利用双色存储中的振荡阶段实现等时曝光复用记录

研究了在双掺杂LiNbO3∶Fe∶Cu晶体中进行双色全息存储时记录初始阶段振荡现象的形成过程,认为敏化后的晶体深浅能级的电子分布达到了一种动态平衡状态,在记录开始时引入调制红光照射晶体导致了浅能级大量电子被激发,使深浅能级的电子数目向一种新的平衡状态转化。理论分析了利用振荡阶段浅能级电子数密度随记录时间递减的特点进行等时曝光,实现等衍射效率的全息复用的可行性,并在实验上在双掺杂LiNbO3∶Fe∶Cu晶体中利用100 s等时曝光实现了15幅全息光栅的等衍射效率复用。结果表明,利用双色存储中的振荡阶段浅能级电子数目逐渐减小的特点,采用等时曝光就可以实现小规模的等衍射效率全息复用记录。

Multiplexed Holographic Recording with Equal Time Exposure in Oscillation Phase of Two-Center Holographic Storage

The oscillation formation at the beginning of the holographic recording phase in two-center holographic storage in double-doped LiNbO3∶Fe∶Cu crystal is investigated. After pre-exposing the crystal with ultraviolet (UV) light before recording, the electron distributions in the deep and shallow trap centers of double-doped crystals are in a dynamic equilibrium state. At the beginning phase of recording, a large quantity of electrons at shallow trap centers are excited by introducing two red beams interference in the crystal, and then the electron distribution transfers to another equilibrium distributions. The feasibility to use the decrease of electron number in shallow trap centers at the oscillation phase for equal time exposure and then realize holographic multiplexing recording with equal diffraction efficiency is analyzed theoretically. The multiplexing of 15 holographic gratings of equal diffraction efficiency is implemented in LiNbO3∶Fe∶Cu crystals with 100 s equal time exposure. The results show that it is feasible to conduct a small scale of hologram multiplexing with equal-time exposure during the oscillation phase of the recording.