arXiv subjects

Jarkko J. Saarinen

Publications and source records attributed to Jarkko J. Saarinen.

3 recordsLinked to original sources

arXiv2024

Controlling Raman enhancement in particle-aperture hybrid nanostructures by interlayer spacing

Here we show how surface-enhanced Raman spectroscopy (SERS) features can be fine-tuned in optically active substrates made of layered materials. To demonstrate this, we used DNA-assisted lithography (DALI) to create substrates with silver bowtie nanoparticle-aperture pairs and then coated the samples with rhodamine 6G (R6G) molecules. By varying the spacing between the aperture and particle layer, we were able to control the strength of the interlayer coupling between the plasmon resonances of the apertures and those of the underlying bowtie particles. The changes in the resulting field enhancements were confirmed by recording the Raman spectra of R6G from the substrates, and the experimental findings were supported with finite difference time domain (FDTD) simulations including reflection/extinction and near-field profiles.

physics.optics↗

arXiv2003

Multiply subtractive generalized Kramers-Kronig relations: application on third harmonic generation susceptibility on polysilane

We present multiply subtractive Kramers-Kronig (MSKK) relations for the moments of arbitrary order harmonic generation susceptibility. Using experimental data on third-harmonic wave from polysilane, we show that singly subtractive Kramers-Kronig (SSKK) relations provide better accuracy of data inversion than the conventional Kramers-Kronig (K-K) relations. The fundamental reason is that SSKK and MSKK relations have strictly faster asymptotic decreasing integrands than the conventional K-K relations. Therefore SSKK and MSKK relations can provide a reliable optical data inversion procedure based on the use of measured data only.

cond-mat.mtrl-sci↗

arXiv2003

Multiply subtractive Kramers-Kroenig relations for arbitrary-order harmonic generation susceptibilities

Kramers-Kroenig (K-K) analysis of harmonic generation optical data is usually greatly limited by the technical inability to measure data over a wide spectral range. Data inversion for real and imaginary part of $χ^{n}(nω; ω, >... ,ω)$ can be more efficiently performed if the knowledge of one of the two parts of the susceptibility in a finite spectral range is supplemented with a single measurement of the other part for a given frequency. Then it is possible to perform data inversion using only measured data and subtractive K-K relations. In this paper multiply subtractive K-K relations are, for the first time, presented for the nonlinear harmonic generation susceptibilities. The applicability of the singly subtractive K-K relations are shown using data for third-order harmonic generation susceptibility of polysilane.

physics.optics↗