Giant colloidal silver crystals for low-loss linear and nonlinear plasmonics

Abstract

The development of ultrasmooth, macroscopic-sized silver (Ag) crystals exhibiting reduced losses is critical to fully characterize the ultimate performance of Ag as a plasmonic material, and to enable cascaded and integrated plasmonic devices. Here we demonstrate the growth of single-crystal Ag plates with millimetre lateral sizes for linear and nonlinear plasmonic applications. Using these Ag crystals, surface plasmon polariton propagation lengths beyond 100 μm in the red wavelength region are measured. These lengths exceed the predicted values using the widely cited Johnson and Christy data. Furthermore, they allow the fabrication of highly reproducible plasmonic nanostructures by focused ion beam milling. We have designed and fabricated double-resonant nanogroove arrays using these crystals for spatially uniform and spectrally tunable second-harmonic generation. In conventional ‘hot-spot'-based nonlinear processes such as surface-enhanced Raman scattering and second-harmonic generation, strong enhancement can only occur in random, localized regions. In contrast, our approach enables uniform nonlinear signal generation over a large area.

Silver nanoparticles-sensitized cobalt complex for highly-efficient photocatalytic activity

“…1d, the SAED pattern displays several diffraction rings, which is the sum of diffraction patterns of Ag NPs and Co-2TPABTz. Among them, the diffraction rings of (111) and (200) are clearly observed, indicative of good crystallinity for Ag NPs [50]. It also contains another plane (021) matching with that of Co-2TPABTz [11,49].…”

“…Simultaneously, the energy levels of the CB and VB edges (Table S2) assure that redox Ag NPs act as sensitizers, which makes Co-2TPABTz highly active under visible light [58]. Owing to the collective oscillations of the surface electrons, Ag NPs can arouse the SPR effect in the system [23,50]. The SPR of Ag NPs locates at the visible light region, making a contribution to the rapid capture and steady transportation of photo-generated electrons [5].…”

Plasmonic Metasurfaces for Nonlinear Optics and Quantitative SERS

“…26 Moreover, hybrid nanostructures, composed of a plasmonic part for the enhancement of the electric field and another material with a noncentrosymmetric atomic lattice for efficient SHG have also been proposed and demonstrated for efficient nonlinear conversion at the nanoscale. 101,102 In the work reported by Wang et al, 35 the ability to precisely tune the resonances on these plasmonic metasurfaces is demonstrated in Figure 5. By only varying the nanogroove depth (100−175 nm) in the nanogroove array (other structure parameters are fixed), the λ 1 (shorter wavelength) resonance, which corresponds to the second-harmonic mode, can be tuned across the full visible spectrum, including blue (440 nm, structure I, depth = 100 nm), green (532 nm, structure V, depth = 140 nm), and red (624 nm, structure X, depth = 175 nm).…”

“…35 Using these crystals with an ALD-deposited alumina surface passivation layer, it is possible to achieve SPP propagation lengths beyond 100 μm in the red wavelength region (see Figure 2). These values even exceed the predicted Figure 1.…”

Multiresonant layered plasmonic films

“…To fabricate arrays of high-quality periodic nanostructures, researchers often turn to electron beam lithography (EBL) or focused ion beam (FIB) milling, where precisely defined nanostructures can be patterned on substrates. 12,13 Both EBL and FIB milling, however, are serial processes that are challenging and expensive to scale up to manufacturing levels.…”