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

Area of Science:

• Nonlinear optics
• Optical spectroscopy
• Materials characterization

Background:

• Accurate measurement of the optical Kerr coefficient (n2) is crucial for nonlinear optical applications.
• Existing single-beam techniques like Z-scan have limitations in precision and require careful calibration.
• Two-beam techniques offer potential for higher accuracy but can be complex to implement.

Purpose of the Study:

• To introduce and demonstrate a phase-sensitive pump-probe hyperspectral imaging technique for absolute two-beam measurements of n2.
• To validate the technique by comparing measurements with the established Z-scan method.
• To analyze uncertainty contributions and discuss future improvements for enhanced precision.

Main Methods:

• Utilizing phase-sensitive pump-probe hyperspectral imaging with raster scanning of the pump beam across the probe beam.
• Acquiring complex-valued hyperspectral images to capture the pump-induced nonlinear response.
• Analyzing spectral responses to extract information about the temporal irradiance profile.

Main Results:

• Successfully measured the optical Kerr coefficient (n2) of a fused silica sample near 1 μm wavelength.
• Demonstrated consistency between the hyperspectral imaging technique and Z-scan measurements when considering the two-beam grating effect.
• Detailed analysis of uncertainty contributions was performed.

Conclusions:

• Phase-sensitive pump-probe hyperspectral imaging is a viable and precise method for absolute two-beam n2 measurements.
• The technique provides reliable results, comparable to established methods when accounting for specific physical effects.
• Further improvements in precision are anticipated with advancements in the technique.