SINGLE POLARIZATION FIBER FOR ULTRALONG WAVELENGTH

摘要

PURPOSE:To decrease the loss of light in the ultralong wavelength range of a single polarization fiber and to improve the characteristic for maintaining polarization by providing stress applying parts on both sides of a core of a chalcogen compd. CONSTITUTION:The compsns. of glass for a core 1 and a clad 2 of a chalcogen compd. which has a low loss at 2-10mum wavelength range are made respectively AsxS1-y, AsyS1-y, and the relation of the equation I is satisfied, whereby the formation of a fiber is made possible. If the equation II is satsified, the refractive index of the core can be made larger than the refractive index of the clad, and a waveguide construction can be formed. If As-Ge-S-Ge is used as the glass material in stress applying parts 3 to be provided on both sides of the core, the difference DELTAbeta in the constant of propagation between an HE11 mode and HE11 mode is larger as the double refractive index B of the mode in the core is larger as shown by the equation III. The loss of light is thus decreased at the large DELTAbeta without receiving the influence of disturbance such as bending and the characteristic for maintaining polarization is improved.