Resumen El Premio Nobel de Física 2021 fue otorgado a Syukuro Manabe, Klaus Hasselmann y Giorgio Parisi por sus "contribuciones innovadoras a nuestra comprensión de los sistemas físicos complejos." Aquí repasamos algunas de las ideas y resultados que sirvieron de base científica al premio. También comentamos los trabajos de nuestro grupo de investigación sobre las propiedades de sistemas complejos de los láseres aleatorios y láseres de fibra aleatorios.

Abstract The 2021 Physics Nobel Prize was awarded to Syukuro Manabe, Klaus Hasselmann, and Giorgio Parisi for their "groundbreaking contributions to our understanding of complex physical systems." Here we review some of the ideas and results which served as the scientific basis to the award. We also comment on the works by our research group on the complex systems properties of random lasers and random fiber lasers.

Abstract: A review is presented on recent research that demonstrate the control of light-bylight in colloids containing silver-nanospheres (Ag-NS) and gold-nanorods (Au-NR). The presentation is based on experiments performed with pulsed lasers by exploiting the ultrafast electronic nonlinearity of samples exhibiting cubic-quintic nonlinearities. Guiding and confinement of light induced by optical vortex solitons in colloidal suspensions of Ag-NS, and nonlinear processes of light scattering, absorption and refraction in colloids with Au-NR were investigated in the experiments. The results are analyzed by numerical simulations based on modified nonlinear Schrödinger equations. The developments herein discussed are in the forefront of interest for plasmonic applications with metal nanoparticles.

Resumen: Este artículo presenta una revisión sobre investigaciones recientes que demuestran el control de la luz por luz en coloides que contienen nanoesferas de plata (Ag-NS) y nanobastones de oro (Au-NR). La presentación se basa en experimentos realizados con láseres pulsados mediante la explotación de la no linealidad electrónica ultrarrápida de las muestras que exhiben no linealidades cúbico-quínticas. Efectos tales como el guiamiento y confinamiento de la luz inducida por solitones ópticos, con estructura vortical, en suspensiones coloidales de AgNS, además de procesos no lineales de dispersión, absorción y refracción de la luz en coloides con Au-NR fueron investigados en los experimentos. Los resultados fueron analizados mediante simulaciones numéricas basadas en adaptaciones de la ecuación de Schrödinger no lineal. Los avances discutidos en el presente artículo están a la vanguardia del interés en aplicaciones plasmónicas con nanopartículas metálicas.

We report on the synthesis of single-crystalline tellurium nanowires with different aspect-ratios prepared via facile surfactant-assisted synthesis under mild conditions. Short and long Te nanowires were synthesized by the reduction of tellurium dioxide by hypophosphorous acid with the assistance of polyoxyethylene (23) laurylether and cetyltrimethylammonium bromide, respectively. We obtained uniform single-crystal Te nanowires with diameter below 30 nm and tunable length from 600 nm to 5 µm. Short and long Te nanowires showed remarkable nonlinear absorption and their third-order nonlinear optical properties were investigated by the Z-scan technique with single 80 ps laser pulses at 532 nm. For the first time, it was observed a distinguished switching behavior from saturated absorption to reverse saturated absorption as a function of the laser intensity in one-dimensional Te nanostructures. Although both short and long Te nanowires display such interesting behavior, the short ones exhibited superior optical limiting performance.

The influence of silver nanoparticles (Ag-NPs) on the optical properties of Bi2O3-GeO2 glasses was investigated aiming the characterization of their potential for applications in photonic devices. The samples were prepared by the melt-quenching technique starting from high purity oxides (GeO2, Bi2O3 and AgNO3). Heat-treatment during different times was performed to nucleate Ag-NPs. A transmission electron microscope was used to confirm the presence of Ag-NPs and to determine their sizes and composition. The glass network was studied by spontaneous Raman scattering. The optical absorption spectra showed an absorption band at ca. 500 nm associated to the bismuth ions, and a 7-fold enhancement of absorption was observed in the samples with Ag-NPs. Photoluminescence (PL) spectra were obtained by exciting the samples with a 808 nm laser. Maximum enhancements of ca. 100% of the PL band centered at 1300 nm and ca. 70% of the Raman spectrum were observed due to the nucleation of the Ag-NPs. The enhanced optical response of the samples with Ag-NPs is attributed to the growth of the local field on the isolated bismuth ions and clusters that are located in the vicinity of the nanoparticles. The results illustrate the large potential of Bi2O3-GeO2 with Ag-NPs to be used in photonic devices.

We present a review of recent works on optically investigated thermal effects in crystalline and amorphous materials doped with trivalent rare-earth (RE) ions. The paper describes how the frequency upconversion (UC) photoluminescence (PL) technique is used to investigate the thermal behavior of samples and how to perform optical measurements of temperature. The UC technique is based on the sequential multiphoton absorption phenomenon that leads to anti-Stokes type emission. By measuring the relative intensity between UC emissions from thermally coupled RE energy levels, the absolute temperature of a sample can be determined. Research in this area is motivated by the possible uses of UC for basic characterization of materials and for noncontact thermometry using nanoscale devices as well as for biological and medical studies. Examples based on the application of bulk materials and nanopowders doped with several RE ions are presented.