Building nanophotonic structures by laser processing

Abstract

Photonic technologies profit enormously from the unique optical response shown by nanophotonic and metamaterials based in oxides. A functional optical response is achieved by either embedding non-oxide nano-resonators to enable a plasmonic behavior, or by modifying their composition/structure to tune its optical, electronic and magnetic properties. In this work we will show the potential of lithography-free nanophotonic materials based on oxides for plasmonic and spintronic photonic applications. For this purpose, we have designed and produced using pulsed laser deposition highly functional thin film oxide metamaterials by either embedding non-oxide nanoparticles which act as optical resonators, or by growing pure nanostructured oxides with a fine control of their composition. In the former case we build robust plasmonic and sensing platforms that profit from the coupling between plasmonic and photonic modes. And in the latter case we control the band-gap and ferroelectric response tuning of the nanostructured oxide. I will review the non-conventional plasmonics based on elements of the p-block. The interband transitions in these elements, usually in the infrared, are responsible for their plasmonic response [1,2]. Especial emphasis will be made on bismuth nano-resonator structures because Bi shows the strongest interband transitions reported so far [3]. Second, we will discuss the key role of the oxide layers in the design of plasmonic metamaterials to enable a strong coupling between plasmonic and photonic modes. Recently, we have shown that such coupling is instrumental to develop a high resolution optical thermometry sensors [4] and infrared perfect absorption with sub-wavelength thick films. Finally, we will discuss the control composition and structure of the oxide layers for the case of the europium monoxide (EO), which is a relevant ferroelectric semiconductor for spintronics. In this case we show the development of EuO nanocrystalline structures with both tunable band-gap and ferroelectric response [5]. [1]. J. Toudert, and R. Serna, Opt. Mat. Expr. 7, 2434 (2016). [2]. J. Toudert, and R. Serna, Opt. Mater. Express 7, 2299 (2017). [3]. J. Toudert, R. Serna, I. Camps, J. Wojcik, P. Mascher, E. Rebollar, T. Ezquerra, J. Phys. Chem. C 121, 3511 ( 2017). [4] G. Baraldi, M.García Pardo, J. Gonzalo, R. Serna and J. Toudert, Adv. Mater. Interfaces 5, 1870058 (2018). [5] J. Toudert, R. Serna, M. Pardo, N. Ramos, R. Peláez, and B. Maté, Opt. Express 26, 34043 (2018). [5] A. Mariscal, A. Quesada, A. Tarazaga Martín-Luengo, Miguel A. García, A. Bonanni, J.F. Fernández and R. Serna, Appl. Surf. Science 456,980 (2018).