| 摘要 |
PCT No. PCT/BR96/00012 Sec. 371 Date Jan. 23, 1997 Sec. 102(e) Date Jan. 23, 1997 PCT Filed Mar. 13, 1996 PCT Pub. No. WO96/30788 PCT Pub. Date Oct. 3, 1996Optical waveguide of the type comprising a core (10) presenting a refractive index (n1), maximal at least at its center; an optical cladding (20) involving core (10) and presenting a refractive index (n2) constant along its diametral extension and lower than the maximum refractive index (n1) of core (10) and further including a region defined by at least a stress-relieving intermediate portion (30) disposed between core (10) and the optical cladding (20), said intermediate portion presenting: a refractive index (n3), maximal along its diametral extension, at the maximum equal to the refractive index (n1) of core (10) and at least equal to refractive index (n2) of optical cladding (20), so as to provide an increase in the cutoff wavelength; a thermal expansion coefficient and a viscosity adequate to reduce the internal stress levels at least in core (10) of the optical waveguide to values which permit the obtention of acceptable attenuation and chromatic dispersion for a wavelength region.
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