高能氧离子注入LN晶体光波导的色心形成

Formation of color centers of optical waveguide in LN crystal by implanting it with 3 MeV oxygen ions

采用高能氧离子注入同成分铌酸锂(LN)晶体中制备离子注入光波导,对制备的光波导进行(200°C–500°C)不同温度的退火处理。采用常规光谱法对退火后的光波导进行光吸收谱研究。研究发现,氧离子注入后会使LN晶体中的锂离子发生缺失,进一步偏离化学剂量比;随氧离子注入剂量的增加,锂离子缺失的现象会加重。研究还发现离子注入后样品的吸收强度增加,注入剂量增大,其光吸收强度也提高,说明经离子注入后产生的色心点缺陷数目随注入剂量而增加。研究表明,主要的吸收色心缺陷有氧空位、激化子、间隙原子缺陷及反位Nb离子捕获电子等缺陷,由于这些色心缺陷的共同作用,导致了氧离子注入LN晶体的光吸收强度的加强。在实验的退火温度范围内,这些色心缺陷消除程度不显著,在LN晶体采用氧离子注入形成的光波导具有优良的温度稳定性。

Optical waveguide was fabricated by implanting 3 MeV oxygen ions of 5×1014and 1.5×1015ions/cm2into congruent lithium niobate（LN） crystals and annealing them at 200°C–500°C.Optical spectrum was used to investigation defects in the optical waveguide.The results revealed the reduction of Li ions in the implanted LN crystals.The absorption of LN crystal increased with the dose of oxygen ion.This showed that the color centers were formed increasingly with the oxygen ion dose.The color centers and defects affecting the optical absorption include oxygen vacancy,exciton,interstitial atoms and electrons captured by Nb ions occupying the Li ion site.The color centers and defects caused increase of the absorption in the implanted the LN crystals.The annealing temperature seemed to have little effect on reduction of color centers.The optical waveguide of the implanted LN crystal exhibits high temperature stability.