ZnO random laser spectra under nanosecond pumping

A random laser as a dynamical network

“…The design of the sample used in the experiment (top panel in figure 1) is similar to that sketched in figure 1 of reference [14]. It is grown on a-plane sapphire (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) is grown on top. This layer structure produces a planar waveguide structure, wave propagation can be regarded thus as two-dimensional.…”

“…The horizontal red-dotted line indicates the level = s 1 i . Black solid and dashed: maximum and minimum of scatterer coherence C i , respectively, in %, equation (11). The inset shows the distributions of coherence below threshold (red dashed) and above threshold (solid black).…”

“…Many RL exhibit co-lasing of multiple modes at seemingly random wavelengths. This feature has been observed in completely different types of RL: powders of amplifying ZnO particles [10,11], passive microparticles in a liquid laser dye [12], human tissues [4], a passive porous glass filled with a laser dye [13], a semiconductor chip with scattering air-holes [14], or in a cold-atom RL [15], to name only few.References [17,18] give an in-depth theoretical explanation of the multi-mode operation, which is, however, limited to the stationary state. In contrast, practically all experiments are performed under pulsed excitation and mostly time-integrated data are recorded.…”

“…Many RL exhibit co-lasing of multiple modes at seemingly random wavelengths. This feature has been observed in completely different types of RL: powders of amplifying ZnO particles [10,11], passive microparticles in a liquid laser dye [12], human tissues [4], a passive porous glass filled with a laser dye [13], a semiconductor chip with scattering air-holes [14], or in a cold-atom RL [15], to name only few.…”

Oxides of third period elements revisited: synthesis, structure and photoluminescence properties of silica, magnesia, and alumina

“…69) Later experiments have further demonstrated that random laser action is observed in a variety of systems, for example, scattering microparticles in a laser dye solution 70) and aggregations of active semiconductor powders such as ZnO. 71) Although random laser action appears to be observed generally in amplifying disordered media, the lasing characteristics, e.g., band width, decay time, lasing threshold, are strongly dependent on the factors that can potentially affect the scattering process, such as particle size, 72) pulse width of the excitation laser, 73) pumping beam diameter. 71) It is hence probable that the lasing behavior of the present colored MgO microcrystals may also be affected by the conditions for pumping and the particle characteristics.…”