Origin of Intrinsic Second-Harmonic Generation in Crystallized GeO 2-SiO2 Glass Films

Takumi Fujiwara, Takashi Sawada, Tsuyoshi Honma, Yasuhiko Benino, Takayuki Komatsu, Masahide Takahashi, Toshinobu Yoko, Junji Nishii

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14 Citations (Scopus)


The origin and properties of second-harmonic generation (SHG) from crystalline particles and their crystalline phases in GeO2-SiO 2 glass films were investigated. GeO2-SiO2 glass films with a thickness of approximately 5 μm were fabricated by the chemical vapor-phase deposition (CVD) method. Heat treatments in the temperature range of 1100-1260°C for durations of 2-8 h have been performed to crystallize the glass films. X-ray diffraction (XRD) peaks at around 2θ = 22° in the crystallized GeO2-SiO2 films were observed, and the obtained XRD patterns in the glass films are exactly the same as those in ultraviolet (UV) poled GeO2-SiO2 glasses with a large second-order optical nonlinearity comparable to that in LiNbO 3 crystals. Using a SHG microscopic technique, it has been found that the intensity of SHG emission from crystalline particles is clearly dependent on stress-induced optical retardation which is accompanied by the formation of crystalline particles of the pseudo-β-cristobalite containing GeO2. In addition, a new technique for enhancing the intrinsic SHG by means of modification of defect states is demonstrated.

Original languageEnglish
Pages (from-to)7326-7330
Number of pages5
JournalJapanese Journal of Applied Physics
Issue number12
Publication statusPublished - 2003 Dec


  • Crystallized glass
  • Defect-state modification
  • Ge-doped SiO film
  • Optical nonlinearity
  • SHG microscopy


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