Augmented spectrum bandwidth of Nd-doped garnet and bixbyite by spectrum tailoring

Although Nd-doped garnet and bixbyite are well-known solid-state laser gain media due to their promising characteristics, they have a clear shortcoming of narrow emission bandwidth from the viewpoint of ultrafast pulse generation. In this work, we estimated the possible designable bandwidth by the spectral tailoring of Nd-doped garnet and bixbyite. Based on the evaluation of fluorescent spectra from Nd³⁺ in the various kinds of ordered and disordered host ceramics with the composition of Y_xLu_2-xO₃, Y_xGd_2-xO₃, Lu_xGd_2-xO₃, Y₃Al_xSc_5-xO₁₂, Y₃Al_xGa_5-xO₁₂, Y_xLu_3-xAl₅O₁₂, Y_xGd_3-xAl₅O₁₂, and Lu_xGd_3-xAl₅O₁₂, we concluded 6-nm spectral bandwidth was possible by use of the stacked composite of at least four kinds of Nd-doped garnet crystals. In addition, we discovered the improvement of the designability and the augmentation of the bandwidth by the temperature tuning of the stacked composite. Consequently, a 6-nm emission bandwidth was demonstrated using the stacked composite of Nd:Gd₃Ga₅O₁₂, Nd:Y₃ScAl₄O₁₂, Nd:Y₃Sc₂Al₃O₁₂, and Nd:Y₃Al₅O₁₂.