Holographic properties of doped stoichiometric LiNbO₃ crystals

Doped stoichiometric LiNbO₃ (SLN) crystals show more advantages over traditional congruent LiNbO₃ (CLN). This paper is focused on the measurement of the holographic performances of doped SLN crystals, including the sensitivity, dynamic range, and angular selectivity. The principles and methods for the measurements are first described, with more attention paid to the measurement of erasure time constants. The results show that the SLN crystal co-doped with Ce and Mn has the largest dynamic range, owing to the extremely long erasure time constants even by the multiplexing method. The SLN crystal co-doped with Tb and Fe and reduced in rich nitrogen atmosphere has the fastest response time and highest sensitivity. The oxidized and as-grown SLN crystals co-doped with Tb and Fe exhibit photochromic effect under UV illumination. With UV pre-illumination these crystals have sensitivity competitive to the heavily Fe doped CLN. The measured selective angles for most of the SLN samples of proper optical quality agree well with the theoretical calculation.