High-accuracy relative arrival time measurement for coherent beam combination based on double-humped interferometry

The precise measurement of the shot-to-shot relative arrival time (RAT) for ultrashort pulses in the coherent beam combination (CBC) was experimentally demonstrated by the double-humped interferometry method in our previous work (Liu et al., 2020). However, the optimization of various parameters has not been systemati-cally evaluated, which is significant for practical applications. In this study, we propose an optimization of the parameter settings for high RAT measurement accuracy, which is characterized by the deformation sensitivity and modulation depth of the multi-peak interference pattern. Based on the analytical derivation and numerical simulations, the influence of the parameters including the incidence angle, spectral notch bandwidth, and beam size on the measurement accuracy is studied, which provides a guideline for practical measurement. Moreover, the applicability of double-humped interferometry to the measurement of RAT for chirped pulses is demonstrated experimentally. Thus, double-humped interferometry is suitable for coherent beam combinations of femtosecond pulses, even with a large amount of chirp from various laser systems.