scholarly journals Experimental Demonstration of the Effect of Magnetic Polaritons on the Radiative Properties of Deep Aluminum Gratings

2019 ◽  
Vol 141 (5) ◽  
Author(s):  
Peiyan Yang ◽  
Hong Ye ◽  
Zhuomin M. Zhang
Keyword(s):  
Periodic Structures ◽  
Coupling Effect ◽  
Incidence Angle ◽  
Infrared Region ◽  
Radiative Properties ◽  
Future Design ◽  
Specular Reflectance ◽  
Magnetic Polaritons ◽  
Rigorous Coupled Wave ◽  
Metal Gratings

Despite the abundant theoretical studies of magnetic polaritons (MPs) in tailoring the radiative properties of nanostructures, experimental investigation of MPs in deep metal gratings is still lacking. This work experimentally demonstrates the excitation of MP from several microfabricated aluminum gratings in the mid-infrared region by measuring the specular reflectance (zeroth-order diffraction) of the specimen using a Fourier-transform infrared (FTIR) spectrometer. The rigorous coupled-wave analysis (RCWA) and an LC-circuit model are employed to elucidate the mechanism of various resonant modes and their coupling effect. The influence of incidence angle, plane of incidence, polarization, and the trench depth on the spectral reflectance is also discussed. Moreover, the MP dispersion for off-plane layout has been investigated and demonstrated for the first time. The insight gained from this work may facilitate future design and applications of subwavelength periodic structures with desired radiative properties.

Measurement of Coherent Thermal Emission From Subwavelength Grating Structures by the Excitation of Magnetic Polaritons

2012 ◽  
Author(s):  
L. P. Wang ◽  
Z. M. Zhang
Keyword(s):  
Elevated Temperatures ◽  
Thermal Emission ◽  
Infrared Region ◽  
Radiative Properties ◽  
Scattering Rate ◽  
Rigorous Coupled Wave Analysis ◽  
Space Cooling ◽  
Dielectric Spacer ◽  
Magnetic Polaritons ◽  
Rigorous Coupled Wave

Tailoring radiative properties such as spectral control of thermal emission is beneficial in many applications such as space cooling and energy harvesting. The effect of magnetic polaritons (MPs) on spectral modulation has been analyzed previously and shown to exhibit omnidirectional behaviors when magnetic polaritons are excited in metallic grating structures with a dielectric spacer on a metallic film. The present work provides an experimental demonstration of coherent thermal emission from such a microstructure in the infrared region at both room and elevated temperatures. Samples with different patterns are fabricated to study the geometric effect on the MPs. The emittance at elevated temperatures is directly measured using a home-built emissometer, while the room-temperature emittance is indirectly obtained from the reflectance measurements. The rigorous coupled-wave analysis and the LC model are employed to elucidate the mechanisms, by incorporating the Drude model with a temperature-dependent scattering rate.

Measurement of Coherent Thermal Emission Due to Magnetic Polaritons in Subwavelength Microstructures

2013 ◽  
Vol 135 (9) ◽  
Author(s):  
L. P. Wang ◽  
Z. M. Zhang
Keyword(s):  
Room Temperature ◽  
Elevated Temperatures ◽  
Thermal Emission ◽  
Coupling Effect ◽  
Infrared Region ◽  
Reflectance Measurement ◽  
Scattering Rate ◽  
Lc Circuit ◽  
Magnetic Polaritons ◽  
Rigorous Coupled Wave

Spectral and directional control of thermal emission is critically important for applications such as space cooling and energy harvesting. The effect of magnetic polaritons (MPs) on spectral modulation has been analyzed in metallic grating structures with a dielectric spacer on a metallic film. It has been predicted that the spectral emission peaks exhibit omnidirectional characteristics when MPs are excited. The present work provides an experimental demonstration of coherent thermal emission from several microfabricated grating structures in the infrared region from room temperature to elevated temperatures. The emittance at elevated temperatures is directly measured using an emissometer, while the room-temperature emittance is indirectly obtained from the reflectance measurement. The rigorous coupled-wave analysis and an LC-circuit model are employed to elucidate the mechanisms of various resonant modes and their coupling effect, taking into consideration the temperature-dependent electron scattering rate of the metals.

Radiative Properties of Pattered Wafers With Linewidth Below 100 nm

2005 ◽  
Author(s):  
Y.-B. Chen ◽  
Z. M. Zhang ◽  
P. J. Timans
Keyword(s):  
Periodic Structures ◽  
Numerical Study ◽  
Radiative Properties ◽  
Angle Of Incidence ◽  
Patterned Wafers ◽  
Rigorous Coupled Wave Analysis ◽  
Recent Developments ◽  
Effective Medium Approach ◽  
Rigorous Coupled Wave ◽  
Very High

Temperature nonuniformity is a critical problem in rapid thermal processing (RTP) of wafers because it leads to uneven diffusion of implanted dopants and introduces thermal stress that can produce defects. One cause of the problem is nonuniform absorption of thermal radiation, especially in patterned wafers, where the optical properties vary across the surface of the wafer. Recent developments in RTP have lead to the use of millisecond-duration heating cycles, where light with very high power density is used to heat the surface of the wafer. Pattern effects are especially important here, because there is very little time for thermal diffusion to even out temperature distributions during the heating cycle. There have been very few studies on the radiative properties of patterned wafers, especially for the structures expected to be used on advanced semiconductor devices. The feature size is already below 100 nm and is comparable or smaller than the wavelengths of radiation (200–1000 nm) emitted by the flash-lamps typically used for millisecond processing. Hence, this work is devoted to a parametric numerical study of the radiative properties of patterned wafers with the smallest dimension down to 30 nm. The effects of wavelength, wave polarization, and angle of incidence on selected periodically patterned wafers are presented. The methods include the rigorous coupled wave analysis (RCWA) and the effective medium approach (EMA). RCWA is used to obtain exact solutions of Maxwell’s equations, and EMA is used to approximate the periodic structures as a planar multilayer structure with an effective dielectric function. This study provides an assessment of the applicability of EMA for simulations of radiative properties of patterned wafers.

Indirect Measurements of Coherent Thermal Emission From a Truncated Photonic Crystal Structure

2007 ◽  
Author(s):  
B. J. Lee ◽  
Y. -B. Chen ◽  
Z. M. Zhang
Keyword(s):  
Photonic Crystal ◽  
Near Infrared ◽  
Thermal Emission ◽  
Incidence Angle ◽  
Stop Band ◽  
Spatial Coherence ◽  
Infrared Region ◽  
Silver Layer ◽  
Specular Reflectance ◽  
Infrared Spectrometer

Recently, coherent thermal emission characteristics have been demonstrated for both polarizations from a multilayer structure consisting of a one-dimensional (1D) photonic crystal (PC) coated on a silver layer, i.e., PC-on-Ag structure. The key to enabling coherent emission is to excite a surface wave at the PC-Ag interface in the stop band of the PC. A detailed experimental investigation is conducted to demonstrate coherent thermal emission in the near-infrared region from the fabricated PC-on-Ag structure. A Fourier-transform infrared spectrometer, together with a specular reflectance accessory and a polarizer, is used to measure the reflectance at incidence angles of 30° and 45°. In addition, an angle-resolved scatterometer is used to measure the reflectance at the wavelength of 891 nm. Measured reflectance shows very good temporal and spatial coherence. Furthermore, the magnitude of the evanescent waves at the PC-Ag interface is plotted in terms of the wavelength and the incidence angle. It is found that dip locations of the measured reflectance precisely match with the condition when the field intensity is largely enhanced.

scholarly journals Design and Fabrication of Moth-Eye Subwavelength Structure with a Waist on Silicon for Broadband and Wide-Angle Anti-Reflection Property

Coatings ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 360 ◽  
Author(s):  
He Lin ◽  
Mingzhao Ouyang ◽  
Bingxu Chen ◽  
Qifan Zhu ◽  
Jinshuang Wu ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Incidence Angle ◽  
Structural Parameters ◽  
Diffraction Order ◽  
Wide Angle ◽  
Subwavelength Structure ◽  
Inductively Coupled ◽  
Beam Laser ◽  
Interferometric Lithography ◽  
Rigorous Coupled Wave

Reflection loss on the optical component surface is detrimental to performance. Several researchers have discovered that the eyes of moths are covered with micro- and nanostructured films that reduce broadband and wide-angle light reflection. This research proposes a new type of moth-eye subwavelength structure with a waist, which is equivalent to a gradient refractive index film layer with high–low–high hyperbolic-type fill factor distribution. The diffraction order characteristics of a moth-eye subwavelength structure are first analyzed using a rigorous coupled wave analysis. The moth-eye structural parameters are optimized within the spectral range of 2–5 μm using the finite-difference time-domain method. The experimental fabrication of the moth-eye structure with a waist array upon a silicon substrate is demonstrated by using three-beam laser interferometric lithography and an inductively coupled plasma process. The experimental and simulation results show good agreement. The experimental results show that the reflectivity of the moth-eye structure with a waist is less than 1.3% when the incidence angle is less than 30°, and less than 4% when the incidence angle is less than 60°. This research can guide the development of AR broadband optical components and wide-angle applications.

scholarly journals Dual broadband infrared absorptance enhanced by magnetic polaritons using graphene-covered compound metal gratings

2019 ◽  
Vol 27 (21) ◽  
pp. 30182 ◽  
Author(s):  
Nghia Nguyen-Huu ◽  
Jaromir Pistora ◽  
Michael Cada
Keyword(s):  
Magnetic Polaritons ◽  
Metal Gratings

Calculation of Spectral Optical Constants Using Combined Ellipsometric and Reflectance Methods for Smooth and Rough Bulk Samples

2021 ◽  
pp. 000370282110478
Author(s):  
Gilles Fortin
Keyword(s):  
Rough Surface ◽  
Optical Constants ◽  
Sample Surface ◽  
Infrared Region ◽  
Homogeneous Sample ◽  
Specular Reflectance ◽  
Scattering Effects ◽  
Spectral Ranges ◽  
Reflectance Measurements ◽  
Polarized Reflectance

Spectra of the optical constants n and k of a substance are often deduced from spectroscopic measurements, performed on a thick and homogeneous sample, and from a model used to simulate these measurements. Spectra obtained for n and k using the ellipsometric method generally produce polarized reflectance simulations in strong agreement with the experimental measurements, but they sometimes introduce significant discrepancies over limited spectral ranges, whereas spectra of n and k obtained with the single-angle reflectance method require a perfectly smooth sample surface to be viable. This paper presents an alternative method to calculate n and k. The method exploits both ellipsometric measurements and s-polarized specular reflectance measurements, and compensates for potential surface scattering effects with the introduction of a specularity factor. It is applicable to bulk samples having either a smooth or a rough surface. It provides spectral optical constants that are consistent with s-polarized reflectance measurements. Demonstrations are performed in the infrared region using a glass slide (smooth surface) and a pellet of compressed ammonium sulfate powder (rough surface).

scholarly journals Phonon-mediated magnetic polaritons
in the infrared region

2011 ◽  
Vol 19 (S2) ◽  
pp. A126 ◽  
Author(s):  
L. P. Wang ◽  
Z. M. Zhang
Keyword(s):  
Infrared Region ◽  
Magnetic Polaritons

s- and p-Polarized Infrared Specular Reflectance of Vitreous Silica at Oblique Incidences: Detection of LO Modes

2000 ◽  
Vol 54 (4) ◽  
pp. 502-507 ◽  
Author(s):  
B. C. Trasferetti ◽  
C. U. Davanzo
Keyword(s):  
High Frequency ◽  
Incidence Angle ◽  
Polarized Light ◽  
Blue Shift ◽  
Refraction Index ◽  
Vitreous Silica ◽  
Reflectance Spectra ◽  
Specular Reflectance ◽  
Longitudinal Optic ◽  
Asymmetrical Mode

Infrared (IR) specular reflectance spectra of a semi-infinite sample of vitreous silica (v-SiO2) were obtained with the use of both s- and p-polarized light and oblique incidence angles. The optical constants of the material and hence its longitudinal optic/transverse optic (LO-TO) functions were determined through the Kramers–Krönig analysis (KKA) of its s-polarized 20° off-normal reflectance spectrum. p-Polarized spectra had their reflection maxima blue-shifting as the incidence angle increased, while they remained unchanged for the s-polarized spectra. Since an LO mode generally lies at wavenumbers higher than its respective TO mode, such a blue shift may be due to the detection of the LO mode in addition to the TO mode as incidence angle increased. The only exception to this observation was the high-frequency shoulder, which underwent a sharp intensification as the incidence increased. The present work shows that it is indeed brought about by the weakly IR active asymmetrical mode (AS2) but only because it takes place immediately after the intense AS1 mode, which causes the refraction index spectrum to have a broad dip below unity. Such a dip is proven to be responsible for the sharp increase in the high-frequency shoulder of the reflectance spectra.

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