Complete elimination of pump scattering in transient absorption spectroscopy using phase and amplitude modulation

Transient absorption (TA) spectroscopy is a powerful technique for studying ultrafast processes in physics, chemistry, biology, and materials. It is challenging to obtain high-quality TA spectra when there is severe light scattering in the sample. We propose an experimental approach to completely remove all noise caused by pump scattering in TA spectra using phase and amplitude modulation. We demonstrate through theoretical analysis and experiments that this method can remove the additive noise and convolution noise, all the noise in TA caused by pump scattering.