First photoconductivity measurement following photoionization of rare-earth dopant in a dielectric powder

Transient response of the dielectric permittivity of dielectric powder of image under pulsed laser excitation were recorded by the 8-mm microwave resonator technique at room temperature. The signal in absorption mode is the signature of image photoionization and photoconductivity effect in the rare-earth-doped dielectric grains. The signal in dispersion mode results from surface defects around each grain leading to electronic traps. This opens new perspectives for photoconductivity measurements on rare-earth-doped insulating nanopowders.