Korean Journal of Optics and Photonics (한국광학회지)

Optical Society of Korea (한국광학회)
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Second harmonic generation of pulsed corona - poled nonlinear optical polymer films

펄스 corona 배향된 비선형광학 고분자박막의 제2 고조파발생

  • 김준수 (아주대학교 분자과학기술학과) ;
  • 이종하 (아주대학교 분자과학기술학과) ;
  • 이황운 (아주대학교 분자과학기술학과) ;
  • 김상열 (아주대학교 분자과학기술학과) ;
  • 원영희 (아주대학교 물리학과)
  • Published : 2002.08.01
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Abstract

The molecular orientational dynamics of the nonlinear optical(NLO) side-chain polymer N-(4-nitrophenyl)-(L)-prolinol-poly (pphenylene terephthalates) have been studied using nonlinear optical responses as measured by second harmonic generation (SHG). A new pulsed corona poling is used to orient the NLO chromophores and the polymer segments into the noncentrosymmetric structure required to obtain the SHG signal. By corona poling of negative high voltage pulses with variable repetition rates (between 0.5 and 10 ㎑) at temperature between 25$^{\circ}C$ and 80$^{\circ}C$, well below and about the glass transition temperature 70$^{\circ}C$, the side-chain chromophores and the polymer chain contour rearrange themselves and create the domain structure observed by atomic force microscopy(AFM). The pulsed corona voltage enhances the orientational ordering of the NLO chromophores and also significantly influences the growth of SHG signal and the improved relaxation behavior after the poling field is removed, reducing the visible damage to the polymer film dramatically. This new pulsed corona poling experiment gave direct in situ evidence that the NLO chromophore and the polymer backbone undergo anisotropic rearrangement during the poling process.

비선형광학(NLO) 곁가지형 고분자계 N-(4-nitrophenul)-(L)-prolinol-poly (p-phenylene terephthalates)로 제작된 박막의 분자 배향거동을 제2 고조파발생(SHG)의 비선형광응답을 사용하여 연구하였다. 새로운 펄스 corona 배향 방법으로 NLO 발색단과 고분자 줄기를 비중심대칭 구조로 배향시켜 SHG 신호를 발생시켰다. 유리전이온도 70$^{\circ}C$를 중심으로 25$^{\circ}C$에서 80$^{\circ}C$까지 온도영역에서 반복율을 0.5 ㎑에서 10 ㎑까지 변화시키면서 인가한 펄스 고압으로 corona 배향한 결과로 곁가지 발색단과 고분자 주사슬이 스스로 재 정렬하여 형성한 구역구조를 원자간력 현미경(AFM)으로 관측하였다. 펄스 corona 전압 인가로 NLO 발색단 배향도가 증가되고, 동시에 고분자박막의 가시적손상을 획기적으로 줄이면서 SHG 신호가 증대되었으며 배향 후 이완거동도 개선되었다. 이 새로운 펄스 corona 배향 실험으로 NLO 발색단 및 고분자 주사슬이 배향과정에서 비등방으로 재배열하는 현상을 in situ로 입증할 수 있었다.

Keywords

References

  1. P. N. Prasad and D. J. Williams, Introduction to Nonlinear Optical Effects in Molecules and Polymers (John Wiley and Sons, NewYork, 1991).
  2. H. S. Nalwa and S. Miyata, Eds. Nonlinear Optics of Organic Molecules and Polymers (CRC Press, New York, 1997).
  3. D. M. Burland, R. D. Miller, and C. A. Walsh, “Second-Order Nonlinearity in Poled-Polymer Systems,” Chem. Rev. vol. 94, pp. 31-75, 1994. https://doi.org/10.1021/cr00025a002
  4. M. A. Mortazavi, A. Knoesen, S. T. Kowel, B. G. Higgins, and A. Dienes, “Second-harmonic generation and absorption studies of polymer-dye films oriented by corona-onset poling at elevated temperatures,” J. Opt. Soc. Am. B, vol. 6, pp. 733-741, 1989. https://doi.org/10.1364/JOSAB.6.000733
  5. H. L. Hampsch, J. M. Torkelson, S. J. Bethke, and S. G. Grubb, “Second harmonic generation in corona poled, doped polymer films as a function of corona processing,” J. Appl. Phys. vol. 67, pp. 1037-1041, 1990. https://doi.org/10.1063/1.345787
  6. C. F. Gallo, “Coronas and Gas Discaharges in Electrophotography,” IEEE Trans. Ind. Appl. IA-11, pp. 739-748, 1975. https://doi.org/10.1109/TIA.1975.349370
  7. J. R. Hill, P. Pantelis, P. L. Dunn, and G. J. Davies, “Organic polymer fimls for second-order nonlinear applications,” proceedings SPIE, vol. 70, 1147, pp. 165-176, 1989.
  8. K. P. Singer, J. E. Sohn, and S. J. Lalama, “Second harmonic generation in poled polymer films,” Appl. Phys. Lett. vol. 49, pp. 248-250, 1986. https://doi.org/10.1063/1.97184
  9. P. N. Prasad and D. R. Ulich, Nonlinear Optical and Electroactive Polymers (Plenum Press, New York, 1988).
  10. S. H. Lee, Y. K. Kim, and Y. H. Won, “Nonlinear Optical Properties of Pyly-p-(phenylene terephthalates) with Side Group Chromophores,” Macromolecules vol. 32, pp. 342-347, 1999. https://doi.org/10.1021/ma9807421
  11. J. Jerphagnon and S. K. Kurtz, “Maker Fringes: A Detailed Comparison of Theory and Experiment for Isotropic and Uniaxial Crystals,” J. Appl. Phys. vol. 41, no. 4, pp. 1667-1681, 1970. https://doi.org/10.1063/1.1659090
  12. H. Wang., R. C., Jarnagin, and E. T., Samulski, “Electric Field Poling Effects on the Molecular Reorientational Dynamics of Side-Chain Nonlinear Optical Polymers,” Macromolecules, vol. 27, pp. 4705-4713, 1994. https://doi.org/10.1021/ma00095a010
  13. H. L. Hampsch, J. Yang, G. K., Wong, and J. M., Torkelson, “Dopant Orientation Dynamics in Doped Second-Order Nonlinear Optical Amorphous Polymers. 1. Effects of Temperature above and below Tg in Corona-Poled Films,” Macromolecules, vol. 23, pp. 3640-3647, 1990. https://doi.org/10.1021/ma00217a017