Twisted light transfers OAM and SAM to electrons in a GaAs photocathode

Ultrafast complex light of twisted photons carrying orbital angular momentum (OAM) with e = ±1 or +2 (generated using q-plates with q= ±½, +1), spin angular momentum (SAM) and total angular momentum (J=L+S) from a femtosecond Ti:Sapphire laser (at select wavelengths between 690 nm and 810 nm) was used to excite a GaAs-based photocathode photonic device. The GaAs photocathode has two functions: detector and sample. Using the recorded signal intensity from the p-GaAs photocathode photonic device and lock-in amplifier, the degree of polarization (P) of the photogenerated electrons based on OAM (????) and SAM (????) beams was investigated. The percent P at 780 nm was approximately ???? = −14.5% and ???? = −0.52%.