Electro-optic coefficient and wavelength dispersion in sillenite crystals

We report on the measurement of the electro-optic or Pockels coefficient of titanosillenite crystals and show that there is no sensible wavelength dispersion, at least in the explored 510–650 nm wavelength range. This result is in close agreement with a previous paper by Papazoglou et al.: Appl. Phys. B 65, 499–503 (1997) for titanosillenites but in contradiction with a recent paper by Efremidis et al.: Appl. Phys. B 95, 467–473 (2009) reporting on a large dispersion for sillenite crystals. We stress on the fact that photoinduced space-charge electrical polarization may be at the origin of a misleading apparent wavelength dependence of the electro-optic coefficient.