Precise measurement of the Kerr coefficient using phase-sensitive pump-probe hyperspectral imaging

TL;DR

This paper introduces a phase-sensitive pump-probe hyperspectral imaging method for precise measurement of the optical Kerr coefficient, demonstrating its accuracy and comparing it with traditional Z-scan measurements.

Contribution

The paper presents a novel two-beam hyperspectral imaging technique for absolute Kerr coefficient measurement, with detailed uncertainty analysis and potential for improved precision.

Findings

The method accurately measures $n_2$ of fused silica near 1 μm.

Good agreement with Z-scan measurements when Raman effects are included.

Uncertainty contributions are thoroughly analyzed.

Abstract

Phase-sensitive pump-probe hyperspectral imaging is a precise technique for absolute two-beam measurements of the optical Kerr coefficient ($n_2$). The irradiance profile is characterized and background effects are rejected by rastering the pump beam across the probe beam to yield a complex-valued hyperspectral image of the pump-induced nonlinear response. Information about the temporal irradiance profile is carried in the spectral response. The technique is demonstrated by measuring $n_2$ of a fused silica sample near 1 $\mu$m wavelength and benchmarked against a measurement using Z-scan [Sheik-Bahae et al., IEEE J. Quantum Electron. 26, 760-769 (1990)], the most commonly used single-beam technique. Good agreement is found when the two-beam grating effect from the Raman contribution to the nonlinearity is considered. Uncertainty contributions are described in detail and the outlook is discussed for improvements in precision.