Stimulated emission and lasing of random-growth oriented ZnO nanowires

Abstract

We report room-temperature ultraviolet stimulated emission and lasing from optically pumped high-quality ZnO nanowires. Emission due to the exciton-exciton scattering process shows apparent stimulated-emission behavior. Several sharp peaks associated with random laser action are seen under high pumping intensity. The mechanism of laser emission is attributed to coherent multiple scattering among the random-growth oriented nanowires. The characteristic cavity length is determined by the Fourier transform of the lasing spectrum.

Room-Temperature Laser Emission of ZnO Nanowires Explained by Many-Body Theory

“…[18]. We find that the vast majority of reported laser thresholds [5][6][7][8][9]12,13,[27][28][29][30][31][32] actually lie above the Mott density, between 1:5 Â 10 24 m À3 and 1:5 Â 10 26 m À3 . Only one group reported a lower threshold [3,4,24].…”

“…Here, it has often been stated that the lasing is due to scattering processes that involve excitons, at least, if the excitation intensity is not too far above the laser threshold [3][4][5][6][7][8][9][10][11][12][13][14]. Excitons are hydrogen-atom-like electron-hole pairs, bound by the Coulomb force.…”

Powerful narrow linewidth random fiber laser

“…But in random lasers, there is no traditional resonator, which provides random lasers with special features compared with conventional cavity lasers. In earlier decades, researchers obtained random lasing in powder of active crystals [2], nanowires [3], and polymers [4]. The simplicity of realization of random lasers gives them an upper hand over conventional lasers.…”

Luminescent materials based on semiconductor compound templates for random laser applications

“…This issue becomes especially important in connection with the growing interest in the development of random lasers (see, e.g., [1] and refs therein). The solid state random lasers developed to date are mainly based on crystal powders with the stimulated emission coming either from the near-bandgap electronic effects (exciton-exciton scattering or electron-hole plasma) as in the case of lasers based on ZnO material [1][2][3][4][5], or from the neodymium related electronic transitions in laser crystal powders doped with neodymium [6][7][8]. Random lasers have been also realized in a number of materials systems, e.g., π-conjugated polymer [9,10], organic dyedoped films [11] and even biological tissues [12].…”