scholarly journals Terahertz Microscopy with Oblique Subwavelength Illumination in near Field

2021 ◽  
Author(s):  
Igor V. Minin ◽  
Oleg V. Minin
Keyword(s):  
Oblique Incidence ◽  
Near Field ◽  
Diffraction Limit ◽  
Terahertz Range ◽  
Promising Tool ◽  
Photonic Jet

Microscopes based on dielectric mesoscale particles, using the effect of a photonic jet or terajet in the terahertz range, are a promising tool for overcoming the diffraction limit. However, the image they generate has limited contrast, which limits the application of this method. In this letter, we demonstrate that it is possible to increase the contrast of an image based on dielectric mesoscale particles that provide the formation of photonic hooks. In this case, the illumination of the object is carried out by an oblique incidence of subwavelength terajet, which significantly (more than 2 times) increases the contrast of the image.

scholarly journals Super-Resolution Imaging with Patchy Microspheres

Photonics ◽  
2021 ◽  
Vol 8 (11) ◽  
pp. 513
Author(s):  
Qingqing Shang ◽  
Fen Tang ◽  
Lingya Yu ◽  
Hamid Oubaha ◽  
Darwin Caina ◽  
...  
Keyword(s):  
Colloidal Particle ◽  
Near Field ◽  
Super Resolution ◽  
Incident Beam ◽  
Diffraction Limit ◽  
Beam Forming ◽  
Feature Size ◽  
Disc Surface ◽  
Promising Tool ◽  
Resolution Imaging

The diffraction limit is a fundamental barrier in optical microscopy, which restricts the smallest resolvable feature size of a microscopic system. Microsphere-based microscopy has proven to be a promising tool for challenging the diffraction limit. Nevertheless, the microspheres have a low imaging contrast in air, which hinders the application of this technique. In this work, we demonstrate that this challenge can be effectively overcome by using partially Ag-plated microspheres. The deposited Ag film acts as an aperture stop that blocks a portion of the incident beam, forming a photonic hook and an oblique near-field illumination. Such a photonic hook significantly enhanced the imaging contrast of the system, as experimentally verified by imaging the Blu-ray disc surface and colloidal particle arrays.

Ultra-broadband unidirectional launching of surface plasmon polaritons by a double-slit structure beyond the diffraction limit

Nanoscale ◽  
2014 ◽  
Vol 6 (22) ◽  
pp. 13487-13493 ◽  
Author(s):  
Jianjun Chen ◽  
Chengwei Sun ◽  
Hongyun Li ◽  
Qihuang Gong
Keyword(s):  
Surface Plasmon ◽  
Surface Plasmon Polaritons ◽  
Near Field ◽  
Diffraction Limit ◽  
Plasmonic Waveguide ◽  
Plasmon Polaritons ◽  
Double Slit

Based on the near-field interference of two slit apertures in a subwavelength plasmonic waveguide, an ultra-broadband unidirectional SPP launcher beyond the diffraction limit was experimentally realized. This ultra-small SPP launcher has important applications in high-integration plasmonic circuits.

scholarly journals Subwavelength Nanostructuring of Gold Films by Apertureless Scanning Probe Lithography Assisted by a Femtosecond Fiber Laser Oscillator

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 536 ◽  
Author(s):  
Ignacio Falcón Casas ◽  
Wolfgang Kautek
Keyword(s):  
Fiber Laser ◽  
Near Field ◽  
Diffraction Limit ◽  
High Repetition Rate ◽  
Scanning Probe ◽  
Optical Methods ◽  
Laser Source ◽  
Gold Films ◽  
Laser Oscillator ◽  
Scanning Probe Lithography

Optical methods in nanolithography have been traditionally limited by Abbe’s diffraction limit. One method able to overcome this barrier is apertureless scanning probe lithography assisted by laser. This technique has demonstrated surface nanostructuring below the diffraction limit. In this study, we demonstrate how a femtosecond Yb-doped fiber laser oscillator running at high repetition rate of 46 MHz and a pulse duration of 150 fs can serve as the laser source for near-field nanolithography. Subwavelength features were generated on the surface of gold films down to a linewidth of 10 nm. The near-field enhancement in this apertureless scanning probe lithography setup could be determined experimentally for the first time. Simulations were in good agreement with the experiments. This result supports near-field tip-enhancement as the major physical mechanisms responsible for the nanostructuring.

Near-field nonlinear imaging of an anapole mode beyond diffraction limit

2021 ◽  
Author(s):  
Tong Cui ◽  
Mingqian Zhang ◽  
Yun Zhao ◽  
Yuanmu Yang ◽  
Benfeng Bai ◽  
...  
Keyword(s):  
Near Field ◽  
Diffraction Limit ◽  
Nonlinear Imaging

Non-Destructive Detection of GIS Aluminum Alloy Shell Weld Based on Oblique Incidence Full Focus Method

2020 ◽  
Vol 1007 ◽  
pp. 105-110
Author(s):  
Xin Xin Wang ◽  
Cheng He ◽  
Pu Zhi Zhao ◽  
Yi Zheng ◽  
Shi Hao Jiang ◽  
...  
Keyword(s):  
Oblique Incidence ◽  
Near Field ◽  
Calibration Coefficient ◽  
Quantitative Detection ◽  
Imaging Method ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Field Range ◽  
Weld Defects ◽  
Non Destructive

In this paper, a new ultrasonic phased array full focus imaging method based on oblique incidence is proposed to solve the problem of the non-destructive testing of the internal defects in the GIS (gas insulated switchgear) shell welds. By using wedge coupling, the measured weld is far away from the near-field range of the transducer, and the detection angle range can be increased by changing the propagation direction of the acoustic beam. Based on Snell's law, the propagation characteristics of the ultrasonic wave in the interface are studied. On the basis of the conventional ultrasonic array matrix and the full focus imaging algorithm, by introducing the energy attenuation calibration coefficient of the acoustic wave propagation through the wedge, the correction amplitude of the specific focus point p(x, z) is obtained, The non-destructive testing of weld defects of GIS shell in the spot is carried out, and the test results show that the qualitative and quantitative detection of the weld defects can be well realized by using this method.

scholarly journals From Far-Field to Near-Field Micro- and Nanoparticle Optical Trapping

2020 ◽  
Vol 10 (4) ◽  
pp. 1375 ◽  
Author(s):  
Theodoros D. Bouloumis ◽  
Síle Nic Chormaic
Keyword(s):  
Optical Tweezers ◽  
Near Field ◽  
Metallic Nanostructures ◽  
Diffraction Limit ◽  
Submicron Particles ◽  
Great Success ◽  
Laser Illumination ◽  
Minimum Particle Size ◽  
Standard Tool ◽  
Established Technique

Optical tweezers are a very well-established technique that have developed into a standard tool for trapping and manipulating micron and submicron particles with great success in the last decades. Although the nature of light enforces restrictions on the minimum particle size that can be efficiently trapped due to Abbe’s diffraction limit, scientists have managed to overcome this problem by engineering new devices that exploit near-field effects. Nowadays, metallic nanostructures can be fabricated which, under laser illumination, produce a secondary plasmonic field that does not suffer from the diffraction limit. This advance offers a great improvement in nanoparticle trapping, as it relaxes the trapping requirements compared to conventional optical tweezers although problems may arise due to thermal heating of the metallic nanostructures. This could hinder efficient trapping and damage the trapped object. In this work, we review the fundamentals of conventional optical tweezers, the so-called plasmonic tweezers, and related phenomena. Starting from the conception of the idea by Arthur Ashkin until recent improvements and applications, we present the principles of these techniques along with their limitations. Emphasis in this review is on the successive improvements of the techniques and the innovative aspects that have been devised to overcome some of the main challenges.

Obtaining Circularly Polarized Optical Spots Beyond the Diffraction Limit Using Plasmonic Nano-Antennas

2009 ◽  
Vol 1208 ◽  
Author(s):  
Erdem Ogut ◽  
Gullu Kiziltas ◽  
Kursat Sendur
Keyword(s):  
Incident Light ◽  
Near Field ◽  
Diffraction Limit ◽  
Polarization Angle ◽  
Circularly Polarized ◽  
All Optical ◽  
Linearly Polarized ◽  
Linearly Polarized Radiation ◽  
Optical Applications ◽  
Polarized Radiation

AbstractWith advances in nanotechnology, emerging plasmonic nano-optical applications, such as all-optical magnetic recording, require circularly-polarized electromagnetic radiation beyond the diffraction limit. In this study, a plasmonic cross-dipole nano-antenna is investigated to obtain a circularly polarized near-field optical spot with a size smaller than the diffraction limit of light. The performance of the nano-antenna is investigated through numerical simulations. In the first part of this study, the nano-antenna is illuminated with a diffraction-limited circularly-polarized radiation to obtain circularly polarized optical spots at nanoscale. In the second part, diffraction limited linearly polarized radiation is used. An optimal configuration for the nano-antenna and the polarization angle of the incident light is identified to obtain a circularly polarized optical spot beyond the diffraction limit from a linearly polarized diffraction limited radiation.

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