Keep in mind that the manganates are materials with electronic correlations. Thinking about their optical properties like with band insulators (glass, pure silicon) leads to wrong conclusions!
E=hc/l where h Planck constant, c speed of light in vacuum and l is wavelength of light. If band gap is < 1 eV then LSMO can absorb only those photons whose wavelength is > 1239.8 nm. So only limited portion of spectrum will be utilized.