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LINEAR & NONLINEAR SPECTROSCOPY

The Fundamental Research of New Photonics Materials

The light-matter interaction is, in fact, one of the most relevant themes in physics due to the amount of information that can be obtained and interpreted by the material's response after this interaction. There are several types of optical phenomena, which can be linear or nonlinear. For example, when photons emitted by a low-intensity light source interact with a medium and are absorbed, we face an absorption process called linear absorption or simply 1PA - one-photon absorption. In addition, a photoluminescence process may follow if the medium is emissive. But when a high-intensity laser is used to cause a light-matter interaction, there is a chance of a nonlinear optical response be observed. There are several types of nonlinear optical phenomena, such as second-harmonic generation (SHG), two-photon absorption (2PA), three-photon absorption (3PA), to mention a few. 

Nonlinear optical phenomena (NLO) can be experimentally and theoretically investigated with different ranges of energy excitation. We can combine both results (experimental and theoretically) to understand the existent materials better, aiming to develop novel ones with optimized optical responses.

The NLO effects can be determined experimentally with laser systems and appropriate optical apparatus. For example, the incoherent SHG in solution (first molecular hyperpolarizability) can be determined by the hyper-Rayleigh scattering (HRS) technique; the 2PA spectra can be recorded using the well-established Z-Scan technique. Fortunately, due to our ongoing collaborations, we have access to the mentioned NLO techniques. Moreover, we can estimate the first molecular hyperpolarizability and the 2PA spectra using QCC in a High-Performance Computing environment.

In this line of research, the main objective is to help chemists and material scientists to synthesize novel optical materials with optimal NLO effects.

If you are interested in exploring 2PA or the first molecular hyperpolarizability spectra of a particular molecular structure, contact us by clicking here!

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