DE LA CRUZ Rosa María University Carlos III of Madrid

Composite LiNbO_3-Ag Nanoparticles Dispersion with Compensated Loss

Co-authors KANYINDA-MALU Clément, MUÑOZ-SANTIUSTE J. Enrique

An extremely large variety of metal/dielectric combinations (types of materials and configurations) are currently the subject of intense studies, revealing new fundamental properties and leading to novel devices with improved performances. As it is well known, lithium niobate is a ferroelectric material with a plenty of applications in non-linear optics among others. To our knowledge, it is the first time that the composite LiNbO3-Ag nanoparticles (NPs) is theoretically proposed as a novel candidate of a metamaterial with plausible photonics applications. We numerically evaluate the effective dielectric function (eff) of the LiNbO3-Ag NPs composite by using Maxwell-Garnett theory. The dielectric function of Ag NPs is described by Drude theory of free electrons, neglecting the interband transitions and considering the NP size effect in the plasmon damping term. On the other hand, the lithium niobate dielectric function is evaluated throught the Sellmeier equations which describe their ordinary and extraordinary refraction indexes, no and ne, respectively, as a function of the incident light wavelength of the source. We consider a refraction index average value of no and ne in order to evaluate the LiNbO3 dielectric function. Once the eff of the composite is obtained, we investigate the lossless optical condition, where Im (eff) = 0 and Re (eff) < 0 at some frequency. We obtained that the above condition is dependent of the volume fraction and sizes of Ag NPs immersed in the LiNbO3 matrix. Besides, we investigate the extinction of the composite as a function of the incident light wavelength for different radii and volume fraction of Ag NP embedded in lithium niobate. These parameters showed a clear influence on the extinction, which is discussed in this work.

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