| 摘要 |
PURPOSE:To produce a core/clad structure of a low loss by coating an acicular single crystal with a glass material having the refractive index lower than the refractive index of the acicular single crystal and the softening temp. lower than the m.p. and stretching this single crystal under heating to the softening temp. or higher. CONSTITUTION:The glass substrate 2 nearly covers the acicular single crystal 1 and the refractive index thereof is smaller than the refractive index of the acicular single crystal 1. In addition, the softening temp. thereof is lower than the m.p. of the acicular single crystal 1. Further, the glass material 2 nearly covering the acicular single crystal 1 is fixed at both ends thereof respectively to stretching bases 5, 6 by fixing means 3, 4. Force is applied in an arrow direction in this state to the stretching bases 5, 6. This state eventually applies the pulling tension in nearly the longitudinal direction of the acicular single crystal 1 to the glass material 2. The part of the glass material 2 covering the acicular single crystal 1 is heated in this state to the softening temp. of the glass material 2 or above and to the m. p. of the acicular single crystal 1 or below and is stretched. Namely, the influence of a difference in the coefft. of thermal expansion between the acicular single crystal 1 and the glass material 2 is decreased. |
