Speaker: Vlatko Gašparić (Ruđer Bošković Institute, Croatia (host: Miklós Veres))

Title: Photonic nanojet and its application in Raman spectroscopy

Date: Tuesday, 26 March 2024, 10:00

Place: KFKI Campus, Bldg. 1, 2nd floor, Conference Room


Raman spectroscopy is a popular and widely used method for substance identification and characterization, however, due to the inelasticity of the Raman scattering, its signal is weak. Therefore, many methods of enhancement have been developed over the years. One of the newest methods is based on a photonic nanojet, which is gaining popularity and attention from the scientific community in recent time. The photonic nanojet is a narrow and intense beam of light produced by illuminating a dielectric microlens in suitable conditions.

After the motivation and general concepts are laid out, some research highlights so far will be presented. The optimization of the enhancement show that the incident beam position is one of the key parameters for the enhancement [1]. The Generalized Lorenz-Mie theory calculations of the photonic nanojet show great dependence of its properties on given parameters [2]. Also, a device for the enhanced mapping [3], the expansion of the upper limit of the refractive index for photonic nanojet generation [4], and effective numerical aperture model will be presented.

Lastly, the plans for the investigation of combined plasmonic and photonic nanojet enhancement, and determination of trends in photonic nanojet properties will be presented.

[1] V. Gašparić, S. Taccheo, H. Gebavi, D. Ristić, M. Ivanda; 2020, Journal of Raman spectroscopy, 51, p165-175, "Photonic nanojet mediated Raman enhancement: Vertical Raman mapping and simple ray matrix analysis"
[2] V. Gašparić, D. Ristić, T. G. Mayerhöfer, N. Baran, H. Gebavi, A. Maksimović, M. Ivanda; 2022, Journal of Quantitative Spectroscopy and Radiative Transfer, 282, p108121, "Photonic Nanojet of a Gaussian Beam Illuminated Low Refractive Index Microsphere in Air: a Comprehensive Variation of Parameters"
[3] V. Gašparić, D. Ristić, H. Gebavi, M. Ivanda; 2021, Applied surface science, 545, p149036, "Resolution and signal enhancement of Raman mapping by photonic nanojet of a microsphere"
[4] V. Gašparić, T. G. Mayerhöfer, D. Zopf, D. Ristić, J. Popp, M. Ivanda; 2022, Optics Letters, 47, p2534-2537, "To generate a photonic nanojet outside a high refractive index microsphere illuminated by a Gaussian beam"