Design of refractive–diffractive hybrid lenses for space–time focusing ultrashort laser pulses

Abstract

We propose a simple formulation for the baseline design of a hybrid lens, consisting of refractive and diffractive elements, intended for focusing ultrashort laser pulses. Lens dispersions up to the second order are considered to obtain easy-to-use formulas. Using this formulation, we designed a refractive–diffractive triplet for near-infrared femtosecond laser pulses and observed that once radius-dependent temporal distortions are removed, chromatic distortions are removed as well, and vice versa. Furthermore, we found that the derived equations for removal of pulse distortions can be readily transformed to traditional lens design equations for optical imaging. This finding facilitates the design of hybridized triplets for ultrafast focusing optics.