Effect of post treatment on the photorefractive properties of Ru‐doped lithium niobate

Abstract

The effect of post treatment on the photorefractive properties of Ru-doped lithium niobate was studied. The absorption spectra examination of Ru-doped LiNbO 3 crystals with different post treatments showed that the absorption coefficient at 530 nm increased after the reduced treatment was employed and the absorption edge of the reduced crystal shifted towards the infrared band. On the contrary, the trend reversed after the oxidized treatment was employed. In addition, the photorefractive properties were investigated with the two-beam coupling method conducted via a 532 nm solid state laser. It was found that the oxidized Ru:LiNbO 3 had smaller exponential gain coefficient and diffraction efficiency because the charges in the shallow level were exchanged to the deep level. On the other hand, the reduced Ru:LiNbO 3 crystals had larger exponential gain coefficient and diffraction efficiency due to the increase of the Ru 3+ which existed in the shallow level. The response times of both oxidized and reduced Ru:LiNbO 3 were longer than those of the as-grown ones.

Absorption characteristic and two-center holographic recording in LiNbO3:Ce:Ru crystals

“…For example, the absorption peak at 477nm and 577nm can be observed in LiNbO3:Fe and LiNbO3:Mn, respectively 18 The absorption spectra of LN1 and LN2 are similar with those of LiNbO3:Ru 19 . The absorption peak around 530nm…”

Effect of reduction/oxidation treatment on blue photorefraction in In:Fe:Cu:LiNbO3 crystals

“…Another is increasing the [Li]/[Nb] ratio in LiNbO 3 crystals [7,8]. The other method is employing the proper post treatment process (reduction or oxidation) on LiNbO 3 crystals [9][10][11].…”