2026/04/11 by J. K. Wahlstrand, C. D. Cruz
Physics and Astronomy · #physics.optics
Phase-sensitive pump-probe hyperspectral imaging is a precise technique for absolute two-beam measurements of the optical Kerr coefficient (n2). 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 n2 of a fused silica sample near 1~μm wavelength and benchmarked against a measurement using Z-scan [Sheik-Bahae et al., IEEE J. Quantum Electron. 26, 760--769 (1990)], the most widely used single-beam technique. The two measurements are consistent 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.