Reflection Technique for Determination of Nonlinear-refractive Index of Thin-film Semiconductors Using an Electrically Focus-tunable Lens

Abstract

In this paper, we propose a technique named reflection F-scan or RF-scan, that can be used to measure the nonlinear-refractive index 2 of thin-film semiconductors. In this technique, a p-polarized Gaussian beam is focused using an electrically focus-tunable lens onto a sample, which is positioned at a fixed distance from the lens and makes an angle with respect to the optical axis. Due to EFTL has the capability to vary its focal distance over a specific range when an electric current is applied to it. The electrically focus-tunable lens varies its focal distance as a function of an applied electric current over a specific range thus, when light is focused on the surface of the sample the beam intensity is high enough to generate nonlinear optical effects such as changes in the refractive index of the material. This changes are then register as variations in reflectance, measured by an intensity detector. Results for three-dimensional CH3NH3PbBr3 hybrid perovskite thin films are presented.

Bimetallic Fe–Ag Nanopyramid Arrays for Optical Communication Applications

“…We studied nonlinear optical properties of nanopyramidal systems, namely pure Ag, pure Fe, and Fe–Ag (with 30 and 90% overlap) at 1550 nm, which exhibited surface plasmon-induced resonant absorption at 750 nm (except for pure Fe nanopyramidal system). The third-order optical nonlinearities were studied by f -scan methods, particularly transmission f -scan and reflection f -scan, which are modifications of the conventional z -scan methods. − The detail about f -scan measurements is presented in the Experimental Section. These methods allow us to measure the third-order nonlinear index of refraction ( n 2 ) in reflection and the nonlinear absorption or two-photon absorption coefficient (β) in transmission modes.…”

Bimetallic Fe-Ag arrays with extraordinary nonlinear refraction and nonlinear Faraday rotation at telecommunication wavelength (1550 nm)

“…pure Ag, pure Fe and Fe-Ag (with 30% and 90% overlap) at 1550 nm whose surface plasmons induced resonant absorption was at 750 nm (except for pure Fe pyramidal system). The third order optical nonlinearities were studied by f-scan methods, particularly transmission f-scan and reflection f-scan, which are modifications of the conventional z-scan method [36][37][38]. These methods allow us to measure the nonlinear index of refraction (n 2 ) in reflection and the nonlinear absorption or two photon absorption coefficient (β ) in transmission modes.…”