  We measured the temperature dependence of the in-plane polarized reflectivity
spectra of twin-free Y$_{1-x}$Ca$_{x}$Ba$_{2}$Cu$_{3}$O$_{7-{\delta}}$ single
crystals with different Ca-concentrations (x=0,0.11 and 0.16) from optimally
doped to heavily overdoped region. Low energy optical conductivity spectra
showed a Drude-like residual conductivity at temperatures far below the
superconducting transition temperature, which indicates the presence of
unpaired-normal carriers in the superconducting state. Comparing the spectra at
a fixed Ca-content or at a fixed doping level, we have revealed that the
carrier overdoping increases unpaired carriers in addition to those induced by
the Ca-disorder. We also found the superconducting behavior of the
one-dimensional CuO chains for the Ca-free samples.
