Optimal spectral phase control of femtosecond laser-induced up-conversion luminescence in Sm³⁺:NaYF₄ glass

The spectral phase of the femtosecond laser field is an important parameter that affects the upconversion (UC) luminescence efficiency of dopant lanthanide ions. In this work, we report an experimental study on controlling the UC luminescence efficiency in Sm³⁺:NaYF₄ glass by 800-nm femtosecond laser pulse shaping using spectral phase modulation. The optimal phase control strategy efficiently enhances or suppresses the UC luminescence intensity. Based on the laser-power dependence of the UC luminescence intensity and its comparison with the luminescence spectrum under direct 266-nm femtosecond laser irradiation, we propose herein an excitation model combining non-resonant two-photon absorption with resonance-mediated three-photon absorption to explain the experimental observations.