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Effect of slit width on surface plasmon resonance
Journal Pre-proofs Microarticle Effect of slit width on surface plasmon resonance Yingying Wang, Feng Qin, Zao Yi, Xifang Chen, Zigang Zhou, Hua Yang, Xu Liao, Yongjian Tang, Weitang Yao, Yougen Yi PII: DOI: Reference:
S2211-3797(19)32250-8 https://doi.org/10.1016/j.rinp.2019.102711 RINP 102711
To appear in:
Results in Physics
Received Date: Revised Date: Accepted Date:
27 July 2019 16 September 2019 26 September 2019
Please cite this article as: Wang, Y., Qin, F., Yi, Z., Chen, X., Zhou, Z., Yang, H., Liao, X., Tang, Y., Yao, W., Yi, Y., Effect of slit width on surface plasmon resonance, Results in Physics (2019), doi: https://doi.org/10.1016/j.rinp. 2019.102711
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
Effect of slit width on surface plasmon resonance Yingying Wang1,3, Feng Qin1,3, Zao Yi 1,3, Xifang Chen1,3, Zigang Zhou1,3*, Hua Yang2, Xu Liao1,3, Yongjian Tang3, Weitang Yao1,3, Yougen Yi4 1Joint
Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and
Technology, Mianyang 621010, China 2 State
Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou
University of Technology, Lanzhou 730050, China 3
Sichuan Civil-Military Integration Institute, Mianyang 621010, China
4 College
of Physics and Electronics, Central South University, Changsha 410083, China
Abstract In this paper, a hybrid resonator composed of an all-metal grating made of copper and a dielectric cavity filled with SiO2 between slits is simulated and calculated by the finite-difference time-domain method (FDTD). We study the effect of slit width on surface plasmon resonance by changing the size of the dielectric cavity. In the case of parallel light incident vertically, the resonator can achieve multi-band absorption and have a perfect absorption peak. The dielectric cavity can not only localize the incident light wave, but also enhance the effect of surface plasmon of metal structure. Our results can be widely used in the field of surface plasmon, which is beneficial to the development of surface plasmon resonators in sensing and detection. Keywords: Multi-band; Surface plasmon resonance; Perfect absorption; Full metal grating; Slit 1. Introduction Recently, the establishment of the structure of precious metals on the nanoscale has attracted great attention of surface plasmons (SPs)[1]. The basic principle is that the electrons on the interface of medium (such as metal and medium) with opposite signs of dielectric constant jointly capture the near-field incident light, make the electrons and photons move together, and induce electromagnetic field enhancement and concentration of light energy[2-4]. At this time, a strong resonance peak appears in the spectrum, which is called surface plasmon resonance (SPR)[5]. In the field of SPR, the current researches mainly focus on the noble metal nanostructures far smaller than the incident light wave Correspondence should be addressed to Zao Yi, and Zigang Zhou. E-mail address: [email protected]; [email protected] 1
length. Due to their excellent performance, SPR is widely used in modulators[6], photodetectors[7], optical filters[8], biosensors[9] and other fields[10-14]. Nanostructures have been particularly attractive in recent years. Because the nanostructure can cause high local electric fields, this is due to the strong coupling of SPs internally and externally[15]. SPR of different structures were studied, including subwavelength slit, subwavelength hole, subwavelength slit cluster and subwavelength hole[16-20]. The recently reported perfect absorber using a plasmonic grating at visible and near-infrared wavelengths indicates that light absorption is controllable when the polarization of light changes[16]. In this paper, a hybrid resonator composed of all-metal copper grating and a dielectric cavity filled with SiO2 between gaps is designed theoretically. In the range of visible light to near infrared band, we realize the multi-band absorption, and get a near unit absorption peak. We mainly study the effect of slit width on SPR. The numerical results show that the resonance wavelength has a red shift as the width decreases. The multi-band absorption results obtained are beneficial to the development of SPR in the field of sensing and detection. 2. Structure and methods The resonator we designed is based on a one-dimensional metal grating with a silicide (SiO2) medium filled between the gaps. The whole structure is composed of copper, with 300 nm thick metal (h2) blocks at the bottom and 900 nm thick grating structure (h1) at the top. The grating period is px=810 nm, py=1000 nm and the slit width is d=70 nm (detailed models can be found in Appendix A-Fig. 1, and manufacturing methods can be found in Appendix A). The metal block at the bottom is used to prevent transmission of incident electromagnetic waves. The copper parameters were derived from Drude model [21]. The refractive index of SiO2 filled between the slits is 1.97. In the simulation process using the FDTD method, the plane light source is vertically incident, the periodic boundary condition is used in both X and Y directions, and the ideal perfect matching layer condition is used in Z direction. Our absorption of A is derived from the relationship
A( ) 1 T ( ) R( ) , where T and R represent
transmission and reflection respectively [22]. Since the bottom metal blocks can offset the incoming electromagnetic waves, we can know that the transmission of the structure is zero. That is, the absorption rate can be converted to
A( ) 1 R( ) .
3. Result and Discussion
2
Fig. 1 (a) When the slit width is d= 70 nm, the spectrum of all-metal copper grating coupled with the dielectric cavity filled with SiO2; (b) Vary the width of the slit. The spectra when d=65 nm, 70 nm and 75 nm, respectively. Fig. 1 (a) shows the absorption of all-metal grating under optimized parameters. It can be seen from the figure that the all-metal grating structure can achieve multi-band absorption in the range of 400-1500 nm. Peak 1 (absorption more than 36%), peak 2 (absorption more than 55%), peak 3 (absorption more than 74%), peak 4 (absorption more than 97%), peak 5 (absorption more than 99%), and peak 6 (absorption more than 96%), the corresponding wavelengths are 526. 344 nm, 573. 424 nm, 642. 375 nm, 756. 532 nm, 942. 305 nm, and 1290. 42 nm, respectively. Peak 5 is the perfect absorption peak. Six absorption peaks appear in the short wavelength range, which indicates that SPs of nano-copper structures are excited by all-metal grating periodic structure under the action of dielectric cavity.Among them, peak 1 is caused by MPs resonance, peak 2 and peak 3 are caused by FP cavity resonance, and peak 4-6 are caused by SPR(the detailed electric field distribution corresponding to each absorption peak is shown in Appendix A-Fig. 2). Then we study the effect of slit width on the SPR of all-metal copper grating. In the research process, we reduced and increased the width by 5nm respectively, and obtained the absorption of d at 65 nm, 70 nm and 75 nm, as shown in Fig. 1 (b). It can be seen from Fig. 1 (b), with the decrease of d, the wavelength of SPR shows a red shift, and the absorption characteristics at the peak of 2-4 are opposite to those at the peak 5 and peak 6. The absorption at peak 1 is basically unchanged. The absorption at peak 2-4 decreases with the decrease of slit width, while that at peak 5 and peak 6 increases. With the decrease of slit width, the space of dielectric cavity becomes narrower, and the limitation of the charge in the cavity is more pronounced. Eventually, the near-field coupling between the nano-copper structures is enhanced [23-25]. This is 3
why the resonance wavelength is red-shifted. The results show that the width of slit has a significant impact on the SPR. By adjusting the width of slit, SPR can be effectively controlled, which is beneficial to its application in the field of sensing and detection. 4. Conclusion In conclusion, we designed a hybrid resonator with a parallel light source incident vertically into the all-metal copper grating and a medium cavity filled with SiO2, and studied the effect of slit width on SPR. The numerical results show that the structure can achieve multi-band absorption in the visible to near-infrared band (400-1500 nm) and perfect absorption in the large band (around 1000 nm). The width of slit has a significant effect on SPR, so we can regulate the effect of SPR by changing the width of the slit. This conclusion can be applied to a wide range of plasmonic structures. By adjusting the slit width, we can apply SPR to optical switches, biosensors, photodetectors and other fields.
Conflict of Interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “Effect of slit width on surface plasmon resonance”.
Acknowledgements The work is supported by the National Natural Science Foundation of China (NNSFC) (51606158, 11875228, 21671160); Funded by Sichuan Science and Technology Program (2018GZ0521). Declarations of interest: none Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at…..
4
References [1] Barnes W L, Dereux A, Ebbesen T W. Surface plasmon sub-wavelength optics. Nature 2003, 424: 824–830. [2] Masson J F. Surface Plasmon Resonance Clinical Biosensors for Medical Diagnostics. ACS Sensors, 2017, 2(1): 16-30. [3] Liang C P, Zhang Y B, Yi Z, et al. A broadband and polarization-independent metamaterial perfect absorber with monolayer Cr and Ti elliptical disks array. Results Phys. 2019, DOI: 10.1016/j.rinp.2019.102635. [4] Li M W, Liang C P, Zhang Y B, et al. Terahertz wideband perfect absorber based on open loop with cross nested structure. Results Phys. 2019, 15: 102603. [5] Liang C P, Yi Z, Chen X F, et al. Dual-band infrared perfect absorber based on a Ag-dielectric-Ag multilayer films with nanoring grooves arrays. Plasmonics 2019, DOI: 10.1007/s11468-019-01018-4. [6] Melikyan A, Lindenmann N, Walheim S, et al. Surface plasmon polariton absorption modulator. Optics Express, 2011, 19(9): 8855-69. [7] Wang X X, Zhu J K, Wen X L, et al. Wide range refractive index sensor based on a coupled structure of Au nanocubes and Au film. Opt. Mater. Express 2019, 9(7): 3079-3088. [8] Liu C, Yang L, Lu X L, et al. Mid-infrared surface plasmon resonance sensor based on photonic crystal fibers. Optics Express, 2017, 25: 14227-14237. [9] Liu C, Yang L, Liu Q, et al. Analysis of a Surface Plasmon Resonance Probe Based on Photonic Crystal Fibers for Low Refractive Index Detection. Plasmonics 2018, 13: 779-784. [10] Yi Z, Li X, Wu H, et al. Fabrication of ZnO@Ag3PO4 Core-Shell Nanocomposite Arrays as Photoanodes and Their Photoelectric Properties. Nanomaterials 2019, 9: 1254. [11] Li H L, Wang G Y, Niu J B, et al. Preparation of TiO2 nanotube arrays with efficient photocatalytic performance and super-hydrophilic properties utilizing anodized voltage method. Results Phys. 2019, 14: 102499. [12] Zhao X X, Yang H, Cui Z M, et al. Synergistically enhanced photocatalytic performance of Bi4Ti3O12 nanosheets by Au and Ag nanoparticles. J. Mater. Sci. Mater. Electron. 2019, 30: 13785-13796. [13] Di L J, Xian T, Sun X F, et al. Facile preparation of CNT/Ag2S nanocomposites with improved visible and NIR light photocatalytic degradation activity and their catalytic mechanism. Micromachines 5
2019, 10: 503. [14] Yan Y X, Yang H, Zhao X X, et al. A hydrothermal route to the synthesis of CaTiO3 nanocuboids using P25 as the titanium source. J. Electron. Mater. 2018, 47: 3045-3050. [15] Wang X X, Bai X L, Pang Z Y, et al. Surface-enhanced Raman scattering by composite structure of gold nanocube-PMMA-gold film. Opt. Mater. Express 2019, 9(4): 1872-1881. [16] Nguyen D M, Lee D, Rho J. Control of light absorbance using plasmonic grating based perfect absorber at visible and near-infrared wavelengths. Scientific Reports, 2017, 7(1): 2611. [17] Koerkamp K, Enoch S, Segerink F, et al. Strong Influence of Hole Shape on Extraordinary Transmission through Periodic Arrays of Subwavelength Holes. Physical Review Letters, 2004, 92(18): 183901-0. [18] Liu Z Q, Liu G Q, Liu X S, et al. Ultra-sharp Plasmonic Super-cavity Resonance and Light Absorption. Plasmonics 2019, https://doi.org/10.1007/s11468-019-01003-x. [19] Liu G, Liu Y, Tang L, et al. Semiconductor-enhanced Raman scattering sensors via quasi-three-dimensional Au/Si/Au structures, Nanophotonics 2019, 8(6): 1095-1107. [20] Li H L, Niu J B, Wang G Y. Dual-band, polarization-insensitive metamaterial perfect absorber based on monolayer graphene in the mid-infrared range. Results Phys. 2019, 13: 102313. [21] Chen J, Fan W F, Mao P, et al. Tailoring Plasmon Lifetime in Suspended Nanoantenna Arrays for High-Performance Plasmon Sensing. Plasmonics 2017, 12(3): 529-534. [22] Yi Z, Liang C P, Chen X F, et al. Dual-Band Plasmonic Perfect Absorber Based on Graphene Metamaterials for Refractive Index Sensing Application. Micromachines 2019, 10(7): 443. [23] Liu G, Chen J, Pan P, Liu Z. Hybrid Metal-Semiconductor Meta-Surface Based Photo-Electronic Perfect Absorber. IEEE Journal of Selected Topics in Quantum Electronics 2019, 25: 1-7. [24] Chen Z Q , Li P, Zhang S, et al. Enhanced extraordinary optical transmission and refractive-index sensing sensitivity in tapered plasmonic nanohole arrays. Nanotechnology 2019, 30: 335201. [25] Babu A, Bhagyaraj C, Ajith R, et al. Dispersion Characteristics of Guided Plasmonic Modes in Metallic Slot Waveguides Using Method of Lines. Journal of Computational and Theoretical Nanoscience, 2013, 10(9):2276-2281.
6
Appendix A. Supplementary data
Effect of Slit Width on Surface Plasmon Yingying Wang1,3, Feng Qin1,3, Zao Yi 1,3, Xifang Chen1,3, Zigang Zhou1,3*, Hua Yang2, Xu Liao1,3, Yongjian Tang3, Weitang Yao1,3, Yougen Yi4 1Joint
Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and
Technology, Mianyang 621010, China 2 State
Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou
University of Technology, Lanzhou 730050, China 3
Sichuan Civil-Military Integration Institute, Mianyang 621010, China
4 College
of Physics and Electronics, Central South University, Changsha 410083, China
Correspondence should be addressed to Zao Yi, and Zigang Zhou. E-mail address: [email protected]; [email protected] 7
Fig. 1 The picture on the left shows a period in the plane structure. On the right is a three-dimensional view of the structure and the meaning of each parameter
As is shown in Fig.1, the height of the whole model is 1200 nm, where the bottom is a copper metal block with a thickness of 300 nm(h2) and the top is a metal copper grating structure with a thickness of 900 nm(h1). Slit width d=70 nm. The period along the X axis is px=810 nm, and the period along the Y axis is py=1000 nm. The finite-difference time-domain method (FDTD) is used to simulate the physical model. The absorption of the physical model is obtained by adding the reflection and transmission electric field monitor and using the relationship between reflection, transmission and absorption. From the absorption curve, we can know whether coupling occurs in the model. After changing the parameters, we can analyze by absorption changes. This phenomenon is described in my manuscript. It is worth mentioning that the fabrication method of the structure is simple in practical application. Firstly, the copper substrate is evaporated on the handle substrate[1]. Then high-resolution electron 8
beam (EB) lithography and reactive ion etching are used to fabricate grating structures on copper substrate. Finally, the spin coating method is used to regulate the viscosity and rotation speed of the coating material to accurately control the thickness of SiO2 layer[2].
Fig. 2 Electric field distribution at peak1, peak 2, peak 3, peak 4, peak 5 and peak 6
Fig. 2 shows the electric field distribution at peak 1-6. It can be seen from the figure that when the absorption peak is peak 1, the electric field energy mainly concentrates on the edge of the metal grating and the concentration point of energy can be observed, which is a typical feature of MPs[3]. Therefore, the absorption at peak 1 is caused by the MPs resonance excited by the metal grating. When the absorption peaks are peak 2 and peak 3, the electric field energy is limited between the slits, which is a typical Fabry - Perot cavity resonance characteristic[4]. Therefore, the absorption at peak 2 and peak 3 comes from FP cavity resonance. When the absorption peak are peak 4-6, the electric field energy is mainly concentrated between the metal grating surface and the slit, which is a typical characteristic of SPR. Therefore, the absorption at peak 4-6 is caused by SPR excited by metal grating. References [1] Zhang J G, Tian J P, Li L. Pantoscopic and temperature-controlled dual-band perfect absorber based on strontium titanate material. Mater. Res. Express, 2018, 5: 065802. [2]Kanamori Y, Roy E, Chen Y. Antireflection sub-wavelength gratings fabricated by spin-coating replication. Microelectronic Engineering, 2005, 78-79: 287-293. [3]Zhao B, Zhao J M, Zhang Z M.
Resonance enhanced absorption in a graphene monolayer using
deep metal gratings. Journal of the Optical Society of America B, 2015, 32(6): 1176. 9
[4]Zhang S, Wang Y, Wang S, Zheng W. Wavelength-tunable perfect absorber basedon guided-mode resonances. Applied optics, 2016, 55(12): 3176-3181.
10
Highlights > The proposed nanostructures have 6 absorption peaks in the range of 400-1500nm and a obvious perfect absorption peak at 942. 305 nm. > The proposed nanostructure is simple and easy to manufacture in practical production. > Cu and SiO2 have low cost and high practicability.
11
S2211-3797(19)32250-8 https://doi.org/10.1016/j.rinp.2019.102711 RINP 102711
To appear in:
Results in Physics
Received Date: Revised Date: Accepted Date:
27 July 2019 16 September 2019 26 September 2019
Please cite this article as: Wang, Y., Qin, F., Yi, Z., Chen, X., Zhou, Z., Yang, H., Liao, X., Tang, Y., Yao, W., Yi, Y., Effect of slit width on surface plasmon resonance, Results in Physics (2019), doi: https://doi.org/10.1016/j.rinp. 2019.102711
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
Effect of slit width on surface plasmon resonance Yingying Wang1,3, Feng Qin1,3, Zao Yi 1,3, Xifang Chen1,3, Zigang Zhou1,3*, Hua Yang2, Xu Liao1,3, Yongjian Tang3, Weitang Yao1,3, Yougen Yi4 1Joint
Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and
Technology, Mianyang 621010, China 2 State
Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou
University of Technology, Lanzhou 730050, China 3
Sichuan Civil-Military Integration Institute, Mianyang 621010, China
4 College
of Physics and Electronics, Central South University, Changsha 410083, China
Abstract In this paper, a hybrid resonator composed of an all-metal grating made of copper and a dielectric cavity filled with SiO2 between slits is simulated and calculated by the finite-difference time-domain method (FDTD). We study the effect of slit width on surface plasmon resonance by changing the size of the dielectric cavity. In the case of parallel light incident vertically, the resonator can achieve multi-band absorption and have a perfect absorption peak. The dielectric cavity can not only localize the incident light wave, but also enhance the effect of surface plasmon of metal structure. Our results can be widely used in the field of surface plasmon, which is beneficial to the development of surface plasmon resonators in sensing and detection. Keywords: Multi-band; Surface plasmon resonance; Perfect absorption; Full metal grating; Slit 1. Introduction Recently, the establishment of the structure of precious metals on the nanoscale has attracted great attention of surface plasmons (SPs)[1]. The basic principle is that the electrons on the interface of medium (such as metal and medium) with opposite signs of dielectric constant jointly capture the near-field incident light, make the electrons and photons move together, and induce electromagnetic field enhancement and concentration of light energy[2-4]. At this time, a strong resonance peak appears in the spectrum, which is called surface plasmon resonance (SPR)[5]. In the field of SPR, the current researches mainly focus on the noble metal nanostructures far smaller than the incident light wave Correspondence should be addressed to Zao Yi, and Zigang Zhou. E-mail address: [email protected]; [email protected] 1
length. Due to their excellent performance, SPR is widely used in modulators[6], photodetectors[7], optical filters[8], biosensors[9] and other fields[10-14]. Nanostructures have been particularly attractive in recent years. Because the nanostructure can cause high local electric fields, this is due to the strong coupling of SPs internally and externally[15]. SPR of different structures were studied, including subwavelength slit, subwavelength hole, subwavelength slit cluster and subwavelength hole[16-20]. The recently reported perfect absorber using a plasmonic grating at visible and near-infrared wavelengths indicates that light absorption is controllable when the polarization of light changes[16]. In this paper, a hybrid resonator composed of all-metal copper grating and a dielectric cavity filled with SiO2 between gaps is designed theoretically. In the range of visible light to near infrared band, we realize the multi-band absorption, and get a near unit absorption peak. We mainly study the effect of slit width on SPR. The numerical results show that the resonance wavelength has a red shift as the width decreases. The multi-band absorption results obtained are beneficial to the development of SPR in the field of sensing and detection. 2. Structure and methods The resonator we designed is based on a one-dimensional metal grating with a silicide (SiO2) medium filled between the gaps. The whole structure is composed of copper, with 300 nm thick metal (h2) blocks at the bottom and 900 nm thick grating structure (h1) at the top. The grating period is px=810 nm, py=1000 nm and the slit width is d=70 nm (detailed models can be found in Appendix A-Fig. 1, and manufacturing methods can be found in Appendix A). The metal block at the bottom is used to prevent transmission of incident electromagnetic waves. The copper parameters were derived from Drude model [21]. The refractive index of SiO2 filled between the slits is 1.97. In the simulation process using the FDTD method, the plane light source is vertically incident, the periodic boundary condition is used in both X and Y directions, and the ideal perfect matching layer condition is used in Z direction. Our absorption of A is derived from the relationship
A( ) 1 T ( ) R( ) , where T and R represent
transmission and reflection respectively [22]. Since the bottom metal blocks can offset the incoming electromagnetic waves, we can know that the transmission of the structure is zero. That is, the absorption rate can be converted to
A( ) 1 R( ) .
3. Result and Discussion
2
Fig. 1 (a) When the slit width is d= 70 nm, the spectrum of all-metal copper grating coupled with the dielectric cavity filled with SiO2; (b) Vary the width of the slit. The spectra when d=65 nm, 70 nm and 75 nm, respectively. Fig. 1 (a) shows the absorption of all-metal grating under optimized parameters. It can be seen from the figure that the all-metal grating structure can achieve multi-band absorption in the range of 400-1500 nm. Peak 1 (absorption more than 36%), peak 2 (absorption more than 55%), peak 3 (absorption more than 74%), peak 4 (absorption more than 97%), peak 5 (absorption more than 99%), and peak 6 (absorption more than 96%), the corresponding wavelengths are 526. 344 nm, 573. 424 nm, 642. 375 nm, 756. 532 nm, 942. 305 nm, and 1290. 42 nm, respectively. Peak 5 is the perfect absorption peak. Six absorption peaks appear in the short wavelength range, which indicates that SPs of nano-copper structures are excited by all-metal grating periodic structure under the action of dielectric cavity.Among them, peak 1 is caused by MPs resonance, peak 2 and peak 3 are caused by FP cavity resonance, and peak 4-6 are caused by SPR(the detailed electric field distribution corresponding to each absorption peak is shown in Appendix A-Fig. 2). Then we study the effect of slit width on the SPR of all-metal copper grating. In the research process, we reduced and increased the width by 5nm respectively, and obtained the absorption of d at 65 nm, 70 nm and 75 nm, as shown in Fig. 1 (b). It can be seen from Fig. 1 (b), with the decrease of d, the wavelength of SPR shows a red shift, and the absorption characteristics at the peak of 2-4 are opposite to those at the peak 5 and peak 6. The absorption at peak 1 is basically unchanged. The absorption at peak 2-4 decreases with the decrease of slit width, while that at peak 5 and peak 6 increases. With the decrease of slit width, the space of dielectric cavity becomes narrower, and the limitation of the charge in the cavity is more pronounced. Eventually, the near-field coupling between the nano-copper structures is enhanced [23-25]. This is 3
why the resonance wavelength is red-shifted. The results show that the width of slit has a significant impact on the SPR. By adjusting the width of slit, SPR can be effectively controlled, which is beneficial to its application in the field of sensing and detection. 4. Conclusion In conclusion, we designed a hybrid resonator with a parallel light source incident vertically into the all-metal copper grating and a medium cavity filled with SiO2, and studied the effect of slit width on SPR. The numerical results show that the structure can achieve multi-band absorption in the visible to near-infrared band (400-1500 nm) and perfect absorption in the large band (around 1000 nm). The width of slit has a significant effect on SPR, so we can regulate the effect of SPR by changing the width of the slit. This conclusion can be applied to a wide range of plasmonic structures. By adjusting the slit width, we can apply SPR to optical switches, biosensors, photodetectors and other fields.
Conflict of Interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled, “Effect of slit width on surface plasmon resonance”.
Acknowledgements The work is supported by the National Natural Science Foundation of China (NNSFC) (51606158, 11875228, 21671160); Funded by Sichuan Science and Technology Program (2018GZ0521). Declarations of interest: none Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at…..
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References [1] Barnes W L, Dereux A, Ebbesen T W. Surface plasmon sub-wavelength optics. Nature 2003, 424: 824–830. [2] Masson J F. Surface Plasmon Resonance Clinical Biosensors for Medical Diagnostics. ACS Sensors, 2017, 2(1): 16-30. [3] Liang C P, Zhang Y B, Yi Z, et al. A broadband and polarization-independent metamaterial perfect absorber with monolayer Cr and Ti elliptical disks array. Results Phys. 2019, DOI: 10.1016/j.rinp.2019.102635. [4] Li M W, Liang C P, Zhang Y B, et al. Terahertz wideband perfect absorber based on open loop with cross nested structure. Results Phys. 2019, 15: 102603. [5] Liang C P, Yi Z, Chen X F, et al. Dual-band infrared perfect absorber based on a Ag-dielectric-Ag multilayer films with nanoring grooves arrays. Plasmonics 2019, DOI: 10.1007/s11468-019-01018-4. [6] Melikyan A, Lindenmann N, Walheim S, et al. Surface plasmon polariton absorption modulator. Optics Express, 2011, 19(9): 8855-69. [7] Wang X X, Zhu J K, Wen X L, et al. Wide range refractive index sensor based on a coupled structure of Au nanocubes and Au film. Opt. Mater. Express 2019, 9(7): 3079-3088. [8] Liu C, Yang L, Lu X L, et al. Mid-infrared surface plasmon resonance sensor based on photonic crystal fibers. Optics Express, 2017, 25: 14227-14237. [9] Liu C, Yang L, Liu Q, et al. Analysis of a Surface Plasmon Resonance Probe Based on Photonic Crystal Fibers for Low Refractive Index Detection. Plasmonics 2018, 13: 779-784. [10] Yi Z, Li X, Wu H, et al. Fabrication of ZnO@Ag3PO4 Core-Shell Nanocomposite Arrays as Photoanodes and Their Photoelectric Properties. Nanomaterials 2019, 9: 1254. [11] Li H L, Wang G Y, Niu J B, et al. Preparation of TiO2 nanotube arrays with efficient photocatalytic performance and super-hydrophilic properties utilizing anodized voltage method. Results Phys. 2019, 14: 102499. [12] Zhao X X, Yang H, Cui Z M, et al. Synergistically enhanced photocatalytic performance of Bi4Ti3O12 nanosheets by Au and Ag nanoparticles. J. Mater. Sci. Mater. Electron. 2019, 30: 13785-13796. [13] Di L J, Xian T, Sun X F, et al. Facile preparation of CNT/Ag2S nanocomposites with improved visible and NIR light photocatalytic degradation activity and their catalytic mechanism. Micromachines 5
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Appendix A. Supplementary data
Effect of Slit Width on Surface Plasmon Yingying Wang1,3, Feng Qin1,3, Zao Yi 1,3, Xifang Chen1,3, Zigang Zhou1,3*, Hua Yang2, Xu Liao1,3, Yongjian Tang3, Weitang Yao1,3, Yougen Yi4 1Joint
Laboratory for Extreme Conditions Matter Properties, Southwest University of Science and
Technology, Mianyang 621010, China 2 State
Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou
University of Technology, Lanzhou 730050, China 3
Sichuan Civil-Military Integration Institute, Mianyang 621010, China
4 College
of Physics and Electronics, Central South University, Changsha 410083, China
Correspondence should be addressed to Zao Yi, and Zigang Zhou. E-mail address: [email protected]; [email protected] 7
Fig. 1 The picture on the left shows a period in the plane structure. On the right is a three-dimensional view of the structure and the meaning of each parameter
As is shown in Fig.1, the height of the whole model is 1200 nm, where the bottom is a copper metal block with a thickness of 300 nm(h2) and the top is a metal copper grating structure with a thickness of 900 nm(h1). Slit width d=70 nm. The period along the X axis is px=810 nm, and the period along the Y axis is py=1000 nm. The finite-difference time-domain method (FDTD) is used to simulate the physical model. The absorption of the physical model is obtained by adding the reflection and transmission electric field monitor and using the relationship between reflection, transmission and absorption. From the absorption curve, we can know whether coupling occurs in the model. After changing the parameters, we can analyze by absorption changes. This phenomenon is described in my manuscript. It is worth mentioning that the fabrication method of the structure is simple in practical application. Firstly, the copper substrate is evaporated on the handle substrate[1]. Then high-resolution electron 8
beam (EB) lithography and reactive ion etching are used to fabricate grating structures on copper substrate. Finally, the spin coating method is used to regulate the viscosity and rotation speed of the coating material to accurately control the thickness of SiO2 layer[2].
Fig. 2 Electric field distribution at peak1, peak 2, peak 3, peak 4, peak 5 and peak 6
Fig. 2 shows the electric field distribution at peak 1-6. It can be seen from the figure that when the absorption peak is peak 1, the electric field energy mainly concentrates on the edge of the metal grating and the concentration point of energy can be observed, which is a typical feature of MPs[3]. Therefore, the absorption at peak 1 is caused by the MPs resonance excited by the metal grating. When the absorption peaks are peak 2 and peak 3, the electric field energy is limited between the slits, which is a typical Fabry - Perot cavity resonance characteristic[4]. Therefore, the absorption at peak 2 and peak 3 comes from FP cavity resonance. When the absorption peak are peak 4-6, the electric field energy is mainly concentrated between the metal grating surface and the slit, which is a typical characteristic of SPR. Therefore, the absorption at peak 4-6 is caused by SPR excited by metal grating. References [1] Zhang J G, Tian J P, Li L. Pantoscopic and temperature-controlled dual-band perfect absorber based on strontium titanate material. Mater. Res. Express, 2018, 5: 065802. [2]Kanamori Y, Roy E, Chen Y. Antireflection sub-wavelength gratings fabricated by spin-coating replication. Microelectronic Engineering, 2005, 78-79: 287-293. [3]Zhao B, Zhao J M, Zhang Z M.
Resonance enhanced absorption in a graphene monolayer using
deep metal gratings. Journal of the Optical Society of America B, 2015, 32(6): 1176. 9
[4]Zhang S, Wang Y, Wang S, Zheng W. Wavelength-tunable perfect absorber basedon guided-mode resonances. Applied optics, 2016, 55(12): 3176-3181.
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Highlights > The proposed nanostructures have 6 absorption peaks in the range of 400-1500nm and a obvious perfect absorption peak at 942. 305 nm. > The proposed nanostructure is simple and easy to manufacture in practical production. > Cu and SiO2 have low cost and high practicability.
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