Third-harmonic generation enhancement in an ITO nanoparticle-coated microresonator

Abstract

We report a ∼3-fold enhancement of third-harmonic generation (THG) conversion efficiency using indium tin oxide (ITO) nanoparticles on the surface of an ultra-high-Q silica microsphere. This is one of the largest microcavity-based THG enhancements reported. Phase-matching and spatial mode overlap are explored numerically to determine the microsphere radius (∼29 µm) and resonant mode numbers that maximize THG. Furthermore, the ITO nanoparticles are uniformly bonded to the cavity surface by drop-casting, eliminating the need for complex fabrication. The significant improvement in THG conversion efficiency establishes functionalized ITO microcavities as a promising tool for broadband frequency conversion, nonlinear enhancement, and applications in integrated photonics.

Quantum-Dot-Induced Modification of Surface Functionalization for Active Applications of Whispering Gallery Mode Resonators

“…Over the last decades, χ (3) -assisted third-harmonic generation processes were studied theoretically and realized experimentally in various types of microcavities, including microdroplets, silica toroid/microsphere/microbottle, SiN microring, silicon photonic-crystal micro-/nanocavities and microcavities with hybrid materials [9,[22][23][24][25][26][27][28][29][30]. Our studies demonstrate further amendments to microresonator functionalization using QDs, confirm the above assumptions, and show the perspectives of QDs applications in higher-order harmonics generation through the analysis of their frequency-generation properties.…”

“…There is not much work reported on the application of deposited nanoparticles for the functionalization of microresonators, as one can judge taking into account the analysis reported in [ 9 ]. Moreover, to the best of our knowledge, there are no reports on the use of QDs for these purposes.…”

“…Moreover, to the best of our knowledge, there are no reports on the use of QDs for these purposes. In [ 9 ], the authors demonstrated a ~3-fold enhancement in third-harmonic generation conversion efficiency using indium tin oxide nanoparticles on the surface of an ultra-high-Q silica microsphere compared with a pure silica microsphere. In our case, we registered a weak THG in the case of the pure silica microsphere; however, it was challenging to obtain a continuous THG signal, which was observed in the case of the HgS coating.…”

“…Some initial tests were performed by coating WGMRs with nanoparticles and quantum dots (QDs). Notice that these nanostructures demonstrate a large nonlinear optical response [ 9 ]. In this paper, we prepared WGM microsphere resonators by melting a telecommunication fiber into a sphere.…”

Bistable solitons in third-harmonic generation frequency combs

“…The generation of such dual THG emission has been demonstrated experimentally in high-Q whisperinggallery-mode resonators, as well as in integrated Kerr microresonators. [7][8][9][10][11][12] In this paper, we present a theoretical model for the temporal and spectral dynamics of THG frequency combs, based on a system of equations with parametric coupling between the fundamental field (FF) and the thirdharmonic (TH) field. In contrast to previous studies of THG, 13,14 we consider dispersive and broadband frequency combs with nonlinear interactions between the full set of combs lines around both FF and TH wavelengths.…”