scholarly journals Experimental investigation of new optical antenna designs found by a genetic algorithm

2020 ◽  
Author(s):  
Thorsten Feichtner ◽  
Oleg Selig ◽  
Markus Kiunke ◽  
Bert Hecht
Keyword(s):  
Field Intensity ◽  
Near Field ◽  
Single Point ◽  
Optical Antenna ◽  
Primitive Elements ◽  
Split Ring ◽  
Experimental Realization ◽  
Intensity Enhancement ◽  
Two Photon ◽  
Metal Case

Most currently studied optical antenna geometries are based on radio wave antenna designs. However, material properties at optical frequency largely differ from the perfect metal case at radio frequencies. Recently, evolutionary algorithms (EA) [1] were used in the field of Plasmonics to find novel geometries however with strongly limited configuration space [2]. We developed an EA capable of handling complex multiparticle geometries. In a first application we optimized near-field intensity enhancement produced by antenna structures in a single point [3]. We found a novel geometry, i.e. a nano antenna/split-ring hybrid antenna for which the near-field intensity enhancement is strongly increased. Yet these structures are not suitable for experimental realization. Here we show the results of an adapted EA which uses primitive elements that are compatible with an experimental fabrication step using FIB. The performance of the realized structures is characterized by means of confocal two-photon-photoluminescence-(2PPL)-microscopy. We find that the hierarchy of performances found in individuals taken from sequential generations of the EA can be reproduced in fabricated structures.

scholarly journals Double moiré localized plasmon structured illumination microscopy

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Ruslan Röhrich ◽  
A. Femius Koenderink
Keyword(s):  
Near Field ◽  
Super Resolution ◽  
Reconstruction Algorithm ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Experimental Realization ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Localized Plasmon ◽  
Plasmonic Grating

AbstractStructured illumination microscopy (SIM) is a well-established fluorescence imaging technique, which can increase spatial resolution by up to a factor of two. This article reports on a new way to extend the capabilities of structured illumination microscopy, by combining ideas from the fields of illumination engineering and nanophotonics. In this technique, plasmonic arrays of hexagonal symmetry are illuminated by two obliquely incident beams originating from a single laser. The resulting interference between the light grating and plasmonic grating creates a wide range of spatial frequencies above the microscope passband, while still preserving the spatial frequencies of regular SIM. To systematically investigate this technique and to contrast it with regular SIM and localized plasmon SIM, we implement a rigorous simulation procedure, which simulates the near-field illumination of the plasmonic grating and uses it in the subsequent forward imaging model. The inverse problem, of obtaining a super-resolution (SR) image from multiple low-resolution images, is solved using a numerical reconstruction algorithm while the obtained resolution is quantitatively assessed. The results point at the possibility of resolution enhancements beyond regular SIM, which rapidly vanishes with the height above the grating. In an initial experimental realization, the existence of the expected spatial frequencies is shown and the performance of compatible reconstruction approaches is compared. Finally, we discuss the obstacles of experimental implementations that would need to be overcome for artifact-free SR imaging.

scholarly journals Infrared vibrational nanocrystallography and nanoimaging

2016 ◽  
Vol 2 (10) ◽  
pp. e1601006 ◽  
Author(s):  
Eric A. Muller ◽  
Benjamin Pollard ◽  
Hans A. Bechtel ◽  
Peter van Blerkom ◽  
Markus B. Raschke
Keyword(s):  
Ion Mobility ◽  
Molecular Orientation ◽  
Hybrid Imaging ◽  
Defect Formation ◽  
Near Field ◽  
Molecular Solids ◽  
Optical Antenna ◽  
Molecular Bond ◽  
Low Symmetry ◽  
Insight Into

Molecular solids and polymers can form low-symmetry crystal structures that exhibit anisotropic electron and ion mobility in engineered devices or biological systems. The distribution of molecular orientation and disorder then controls the macroscopic material response, yet it is difficult to image with conventional techniques on the nanoscale. We demonstrated a new form of optical nanocrystallography that combines scattering-type scanning near-field optical microscopy with both optical antenna and tip-selective infrared vibrational spectroscopy. From the symmetry-selective probing of molecular bond orientation with nanometer spatial resolution, we determined crystalline phases and orientation in aggregates and films of the organic electronic material perylenetetracarboxylic dianhydride. Mapping disorder within and between individual nanoscale domains, the correlative hybrid imaging of nanoscale heterogeneity provides insight into defect formation and propagation during growth in functional molecular solids.

ontrolled implementation of two-photon controlled phase gate within a network

2010 ◽  
Vol 10 (9&10) ◽  
pp. 821-828
Author(s):  
Yan Xia ◽  
Jie Song ◽  
Zhen-Biao Yang ◽  
Shi-Biao Zheng
Keyword(s):  
Quantum Computer ◽  
Photon Detectors ◽  
Optical Elements ◽  
Experimental Realization ◽  
Two Photon ◽  
Phase Gate ◽  
Controlled Phase Gate ◽  
Linear Optical ◽  
Polarized Photons ◽  
Linear Optical Elements

We propose a protocol to controlled implement the two-photon controlled phase gate within a network by using interference of polarized photons. The realization of this protocol is appealing due to the fact that the quantum state of light is robust against the decoherence, and photons are ideal carriers for transmitting quantum information over long distances. The proposed setup involves simple linear optical elements and the conventional photon detectors that only distinguish the vacuum and nonvacuum Fock number states. This can greatly simplify the experimental realization of a linear optical quantum computer.

electromagnetic field at the particl e has to be computed numerically. An example of such a computation using a program based on [49] is given in Fig. 4. But not only doe s the Mie theory describe an enhancement of the laser intensity in the particles' near field, it also predicts that for certain values of the size parameter nd/X (d denoting the particle diameter, À the laser wavelength) the enhancement should be particularly efficient, resulting in a resonant intensity enhancement, the so-called "Mie-resonances". 3.2.2. Near-field induced substrate damage When inspecting contaminated samples by scanning electron microscopy (SEM) or atomic force microscopy (AFM ) after DLC using ns laser pulses, the consequences of the field enhancement process became obvious: all over the cleaned areas w e found substrate damages localized exactly at the former particle positions [35, 37-39]. These damages manifested as melting pools or even holes in the surface, typical examples can be seen in Fig. 5. The consequences for the laser cleaning process are obvious. The intensity enhancement reduces the maximum laser fluence that can be applied in the process. Usually in laser cleaning studies [19, 31 ] the laser fluence corresponding to the melting threshold of a bare surface is taken as the damage threshold fluence. Our experiments show clearly that this is an inadequate definition. Instead one must take into account the enhanced laser fluence underneath the particles, as it will be discussed in Section 4. Fro m the obtained AFM images we were able to analyse in detail the surface profile at the damaged sites. Here we found that for high field enhancement factors the silicon substrate was not only molten , but that some material was even ablated (see Sec. 4). The momentum transfer to the particles during the ablation process significantly contributes to the cleanin g process and hence local substrate ablation

2003 ◽  
pp. 327-330
Keyword(s):  
Laser Fluence ◽  
Near Field ◽  
Particle Diameter ◽  
Surface Profile ◽  
Field Enhancement ◽  
Damage Threshold ◽  
Laser Pulses ◽  
Laser Wavelength ◽  
Laser Cleaning ◽  
Intensity Enhancement
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