Refractive index dispersion measurement using carrier-envelope phasemeters
P. Hansinger, Ph. Töpfer, N. Dimitrov, D. Adolph, D. Hoff, T. Rathje, A. Max Sayler, A. Dreischuh and G. G. Paulus
We introduce a novel method for direct and accurate measurement of refractive index dispersion based on carrier-envelope phase detection of few-cycle laser pulses, exploiting the difference between phase and group velocity in a dispersive medium. In a layout similar to an interferometer, two carrier envelope phasemeters are capable of measuring the dispersion of a transparent or reflective sample, where one phasemeter serves as the reference and the other records the influence of the sample. Here we report on proof-of-principle measurements that already reach relative uncertainties of a few 10-4. Further development is expected to allow for unprecedented precision.
Keywords: wave propagation, optical and dielectric properties, ultrafast processes, photoionization, carrier-envelope phase, refractive index dispersion.