title: Large optical nonlinearity of indium tin oxide in its epsilon-near-zero region.
abstract: Nonlinear optical phenomena are crucial for a broad range of applications, such as microscopy, all-optical data processing, and quantum information. However, materials usually exhibit a weak optical nonlinearity even under intense coherent illumination. We report that indium tin oxide can acquire an ultrafast and large intensity-dependent refractive index in the region of the spectrum where the real part of its permittivity vanishes. We observe a change in the real part of the refractive index of 0.72 ± 0.025, corresponding to 170% of the linear refractive index. This change in refractive index is reversible with a recovery time of about 360 femtoseconds. Our results offer the possibility of designing material structures with large ultrafast nonlinearity for applications in nanophotonics.
authors.affiliation: Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton Street, Ottawa, ON, K1N 6N5, Canada.
authors.forename: M Zahirul
authors.initials: MZ
authors.lastname: Alam
authors.affiliation: Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton Street, Ottawa, ON, K1N 6N5, Canada. School of Engineering and Sciences, Tecnológico de Monterrey, Monterrey, Nuevo León 64849, Mexico. ideleon@itesm.mx.
authors.forename: Israel
authors.initials: I
authors.lastname: De Leon
authors.affiliation: Department of Physics and Max Planck Centre for Extreme and Quantum Photonics, University of Ottawa, 25 Templeton Street, Ottawa, ON, K1N 6N5, Canada. Institute of Optics and Department of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Boyd