Fig. 4: Theoretical calculations of the nonlinear optical response of 2H and 1 T’ MoSSe.
From: Giant room-temperature nonlinearities in a monolayer Janus topological semiconductor
a Band structure of 1 T’ MoSSe. The energy is offset to the valence band maximum. The band edge of 1 T’ MoSSe is located at the \(\varLambda\) point, which is marked in (a). b, c The magnitude of the interband transition dipole \(\left|{r}_{{vc}}\left(k\right)\right|\) for (b) 2H and (c) 1 T’ MoSSe in the first Brillouin zone. The colormap is in the unit of \(\mathring{\rm A}\). d–f First, second, and third-order optical responses of 1 T’ and 2H MoSSe as a function of incident light frequency ω. Insets of (d–f) show the \(k\)-resolved contributions (with arbitrary units) to the total response function at \(\omega=1\) eV for (left) 2H and (right) 1 T’ MoSSe. Red (blue) arrows in (b, c) and insets of (d–f) denote the \(\pm K\) \((\pm \varLambda )\) points, which are the bandedge of 2H (1 T’) MoSSe. In insets of (d–f), the Brillouin zone is zoomed in around the \(\pm \varLambda\) points for 1 T’ MoSSe to give better visibility. g The NEP (left y axis) and photo-responsivity (right y axis) of 1 T’ JTMD THz detector as a function of the light frequency \(\omega\).
