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Nguyen LYT, Chang YF, Tseng YE, Chang HM, Hsu CC, Lin JY, Kan HC. Focusing of surface plasmon polaritons propagating at the SiO 2/Ag interface with 2-level and 4-level Fresnel phase zone pad structures. NANOSCALE 2023; 15:17198-17205. [PMID: 37855162 DOI: 10.1039/d3nr04121b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2023]
Abstract
We propose and demonstrate dielectric Fresnel phase zone pad (FPZP) structures for focusing surface plasmon polaritons (SPPs) propagating at the SiO2/Ag interfaces. We exploited up-conversion fluorescence microscopy to characterize the SPP focusing. We first report on the SPP focusing with 2-level FPZP structures that introduced a π-phase shift in the SPP wavefront between adjacent zones. We optimized the SPP focusing by fine-tuning the longitudinal width of the FPZP structure. This led to the enhancement of the peak intensity of the SPP focal spot and the reduction of the focal spot size in both the longitudinal and transverse directions. Such focusing was also demonstrated with different focal lengths. To further improve the SPP focusing, we developed a 4-level FPZP structure, which introduced a π/2-phase shift in the SPP wavefront between adjacent zones. With the optimized 4-level FPZP structure, the SPP focal spot peak intensity is further improved, and the spot size is reduced. To assist the design of the FPZP structures, we carried out theoretical analysis and numerical calculations to determine the SPP wavelengths at various oxide/Ag interfaces. We also carried out finite difference time domain (FDTD) calculations to simulate the SPP focusing with the FPZP structures. The results of the FDTD simulation agree with the experimental results qualitatively.
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Affiliation(s)
- Lam Yen Thi Nguyen
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
| | - Yu-Fang Chang
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
| | - Yang-En Tseng
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
| | - Hao-Ming Chang
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
| | - Chia-Chen Hsu
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
| | - Jiunn-Yuan Lin
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
| | - Hung-Chih Kan
- National Chung Cheng University, 168, Sec. 1, University Rd. Min-Hsiung, Chiayi 62102, Taiwan, Republic of China.
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Crampton KT, Joly AG, El-Khoury P. Femtosecond photoemission electron microscopy of surface plasmon polariton beam steering via nanohole arrays. J Chem Phys 2020; 153:081103. [PMID: 32872854 DOI: 10.1063/5.0021032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Directional control over surface plasmon polariton (SPP) waves is a prerequisite for the development of miniaturized optical circuitry. Here, the efficacy of single and dual component SPP steering elements is explored through photoemission electron microscopy. Our imaging scheme relies on two-color photoemission and counter-propagating SPP generation, which collectively allow SPPs to be visualized in real space. Wave-vector difference mixing between the two-dimensional nanohole array and photon momenta enables SPP steering with directionality governed by the array lattice constant and input photon direction. In our dual component configuration, separate SPP generation and Bragg diffraction based steering optics are employed. We find that array Bragg planes principally influence the SPP angles through the array band structure, which allows us to visualize both positive and negative refractory waves.
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Affiliation(s)
- Kevin T Crampton
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
| | - Alan G Joly
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
| | - Patrick El-Khoury
- Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, USA
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Crampton KT, Joly AG, El-Khoury PZ. Direct Visualization of Counter-Propagating Surface Plasmons in Real Space-Time. J Phys Chem Lett 2019; 10:5694-5699. [PMID: 31498629 DOI: 10.1021/acs.jpclett.9b02151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We deploy two-dimensional nanohole arrays as resonant surface plasmon polariton (SPP) couplers that enable counter-propagation and excitation field interference-free imaging of SPP wave packets. We monitor the spatiotemporal evolution of the resulting SPPs using two-color photoemission electron microscopy. The measurements track the electric field envelope of the SPP in real space and time and enable direct characterization of their spatiotemporal properties in a regime where the SPP wave packet is the principal observable. We provide an analysis of the observables for both the co- and counter-propagating directions via SPP trajectories that are recorded in tandem. Our results highlight the advantages of isolating SPPs through counter-propagation, where excitation field-SPP interactions are suppressed.
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Affiliation(s)
- Kevin T Crampton
- Physical Sciences Division , Pacific Northwest National Laboratory , P.O. Box 999, Richland , Washington 99352 , United States
| | - Alan G Joly
- Physical Sciences Division , Pacific Northwest National Laboratory , P.O. Box 999, Richland , Washington 99352 , United States
| | - Patrick Z El-Khoury
- Physical Sciences Division , Pacific Northwest National Laboratory , P.O. Box 999, Richland , Washington 99352 , United States
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Cesaria M, Taurino A, Manera MG, Minunni M, Scarano S, Rella R. Gold nanoholes fabricated by colloidal lithography: novel insights into nanofabrication, short-range correlation and optical properties. NANOSCALE 2019; 11:8416-8432. [PMID: 30985849 DOI: 10.1039/c8nr09911a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Colloidal lithography is widely used as a low cost and large-area deposition approach, alternative to the conventional small-area expensive lithographic techniques, for the fabrication of short-range ordered sub-wavelength metallic nanostructures. This paper contributes to the understanding of the impact of the fabrication protocol of a colloidal mask on the optical and sensing properties of short range-ordered nanohole (NH) distributions fabricated by colloidal lithography in optically thin (20 nm thick) gold films. We consider polystyrene nanospheres (PS-NSPs) with a nominal diameter of 80 nm, electrostatically adsorbed from a salt-free colloidal solution onto a polydiallyldimethylammonium (PDDA) countercharged monolayer. By avoiding the conventional polyelectrolyte multilayer and based on the interplay between the deposition times of both PDDA and PS-NSPs, we demonstrate effective simplification of the commonly applied deposition protocol and effective tuning of the NH-to-NH spacing (dNN) with negligible agglomeration. Comparison with NH samples prepared by salt-containing colloidal solutions points out the negative impact of salt addition on the optical properties. The effective tuning of dNN obtained by our protocol demonstrates highly correlated disorder under unsaturated adsorption and allows a discussion on the analogies of the optical response between long- and short- range ordered NH systems, which is a still debated topic. By Fast Fourier Transform of autocorrelation images of scanning electron microscopy micrographs we demonstrate quantitatively, rather than in principle, the correspondence between an inherent ordering length-scale and dNN. As optical transducers for detecting refractive index changes, our samples exhibit significant bulk sensitivity (∼309 nm RIU-1) in the framework of short range ordered NH systems.
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Affiliation(s)
- Maura Cesaria
- Institute for Microelectronics and Microsystems, IMM-CNR, Via Monteroni, I-73100 Lecce, Italy.
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Gong Y, Joly AG, Hu D, El-Khoury PZ, Hess WP. Ultrafast imaging of surface plasmons propagating on a gold surface. NANO LETTERS 2015; 15:3472-3478. [PMID: 25844522 DOI: 10.1021/acs.nanolett.5b00803] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We record time-resolved nonlinear photoemission electron microscopy (tr-PEEM) images of propagating surface plasmons (PSPs) launched from a lithographically patterned rectangular trench on a flat gold surface. Our tr-PEEM scheme involves a pair of identical, spatially separated, and interferometrically locked femtosecond laser pulses. Power-dependent PEEM images provide experimental evidence for a sequential coherent nonlinear photoemission process, in which one laser source launches a PSP through a linear interaction, and the second subsequently probes the PSP via two-photon photoemission. The recorded time-resolved movies of a PSP allow us to directly measure various properties of the surface-bound wave packet, including its carrier wavelength (783 nm) and group velocity (0.95c). In addition, tr-PEEM images reveal that the launched PSP may be detected at least 250 μm away from the coupling trench structure.
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Affiliation(s)
- Yu Gong
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Alan G Joly
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Dehong Hu
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Patrick Z El-Khoury
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
| | - Wayne P Hess
- †Physical Sciences Division, ‡Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, United States
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