1
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Ko JH, Seo DH, Jeong HH, Kim S, Song YM. Sub-1-Volt Electrically Programmable Optical Modulator Based on Active Tamm Plasmon. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2310556. [PMID: 38174820 DOI: 10.1002/adma.202310556] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Revised: 11/26/2023] [Indexed: 01/05/2024]
Abstract
Reconfigurable optical devices hold great promise for advancing high-density optical interconnects, photonic switching, and memory applications. While many optical modulators based on active materials have been demonstrated, it is challenging to achieve a high modulation depth with a low operation voltage in the near-infrared (NIR) range, which is a highly sought-after wavelength window for free-space communication and imaging applications. Here, electrically switchable Tamm plasmon coupled with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is introduced. The device allows for a high modulation depth across the entire NIR range by fully absorbing incident light even under epsilon near zero conditions. Optical modulation exceeding 88% is achieved using a CMOS-compatible voltage of ±1 V. This modulation is facilitated by precise electrical control of the charge carrier density through an electrochemical doping/dedoping process. Additionally, the potential applications of the device are extended for a non-volatile multi-memory state optical device, capable of rewritable optical memory storage and exhibiting long-term potentiation/depression properties with neuromorphic behavior.
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Affiliation(s)
- Joo Hwan Ko
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea
| | - Dong Hyun Seo
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea
| | - Hyeon-Ho Jeong
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea
- Department of Semiconductor Engineering, Gwangju Institute of Science AND Technology, Gwangju, 61005, Republic of Korea
| | - Sejeong Kim
- Department of Electrical and Electronic Engineering, University of Melbourne, Victoria, 3000, Australia
| | - Young Min Song
- School of Electrical Engineering and Computer Science, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea
- Department of Semiconductor Engineering, Gwangju Institute of Science AND Technology, Gwangju, 61005, Republic of Korea
- AI Graduate School, Gwangju Institute of Science and Technology, Gwangju, 61005, Republic of Korea
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2
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Wu J, Clementi M, Huang C, Ye F, Fu H, Lu L, Zhang S, Li Q, Brès CS. Thermo-optic epsilon-near-zero effects. Nat Commun 2024; 15:794. [PMID: 38278795 PMCID: PMC10817958 DOI: 10.1038/s41467-024-45054-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 01/12/2024] [Indexed: 01/28/2024] Open
Abstract
Nonlinear epsilon-near-zero (ENZ) nanodevices featuring vanishing permittivity and CMOS-compatibility are attractive solutions for large-scale-integrated systems-on-chips. Such confined systems with unavoidable heat generation impose critical challenges for semiconductor-based ENZ performances. While their optical properties are temperature-sensitive, there is no systematic analysis on such crucial dependence. Here, we experimentally report the linear and nonlinear thermo-optic ENZ effects in indium tin oxide. We characterize its temperature-dependent optical properties with ENZ frequencies covering the telecommunication O-band, C-band, and 2-μm-band. Depending on the ENZ frequency, it exhibits an unprecedented 70-93-THz-broadband 660-955% enhancement over the conventional thermo-optic effect. The ENZ-induced fast-varying large group velocity dispersion up to 0.03-0.18 fs2nm-1 and its temperature dependence are also observed for the first time. Remarkably, the thermo-optic nonlinearity demonstrates a 1113-2866% enhancement, on par with its reported ENZ-enhanced Kerr nonlinearity. Our work provides references for packaged ENZ-enabled photonic integrated circuit designs, as well as a new platform for nonlinear photonic applications and emulations.
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Affiliation(s)
- Jiaye Wu
- École Polytechnique Fédérale de Lausanne (EPFL), Photonic Systems Laboratory (PHOSL), STI-IEM, Station 11, Lausanne, CH-1015, Switzerland.
| | - Marco Clementi
- École Polytechnique Fédérale de Lausanne (EPFL), Photonic Systems Laboratory (PHOSL), STI-IEM, Station 11, Lausanne, CH-1015, Switzerland
| | - Chenxingyu Huang
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Feng Ye
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China
| | - Hongyan Fu
- Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen, 518055, China
| | - Lei Lu
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China
| | - Shengdong Zhang
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China
| | - Qian Li
- School of Electronic and Computer Engineering, Peking University, Shenzhen, 518055, China.
| | - Camille-Sophie Brès
- École Polytechnique Fédérale de Lausanne (EPFL), Photonic Systems Laboratory (PHOSL), STI-IEM, Station 11, Lausanne, CH-1015, Switzerland.
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3
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Korneluk A, Szymczak J, Stefaniuk T. Annealing-free fabrication of high-quality indium tin oxide films for free-carrier-based hybrid metal-semiconductor nanophotonics. Sci Rep 2023; 13:18520. [PMID: 37898688 PMCID: PMC10613292 DOI: 10.1038/s41598-023-45651-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/22/2023] [Indexed: 10/30/2023] Open
Abstract
Recent discoveries have revealed that indium tin oxide (ITO), due to the presence of an epsilon-near-zero (ENZ) point and suitable carrier concentration and mobility, can be used to modulate the refractive index, confine fields in the nanoscale, enhance nonlinear effects, achieve ultrafast light switching or to construct so-called time-varying media. While this potential positions ITO as a key material for future nanophotonic devices, producing ITO films with precisely engineered properties remains a significant challenge. Especially when the device's complex geometry or incorporated materials require the fabrication process to be conducted at substrate temperatures below 100 °C and without any post-annealing treatment. Here we present a comprehensive study on the low-temperature deposition of 70 nm thick ITO films using an e-beam PVD system. The nanolayers evaporated under different conditions were characterized by SEM and AFM microscopy, Hall effect measurement system as well as spectroscopic ellipsometry. We discuss the factors influencing the optical, electrical, and morphological properties of ITO films. We show that smooth nanolayers of similar quality to annealed samples can be obtained at 80 °C by controlling the oxygen plasma parameters, and the ENZ wavelength can be tuned throughout the NIR spectral range. Finally, we show that using the proposed methodology, we fabricated ITO films with resistivity as low as 5.2 × 10-4 Ω cm, smooth surface with RMS < 1 nm, high carrier concentration reaching 1.2 × 1021 cm-3 and high transmittance (85%) in the Vis/NIR spectrum.
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Affiliation(s)
- Alexander Korneluk
- Faculty of Physics, University of Warsaw, Pasteura 5 St., 02-093, Warsaw, Poland.
| | - Julia Szymczak
- Faculty of Physics, University of Warsaw, Pasteura 5 St., 02-093, Warsaw, Poland
| | - Tomasz Stefaniuk
- Faculty of Physics, University of Warsaw, Pasteura 5 St., 02-093, Warsaw, Poland
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4
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Hu J, Li ZZ, Zhao YY, Xu YS, Wang L, Han M, Hyde L, Ng SH, Wang L, Juodkazis S. Nanoscale Printing of Indium-Tin-Oxide by Femtosecond Laser Pulses. NANOMATERIALS (BASEL, SWITZERLAND) 2022; 12:4092. [PMID: 36432377 PMCID: PMC9694177 DOI: 10.3390/nano12224092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/15/2022] [Accepted: 11/16/2022] [Indexed: 06/16/2023]
Abstract
For constructing optical and electrical micro-devices, the deposition/printing of materials with sub-1 μm precision and size (cross-section) is required. Crystalline c-ITO (indium tin oxide) nanostructures were patterned on glass with sufficient precision to form 20-50 nm gaps between individual disks or lines of ∼250 nm diameter or width. The absorbed energy density [J/cm3] followed a second-order dependence on pulse energy. This facilitated high-resolution and precise nanoscale laser-writing at a laser wavelength of 515 nm. Patterns for optical elements such as circular gratings and micro-disks were laser-printed using ITO as a resist. Unexposed amorphous a-ITO was chemically removed in aqueous 1% vol. HF solution. This use of a-ITO as a solid resist holds promise for metamaterial and micro-optical applications.
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Affiliation(s)
- Jingwen Hu
- Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
| | - Zhen-Ze Li
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Yang-Yang Zhao
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Yi-Shi Xu
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Lin Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Molong Han
- Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
- Melbourne Centre for Nanofabrication (MCN-ANFF), 151 Wellington Rd, Clayton, VIC 3168, Australia
| | - Lachlan Hyde
- Space Technology and Industry Institute, Graphene Certification Labs, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
| | - Soon Hock Ng
- Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
- Melbourne Centre for Nanofabrication (MCN-ANFF), 151 Wellington Rd, Clayton, VIC 3168, Australia
| | - Lei Wang
- State Key Laboratory of Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012, China
| | - Saulius Juodkazis
- Optical Sciences Centre and ARC Training Centre in Surface Engineering for Advanced Materials (SEAM), School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia
- World Research Hub Initiative (WRHI), School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1, Ookayama, Meguro-ku, Tokyo 152-8550, Japan
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5
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Lotkov ES, Baburin AS, Ryzhikov IA, Sorokina OS, Ivanov AI, Zverev AV, Ryzhkov VV, Bykov IV, Baryshev AV, Panfilov YV, Rodionov IA. ITO film stack engineering for low-loss silicon optical modulators. Sci Rep 2022; 12:6321. [PMID: 35428848 PMCID: PMC9012746 DOI: 10.1038/s41598-022-09973-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 03/21/2022] [Indexed: 11/17/2022] Open
Abstract
The Indium Tin Oxide (ITO) platform is one of the promising solutions for state-of-the-art integrated optical modulators towards low-loss silicon photonics applications. One of the key challenges on this way is to optimize ITO-based thin films stacks for electro-optic modulators with both high extinction ratio and low insertion loss. In this paper we demonstrate the e-beam evaporation technology of 20 nm-thick ITO films with low extinction coefficient of 0.14 (Nc = 3.7·1020 cm−3) at 1550 nm wavelength and wide range of carrier concentrations (from 1 to 10 × 1020 cm−3). We investigate ITO films with amorphous, heterogeneously crystalline, homogeneously crystalline with hidden coarse grains and pronounced coarsely crystalline structure to achieve the desired optical and electrical parameters. Here we report the mechanism of oxygen migration in ITO film crystallization based on observed morphological features under low-energy growth conditions. Finally, we experimentally compare the current–voltage and optical characteristics of three electro-optic active elements based on ITO film stacks and reach strong ITO dielectric permittivity variation induced by charge accumulation/depletion (Δn = 0.199, Δk = 0.240 at λ = 1550 nm under ± 16 V). Our simulations and experimental results demonstrate the unique potential to create integrated GHz-range electro-optical modulators with sub-dB losses.
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Affiliation(s)
- Evgeniy S Lotkov
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia. .,Dukhov Automatics Research Institute, (VNIIA), Moscow, 127055, Russia.
| | - Aleksandr S Baburin
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia.,Dukhov Automatics Research Institute, (VNIIA), Moscow, 127055, Russia
| | - Ilya A Ryzhikov
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia.,Institute for Theoretical and Applied Electromagnetics RAS, Moscow, 125412, Russia
| | - Olga S Sorokina
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia.,Dukhov Automatics Research Institute, (VNIIA), Moscow, 127055, Russia
| | - Anton I Ivanov
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia.,Dukhov Automatics Research Institute, (VNIIA), Moscow, 127055, Russia
| | - Alexander V Zverev
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia.,Dukhov Automatics Research Institute, (VNIIA), Moscow, 127055, Russia
| | - Vitaly V Ryzhkov
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia
| | - Igor V Bykov
- Institute for Theoretical and Applied Electromagnetics RAS, Moscow, 125412, Russia
| | | | - Yuri V Panfilov
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia
| | - Ilya A Rodionov
- FMN Laboratory, Bauman Moscow State Technical University, Moscow, 105005, Russia.,Dukhov Automatics Research Institute, (VNIIA), Moscow, 127055, Russia
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6
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Kwon S, Kim MJ, Chung KB. Multi-level characteristics of TiO x transparent non-volatile resistive switching device by embedding SiO 2 nanoparticles. Sci Rep 2021; 11:9883. [PMID: 33972612 PMCID: PMC8110581 DOI: 10.1038/s41598-021-89315-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/20/2021] [Indexed: 11/26/2022] Open
Abstract
TiOx-based resistive switching devices have recently attracted attention as a promising candidate for next-generation non-volatile memory devices. A number of studies have attempted to increase the structural density of resistive switching devices. The fabrication of a multi-level switching device is a feasible method for increasing the density of the memory cell. Herein, we attempt to obtain a non-volatile multi-level switching memory device that is highly transparent by embedding SiO2 nanoparticles (NPs) into the TiOx matrix (TiOx@SiO2 NPs). The fully transparent resistive switching device is fabricated with an ITO/TiOx@SiO2 NPs/ITO structure on glass substrate, and it shows transmittance over 95% in the visible range. The TiOx@SiO2 NPs device shows outstanding switching characteristics, such as a high on/off ratio, long retention time, good endurance, and distinguishable multi-level switching. To understand multi-level switching characteristics by adjusting the set voltages, we analyze the switching mechanism in each resistive state. This method represents a promising approach for high-performance non-volatile multi-level memory applications.
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Affiliation(s)
- Sera Kwon
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea
| | - Min-Jung Kim
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea
| | - Kwun-Bum Chung
- Division of Physics and Semiconductor Science, Dongguk University, Seoul, 04620, Republic of Korea.
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7
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Parra J, Pernice WHP, Sanchis P. All-optical phase control in nanophotonic silicon waveguides with epsilon-near-zero nanoheaters. Sci Rep 2021; 11:9474. [PMID: 33947896 PMCID: PMC8096950 DOI: 10.1038/s41598-021-88865-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 04/19/2021] [Indexed: 12/02/2022] Open
Abstract
A wide variety of nanophotonic applications require controlling the optical phase without changing optical absorption, which in silicon (Si) photonics has been mostly pursued electrically. Here, we investigate the unique light–matter interaction exhibited by epsilon-near-zero (ENZ) materials for all-optical phase control in nanophotonic silicon waveguides. Thermo-optic all-optical phase tuning is achieved using an ENZ material as a compact, low-loss, and efficient optical heat source. For a 10-\documentclass[12pt]{minimal}
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\begin{document}$$\hbox {mW}^{-1}$$\end{document}mW-1. Our proposal provides a new approach to achieve all-optical, on-chip, and low-loss phase tuning in silicon photonic circuits.
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Affiliation(s)
- Jorge Parra
- Nanophotonics Technology Center, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain
| | - Wolfram H P Pernice
- Institute of Physics, CeNTech, University of Münster, Heisenbergstr. 11, 48161, Münster, Germany
| | - Pablo Sanchis
- Nanophotonics Technology Center, Universitat Politècnica de València, Camino de Vera s/n, 46022, Valencia, Spain.
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8
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Indium Tin Oxide Thin Film Deposition by Magnetron Sputtering at Room Temperature for the Manufacturing of Efficient Transparent Heaters. COATINGS 2021. [DOI: 10.3390/coatings11010092] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Indium tin oxide (ITO) thin films are widely used as transparent electrodes in electronic devices. Many of those electronic devices are heat sensitive, thus their manufacturing process steps should not exceed 100 °C. Manufacturing competitive high-quality ITO films at low temperature at industrial scale is still a challenge. Magnetron sputtering technology is the most suitable technology fulfilling those requirements. However, ITO layer properties and the reproducibility of the process are extremely sensitive to process parameters. Here, morphological, structural, electrical, and optical characterization of the ITO layers deposited at low temperature has been successfully correlated to magnetron sputtering process parameters. It has been demonstrated that the oxygen flow controls and influences layer properties. For oxygen flow between 3–4 sccm, high quality crystalline layers were obtained with excellent optoelectronic properties (resistivity <8 × 10−4 Ω·cm and visible transmittance >80%). The optimized conditions were applied to successfully manufacture transparent ITO heaters on large area glass and polymeric components. When a low supply voltage (8 V) was applied to transparent heaters (THs), de-icing of the surface was produced in less than 2 min, showing uniform thermal distribution. In addition, both THs (glass and polycarbonate) showed a great stability when exposed to saline solution.
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9
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Meng Z, Cao H, Liu R, Wu X. An Electrically Tunable Dual-Wavelength Refractive Index Sensor Based on a Metagrating Structure Integrating Epsilon-Near-Zero Materials. SENSORS 2020; 20:s20082301. [PMID: 32316493 PMCID: PMC7219054 DOI: 10.3390/s20082301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/13/2020] [Accepted: 04/16/2020] [Indexed: 11/16/2022]
Abstract
In this paper, a reconfigurable sensing platform based on an asymmetrical metal-insulator-metal stacked structure integrating an indium tin oxide (ITO) ultrathin film is proposed and investigated numerically. The epsilon-near-zero (ENZ) mode and antisymmetric mode can be resonantly excited, generating near-perfect absorption of over 99.7% at 1144 and 1404 nm, respectively. The absorptivity for the ENZ mode can be modulated from 90.2% to 98.0% by varying the ENZ wavelength of ITO by applying different voltages. To obtain a highly sensitive biosensor, we show that the proposed structure has a full-width at half-maximum (FWHM) of 8.65 nm and a figure-of-merit (FOM) of 24.7 with a sensitivity of 213.3 nm/RI (refractive index) for the glucose solution. Our proposed device has potential for developing tunable biosensors for real-time health monitoring.
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Affiliation(s)
- Zhenya Meng
- School of Microelectronics and Communication Engineering, Chongqing University, Chongqing 400044, China
| | - Hailin Cao
- School of Microelectronics and Communication Engineering, Chongqing University, Chongqing 400044, China
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400044, China
- Correspondence:
| | - Run Liu
- School of Microelectronics and Communication Engineering, Chongqing University, Chongqing 400044, China
| | - Xiaodong Wu
- School of Microelectronics and Communication Engineering, Chongqing University, Chongqing 400044, China
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10
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Parra J, Hurtado J, Griol A, Sanchis P. Ultra-low loss hybrid ITO/Si thermo-optic phase shifter with optimized power consumption. OPTICS EXPRESS 2020; 28:9393-9404. [PMID: 32225547 DOI: 10.1364/oe.386959] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 02/21/2020] [Indexed: 06/10/2023]
Abstract
Typically, materials with large optical losses such as metals are used as microheaters for silicon based thermo-optic phase shifters. Consequently, the heater must be placed far from the waveguide, which could come at the expense of the phase shifter performance. Reducing the gap between the waveguide and the heater allows reducing the power consumption or increasing the switching speed. In this work, we propose an ultra-low loss microheater for thermo-optic tuning by using a CMOS-compatible transparent conducting oxide such as indium tin oxide (ITO) with the aim of drastically reducing the gap. Using finite element method simulations, ITO and Ti based heaters are compared for different cladding configurations and TE and TM polarizations. Furthermore, the proposed ITO based microheaters have also been fabricated using the optimum gap and cladding configuration. Experimental results show power consumption to achieve a π phase shift of 10 mW and switching time of a few microseconds for a 50 µm long ITO heater. The obtained results demonstrate the potential of using ITO as an ultra-low loss microheater for high performance silicon thermo-optic tuning and open an alternative way for enabling the large-scale integration of phase shifters required in emerging integrated photonic applications.
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