1
|
Feng H, Meng H, Wang G, Liu J, Zhang X, Li M, Yang S, Jia Y, Du H, Gao Y, Gao Y. A tunable ultra-broadband and ultra-high sensitivity far-infrared metamaterial absorber based on VO 2 and graphene. Phys Chem Chem Phys 2024; 26:14919-14929. [PMID: 38738775 DOI: 10.1039/d4cp00331d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
We proposed a far-infrared tunable metamaterial absorber using vanadium dioxide (VO2) and graphene as controlling materials. The properties of the absorber are investigated theoretically using the finite-difference time-domain (FDTD) technique. It was found that when the Fermi energy level of graphene is fixed at zero, VO2 is in the insulated state, and the metasurface exhibits far-infrared broadband absorption performance, with absorptance exceeding 90% in the wavelength range of 12.6 μm to 23.2 μm. In addition, by elevating the Fermi energy level of graphene, the absorption bandwidth of the device is expanded continuously. When the VO2 is in the metallic state, the device can flexibly transform into a far-infrared narrowband absorber. The device also has the advantage of being insensitive to changes in polarization and incident angle. The origin of the absorption and the tuning principle of the device were analyzed and verified successfully by using an equivalent circuit model (ECM). Besides, we also studied the refraction index sensing characteristics of the absorber. Surprisingly, the absorber exhibits excellent sensing characteristics, and its sensitivity (S) reaches 14.108 μm per RIU and the figure of merit (FOM) is 6.13 per RIU.
Collapse
Affiliation(s)
- Hengli Feng
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Hongyan Meng
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
- College of Communication and Electronic Engineering, Qiqihar University, Qiqihar 161000, China
| | - Guan Wang
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Jia Liu
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Xin Zhang
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Meichen Li
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Shuang Yang
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Yang Jia
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
- College of Communication and Electronic Engineering, Qiqihar University, Qiqihar 161000, China
| | - Hanmo Du
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Yang Gao
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| | - Yachen Gao
- Electronic Engineering College, Heilongjiang University, Harbin, 150080, China.
| |
Collapse
|
2
|
Carr Delgado H, Moradifar P, Chinn G, Levin CS, Dionne JA. Toward "super-scintillation" with nanomaterials and nanophotonics. NANOPHOTONICS 2024; 13:1953-1962. [PMID: 38745841 PMCID: PMC11090085 DOI: 10.1515/nanoph-2023-0946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 03/18/2024] [Indexed: 05/16/2024]
Abstract
Following the discovery of X-rays, scintillators are commonly used as high-energy radiation sensors in diagnostic medical imaging, high-energy physics, astrophysics, environmental radiation monitoring, and security inspections. Conventional scintillators face intrinsic limitations including a low extraction efficiency of scintillated light and a low emission rate, leading to efficiencies that are less than 10 % for commercial scintillators. Overcoming these limitations will require new materials including scintillating nanomaterials ("nanoscintillators"), as well as new photonic approaches that increase the efficiency of the scintillation process, increase the emission rate of materials, and control the directivity of the scintillated light. In this perspective, we describe emerging nanoscintillating materials and three nanophotonic platforms: (i) plasmonic nanoresonators, (ii) photonic crystals, and (iii) high-Q metasurfaces that could enable high performance scintillators. We further discuss how a combination of nanoscintillators and photonic structures can yield a "super scintillator" enabling ultimate spatio-temporal resolution while enabling a significant boost in the extracted scintillation emission.
Collapse
Affiliation(s)
- Hamish Carr Delgado
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305, USA
| | - Parivash Moradifar
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305, USA
| | - Garry Chinn
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Craig S. Levin
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| | - Jennifer A. Dionne
- Department of Materials Science and Engineering, Stanford University, Stanford, CA94305, USA
- Department of Radiology, Stanford University, Stanford, CA, 94305, USA
| |
Collapse
|
3
|
Shen L, Yin X. Solar spectral management for natural photosynthesis: from photonics designs to potential applications. NANO CONVERGENCE 2022; 9:36. [PMID: 35930145 PMCID: PMC9356122 DOI: 10.1186/s40580-022-00327-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 07/13/2022] [Indexed: 06/15/2023]
Abstract
Photosynthesis is the most important biological process on Earth that converts solar energy to chemical energy (biomass) using sunlight as the sole energy source. The yield of photosynthesis is highly sensitive to the intensity and spectral components of light received by the photosynthetic organisms. Therefore, photon engineering has the potential to increase photosynthesis. Spectral conversion materials have been proposed for solar spectral management and widely investigated for photosynthesis by modifying the quality of light reaching the organisms since the 1990s. Such spectral conversion materials manage the photon spectrum of light by a photoconversion process, and a primary challenge faced by these materials is increasing their efficiencies. This review focuses on emerging spectral conversion materials for augmenting the photosynthesis of plants and microalgae, with a special emphasis on their fundamental design and potential applications in both greenhouse settings and microalgae cultivation systems. Finally, a discussion about the future perspectives in this field is made to overcome the remaining challenges.
Collapse
Affiliation(s)
- Lihua Shen
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA
| | - Xiaobo Yin
- Department of Mechanical Engineering, University of Colorado, Boulder, CO, 80309, USA.
- Materials Science and Engineering Program, University of Colorado, Boulder, CO, 80309, USA.
- Department of Mechanical Engineering, The University of Hong Kong, Hong Kong, China.
| |
Collapse
|
4
|
Wankerl H, Wiesmann C, Kreiner L, Butendeich R, Luce A, Sobczyk S, Stern ML, Lang EW. Directional emission of white light via selective amplification of photon recycling and Bayesian optimization of multi-layer thin films. Sci Rep 2022; 12:5226. [PMID: 35347188 PMCID: PMC8960816 DOI: 10.1038/s41598-022-08997-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 03/14/2022] [Indexed: 11/23/2022] Open
Abstract
Over the last decades, light-emitting diodes (LED) have replaced common light bulbs in almost every application, from flashlights in smartphones to automotive headlights. Illuminating nightly streets requires LEDs to emit a light spectrum that is perceived as pure white by the human eye. The power associated with such a white light spectrum is not only distributed over the contributing wavelengths but also over the angles of vision. For many applications, the usable light rays are required to exit the LED in forward direction, namely under small angles to the perpendicular. In this work, we demonstrate that a specifically designed multi-layer thin film on top of a white LED increases the power of pure white light emitted in forward direction. Therefore, the deduced multi-objective optimization problem is reformulated via a real-valued physics-guided objective function that represents the hierarchical structure of our engineering problem. Variants of Bayesian optimization are employed to maximize this non-deterministic objective function based on ray tracing simulations. Eventually, the investigation of optical properties of suitable multi-layer thin films allowed to identify the mechanism behind the increased directionality of white light: angle and wavelength selective filtering causes the multi-layer thin film to play ping pong with rays of light.
Collapse
Affiliation(s)
- Heribert Wankerl
- University of Regensburg, 93053, Regensburg, Germany. .,OSRAM Opto Semiconductors GmbH, 93055, Regensburg, Germany.
| | | | - Laura Kreiner
- OSRAM Opto Semiconductors GmbH, 93055, Regensburg, Germany
| | | | - Alexander Luce
- OSRAM Opto Semiconductors GmbH, 93055, Regensburg, Germany.,Max Planck Institute for the Science of Light, 91058, Erlangen, Germany.,Friedrich Alexander University Erlangen Nuremberg, 91054, Erlangen, Germany
| | - Sandra Sobczyk
- OSRAM Opto Semiconductors GmbH, 93055, Regensburg, Germany
| | | | | |
Collapse
|
5
|
Shen L, Lou R, Yin X. Asymmetrical interface design for unidirectional light extraction from spectrum conversion films. OPTICS EXPRESS 2022; 30:4642-4654. [PMID: 35209696 DOI: 10.1364/oe.449835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
In this study, we propose a micro-sized photonic structure that extracts 89% of the intrinsic trapped photons from the spectrum conversion film into free space using the Monte-Carlo ray-tracing method. Furthermore, the spectrum of the spectral-shifting film can be accurately simulated based on a mean free path concept, providing the estimation of its overall performance including the external quantum efficiency and the self-absorption efficiency. The simulations show that the spectrum conversion film with micro-structures shows a two-fold increase in the total external quantum efficiency and a four-fold increase in the external quantum efficiency in the forward viewing direction compared to the planar spectrum conversion films without micro-structures.
Collapse
|
6
|
Wu X, Fang C, Xu W, Zhang D. Bioinspired Compound Eyes for Diffused Light-Harvesting Application. ACS APPLIED MATERIALS & INTERFACES 2022; 14:4767-4774. [PMID: 35014247 DOI: 10.1021/acsami.1c22501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Natural compound eyes endow arthropods with wide-field high-performance light-harvesting capability that enables them to capture prey and avoid natural enemies in dim light. Inspired by natural compound eyes, a curved artificial-compound-eye (cACE) photodetector for diffused light harvesting is proposed and fabricated, and its light-harvesting capability is systematically investigated. The cACE photodetector is fabricated by introducing a cACE as a light-harvesting layer on the surface of a silicon-based photodetector, with the cACE being prepared via planar artificial-compound-eye (pACE) template deformation. The distinctive geometric morphology of the as-prepared cACE effectively reduces its surface reflection and the dependence of the projected area on the incident light direction, thereby significantly improving the light-harvesting ability and output photocurrent of the silicon-based photodetector. Furthermore, the performances of cACE, pACE, and bare polydimethylsiloxane (PDMS)-attached photodetectors as diffused light detectors are investigated under different luminances. The cACE-photodetector output photocurrent is 1.395 and 1.29 times those of the bare PDMS-attached and pACE photodetectors, respectively. Moreover, this photodetector has a desirable geometric shape. Thus, the proposed cACE photodetector will facilitate development of high-performance photodetectors for luminance sensing.
Collapse
Affiliation(s)
- Xinxue Wu
- Wenzhou Key Laboratory of Micro-nano Optoelectronic Devices, College of Electrical and Electronic Engineering, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Chaolong Fang
- Wenzhou Key Laboratory of Micro-nano Optoelectronic Devices, College of Electrical and Electronic Engineering, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Wangdong Xu
- Wenzhou Key Laboratory of Micro-nano Optoelectronic Devices, College of Electrical and Electronic Engineering, Wenzhou University, Wenzhou, Zhejiang 325035, China
| | - Dawei Zhang
- Engineering Research Center of Optical Instrument and System, the Ministry of Education, Shanghai Key Laboratory of Modern Optical System, University of Shanghai for Science and Technology, Shanghai 200093, China
| |
Collapse
|
7
|
Yuan D, Liu B, Guo Y, Zhu Z, Liu M, Cheng C, Gu M, Zhou S, Xu Q, Chen L, Liu J, Ouyang X. Light output enhancement of scintillators by using mixed-scale microstructures. OPTICS EXPRESS 2021; 29:24792-24803. [PMID: 34614827 DOI: 10.1364/oe.432114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 07/10/2021] [Indexed: 06/13/2023]
Abstract
Scintillators play an important role in the field of nuclear radiation detection. However, the light output of the scintillators is often limited by total internal reflection due to the high refractive indices of the scintillators. Furthermore, the light emission from scintillators typically has an approximately Lambertian profile, which is detrimental to the collection of the light. In this paper, we demonstrate a promising method to achieve enhancement of the light output from scintillators through use of mixed-scale microstructures that are composed of a photonic crystal slab and a microlens array. Simulations and experimental results both show significant improvements in the scintillator light output. The X-ray imaging characteristics of scintillators are improved by the application of the mixed-scale microstructures. The results presented here suggest that the application of the proposed mixed-scale microstructures to scintillators will be beneficial in the nuclear radiation detection field.
Collapse
|
8
|
Zhou Y, Qin Z, Liang Z, Meng D, Xu H, Smith DR, Liu Y. Ultra-broadband metamaterial absorbers from long to very long infrared regime. LIGHT, SCIENCE & APPLICATIONS 2021; 10:138. [PMID: 34226489 PMCID: PMC8257711 DOI: 10.1038/s41377-021-00577-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 06/01/2021] [Accepted: 06/17/2021] [Indexed: 05/25/2023]
Abstract
Broadband metamaterials absorbers with high absorption, ultrathin thickness and easy configurations are in great demand for many potential applications. In this paper, we first analyse the coupling resonances in a Ti/Ge/Ti three-layer absorber, which can realise broadband absorption from 8 to 12 μm. Then we experimentally demonstrate two types of absorbers based on the Ti/Ge/Si3N4/Ti configuration. By taking advantage of coupling surface plasmon resonances and intrinsic absorption of lossy material Si3N4, the average absorptions of two types of absorbers achieve almost 95% from 8 to 14 μm (experiment result: 78% from 6.5 to 13.5 μm). In order to expand the absorption bandwidth, we further propose two Ti/Si/SiO2/Ti absorbers which can absorb 92% and 87% of ultra-broadband light in the 14-30 μm and 8-30 μm spectral range, respectively. Our findings establish general and systematic strategies for guiding the design of metamaterial absorbers with excellent broadband absorption and pave the way for enhancing the optical performance in applications of infrared thermal emitters, imaging and photodetectors.
Collapse
Affiliation(s)
- Yu Zhou
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033, Changchun, Jilin, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Zheng Qin
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033, Changchun, Jilin, China
- University of Chinese Academy of Sciences, 100049, Beijing, China
| | - Zhongzhu Liang
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033, Changchun, Jilin, China.
- University of Chinese Academy of Sciences, 100049, Beijing, China.
- Center for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, College of Physics, Northeast Normal University, 130024, Changchun, China.
| | - Dejia Meng
- State Key Laboratory of Applied Optics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 130033, Changchun, Jilin, China
| | - Haiyang Xu
- Center for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, College of Physics, Northeast Normal University, 130024, Changchun, China
| | - David R Smith
- Center for Metamaterials and Integrated Plasmonics, Duke University, P.O. Box 90291, Durham, NC, 27708, USA
| | - Yichun Liu
- Center for Advanced Optoelectronic Functional Materials Research and Key Laboratory of UV Light-Emitting Materials and Technology of Ministry of Education, College of Physics, Northeast Normal University, 130024, Changchun, China
| |
Collapse
|
9
|
Zhu Z, Liu B, Zhang F, Tang H, Xu J, Gu M, Zhang C, Chen L, Liu J, Ouyang X. Improved light output from thick β-Ga 2O 3 scintillation crystals via graded-refractive-index photonic crystals. OPTICS EXPRESS 2021; 29:18646-18653. [PMID: 34154117 DOI: 10.1364/oe.428671] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 05/24/2021] [Indexed: 06/13/2023]
Abstract
β-Ga2O3 is a promising candidate as a fast scintillation crystal for radiation detection in fast X-ray imaging and high-energy physics experiments. However, total internal reflection severely limits its light output. Conventional photonic crystals can improve the light output, but such improvement decreases dramatically with increased scintillator thickness due to the strong backward reflection by the photonic crystals. Here, graded-refractive-index photonic crystals composed of nanocone arrays are designed and fabricated on the surfaces of β-Ga2O3 crystals with various thicknesses. Compared to the conventional photonic crystals, there is still an obvious light output improvement by using the graded-refractive-index photonic crystals when the thickness of the crystals is increased by three times. The effect of thickness on the improved light output is investigated with numerical simulations and experiments. Overall, the graded-refractive-index photonic crystals are beneficial to the improvement of light output from thick scintillators.
Collapse
|
10
|
Yuan D, Liu B, Zhu Z, Guo Y, Cheng C, Chen H, Gu M, Xu M, Chen L, Liu J, Ouyang X. Directional Control and Enhancement of Light Output of Scintillators by Using Microlens Arrays. ACS APPLIED MATERIALS & INTERFACES 2020; 12:29473-29480. [PMID: 32510919 DOI: 10.1021/acsami.0c06779] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Scintillators play an important role in the field of nuclear radiation detection, such as nuclear medical imaging, dark matter detection, nuclear physics experiments, and national security. However, the light extraction efficiency of a scintillator with a high refractive index is severely restricted because of the total internal reflection. In this paper, microlens arrays have been applied onto the surface of a cerium-doped lutetium-yttrium oxyorthosilicate scintillator to improve the light extraction efficiency and to control the directivity of the light output. Compared to that of a reference sample, a 3.26-fold enhancement with an emission angle of 45° has been obtained by using microlens arrays with optimal parameters. It was also found that the enhancement ratio can be affected by the refractive index of the microlens, the spacing of individual microlens. The control mechanism of microlens arrays is revealed by a combination of simulations and experiments. X-ray imaging characteristics exhibit an improved gray scale amplitude without any loss of the spatial resolution. The present results suggest that the application of microlens arrays to scintillators is beneficial to the field of nuclear radiation detection.
Collapse
Affiliation(s)
- Di Yuan
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Bo Liu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Zhichao Zhu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Yaozhen Guo
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Chuanwei Cheng
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Hong Chen
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Mu Gu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, P.R. China
| | - Mengxuan Xu
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024, P.R. China
| | - Liang Chen
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024, P.R. China
| | - Jinliang Liu
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024, P.R. China
| | - Xiaoping Ouyang
- State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Xi'an 710024, P.R. China
| |
Collapse
|
11
|
Zhou Y, Liang Z, Qin Z, Hou E, Shi X, Zhang Y, Xiong Y, Tang Y, Fan Y, Yang F, Liang J, Chen C, Lai J. Small-sized long wavelength infrared absorber with perfect ultra-broadband absorptivity. OPTICS EXPRESS 2020; 28:1279-1290. [PMID: 32121842 DOI: 10.1364/oe.382776] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Accepted: 12/22/2019] [Indexed: 05/28/2023]
Abstract
Two types of ultra-broadband long wavelength infrared (LWIR) absorbers with small period and super thin thickness are designed. The absorption with high absorptivity and large bandwidth is achieved through combined propagating and localized surfaced plasmon resonances. We first design a three-layer absorber with a Ti-Ge-Ti configuration, the period of the structure is only 1.4 µm (nearly 1/8 of the center wavelength), the thickness of its dielectric is only 0.5 µm (1/22 of the center wavelength), and the average absorption is 87.9% under normal incident from 8µm to 14µm. Furthermore, the four-layer absorber with a Ti-Ge-Si3N4-Ti configuration is designed to obtain more average absorption increasing to 94.5% from 8 µm to 14µm under normal incident, the period of the structure increases to 1.6 µm and the total thickness of dielectric increases to 0.6µm. The proposed absorber is polarization-independent and possesses a good tolerance of incident angle. We calculate that the average absorption of the four-layer absorber for both TE- and TM-modes still exceeds 90% up to an incident angle of θ = 40° (90.7% for TE-mode, 91.9% for TM-mode), and exceed 80% up to an incident angle of θ = 60° (80.2% for TE-mode, 82.1% for TM-mode).
Collapse
|
12
|
Gain AK, Zhang L. Mechanisms and optimization for the rapid fabrication method of polymeric microlens arrays. APPLIED OPTICS 2020; 59:405-412. [PMID: 32225319 DOI: 10.1364/ao.383365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 12/16/2019] [Indexed: 06/10/2023]
Abstract
This paper presents a simple and cost-effective rapid method to make defect-free polymeric microlens arrays at room temperature without applying external pressure. This method uses an optically clear and high-transparency Norland Optical Adhesive (NOA) monomer solution. This is realized by using a combination of a mold and an ultraviolet (UV) polymerization technique. NOA can cross-link in a tenth of a second upon UV exposure. The uniformity and surface quality of the manufactured microlens arrays are investigated through atomic force microscopy and optical microscopy techniques. Experimental results show that the microlens arrays manufactured by the polymerization process are of very high quality without any defects. Further, the surface quality of the lenses can be significantly enhanced by increasing the viscosity of the photosensitive monomer solution.
Collapse
|