Macroscopic and Microscopic Mechanisms in Solid High Harmonic Generation

High harmonic generation (HHG) in solids is an emerging area of extreme nonlinear optics with applications in ultrafast spectroscopy and novel quantum materials. Experimental HHG spectra from bulk solids is influenced by both electronic structure through the microscopic HHG mechanism and macroscopic factors including wave propagation which introduce significant computational expense in simulations. However, accounting for such factors when analyzing HHG spectra is essential for extracting information of interest, such as features of the electronic structure. Using the semiconductor Bloch equations (SBEs) to model material response, we compare two wave propagation approaches (unidirectional propagation and finite-difference time-domain methods, implemented in Lightwave Explorer) in a series of semiconductor and insulator materials in order to examine the interplay of macro- and microscopic mechanisms within different regimes of light-matter interaction. The resulting insights into HHG propagation through bulk solids are prerequisite to connecting the output spectra to the underlying microscopic mechanism and thereby essential to facilitating material engineering control of attosecond HHG pulses.