Optimal performance of NdAl3(BO3)4 nanocrystals random lasers

Resonant pumping associated with the influence of the quantum-defect between the excitation and the emitted laser photons allow optimal performance of neodymium ions (Nd3+) based random lasers (RLs), as demonstrated here for the first time. The RL emission at 1063.5 nm due to the Nd3+ transition 4F3/2 → 4I11/2 in a powder consisting of NdAl3(BO3)4 nanocrystals, was investigated by exciting the powder at 690 nm, 750 nm, 810 nm, and 884 nm in resonance with the Nd3+ transitions from the ground state (4I9/2) to the 4F9/2, {4F7/2,4S3/2}, {4F5/2,4H9/2}, and 4F3/2 states, respectively. Although the Nd3+ absorption cross-section at 884 nm is smaller than those centered at 810 and 750 nm, excitation at 884 nm, that is in resonance with the emitting level, provided the smaller excitation pulse energy threshold and the larger slope efficiency due to the lower quantum defect.