Bulk photogalvanic effects beyond second order

Examining the bulk photogalvanic effect (BPE) at nonperturbative laser fields, it is shown that illuminating a thin noncentrosymmetric crystal, quasicrystal, or nanotube the point group of which is D_n>2, C_{(3,5, . . .)h}, or D_{(3,5, . . .)h} with a monochromatic linearly polarized field, at practically any orientation, induces a nonvanishing directed current component j_z along its polar axis. This is in contrast to the vanishing j_z predicted by the commonly employed photogalvanic tensor. Similarly, we discuss the appearance of an angular-dependent j_z, already for C_(n>2)v and C_n>2, and circular dichroism in the BPE that are not resolved in second order. We suggest the possible observation of these currents in, e.g., thin α-quartz and LiNbO₃:Fe crystals and single-walled chiral carbon nanotubes.