Dependence of gain coefficient and response time on the applied electric field in LiNbO3:Fe crystal

Abstract

In this paper, the characteristics of two-wave mixing in photorefractive crystal LiNbO3:Fe are theoretically and experimentally analyzed. The relationship between the gain coefficient and the external dc electric field is investigated. The effects of the external dc electric field, incident intensity and density of electron donor on the response time are analyzed It has been found that the gain coefficient can be increased by applying the external electric field when the incident intensity and beam crossing angle are 12 mW/cm2 and 15°, respectively. The response time of two-wave mixing can be reduced by enhancing the external electric field incident intensity or density of electron donor. Experimental results show that when the external electric field is increased from 0 to 8 kV/cm, the response time of LiNbO3:Fe crystal drops from 87 s to 72 s. Furthermore, the response time decreases rapidly and then slowly with the enhancement of the incident intensity. The response time reduces from 180 s to 42 s with the increase of the incident intensity when the external electric field is constant at 10 kV/cm. The response time with an external electric field is slightly shorter than that without an external electric field. The experimental results are consistent with the theoretical simulation. The present work can provide application guidance for the research of photorefractive crystals.