Browsing by Author "Osgouei, Ataollah Kalantari"
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Item Open Access Correction to: Active tuning from narrowband to broadband absorbers using a sub-wavelength VO2 embedded layer(Springer, 2021-02-04) Osgouei, Ataollah Kalantari; Hajian, Hodjat; Khalichi, Bahram; Serebryannikov, Andriy E.; Ghobadi, Amir; Özbay, EkmelMetamaterial perfect absorbers (MPAs) with dynamic thermal tuning features are able to control the absorption performance of the resonances, providing diverse applications spanning from optical switches and filters to modulators. In this paper, we propose an MPA with diverse functionalities enabled by vanadium dioxide (VO2) embedded in a metal-dielectric plasmonic structure. For the initial design purpose, a silicon (Si) nanograting on a silver (Ag) mirror is proposed to have multiple resonant responses in the near infrared (NIR) region. Then, the insertion of a thin VO2 layer at the right position enables the design to act as an on/off switch and resonance tuner. In the insulator phase of VO2, in which the permittivity data of VO2 is similar to that of Si, a double strong resonant behavior is achieved within the NIR region. By increasing the temperature, the state of VO2 transforms from insulator to metallic so that the absorption bands turn into three distinct resonant peaks with close spectral positions. Upon this transformation, a new resonance emerges and the existing resonance features experience blue/red shifts in the spectral domain. The superposition of these peaks makes the overall absorption bandwidth broad. Although Si has a small thermo-optic coefficient, owing to strong light confinement in the ultrasmall gaps, a substantial tuning can be achieved within the Si nanogratings. Therefore, the proposed hybrid design can provide multi-resonance tunable features to cover a broad range and can be a promising strategy for the design of linearly thermal-tunable and broadband MPAs. Owing to the proposed double tuning feature, the resonance wavelengths exhibits great sensitivity to temperature, covering a broad wavelength range. Overall, the proposed design strategy demonstrates diverse functionalities enabled by the integration of a thin VO2 layer with plasmonic absorbers.Item Open Access Diode like high-contrast asymmetric transmission of linearly polarized waves based on plasmon-tunneling effect coupling to electromagnetic radiation modes(Institute of Physics Publishing Ltd., 2021-06-25) Khalichi, Bahram; Ghobadi, Amir; Osgouei, Ataollah Kalantari; Özbay, EkmelWe present a narrow-band optical diode with a high-contrast forward-to-backward ratio at the near-infrared region. The design has a forward transmission of approximately $88\% $, and a backward one of less than $3\% $, yielding a contrast ratio of greater than $14.5\,$ dB at a wavelength of $1550\,$ nm. The structure is composed of a one-dimensional diffraction grating on top of a dielectric slab waveguide, both of which are made of silicon nitride (Si3N4), and all together are placed over a silver (Ag) thin film embedded on a dielectric substrate. Utilizing a dielectric-based diffraction grating waveguide on a thin silver layer leads to the simultaneous excitation of two surface plasmon modes known as long- and short-range surface plasmon polaritons (SPPs) at both interfaces of the metallic layer. The plasmon-tunneling effect, which is the result of the coupling of SPPs excited at the upper interface of the metallic layer to the radiation modes, provides a high asymmetric transmission (AT) property. The spectral response of the proposed high-contrast AT device is verified using both rigorous coupled-wave analysis as an analytical approach and finite difference time domain as a numerical one.Item Open Access Highly one-way electromagnetic wave transmission based on outcoupling of surface plasmon polaritons to radiation modes(Institute of Electrical and Electronics Engineers, 2022-09-21) Khalichi, Bahram; Omam, Zahra Rahimian; Osgouei, Ataollah Kalantari; Ghobadi, Amir; Özbay, EkmelUnidirectional transmission of electromagnetic waves has attracted great interest due to its wide modern optical applications. This study theoretically demonstrates a one-way transmissive optical device with a high-contrast forward-to-backward ratio at the near-infrared region. The polarization-independent optical diode-like mechanism is designed using a metasurface diffraction grating configuration with symmetry breaking property along the wave propagation in which the working principle is based on the excitation of surface plasmon modes at the interfaces of thin metallic interlayer and their coupling to the radiation modes.Item Open Access Hybrid indium tin oxide-Au metamaterial as a multiband bi-functional light absorber in the visible and near-infrared ranges(2021-04-23) Osgouei, Ataollah Kalantari; Hajian, Hodjat; Serebryannikov, Andriy E.; Özbay, EkmelMetamaterial nearly perfect light absorbers (MPAs) with dual-narrowband functionality—that absorb light in two narrowband adjacent wavelength regions—have attracted considerable attention due to their intriguing applications, such as sensing, photovoltaic, and thermal emission. Here, we propose a multi-band MPA with two narrowband absorption responses that are centered on the visible and near-infrared (NIR) wavelengths (773 nm and 900 nm, respectively) and a broadband absorptive characteristic in another window in the NIR region (ranging from 1530 nm to 2700 nm with a bandwidth of 1170 nm). The MPA comprises a periodic array of self-aligned hybrid indium tin oxide (ITO)-Au split-ring-resonators that are separated from an optically thick bottom reflector with a SiO2 layer. Based on numerical calculations, which are accompanied with a semi-analytical examination, we find that the dual narrowband and broadband responses are attributed to the hybridization of the optical responses of gold as a plasmonic material with the ones of ITO. Note that ITO acts as a low-loss dielectric in the visible range and a lossy plasmonic material in the NIR region. Moreover, due to the applied symmetry in the unit cell of the metamaterial, the proposed MPA represents polarization insensitive and omnidirectional absorptive features. The proposed metastructure can find potential applications in selective thermophotovoltaic devices, thermal emitters, and sensors.Item Open Access Multi-band light-matter interaction in hBN-based metasurface absorber(Institute of Electrical and Electronics Engineers, 2022-09-28) Omam, Zahra Rahimian; Khalichi, Bahram; Osgouei, Ataollah Kalantari; Ghobadi, Amir; Özbay, EkmelThis paper presents a multi-band metamaterial-based absorber using phononic two-dimensional (2D) material. The structure consists of a top hexagonal boron nitride (hBN) layer on an aluminum nanograting structure deposited on a dielectric slab waveguide and a thick metallic reflector forming an MIM (metal-insulator-metal) configuration. The proposed absorber exhibits a hyperbolic phonon polariton (HPPs) in hBN, surface plasmon (SP) modes in the spacer (ZnTe: zinc telluride), and Fabry-Perot resonances in the MIM configuration, resulting in five sharp, high absorption peaks in the mid-infrared (MIR) spectral range. The proposed multi-band absorber can be utilized in various applications, ranging from optical detection devices to multispectral thermoelectric volt.Item Open Access Plasmonic metamaterial based structures for designing of multiband and thermally tunable light absorbers, multiple thermal infrared emitter, and high-contrast asymmetric transmission optical diode(2021-07) Osgouei, Ataollah KalantariMetamaterials with sub-wavelength nanostructures refer to a class of synthetic materials that possess exotic electromagnetic properties which cannot be observed with natural materials. Negative refractive index, asymmetric light transmission, invisible cloaking, and lasing are examples of these attributes. Among these possible applications, the concept of light confinement and harvesting by subwavelength structures have attracted considerable attention due to their widespread applications ranging from thermal emission, optical modulator, sensing, and photodetectors. Here, we propose and design plasmonic metamaterials with subwavelength structures in four different application areas, namely 1) Hybrid indium tin oxide-Au metamaterial absorber in the visible and near-infrared ranges for selective thermal emissions and sensors. 2) Active tuning from narrowband to broadband absorbers using a sub-wavelength VO2 for optical modulator. 3) A spectrally selective nanoantenna emitter compatible with multiple thermal infrared applications. 4) Diode like high-contrast asymmetric transmission of linearly polarized waves. In the first work, we propose a multi-band Metamaterial Perfect absorber (MPA) with two narrowband absorption responses that are centered on the visible and near-infrared (NIR) wavelengths [773 and 900 , respectively] and a broadband absorptive characteristic in another window in the NIR region [ranging from 1,530 to 2,700 with a bandwidth of 1,170 ]. The MPA comprises a periodic array of self-aligned hybrid indium tin oxide (ITO)-Au split-ring-resonators that are separated from an optically thick bottom reflector with a SiO2 layer. Based on numerical calculations, which are accompanied with a semi-analytical examination, we find that the dual narrowband and broadband responses are attributed to the hybridization of the optical responses of gold as a plasmonic material with the ones of ITO. Note that ITO acts as a low-loss dielectric in the visible range and a lossy plasmonic material in the NIR region. Moreover, due to the applied symmetry in the unit cell of the metamaterial, the proposed MPA represents polarization insensitive and omnidirectional absorptive features. The proposed metastructure can find potential applications in selective thermophotovoltaic devices, thermal emitters, and sensors. In the second work, we propose an MPA with diverse functionalities enabled by vanadium dioxide (VO2) embedded in a metal-dielectric plasmonic structure. For the initial design purpose, a Silicon (Si) nanograting on a Silver (Ag) mirror is proposed to have multiple resonant responses in the near infrared (NIR) region. Then, the insertion of a thin VO2 layer at the right position enables the design to act as an on/off switch and resonance tuner. In the insulator phase of VO2, in which the permittivity data of VO2 is similar to that of Si, a double strong resonant behavior is achieved within the NIR region. By increasing the temperature, the state of VO2 transforms from insulator to metallic so that the absorption bands turn into three distinct resonant peaks with close spectral positions. Upon this transformation, a new resonance emerges and the existing resonance features experience blue/red shifts in the spectral domain. The superposition of these peaks makes the overall absorption bandwidth broad. Although Si has a small thermo-optic coefficient, owing to strong light confinement in the ultrasmall gaps, a substantial tuning can be achieved within the Si nanogratings. Therefore, the proposed hybrid design can provide multi-resonance tunable features to cover a broad range and can be a promising strategy for the design of linearly thermal-tunable and broadband MPAs. Owing to the proposed double tuning feature, the resonance wavelengths exhibits great sensitivity to temperature, covering a broad wavelength range. Overall, the proposed design strategy demonstrates diverse functionalities enabled by the integration of a thin VO2 layer with plasmonic absorbers. In the third work, we design a wavelength-selective nanoantenna emitter based on the excitation of gap-surface plasmon modes using a metal–insulator–metal configuration (silicon dioxide (SiO2) sandwiched between silver (Ag) layers) for satisfying multiple infrared applications. The proposed design, which is called design I, realizes triple narrowband perfect absorptions at the resonance wavelengths of 1524 nm, 2279 nm, and 6000 nm, which perfectly match the atmospheric absorption bands while maintaining relatively low emissivity in the atmospheric transparency windows of 3 − 5 m and 8 − 12 m. Later, the functionality of design I is extended, which is called design II, to include a broadband absorption at the near-infrared region to minimize the solar irradiation reflection from the nanoantenna emitter. Finally, single- and three-layer graphene are introduced to provide a real-time tuning of the infrared signature of the proposed nanoantenna emitter (design II). It is also demonstrated that the three-layer graphene structure can suppress an undesired absorption resonance wavelength related to the intrinsic vibrational modes (optical phonons) of the SiO2 layer by 53.19% compared to 25.53% for the single-layer one. The spectral analysis of design I is validated using both analytical and numerical approaches where the numerical simulation domain is extended for the analysis of design II. The thermal characteristic analyses of design I and design II (without/with graphene layers) reveal that infrared signatures of the blackbody radiation are significantly reduced for the whole wavelength spectrum at least by 96% and 91% within a wide temperature ranging from room temperature to 500 , respectively. In the fourth and final work, we present a narrow-band optical diode with a high-contrast forward-to-backward ratio at the near-infrared (NIR) region. The design has a forward transmission of approximately 88%, and a backward one of less than 3%, yielding a contrast ratio of greater than 14.5 dB at a wavelength of 1550 nm. The structure is composed of a one-dimensional diffraction grating on top of a dielectric slab waveguide, both of which are made of silicon nitride (Si3N4), and all together are placed over a silver (Ag) thin film embedded on a dielectric substrate. Utilizing a dielectric-based diffraction grating waveguide on a thin silver layer leads to the simultaneous excitation of two surface plasmon modes known as long- and short-range surface plasmon polaritons (SPPs) at both interfaces of the metallic layer. The plasmon-tunneling effect, which is the result of the coupling of SPPs excited at the upper interface of the metallic layer to the radiation modes, provides a high asymmetric transmission (AT) property. The spectral response of the proposed high-contrast AT device is verified using both rigorous coupled-wave analysis as an analytical approach and finite difference time domain as a numerical one.Item Open Access Polarization insensitive phase change material-based nanoantenna array for thermally tunable infrared applications(Institute of Electrical and Electronics Engineers, 2022-09-21) Khalichi, Bahram; Omam, Zahra Rahimian; Osgouei, Ataollah Kalantari; Ghobadi, Amir; Özbay, EkmelThermal radiation management is an emerging application of metamaterials owing to their exotic electromagnetic radiative properties. Herein, a thermally tunable phase change material-based nanoantenna array is reported to manipulate electromagnetic waves for potential applications in radiative cooling and multispectral camouflage from thermal infrared detectors. The simulation results show that the proposed nanoantenna array possesses high reflectance exceeding at least 60% within the 3−5 µm and 8−12 µm wavelength ranges, indicating low thermal emissivity, while the reflectance value increases as the temperature rises. Additionally, the wavelength-selective nanoantenna emitter operates with high absorption and therefore emission within the non-atmospheric window (5−8 µm). The thermally tuning feature leads to further controlling the absorption and, therefore, the emission performance of the nanoantenna and corresponding infrared signatures detected by thermal cameras.Item Open Access A spectrally selective gap surface-plasmon-based nanoantenna emitter compatible with multiple thermal infrared applications(Institute of Physics Publishing Ltd., 2021-08-20) Osgouei, Ataollah Kalantari; Ghobadi, Amir; Khalichi, Bahram; Özbay, EkmelWavelength-selective nanoantenna emitters have attracted considerable attention due to their widespread applications ranging from thermal radiation management to thermophotovoltaics. In this paper, we design a wavelength-selective nanoantenna emitter based on the excitation of gap-surface plasmon modes using a metal–insulator–metal configuration (silicon dioxide (SiO2) sandwiched between silver (Ag) layers) for satisfying multiple infrared applications. The proposed design, which is called design I, realizes triple narrowband perfect absorptions at the resonance wavelengths of 1524nm,2279nm, and 6000nm, which perfectly match the atmospheric absorption bands while maintaining relatively low emissivity in the atmospheric transparency windows of 3-5 µm and 8-12 µm. Later, the functionality of design I is extended, which is called design II, to include a broadband absorption at the near-infrared region to minimize the solar irradiation reflection from the nanoantenna emitter. Finally, single- and three-layer graphene are introduced to provide a real-time tuning of the infrared signature of the proposed nanoantenna emitter (design II). It is also demonstrated that the three-layer graphene structure can suppress an undesired absorption resonance wavelength related to the intrinsic vibrational modes (optical phonons) of the SiO2 layer by 53.19% compared to 25.53% for the single-layer one. The spectral analysis of design I is validated using both analytical and numerical approaches where the numerical simulation domain is extended for the analysis of design II. The thermal characteristic analyses of design I and design II (without/with graphene layers) reveal that infrared signatures of the blackbody radiation are significantly reduced for the whole wavelength spectrum at least by 96% and 91% within a wide temperature ranging from room temperature to 500K, respectively.Item Unknown A Transmissive all-dielectric metasurface-based nanoantenna array for selectively manipulation of thermal radiation(Institute of Electrical and Electronics Engineers, 2022-09-21) Khalichi, Bahram; Omam, Zahra Rahimian; Osgouei, Ataollah Kalantari; Ghobadi, Amir; Özbay, EkmelIn this study, a wavelength-selective thermal nanoantenna emitter based on metamaterial design with heat radiation signature management and radiative cooling property is proposed. The design can be considered as a multifunctional window by reducing the heat signature and releasing the heat energy within the non-atmospheric window. The approach relies on the indium tin oxide cubic-shaped unit cell coated on a flexible and transparent substrate (polystyrene). The spectral behaviors of the proposed structure are obtained using the finite difference time domain method, where the power calculation model is utilized to demonstrate the radiative cooling efficiency and low power detection on infrared cameras.Item Open Access A Transparent all-dielectric multifunctional Nanoantenna emitter compatible with thermal infrared and cooling scenarios(IEEE, 2021-06-30) Ghobadi, Amir; Osgouei, Ataollah Kalantari; Koçer, Hasan; Özbay, EkmelIn modern thermal infrared applications, multi-spectral camouflage scenarios should be developed to mitigate the thermal signature of an object. In general, camouflage needs to be satisfied in two main optical ranges: visible, and infrared (IR). In the IR range, two main camera modes are deployed to detect the IR signature of an object: i) short-wave IR (SWIR) cameras that detect the solar photons reflected off a surface, ii) mid-wave IR (MWIR) and long-wave IR (LWIR) cameras that directly collect the blackbody photons emitted from a hot object. Therefore, in an ideal scheme to acquire a multi-spectral camouflage function with self-cooling capability, the object should have: i) perfect absorption in the SWIR range, ii) perfect reflection in the MWIR and LWIR ranges, iii) perfect absorption and one-way transmission in non-transmissive IR (NTIR) window (to radiatively cool itself), and iv) visible transparency (to keep background visual appearance intact and to minimize the heat build-up due to solar absorption). In this paper, an all-dielectric nanoantenna emitter design is developed to comply with all the above-mentioned requirements. The approach relies on the indium tin oxide (ITO) grating structures coated on a flexible and transparent substrate (polystyrene). The spectral behaviors of the proposed structure are obtained using both analytical and numerical approaches. The design has an absorption peak with 0.8 amplitude in the SWIR mode (for the backward and forward illuminations), while it shows average reflections ≅ 0.7 in the MWIR and LWIR ranges for the forward illumination. The peak values of transmission and absorption within the NTIR window for the forward illumination are around 0.6 and 0.9, respectively. Meanwhile, the use of lossless materials within the visible range provides visible light transmission and minimizes the heat build-up due to solar absorption. In addition, the radiated power calculation model is utilized to demonstrate the low power detection on the IR cameras.Item Open Access Visible light metasurface for adaptive photodetection(Institute of Physics Publishing Ltd., 2022-10-05) Osgouei, Ataollah Kalantari; Ghobadi, Amir; Khalichi, Bahram; Sabet, Rana Asgari; Tokel, Onur; Özbay, EkmelSemiconductor-based sub-wavelength metasurfaces are promising device platforms for the realization of optically thick and electrically thin photodetectors. Strong light–matter interactions in ultrathin film regions provide an opportunity to achieve near-unity absorption in dimensions comparable with carrier diffusion length and this, in turn, leads to an efficient collection of photogenerated carriers. Moreover, the use of phase change materials can provide real-time active tuning of optical responses of metasurface-based devices. In the first part of this paper, a tunable color filtering device is demonstrated using a metasurface design made of sub-wavelength antimony trisulphide (Sb2S3) grating placed on top of a continuous silver layer. Four distinct optical states can be acquired upon (a) the changes in the incident light polarization and (b) the phase transitions of Sb2S3. Numerical simulations and theoretical modeling data show that Fabry–Perot resonances are the driving phenomena when the proposed design is normally illuminated by an electromagnetic field with transverse electric polarization. In contrast, surface plasmon resonances are excited in transverse magnetic polarization. Furthermore, it is shown that the resonance wavelengths of the proposed design can be dynamically tuned using the geometrical parameters. Later, in the second part of the paper, adaptive photodetection is designed by integrating a $5\,$ nm Sb2S3 layer as a collection layer into the structure. The proposed metasurface design provides light–matter interaction in the Sb2S3 layer and maximizes the photogenerated carriers' collection efficiency. The optically thick and electrically thin adaptive photodetection offers an opportunity to design efficient active optoelectronic and photonic devices.Item Open Access A wavelength-selective multilayer absorber for heat signature control(Institute of Electrical and Electronics Engineers, 2022-09-28) Osgouei, Ataollah Kalantari; Khalichi, Bahram; Omam, Zahra Rahimian; Ghobadi, Amir; Özbay, EkmelEngineering the thermal radiation using wavelength-selective thermal emitters is of great importance in the field of thermophotovoltaics, radiative cooling, and heat signature control. In this paper, a wavelength-selective Vanadium/Germanium (V/Ge) multilayer absorber is demonstrated. The proposed design realizes a perfect absorption at the resonance wavelength of 5870 nm, placed within the nonatmospheric window (5-8 μ m) while maintaining low absorptivity within the atmospheric windows. It is verified that the proposed emitter represents angle insensitive feature for oblique incidence up to 60° for both transverse magnetic (TM) and transverse electric (TE) polarizations.