Improvement of diffraction efficiency for 90-degree holographic recording geometry by using external electric fields in Fe-doped LiNbO_3 crystals

摘要

Significant improvements of photorefractive properties such as diffraction efficiency with 90-degree holographic recording geometry have been obtained by the application of external electric fields. Experimental results show that the highest diffraction efficiency can be obtained at least 3 times than without external electric field in Fe-doped LiNbO_3 crystals. The vectorial Kukhtarev equations are modified in single center model taking into account the directions of optical axis and external electric field. The photorefractive properties of single doped LiNbO_3:Fe crystal using 90-degree storage geometry are theoretically investigated by jointly solving the vectorial material equations and the two dimensional coupled wave equations. The variation trends of the theoretical results are similar to the experimental results.