The interaction of twisted Laguerre-Gaussian light with a GaAs photocathode to investigate photogenerated polarized electrons

The interaction of Laguerre-Gauusian light at select wavelengths from 690 to 810 nm with a p-type gallium arsenide (GaAs) photocathode photonic device and the production of photogenerated electrons was investigated. Spin angular momentum (SAM) and orbital angular momentum (OAM) were generated using linear or circular polarization and q-plates. The degree of polarization P from the photogenerated electron signal was measured. At an excitation of 695 nm ($E=1.78$ $eV$), $P_{OAM}=~2.1 \%$, $P_{SAM}=~1.3 \%$ and $P_{SAM, OAM (q=1)}= ~3.4\%$, whereas, at 800 nm ($E=1.55$ $eV$), near bandgap, $P_{OAM}=~-14.7\%$, $P_{SAM}=~-2.6\%$ and $P_{SAM,OAM (q=1)} = ~4.0\%$.