Figure 2. Random laser slope efficiency.

Intensity dependence of the emission at 1062.0 nm with the excitation pulse energy for the four excitation wavelengths, in resonance with Nd³⁺ transitions starting from the ground state, indicated in Fig. 1(a). Error bars are comparable or smaller than the symbols representing the measured values. The illuminated area of the sample and the excitation pulse duration were 1.2 mm² and 7 ns, respectively.