Stack-based grating for wideband polarization splitter in terahertz

2021 ◽  
Author(s):  
Zefan Lin ◽  
Bo Wang ◽  
Chen Fu
Keyword(s):  
Communication Systems ◽  
Simulated Annealing Algorithm ◽  
High Efficiency ◽  
Incident Angle ◽  
Reference Value ◽  
Transverse Magnetic ◽  
Large Bandwidth ◽  
Rigorous Coupled Wave Analysis ◽  
Terahertz Band ◽  
Rigorous Coupled Wave

Abstract A novel wideband terahertz polarization beam splitter with special diffraction orders working at terahertz band is described in this paper. The polarizer can achieve high diffraction efficiency and uniformity in the 2.50 - 2.56 THz band. Based on rigorous coupled-wave analysis (RCWA) and simulated annealing algorithm, we proposed an efficient algorithm to optimize the polarizer. After calculations, 98.45% single-port high-efficiency reflection for transverse electric (TE) polarization and 42.33%/42.57% highly uniform dual-port beam splitting for transverse magnetic (TM) polarization were finally obtained. In addition, through RCWA and simplified modal method, the electromagnetic field distributions of TE and TM polarizations are shown visually and described quantitatively. Moreover, the results displayed in Sec. 3 prove that the grating possesses the characteristics of relatively large bandwidth and insensitivity to the incident angle. Therefore, the novel scheme in this paper has great reference value for the research of terahertz modulation devices and the integration of terahertz communication systems.

Reflective three-port high-efficiency grating with two dielectric layers based on a sandwiched configuration

2016 ◽  
Vol 30 (12) ◽  
pp. 1650072 ◽  
Author(s):  
Hongtao Li ◽  
Bo Wang ◽  
Hao Pei ◽  
Wenhao Shu ◽  
Li Chen ◽  
...  
Keyword(s):  
High Efficiency ◽  
Transverse Electric ◽  
Transverse Magnetic ◽  
Wave Analysis ◽  
Beam Splitting ◽  
Practical Applications ◽  
Rigorous Coupled Wave Analysis ◽  
Dielectric Layers ◽  
Rigorous Coupled Wave ◽  
Sandwiched Structure

In this paper, we describe a novel reflective sandwiched three-port grating with two dielectric layers. The two-layer sandwiched grating can separate incident wave into the [Formula: see text] and the 0th-order with high-efficiency beam splitting and good splitting ratios for both transverse electric (TE) and transverse magnetic (TM) polarizations. The grating parameters can be optimized by using rigorous coupled-wave analysis (RCWA) with a special duty cycle of 0.6. With the optimized results, efficiencies more than 32% in the [Formula: see text]st-orders and the 0th-order can be obtained. Furthermore, performance of the incident bandwidth and aspect ratio can be improved. Compared with conventional surface-relief grating, the grating with sandwiched structure is aimed at cleaning and protecting grating surface. The presented reflective two-layer sandwiched three-port grating would be put into practical applications for its beneficial performances.

Spectral Features of an Omnidirectional Narrowband Emitter

2012 ◽  
Vol 134 (10) ◽  
Author(s):  
Yutao Zhang ◽  
Yimin Xuan
Keyword(s):  
Incident Angle ◽  
Structural Parameters ◽  
Infrared Region ◽  
Transverse Magnetic ◽  
Silver Layer ◽  
Spectral Features ◽  
Structured Surface ◽  
Rigorous Coupled Wave Analysis ◽  
Spectral Emittance ◽  
Rigorous Coupled Wave

A microscale-structured surface consisting of heavily doped silicon rectangle grating and slotted silver layer is studied for omnidirectional narrowband emitter. Numerical simulation is implemented to obtain spectral emittance in mid-infrared region (6–16 μm) for the transverse magnetic incidence by using the rigorous coupled-wave analysis (RCWA) method. The effects of structural parameters and incident angle on its spectral emittance are investigated. In virtue of the microcavity effect, an omnidirectional narrowband emitter is proposed. By selecting a group of structural parameters, its peak emittance reaches as high as 0.998, and the peak width Δλ/λ of the emittance peak is as narrow as 0.03 at the specified wavelength. The results reveal that our proposed structured surface has the nice spectral features of angular uniformity and wavelength-selective characteristic, which can be applied to design novel narrowband thermal emitters and detectors in the infrared region.

scholarly journals Extraordinary Optical Transmission by Hybrid Phonon–Plasmon Polaritons Using hBN Embedded in Plasmonic Nanoslits

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1567
Author(s):  
Shinpei Ogawa ◽  
Shoichiro Fukushima ◽  
Masaaki Shimatani
Keyword(s):  
Optical Transmission ◽  
Hexagonal Boron Nitride ◽  
Incident Angle ◽  
Optical Filters ◽  
Extraordinary Optical Transmission ◽  
Light Manipulation ◽  
Rigorous Coupled Wave Analysis ◽  
Fabry Perot ◽  
Hyperbolic Dispersion ◽  
Rigorous Coupled Wave

Hexagonal boron nitride (hBN) exhibits natural hyperbolic dispersion in the infrared (IR) wavelength spectrum. In particular, the hybridization of its hyperbolic phonon polaritons (HPPs) and surface plasmon resonances (SPRs) induced by metallic nanostructures is expected to serve as a new platform for novel light manipulation. In this study, the transmission properties of embedded hBN in metallic one-dimensional (1D) nanoslits were theoretically investigated using a rigorous coupled wave analysis method. Extraordinary optical transmission (EOT) was observed in the type-II Reststrahlen band, which was attributed to the hybridization of HPPs in hBN and SPRs in 1D nanoslits. The calculated electric field distributions indicated that the unique Fabry–Pérot-like resonance was induced by the hybridization of HPPs and SPRs in an embedded hBN cavity. The trajectory of the confined light was a zigzag owing to the hyperbolicity of hBN, and its resonance number depended primarily on the aspect ratio of the 1D nanoslit. Such an EOT is also independent of the slit width and incident angle of light. These findings can not only assist in the development of improved strategies for the extreme confinement of IR light but may also be applied to ultrathin optical filters, advanced photodetectors, and optical devices.

Research on reflective three-output by packaged grating under second Bragg angle

2019 ◽  
Vol 33 (25) ◽  
pp. 1950305 ◽  
Author(s):  
Wenhua Zhu ◽  
Bo Wang ◽  
Chenhao Gao ◽  
Kunhua Wen ◽  
Ziming Meng ◽  
...  
Keyword(s):  
High Efficiency ◽  
Incident Light ◽  
Polarized Light ◽  
Bragg Angle ◽  
Duty Ratio ◽  
Wave Analysis ◽  
Incident Wavelength ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
The Given

This paper designed a novel three-output reflective packaged grating. The optimized parameters such as the period and depth of the high-efficiency three-output grating with an incident wavelength of 1550 nm can be calculated by rigorous coupled-wave analysis (RCWA). According to the optimized result, the grating can diffract the incident light energy into three orders with an efficiency of nearly 33% under the premise of second Bragg angle incidence and the given duty ratio of 0.5. The diffraction efficiency of the packaged grating is improved compared to the surface-relief three-output grating under second Bragg angle incidence, especially for TE-polarized light.

SURFACE-COVERED 1×3 GRATING WITH DIELECTRIC-METAL SLABS UNDER SECOND BRAGG INCIDENCE

2020 ◽  
Vol 27 (09) ◽  
pp. 1950201
Author(s):  
CHEN FU ◽  
BO WANG ◽  
WENHUA ZHU ◽  
KUNHUA WEN ◽  
ZIMING MENG ◽  
...  
Keyword(s):  
Incident Light ◽  
Polarized Light ◽  
Transverse Magnetic ◽  
Second Order ◽  
Bragg Angle ◽  
Efficiency Ratio ◽  
First Order ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
The Given

This paper designed a novel three-port reflective surface-covered grating with a connecting layer. The grating can be used as a splitter, and the polarized light can be divided into zero order, first order and second order. Through rigorous coupled-wave analysis, the efficiency of the three orders of diffraction light is close to 33% under the condition that the incident light at 1550 nm is incident at the second Bragg angle and the given duty cycle is 0.5. The efficiency and bandwidth of the surface-covered grating are improved compared with that of the surface-relief grating reported in the past. Especially for transverse magnetic polarized light, the beam splitting effect is more uniform, the efficiency ratio of the zeroth order to first order can reach 1.01, and the efficiency ratio of the first order to second order can reach 1.

Encapsulated grating for three-port beam splitter in reflection

2016 ◽  
Vol 30 (06) ◽  
pp. 1650070 ◽  
Author(s):  
Wenhao Shu ◽  
Bo Wang ◽  
Hongtao Li ◽  
Liang Lei ◽  
Li Chen ◽  
...  
Keyword(s):  
Beam Splitter ◽  
High Efficiency ◽  
Normal Incidence ◽  
Grating Period ◽  
Practical Application ◽  
Wave Analysis ◽  
Incident Wavelength ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
Independent Property

An encapsulated grating with a metal slab is designed as a reflection three-port beam splitter at the wavelength of 1550 nm under normal incidence. Such a new grating is aimed to separate energies into the ±1st and the 0th orders for both TE and TM polarizations. The grating parameters such as grating period, duty cycle and grating depth are optimized by using rigorous coupled-wave analysis. Based on optimized grating parameters, efficiencies can reach more than 32% with the polarization-independent property. It indicates that reflection three-port beam splitter with high efficiency can be obtained by the encapsulated grating. Moreover, the presented reflection three-port grating has advantages of wide incident wavelength range and angular bandwidth, which would be useful in practical application.

Impacts of Nanoscale Features on Infrared Radiative Properties of Metallic Slit Arrays

2009 ◽  
Author(s):  
Y.-B. Chen ◽  
J.-S. Chen ◽  
P.-F. Hsu
Keyword(s):  
Transverse Magnetic ◽  
Radiative Properties ◽  
Cavity Resonance ◽  
Resonance Excitation ◽  
Angle Of Incidence ◽  
Resonance Modes ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
Nanoscale Features ◽  
Poynting Vectors

Radiative properties (absorptance, reflectance, and transmittance) of deep slits with five nanoscale slit profile variations at the transverse magnetic wave incidence are numerically investigated in this work by employing the rigorous coupled-wave analysis. For slits with attached features, their radiative properties can be much different due to the modified cavity geometry and dangled structures, even at wavelengths between 3 and 15 μm. The shifts of cavity resonance excitation result in higher transmittance through narrower slits at specific wavelengths and resonance modes are confirmed with the electromagnetic fields. Opposite roles possibly played by features in increasing or decreasing absorptance are determined by the feature position and demonstrated by Poynting vectors. Correlations among all properties of a representative slit array, the angle of incidence, and the slit density are also comprehensively studied.

Dual-function splitting of the embedded grating with connecting layer

2019 ◽  
Vol 33 (11) ◽  
pp. 1850129
Author(s):  
Wenhua Zhu ◽  
Bo Wang ◽  
Chenhao Gao ◽  
Kunhua Wen ◽  
Ziming Meng ◽  
...  
Keyword(s):  
Transverse Electric ◽  
Groove Depth ◽  
Transverse Magnetic ◽  
Dual Function ◽  
First Order ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
Plane Light ◽  
High Diffraction ◽  
Modal Method

We design and optimize the embedded dual-function grating with connecting layer in Littrow mounting. By using modal method and rigorous coupled-wave analysis, grating parameters are analyzed and calculated including grating groove depth, thickness of connecting layer, and so on. The grating device can diffract the transverse electric-polarized plane light mainly in the first-diffractive order with high-diffraction efficiency of 98.36%. Meanwhile, for the transverse magnetic-polarized plane light, the diffraction efficiencies in the zeroth-order and the first-order corresponding to 49.34% and 49.29% are obtained, respectively.

Study of the Absorptance of Si-gratings and of arrays of SiO2-filled trenches on Si-grating substrate

2016 ◽  
Vol 12 (2) ◽  
pp. 4278-4290
Author(s):  
Faouzi Ghmari ◽  
Ilhem Mezni
Keyword(s):  
Transverse Electric ◽  
Transverse Magnetic ◽  
Radiative Properties ◽  
Geometrical Parameters ◽  
Perfect Absorber ◽  
Angle Of Incidence ◽  
Patterned Wafers ◽  
Rigorous Coupled Wave Analysis ◽  
Rigorous Coupled Wave ◽  
Model Structures

The purpose of this paper is to study the radiative properties of two model structures. The first model (A-1) is a rectangular grating of silicon (Si). The second one (A-2) is obtained from A-1 by filling their trenches by SiO2. These patterned wafers are characterized by three geometrical parameters, the period d, the filling factorand the thickness h. To derive and compute the radiative properties we use a rigorous coupled wave analysis (RCWA) method. Our attention is focused on the absorptance of these structures when they are illuminated by a monochromatic plane wave. We investigate the effect of the filling factor on the absorptance versus the direction of the incident wave. At specific angles of incidence the effect of the period is also studied. Besides, the influence of the thickness h on the absorptance is included throughout this work. At the wavelength = 632,8nm, we especially show that we can identify several perfect absorber model structures characterized by specific parameters and by accurate angle of incidence. We show that this will be done in both transverse electric (TE) and transverse magnetic (TM) polarization cases.

Optical Properties of Thin Crystalline Silicon Nanostructures for Photovoltaic Applications

2013 ◽  
Author(s):  
Xing Fang ◽  
Changying Zhao ◽  
Hua Bao
Keyword(s):  
Lattice Constant ◽  
Crystalline Silicon ◽  
Incident Angle ◽  
Nanowire Arrays ◽  
Raw Material ◽  
Silicon Nanostructures ◽  
Rigorous Coupled Wave Analysis ◽  
Nanohole Arrays ◽  
Rigorous Coupled Wave ◽  
Ultimate Efficiency

The optical performance of four lattice crystalline silicon nanostructures, i.e., cylinder nanowire arrays, cylinder nanohole arrays, square nanowire arrays and square nanohole arrays is numerically investigated in this paper. The method of rigorous coupled-wave analysis (RCWA), an efficient and accurate computational tool, is used to calculate the optical absorption for the lattice constant from 100 nm to 1500 nm. The results indicate that the lattice constant is the foremost structure parameter to determine the ultimate efficiency, and the ultimate efficiencies are reached at the lattice constant around 600 nm. The optimal filling ratio of square nanowire arrays is the lowest among the four nonostructures, whereas the cylinder nanohole arrays exhibit a broad range of optimal filling ratios. Lower optimal filling ratios implies that the nanostructures cost less raw material while maintain the high ultimate efficiencies. The high ultimate efficiency of all structures can be achieved over a large range of incident angles, even the efficiency will slowly decrease as the incident angle increases.

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