Naslov
To generate a photonic nanojet outside a high refractive index microsphere illuminated by a Gaussian beam

Autori
Gašparić, Vlatko ; Mayerhöfer, Thomas G. ; Zopf, David ; Ristić, Davor ; Popp, Jürgen ; Ivanda, Mile

Izvornik
Optics letters (0146-9592) 47 (2022), 10; 2534-2537

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Gaussian beams ; Geometric optics ; Light beams ; Light scattering ; Raman scattering ; Refractive index

Sažetak
A non-resonant, concentrated, narrow beam of light emerging from an illuminated microlens is called a photonic nanojet (PNJ). According to currently prevailing opinion, microspheres and microcylinders are only able to generate a PNJ in their exterior when their refractive index ns (or refractive index contrast) is less than 2. In this Letter we demonstrate that a PNJ can emerge from a microsphere even when ns > 2: first by employing the laws of geometrical optics for a divergent light source ; then, by using ray transfer matrix analysis, a mathematical condition for the Gaussian beam (GB) outside the high ns microsphere is derived. The PNJ outside the microsphere with ns = 2.5 is simulated using Generalized Lorenz–Mie theory (GLMT), by using a front focused GB source. The simulated difference between front and back focusing on the dependence of ns is confirmed experimentally by Raman imaging. By opening the PNJ field for high refractive index materials, we believe this work will be a nucleus for new ideas in the field and enable new PNJ applications.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Interdisciplinarne prirodne znanosti

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