  We elucidate light-induced orbital and spin current through nonlinear
response theory, which generalizes the well-known bulk photovoltaic effect in
centrosymmetric broken materials from charge to the spin and orbital degrees of
freedom. We use two-dimensional nonmagnetic ferroelectric materials (such as
GeS and its analogues) to illustrate this bulk orbital/spin photovoltaic
effect, through first-principles calculations. These materials possess a
vertical mirror symmetry and time-reversal symmetry but lack of inversion
symmetry. We reveal that in addition to the conventional photocurrent that
propagates parallel to the mirror plane (under linearly polarized light), the
symmetric forbidden current perpendicular to the mirror actually contains
electron flows, which carry angular momentum information and move oppositely.
One could observe a pure orbital moment current with zero electric charge
current. This hidden photo-induced orbital current leads to a pure spin current
via spin-orbit coupling interactions. Therefore, a four-terminal device can be
designed to detect and measure photo-induced charge, orbital, and spin currents
simultaneously. All these currents couple with electric polarization $P$, hence
their amplitude and direction can be manipulated through ferroelectric phase
transition. Our work provides a route to generalizing nanoscale devices from
their photo-induced electronics to orbitronics and spintronics.
