Fig. 5: Numerical simulation based on the time-dependent density matrix method.

a Decomposition of the \(I_2^{{\mathrm{HH}}}\) component into interband and intraband contributions. The gray filled region, blue curve, and red curve show the total spectrum, interband, and intraband contributions, respectively, calculated for φ = 15°. b Calculated φ dependence of HH intensities \(I_1^{{\mathrm{HH}}}\) and \(I_2^{{\mathrm{HH}}}\) for the (2,2), (1,2), (2,1), and (4,1) orders. (Either \(I_1^{{\mathrm{HH}}}\) or \(I_2^{{\mathrm{HH}}}\) for each order is normalized, and their intensity ratios for the same order are maintained).