(s):  
Zone Plate ◽  
Depth Of Focus

scholarly journals Comparison of the focused optical vortices produced by high-aperture phase conventional and spiral zone plates

2021 ◽  
Vol 2103 (1) ◽  
pp. 012175
Author(s):  
A A Savelyeva ◽  
E S Kozlova ◽  
V V Kotlyar
Keyword(s):  
Gaussian Beam ◽  
Focal Plane ◽  
Topological Charge ◽  
Focal Spot ◽  
Zone Plate ◽  
Fdtd Simulation ◽  
Optical Vortices ◽  
Phase Zone ◽  
Linearly Polarized ◽  
Sharp Focusing

Abstract Using the FDTD simulation, sharp focusing of a linearly polarized Gaussian beam with an embedded topological charge m = 3 by a phase zone plate and focusing of a Gaussian beam by a phase spiral zone plate with topological charge m = 3 were studied. The obtained results showed that proposed elements formed different patterns of intensity at a focal plane. The spiral zone plate forms a focal spot with three petals. At a distance of 13.5 μm from the focus, the lobe structure of the intensity (and energy flux) is replaced by an annular distribution.

scholarly journals Proposal for Inverse-Phase Composite Zone Plate for Deeper Depth of Focus

2018 ◽  
Vol 24 (S2) ◽  
pp. 280-281 ◽  
Author(s):  
Yasushi Kagoshima ◽  
Yuki Takayama
Keyword(s):  
Zone Plate ◽  
Depth Of Focus
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