Coupled Plasmon Wave Dynamics beyond Anomalous Reflection: A Phase Gradient Copper Metasurface for the Visible to Near-Infrared Spectrum

Abstract

In nanoscale photonic devices, the demand for multifunctionality from 2D metasurface optics has increased rapidly. To explore the required fine-tuning in the design metrics, we reinvestigated the trapezoid-shape copper metasurface using finite-difference time-domain simulation to efficiently utilize linearly polarized light for two different functionalities. From the plasmonic band structure, we could see how the degree of asymmetry in the geometry affected the efficient resonance coupling of the traveling plasmonic modes, along with the different types of mode hybridization profiles that were related to the nanoantenna’s geometric shape. By tuning the nanoantenna’s length, we could excite the effective plasmon mode that was supported by this configuration and guide surface waves unidirectionally from the normal incidence free-space light within the visible to infrared range. The directed surface plasmon polaritons had both antisymmetric and symmetric modes that oscillated between the top and bottom surfaces of the continuous metal layer, depending on the nanoantenna’s length and wavelength. This proposed copper metasurface was optimized for a far-field application of broadband (600–900 nm) anomalous beam steering for an average of 60% efficiency with a maximum angle of 64°. This work offers more understanding of a metasurface being implemented in small plasmonic devices, waveguide mode controlling and beam steering with wavelength-dependent functionalities.

Lateral Flow Assays Biotesting by Utilizing Plasmonic Nanoparticles Made of Inexpensive Metals – Replacing Colloidal Gold

“…17 In general, TiN and Cu-Au NPs are promising to be useful in several fields such as catalysis, light harvesting, optoelectronics, and biotechnologies. 25–30…”

“…17 In general, TiN and Cu-Au NPs are promising to be useful in several fields such as catalysis, light harvesting, optoelectronics, and biotechnologies. [25][26][27][28][29][30] We assess the biotesting LFA-performance of three different NPs (Fig. 1B) and show that inexpensive plasmonic TiN-and Cu@Au-based LFAs perform comparable to Au NPs-based LFAs, in some cases even better.…”

“…On the one hand, TiN has proved to be a good plasmonic material in the vis/NIR region, and additionally is a good refractory material, with a high melting point and high chemical stability in harsh environments [20]. On the other hand, bare Cu-structures show an interband transition energy level of 2.15 eV, hence having the capability of interband excitation within the visible range, although oxidation of their surfaces is still an issue [21].…”

Lateral Flow Assay Biotesting by Utilizing Plasmonic Nanoparticles Made of Inexpensive Metals─Replacing Colloidal Gold

“…Furthermore, they show a superior photothermal efficiency in solar-induced water evaporation as compared to Au NPs . In general, TiN and Cu–Au NPs are promising to be useful in several fields such as catalysis, light harvesting, optoelectronics, and biotechnologies. − …”