In their recent Journal of Physics D: Applied Physics special issue paper, invited as part of our Emerging Leaders special issue, Rachel Grange et al investigate the use of nanoscale materials in nonlinear optics.
The goal of the Optical Nanomaterial Group at ETH Zurich is to understand the behavior of oxide materials at the nanoscale as for examples lithium niobate (LiNbO3) nanowires or barium titanate (BaTiO3) nanoparticles for developing applications in nonlinear optics. To do so, we use non-scanning far-field imaging techniques based on nonlinear multiphoton process. With this research, we want to address open issues for developing optoelectronic devices or new microscope designs. Recently, we demonstrated several waveguiding experiment of nonlinear light in LiNbO3 nanowires, which are challenging to fabricate with sub-micron cross-section. The advantage of nanowires is that they can both concentrate light by their sub-wavelength cross-section and also guide it for the length much larger than the wavelength of light.
Besides well-known metallic and semiconductor nanomaterials, oxides materials as perovskite in the form ABO3 are of great interest at the nanoscale. Historically known for their ferroelectricity used in electronic memories, perovskites have a non-centrosymmetric crystal structure allowing for second-order nonlinear optical properties, which can convert near infrared into visible light simply by the intrinsic material properties. Therefore, combining nanowires as waveguides and ABO3 material can offer very versatile light delivery system down to the nanoscale and with a large variety of colors.
However, nonlinear optics at the nanoscale is suffering from the low signal, which scales down with the volume of the material. Therefore, our research group focuses on strategies to enhance nonlinear optical signal in nanomaterials. In our publication in the Journal of Physics D, we demonstrate generation and waveguiding of the sum-frequency generation signal in a single LiNbO3 nanowire with a cross-section of 517 nm×654 nm, which we furthermore enhance nearly 14 times by means of modal phase-matching. We also display tuning of the phase-matched wavelength by varying the nanowire cross-section and changing the polarization of the incident laser. The results prove that LiNbO3 nanowires can be successfully used for nonlinear wave-mixing applications and assist the miniaturization of optical devices.
About the authors:
Anton Sergeyev is a postdoctoral researcher in the group of Rachel Grange. He did his doctoral studies at ETH Zurich. He mostly investigates nonlinear optical effects in lithium niobate nanowires and optical applications of nanowires.
Marc Reig Escalé is a PhD student in the group of Rachel Grange. In 2012 he obtained a major in Physics from the Autonomous University of Barcelona, Spain. In 2015 he completed a Master’s degree in Photonics at the Friedrich-Schiller University in Jena Germany.
Rachel Grange is assistant professor at the Department of Physics at ETH Zurich. Her laboratory investigates the optical behavior of nanomaterials for developing applications in optoelectronics or imaging. In 2016, she received an ERC starting grant to work on strategies to enhance optical nonlinearities in oxide nanomaterials.
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Categories: Journal of Physics D: Applied Physics