  Linear and nonlinear optical response of WSe$_{2}$ monolayer is investigated
by two-dimensional Maxwell plus time-dependent density functional theory with
spin-orbit interaction. By applying the chiral resonant pulses, the electron
dynamics along with high harmonic generation are examined at weak and strong
laser fields. WSe$_{2}$ monolayer shows the linear optical response at the
intensity I = 10$^{10}$~W/cm$^{2}$ while a complex nonlinear behavior is
observed at I = 10$^{12}$~W/cm$^{2}$. The nonlinear response of WSe$_{2}$
monolayer in terms of saturable absorption is observed at strong laser field.
By changing the chirality of the resonant light, a strong circular dichroic
effect is observed in the excited state population. A relatively weak laser
field shows effective valley polarization while strong field induces
spin-polarized carrier peak between $K$($K'$) and $\mathit{\Gamma}$-point via
nonlinear process. On the other hand, the strong laser field shows high
harmonics up to the 11th order. Our results demonstrate that circularly
polarized resonant pulse generate high harmonics in WSe$_{2}$ monolayer of
order 3n$\pm1$.
