Infrared band strengths for amorphous and crystalline methyl propionate, a candidate interstellar molecule

In this paper, one spin-selected vortex metalens composed of silicon nanobricks is designed and numerically investigated at the mid-infrared band, which can produce vortex beams with different topological charges and achieve different spin lights simultaneously. Another type of spin-independent vortex metalens is also designed, which can focus the vortex beams with the same topological charge at the same position for different spin lights, respectively. Both of the two vortex metalenses can achieve high-efficiency focusing for different spin lights. In addition, the spin-to-orbital angular momentum conversion through the vortex metalens is also discussed in detail. Our work facilitates the establishment of high-efficiency spin-related integrated devices, which is significant for the development of vortex optics and spin optics.

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MOCVD Grown HgCdTe Heterostructures for Medium Wave Infrared Detectors

Coatings ◽

10.3390/coatings11050611 ◽

2021 ◽

Vol 11 (5) ◽

pp. 611

Author(s):

Waldemar Gawron ◽

Jan Sobieski ◽

Tetiana Manyk ◽

Małgorzata Kopytko ◽

Paweł Madejczyk ◽

...

Keyword(s):

Buffer Layer ◽

Infrared Detectors ◽

Lattice Mismatch ◽

Layer Growth ◽

Ex Situ ◽

Current Status ◽

Organic Chemical ◽

Infrared Band ◽

Donor And Acceptor ◽

Wide Range

This paper presents the current status of medium-wave infrared (MWIR) detectors at the Military University of Technology’s Institute of Applied Physics and VIGO System S.A. The metal–organic chemical vapor deposition (MOCVD) technique is a very convenient tool for the deposition of HgCdTe epilayers, with a wide range of compositions, used for uncooled infrared detectors. Good compositional and thickness uniformity was achieved on epilayers grown on 2-in-diameter, low-cost (100) GaAs wafers. Most growth was performed on substrates, which were misoriented from (100) by between 2° and 4° in order to minimize growth defects. The large lattice mismatch between GaAs and HgCdTe required the usage of a CdTe buffer layer. The CdTe (111) B buffer layer growth was enforced by suitable nucleation procedure, based on (100) GaAs substrate annealing in a Te-rich atmosphere prior to the buffer deposition. Secondary-ion mass spectrometry (SIMS) showed that ethyl iodide (EI) and tris(dimethylamino)arsenic (TDMAAs) were stable donor and acceptor dopants, respectively. Fully doped (111) HgCdTe heterostructures were grown in order to investigate the devices’ performance in the 3–5 µm infrared band. The uniqueness of the presented technology manifests in a lack of the necessity of time-consuming and troublesome ex situ annealing.

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Asymmetric Diffraction in Plasmonic Meta-Gratings Using an IT-Shaped Nanoslit Array

Sensors ◽

10.3390/s21124097 ◽

2021 ◽

Vol 21 (12) ◽

pp. 4097

Author(s):

Hee-Dong Jeong ◽

Seong-Won Moon ◽

Seung-Yeol Lee

Keyword(s):

Plane Wave ◽

Periodic Structures ◽

Single Layer ◽

Optical Diffraction ◽

Back Side ◽

Infrared Band ◽

Effective Period ◽

Wave Nature ◽

Control Light ◽

Meta Atom

Diffraction is a fundamental phenomenon that reveals the wave nature of light. When a plane wave is transmitted or reflected from a grating or other periodic structures, diffracted light waves propagate at several angles that are specified by the period of the given structure. When the optical period is shorter than the wavelength, constructive interference of diffracted light rays from the subwavelength-scale grating forms a uniform plane wave. Many studies have shown that through the appropriate design of meta-atom geometry, metasurfaces can be used to control light properties. However, most semitransparent metasurfaces are designed to perform symmetric operation with regard to diffraction, meaning that light diffraction occurs identically for front- and back-side illumination. We propose a simple single-layer plasmonic metasurface that achieves asymmetric diffraction by optimizing the transmission phase from two types of nanoslits with I- and T-shaped structures. As the proposed structure is designed to have a different effective period for each observation side, it is either diffractive or nondiffractive depending on the direction of observation. The designed structure exhibits a diffraction angle of 54°, which can be further tuned by applying different period conditions. We expect the proposed asymmetric diffraction meta-grating to have great potential for the miniaturized optical diffraction control systems in the infrared band and compact optical diffraction filters for integrated optics.

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The Equivalent Thermal Conductivity of the Micro/Nano Scaled Periodic Cubic Frame Silver and Its Thermal Radiation Mechanism Analysis

Energies ◽

10.3390/en14144158 ◽

2021 ◽

Vol 14 (14) ◽

pp. 4158

Author(s):

Haiyan Yu ◽

Haochun Zhang ◽

Heming Wang ◽

Dong Zhang

Keyword(s):

Thermal Conductivity ◽

Thermal Radiation ◽

Cell Size ◽

Near Infrared ◽

High Porosity ◽

Mechanism Analysis ◽

Infrared Band ◽

Spectral Radiation ◽

Radiation Mechanism ◽

Equivalent Thermal Conductivity

Currently, there are few studies on the influence of microscale thermal radiation on the equivalent thermal conductivity of microscale porous metal. Therefore, this paper calculated the equivalent thermal conductivity of high-porosity periodic cubic silver frame structures with cell size from 100 nm to 100 µm by using the microscale radiation method. Then, the media radiation characteristics, absorptivity, reflectivity and transmissivity were discussed to explain the phenomenon of the radiative thermal conductivity changes. Furthermore, combined with spectral radiation properties at the different cross-sections and wavelength, the radiative transmission mechanism inside high-porosity periodic cubic frame silver structures was obtained. The results showed that the smaller the cell size, the greater radiative contribution in total equivalent thermal conductivity. Periodic cubic silver frames fluctuate more in the visible band and have better thermal radiation modulation properties in the near infrared band, which is formed by the Surface Plasmon Polariton and Magnetic Polaritons resonance jointly. This work provides design guidance for the application of this kind of periodic microporous metal in the field of thermal utilization and management.

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