Correlation between Yb<sup>3+</sup> optical properties and structural disorder of glass network has been investigated by using good
quality Yb-doped silica glasses fabricated by MCVD method. Absorption spectra strongly depend on the fictive
temperature, which is a good indicator of structural disorder in silica glass. Their dependences are affected by the
codopants (Al and F). Fictive temperature dependence of refractive index has been also elucidated.