Approximations used in the analysis of signals in pump-probe spectroscopy

Abstract

In pump-probe spectroscopy, one often needs to analyse the transmission or reflection of electromagnetic waves through optically pumped media. Here, it is common practice to approximate the analysis in order to extract non-equilibrium values for the optical constants of the media. Concentrating on optical pump-THz probe spectroscopy, and using the transfer matrix approach, we present a general method for evaluating the applicability of the most common approximations. Somewhat surprisingly, we find that these approximations are truly valid only in extreme cases where the optical thickness of the sample is several orders of magnitude smaller or larger than the probe wavelength.

This article went through 2 rounds of review with JOSA B during 2018. While the reviewers approved of the subject and results presented in the article, they felt that additional simulations and results were needed before they could approve the article for publication. Since I am unable to continue work on this article due to personal circumstances, I am submitting it to ArXiv for the time being