  Recent progress in orbitronics reveals the possibility of using orbit current
as an information carrier. The interconversion between orbit currents and
charge currents is crucial for orbit information processing. Although orbit
currents can be created from charge currents via the orbital Hall effect, the
conversion from orbit currents into charge currents has been observed only in
very few systems due to the lack of a reliable orbit current source and the
disturbance of the omnipresent inverse spin Hall effect. In this study, we show
that ultrafast pulses of orbit current can be generated in Ni layers by
femtosecond laser pulses. We demonstrate that, by injecting such orbit current
pulses into nonmagnetic metals, a transient charge current is induced and emits
terahertz electromagnetic pulses. The nonmagnetic metal layer acts as a
converter of the orbit current into the charge current. The discovery of the
generation and conversion of light-induced orbit current opens a new route for
developing future orbitronic devices.

Mesoscale and Nanoscale Physics