Spectral Domain Z-scan Technique

TL;DR

This paper introduces a spectral domain Z-scan technique that effectively measures nonlinear optical properties in highly scattering media, overcoming limitations of traditional methods by utilizing wavelength-insensitive scattering efficiency.

Contribution

The paper presents a novel spectral domain Z-scan method that enables nonlinear optical measurements in scattering media, expanding the applicability of Z-scan techniques.

Findings

Accurately measured nonlinear refraction of polished and frosted slides.

Demonstrated insensitivity of scattering efficiency to wavelength in Mie scattering.

Validated the method's effectiveness with results consistent with previous reports.

Abstract

Characterizing the nonlinear optical properties of various materials plays a prerequisite role in nonlinear optics. Among different methods, the well-known Z-scan technique and the modified versions have been recognized as a simple and accurate method for measuring both the real and imaginary parts of the nonlinear refractive index. However, all the Z-scan methods based on detecting small beam variations put forward a severe restriction on the roughness of materials. Therefore, measuring nonlinear optical properties of highly scattering media still remain challenging. Inspired by the innovation of conventional Z-scan method that converting the wavefront phase shift to the easily measurable spatial pattern in far-field, the alternative spectral domain Z-scan technique was presented in this paper. It has a great potential for highly scattering medium, based on the scattering efficiency is insensitive to the wavelength for Mie scattering as the wavelengths are far smaller than the roughness. Moreover, to demonstrate the advantages of spectral domain Z-scan technique, the nonlinear refraction of polished slides and frosted slides was measured, which agrees well with previous reports.