Low dispersion phase-modulated rapid-scanning interferometry

Time-domain interferometry is an important principle in Fourier transform (FT) and nonlinear femto- to attosecond spectroscopy. To optimize the resolution and sensitivity of this approach, various interferometer stabilization schemes have been developed. Among them, acousto-optical phase modulation (AOPM) of the interferometer arms combined with phase-synchronous lock-in detection has proven as a particular sensitive technique. However, the acousto-optical modulators (AOMs), required for this technique, introduce several disadvantages. Here, we demonstrate an alternative phase modulation scheme that omits AOMs, termed PM scheme here. As a benchmark, we directly compare the performance between the PM and the AOPM scheme in a linear FT spectroscopy experiment and find comparable sensitivity in both approaches.