Reduced photorefraction in hafnium-doped single-domain and periodically poled lithium niobate crystals

Abstract

Transient and steady-state measurements of photoinduced birefringence in single-domain and periodically poled lithium niobate (LN) crystals containing different nonphotorefractive impurities are presented. The birefringence change is induced by a 532 nm beam and probed by a 633 nm beam. Data were taken at 25 and 50 °C. We find that doping by HfO2 is very effective in reducing the photorefraction. This is interesting also because it is known that hafnium-doped LN crystals can be periodically poled during growth. The analysis of the rise and decay of the induced birefringence shows that doping considerably increases both the photoconductivity and the dark conductivity of the LN crystals.