Design and optimization of nano-antenna for thermal ablation of liver cancer cells

One method of cancer therapy is to utilize nano-antenna for thermal ablation.In this method,the electromagnetic waves emitted from the nano-antenna are absorbed by the tissue and lead to heating of cancer cells.If temperature of cancer cells reaches a threshold,they will begin to die.For this purpose,an L-shaped frame nano-antenna(LSFNA) is designed to introduce into the biological tissue.Thus,the radiation characteristics of the LSFNA such as near and far-field intensities,directivity,and sensitivity to its gap width are studied to the optimization of the nano-antenna.The bio-heat and Maxwell equations are solved using the finite element method.To prevent damage to healthy tissues in this method,the antenna radiation must be completely controlled and performed carefully.Thus,penetration depth,special absorption rate,temperature distribution,and the fraction of tissue necrosis are analyzed in the biological tissue.That is why the design and optimization of the nano-antennas as a radiation source is important.Also,a pulsed source is used to excite the LSFNA.Furthermore,focusing and efficiency of the nano-antenna radiation on the cancer cell is tuned using an adjustable liquid crystal lens.The focus of this lens is changing under an electric field applied to its surrounding cathode.

Design and optimization of a nano-antenna hybrid structure for solar energy harvesting application

A novel hybrid structure with high responsivity and efficiency is proposed based on an L-shaped frame nano-antenna(LSFNA)array for solar energy harvesting application.So,two types of LSFNAs are designed and optimized to enhance the harvesting characteristics of traditional simple electric dipole nano-antenna(SEDNA).The LSFNA geometrical dimensions are optimized to have the best values for the required input impedance at three resonance wavelengths ofλ_(res)=10μm,15μm,and 20μm.Then the LSFNAs with three different sizes are modeled like a planar spiral-shaped array(PSSA).Also,a fractal bowtie nano-antenna is connected with the PSSA in the array gap.This proposed hybrid structure consists of two main elements:(I)Three different sizes of the LSFNAs with two different material types are designed based on the thin-film metal-insulator-metal diodes that are a proper method for infrared energy harvesting.(Ⅱ)The PSSA gap is designed based on the electron field emission proposed by the Fowler-Nordheim theory for the array rectification.Finally,the proposed device is analyzed.The results show that the PSSA not only has an averaged 3-time enhancement in the harvesting characteristics(such as return loss,harvesting efficiency,etc.)than the previously proposed structures but also is a multi-resonance wide-band device.Furthermore,the proposed antenna takes up less space in the electronic circuit and has an easy implementation process.

Performance of a superconducting single photon detector with nano-antenna

The performance of single-photon detectors can be enhanced by using nano-antenna. The characteristics of the superconducting nano-wire single-photon detector with cavity plus anti-reflect coating and specially designed nano~ antenna is analysed. The photon collection efficiency of the detector is enhanced without damaging the detector＇s speed, thus getting rid of the dilemma of speed and efficiency. The characteristics of nano-antenna are discussed, such as the position and the effect of the active area, and the best result is given. The photon collection efficiency is increased by 92 times compared with that of existing detectors.

Extraordinary Optical Transmission through Single Sub-Wavelength Slot Nano Antennas

This paper investigates the electromagnetic transmission through the sub-wavelength slot model on a metal film for TM- and TE-polarized light. The influence of several parameters such as the slot width, the metal film thickness and the polarization of the incident field is investigated using FDTD method. The FDTD simulation’s results have shown that the sub-wavelength slot in the metal films has extraordinary optical transmission (EOT) properties for TM-polarized light. The EOT has been observed as being symmetrically punctured and characterized by the appearance of a series of transmission peaks and dips in the transmission field. By varying the slot thickness we have investigated the effect of the Fabry-Pérot like resonance in the sub wavelength slot. This component can be a key element in many applications. High-spatial-resolution imaging and information and communications technologies and sensing with high spectral and spatial precision, enhanced solar cells, efficient optical sources and detectors, disease treatment, are such examples.

Photonic-plasmonic hybrid microcavities: Physics and applications

Photonic-plasmonic hybrid microcavities,which possess a higher figure of merit Q/V(the ratio of quality factor to mode volume)than that of pure photonic microcavities or pure plasmonic nano-antennas,play key roles in enhancing light–matter interaction.In this review,we summarize the typical photonic-plasmonic hybrid microcavities,such as photonic crystal microcavities combined with plasmonic nano-antenna,whispering gallery mode microcavities combined with plasmonic nano-antenna,and Fabry–Perot microcavities with plasmonic nano-antenna.The physics and applications of each hybrid photonic-plasmonic system are illustrated.The recent developments of topological photonic crystal microcavities and topological hybrid nano-cavities are also introduced,which demonstrates that topological microcavities can provide a robust platform for the realization of nanophotonic devices.This review can bring comprehensive physical insights of the hybrid system,and reveal that the hybrid system is a good platform for realizing strong light–matter interaction.

Performance of superconducting nanowire single-photon detector with the fan coupling antenna array

The performance of superconducting nanowire single-photon detector （SNSPD） involving niobium nitride with the fan coupling antenna array is analyzed. The SNSPD has a high detection efficiency and counting rate. Hydrogen silsesquioxane and niobium nitride are filled in the gold grating deposited on the substrate in which the fan coupling antenna arrays are embedded. By changing the position of the fan coupling antenna array, the maximum area of optical intensity is obtained and the photon collection efficiency is increased by 26.5 times. The detection efficiency of SNSPD is improved without changing the detection speed. These parameters are important for designing a practical single-photon detector,

Ultra-thin, planar, Babinet-inverted plasmonic metalenses

We experimentally demonstrate the focusing of visible light with ultra-thin,planar metasurfaces made of concentrically perforated,30-nm-thick gold films.The perforated nano-voids—Babinet-inverted(complementary)nano-antennas—create discrete phase shifts and form a desired wavefront of cross-polarized,scattered light.The signal-to-noise ratio in our complementary nano-antenna design is at least one order of magnitude higher than in previous metallic nano-antenna designs.We first study our proof-of-concept‘metalens’with extremely strong focusing ability:focusing at a distance of only 2.5 mm is achieved experimentally with a 4-mm-diameter lens for light at a wavelength of 676 nm.We then extend our work with one of these‘metalenses’and achieve a wavelength-controllable focal length.Optical characterization of the lens confirms that switching the incident wavelength from 676 to 476 nm changes the focal length from 7 to 10 mm,which opens up new opportunities for tuning and spatially separating light at different wavelengths within small,micrometer-scale areas.All the proposed designs can be embedded on-chip or at the end of an optical fiber.The designs also all work for two orthogonal,linear polarizations of incident light.

Beaming light from a quantum emitter with a planar optical antenna

The efficient interaction of light with quantum emitters is crucial to most applications in nano and quantum photonics,such as sensing or quantum information processing.Effective excitation and photon extraction are particularly important for the weak signals emitted by a single atom or molecule.Recent works have introduced novel collection strategies,which demonstrate that large efficiencies can be achieved by either planar dielectric antennas combined with high numerical aperture objectives or optical nanostructures that beam emission into a narrow angular distribution.However,the first approach requires the use of elaborate collection optics,while the latter is based on accurate positioning of the quantum emitter near complex nanoscale architectures;hence,sophisticated fabrication and experimental capabilities are needed.Here we present a theoretical and experimental demonstration of a planar optical antenna that beams light emitted by a single molecule,which results in increased collection efficiency at small angles without stringent requirements on the emitter position.The proposed device exhibits broadband performance and is spectrally scalable,and it is simple to fabricate and therefore applies to a wide range of quantum emitters.Our design finds immediate application in spectroscopy,quantum optics and sensing.