  We characterize the properties of extreme ultraviolet (EUV) light source
plasmas driven by laser wavelengths in the $\lambda_{\mathrm{laser}} = 1.064 -
10.6 $ $\mu$m range. Detailed numerical simulations of laser-irradiated
spherical tin microdroplet targets reveal a strong laser-wavelength dependence
on laser light absorptivity and the conversion efficiency of generating EUV
radiation. Radiative losses are found to dominate the power balance for all
laser wavelengths, and a clear shift from kinetic to in-band radiative losses
with increasing laser wavelength is identified. We find that the existence of
maximum conversion efficiency, near $ \lambda_{\mathrm{laser}} = 4 $ $\mu$m,
originates from the interplay between the optical depths of the laser light and
the in-band EUV photons for this specific target geometry.
