Reduction of beam-divergence fluctuation for KTN optical beam deflector

We report a new technique to suppress beam-divergence fluctuations in a DC-biased KTa 1- x Nb x O 3 (KTN) optical beam deflector. In our new configuration, we introduced a temperature gradient in the direction of the electric field applied to the KTN crystal, to produce a permittivity gradient in the direction required to cancel out the effect of the asymmetry of the electron injection. We demonstrated experimentally that this temperature gradient successfully reduced the beam-divergence fluctuation.