Photoinduced charge transfer in BSO:Cr3+ homegrown single crystal at room temperature during grating formation under Ar+ laser illumination in EPR experiment

With a view to understand the microscopic origin of photoinduced charge transfer in the cubic BSO crystal, we have studied the EPR spectrum of BSO:Fe3+ and the effect of laser illumination on the EPR signal during photorefractive grating formation at liquid nitrogen and room temperatures. The BSO:Cr crystal was grown at Alabama A&M University using Czochralski technique and the EPR spectrum was recorded at room temperature. Three EPR signals were observed. The EPR signals are due to the main dopant Cr3+ and the weak presence of Fe3+ which is inherent in BSO crystal. The effect of Ar+ laser illumination revealed new facts about the behavior of Cr3+ under laser illumination which is opposite to the behavior of Fe3+ in BSO:Fe3+ under laser illumination. Forming a grid on the face of the crystal increases the light-induced charge transfer Cr2+/Cr4+ is equivalent to Cr3+. The use of laser illumination helped to shed more understanding on the assignment of the EPR signals as well as the dynamic behavior of the charge transfer processes.