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Aryana K, Kim HJ, Popescu CC, Vitale S, Bae HB, Lee T, Gu T, Hu J. Toward Accurate Thermal Modeling of Phase Change Material-Based Photonic Devices. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2304145. [PMID: 37649187 DOI: 10.1002/smll.202304145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/11/2023] [Indexed: 09/01/2023]
Abstract
Reconfigurable or programmable photonic devices are rapidly growing and have become an integral part of many optical systems. The ability to selectively modulate electromagnetic waves through electrical stimuli is crucial in the advancement of a variety of applications from data communication and computing devices to environmental science and space explorations. Chalcogenide-based phase-change materials (PCMs) are one of the most promising material candidates for reconfigurable photonics due to their large optical contrast between their different solid-state structural phases. Although significant efforts have been devoted to accurate simulation of PCM-based devices, in this paper, three important aspects which have often evaded prior models yet having significant impacts on the thermal and phase transition behavior of these devices are highlighted: the enthalpy of fusion, the heat capacity change upon glass transition, as well as the thermal conductivity of liquid-phase PCMs. The important topic of switching energy scaling in PCM devices, which also helps explain why the three above-mentioned effects have long been overlooked in electronic PCM memories but only become important in photonics, is further investigated. These findings offer insight to facilitate accurate modeling of PCM-based photonic devices and can inform the development of more efficient reconfigurable optics.
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Affiliation(s)
| | - Hyun Jung Kim
- NASA Langley Research Center, Hampton, VA, 23681, USA
| | - Cosmin-Constantin Popescu
- Department of Materials & Science Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Steven Vitale
- Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA, 02421, USA
| | - Hyung Bin Bae
- KAIST Analysis Center, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon, 34141, South Korea
| | - Taewoo Lee
- KAIST Analysis Center, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon, 34141, South Korea
| | - Tian Gu
- Department of Materials & Science Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Materials Research Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Juejun Hu
- Department of Materials & Science Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Materials Research Laboratory, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
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Cai Z, Ding Y, Chen Z, Zheng Z, Ding F. Dynamic dual-functional optical wave plate based on phase-change meta-molecules. OPTICS LETTERS 2023; 48:3685-3688. [PMID: 37450725 DOI: 10.1364/ol.495812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 06/14/2023] [Indexed: 07/18/2023]
Abstract
Optical metasurfaces have shown great potential for revolutionizing wave plates by enabling compact footprints and diversified functionalities. However, most metasurface wave plates (meta-WPs) are typically passive, featuring defined responses after fabrication, whereas dynamic meta-WPs have so far often been limited to ON and OFF states. Here, we design a dynamic dual-functional meta-WP based on judiciously designed low-loss Sb2Se3 meta-molecules at the telecom wavelength of 1.55 µm which enables reconfigurable linear-to-circular and linear-to-linear polarization conversion for orthogonal linear polarizations when Sb2Se3 transits between amorphous and crystalline states. In addition, a comprehensive electro-thermal simulation is carried out to verify the phase change process for realistic implementation. The designed dynamic dual-functional wave plate may open new avenues for developing integrated adaptive photonics with dynamic and multiplexed functionalities.
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Ghaffari V, Yousefi L. Integrated optical beam steering device using switchable nanoantennas and a reflective metalens. Sci Rep 2023; 13:7099. [PMID: 37130970 PMCID: PMC10154304 DOI: 10.1038/s41598-023-33939-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 04/21/2023] [Indexed: 05/04/2023] Open
Abstract
In this paper, an integrated optical device is proposed in which a reflective meta-lens and five switchable nano-antennas are combined to provide optical beam steering at the standard telecommunication wavelength of 1550 nm. For this purpose, a graphene-based switchable power divider is designed and integrated with nano-antennas to control the flow of the light entering the device. To achieve a higher angular accuracy in the radiated beams, a new algorithm is proposed and utilized to optimize the location of feeding nano-antennas in accordance with the reflective meta-lens. In order to achieve a minimum fluctuation in the light intensity when the beams are rotated in the space, an algorithm is developed to select optimum unit cells for the engineered meta-lens. The whole device is numerically analyzed using Electromagnetic full-wave simulations illustrating an optical beam steering with high accuracy (better than 1 degree) in the beam direction, and a low variation (less than 1 dB) in the radiated light intensity. The proposed integrated device can be used for many applications such as inter- and intra-chip optical interconnects, optical wireless communication systems, and advanced integrated LIDARs.
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Affiliation(s)
- Vahid Ghaffari
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1417614411, Iran
| | - Leila Yousefi
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1417614411, Iran.
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Esfahani AM, Yousefi L. Low profile multi-layered invisibility carpet cloak using quantum dot core-shell nanoparticles. Sci Rep 2023; 13:3450. [PMID: 36859537 PMCID: PMC9977955 DOI: 10.1038/s41598-023-30389-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 02/22/2023] [Indexed: 03/03/2023] Open
Abstract
In this paper, a method to reduce the profile of layered carpet cloaks is proposed. We analytically prove and numerically demonstrate that using a Low Index Material (LIM), a material with a relative dielectric constant smaller than 1, in construction of carpet cloaks can remarkably reduce their profiles. Using the proposed technique, a carpet cloak consisting of alternating LIM and silicon layers is designed to provide invisibility at visible wavelengths. The designed cloak has a profile that is 2.3 times smaller than a carpet cloak without LIM layers. To realize low index materials at optical wavelengths, silver-coated CdSe/CdS quantum dots dispersed in a polymer host are used. Quantum dots are utilized to compensate the loss of Silver and to achieve a low index medium with neglectable loss. The designed low profile carpet cloak is numerically analyzed showing a good performance for a wide range of incident angles which is the advantage of the proposed structure in comparison with metasurface-based carpet cloaks which work only for a very narrow range of incident angles.
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Affiliation(s)
- Amin Monemian Esfahani
- grid.46072.370000 0004 0612 7950School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1417614411 Iran
| | - Leila Yousefi
- School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran, 1417614411, Iran.
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Developing a carpet cloak operating for a wide range of incident angles using a deep neural network and PSO algorithm. Sci Rep 2023; 13:670. [PMID: 36635479 PMCID: PMC9837171 DOI: 10.1038/s41598-023-27458-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 01/02/2023] [Indexed: 01/13/2023] Open
Abstract
Designing invisibility cloaks has always been one of the most fascinating fields of research; in this regard, metasurface-based carpet cloaks have drawn researchers' attention due to their inherent tenuousness, resulting in a lower loss and easier fabrication. However, their performances are dependent on the incident angle of the coming wave; as a result, designing a carpet cloak capable of rendering objects under it invisible for a wide range of angles requires advanced methods. In this paper, using the Particle Swarm Optimization (PSO) algorithm, along with a trained neural network, a metasurface-based carpet cloak is developed capable to operate for a wide range of incident angles. The deep neural network is trained and used in order to accelerate the process of calculation of reflection phases provided by different unit cell designs. The resultant carpet cloak is numerically analyzed, and its response is presented and discussed. Both near-field and far-field results show that the designed carpet cloak operates very well for all incident angles in the range of 0 to 65 degrees.
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Akbari-Chelaresi H, Salami P, Yousefi L. Far-field sub-wavelength imaging using high-order dielectric continuous metasurfaces. OPTICS EXPRESS 2022; 30:39025-39039. [PMID: 36258453 DOI: 10.1364/oe.470221] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 08/26/2022] [Indexed: 05/20/2023]
Abstract
Due to the wave nature of light, the resolution achieved in conventional imaging systems is limited to around half of the wavelength. The reason behind this limitation, called diffraction limit, is that part of the information of the object carried by the evanescent waves scattered from an abject. Although retrieving information from propagating waves is not difficult in the far-field region, it is very challenging in the case of evanescent waves, which decay exponentially as travel and lose their power in the far-field region. In this paper, we design a high-order continuous dielectric metasurface to convert evanescent waves into propagating modes and subsequently to reconstruct super-resolution images in the far field. The designed metasurface is characterized and its performance for sub-wavelength imaging is verified using full wave numerical simulations. Simulation results show that the designed continuous high-order metasurface can convert a large group of evanescent waves into propagating ones. The designed metasurface is then used to reconstruct the image of objects with sub-wavelength features, and an image with the resolution of λ/5.5 is achieved.
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Zamani N, Hatef A, Nadgaran H. Temporal Analysis of Photo‐Thermally Induced Reconfigurability in a 1D Gold Grating Filled with a Phase Change Material. ADVANCED THEORY AND SIMULATIONS 2021. [DOI: 10.1002/adts.202100240] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Naser Zamani
- Department of Physics Shiraz University Shiraz 71454 Iran
| | - Ali Hatef
- Nipissing Computational Physics Laboratory (NCPL), Department of Computer Science and Mathematics Nipissing University North Bay Ontario P1B8L7 Canada
| | - Hamid Nadgaran
- Department of Physics Shiraz University Shiraz 71454 Iran
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