ポリイミド基板上に作製されたVOPc薄膜の形態と非線形光学特性へのコロナ帯電効果

Abstract

One important factor for a nonlinear optical thin film having high second and third nonlinear optical susceptibilities is a high packing density. Vanadyl-phthalocyanine (VOPc) thin films were prepared on non-charged and corona-charged polyimide substrates by the molecular beam epitaxy (MBE). The VTS/UV spectrum of Sample 1 on a non-charged substrate had a maximum absorption peak at 835nm. According to Griffiths et al., the VOPc thin film has a maximum absorption peak at 830nm, after prepared on a glass at room temperature and heated at 325℃ for 2 hours. He called the morphology of Phase III. The maximum absorption peak of Sample 1 shifted longer by 5nm than that reported by Griffiths. This means that the packing density of Sample 1 is higher than that of the VOPc thin film reported by Griffiths. A maximum absorption peak in Q band region of Sample 4 on a corona charged substrate appeared at 845nm, which is longer by lOnm than that of Sample 1. This suggests that a strong interaction between VOPc molecule and electric charge on polyimide substrate makes a high molecular packing of Sample 4. The third harmonic (TH) generations of Samples 1 and 4 were measured by Maker fringe with P polarized laser light. The peak value of TH intensity of Sample 4 was larger by 2 times than that of Sample 1. This means that the nonlinear optical property of VOPc thin film is improved by corona charging.