Silent enhancement of SERS signal without increasing hot spot intensities

Abstract

Plasmonic nanostructures enhance nonlinear response, such as surface enhanced Raman scattering (SERS), by localizing the incident field into hot spots. The localized hot spot field can be enhanced even further when linear Fano resonances (FR) take place in a double resonance scheme. However, hot spot enhancement is limited with the modification of the vibrational modes, the break-down of the molecule and the tunnelling regime. Here, we present a method which can circumvent these limitations. Our analytical model and solutions of 3D Maxwell equations show that: enhancement due to the localized field can be multiplied by a factor of 10 2 to 10 3 . Moreover, this can be performed without increasing the hot spot intensity which also avoids the modification of the Raman modes. Unlike linear Fano resonances, we create a path interference in the nonlinear response. We demonstrate on a single equation that enhancement takes place due to cancellation of the contributing terms in the denominator of the SERS response.arXiv:1709.09230v3 [physics.optics]

Gold nanoisland substrates for SERS characterization of cultured cells

“…In order to provide experimental proof of the influence of average local field enhancement on our fabricated SERS substrates, experiments using CV as analyte were performed (Fig. 4(A)), as described above (although we do emphasize that local field enhancement is not the only mechanism underlying observed SERS enhancements [48,49]). The experimentally determined EF values for subsequent fabrication steps are shown in Fig.…”

Continuously-tunable Cherenkov-radiation-based detectors via plasmon index control

“…Besides facilitating the movements in CR imaging, MNSs also provided a medium for observing plasmon analogs [10] of electromagnetically-induced transparency (EIT)-like effects [26][27][28], originally observed for three or more level atoms [29][30][31]. Fano resonances [26,27,32], plasmon-analog of EIT, and nonlinear response enhancement [33][34][35][36] have been demonstrated in MNSs. Very recently, the plasmon-analog of refractive index enhancement was finally also demonstrated via simple analytical calculations which are supported by the exact solutions of the three-dimensional (3D) Maxwell equations [37].…”

Controlling steady-state second harmonic signal via linear and nonlinear Fano resonances

“…Localization also strengthens the nonlinear properties of molecules positioned in the vicinity of the hot spots. Signal from a Raman-reporter molecule can be enhanced remarkably (6 ). Such a great increase in the signal results from the localization of both the incident and the produced (Raman) fields (7 ).…”

“…The scheme we use, a novel scheme to our best knowledge, enhances the hot spot field intensity in the steady-state, which also leads to enhancement in the second harmonic field intensity. Next, we use a path interference scheme (6 ) which enhances only (ii ) the nonlinear response without increasing the hot spot field intensity. This method can be useful when MNP-QE hybrid system is excited with a strong pulsed laser.…”