Phase matching and quasi-phase matching of high-order harmonic generation—a tutorial

Abstract In this tutorial we discuss the macroscopic aspects of the extreme nonlinear frequency conversion process of high-order harmonic generation. For most, this entails describing the phase mismatch of the process and the means to mitigate it by tuning global parameters or by modulations perturbing the process. Additionally, we consider applications of phase matching in general for probing and for controlling different parameters of the emitted radiation.