Palestrante
Descrição
Random lasers are systems that combines scattering and fluorescence effects to produce laser light.(1) Depending on the random laser emission features, those systems are classified as coherent or incoherent random lasers.(2) In this work, we produced Rhodamine B (RhB)-doped PMMA nanofibers via electrospinning technique. The samples RhB concentrations were 1% and 5% (m/m). The random laser action of the nanofibers were measured with a Nd:YAG frequency doubled emitting at 532 nm with 100 ps pulse duration and 10 Hz repetition rate. The scattering effect is provided by the randomly distributed nanofibers, which presents average fiber diameter of about 480 nm, measured via MEV imaging. The 5% and 1% (m/m) samples showed random laser action with energy threshold of about 1 and 2.5 µJ/pulse, respectively. In addition, for the 5% sample, it was observed incoherent and coherent random laser emission depending on the place the sample is excited. Concerning the mode competition dynamics, it was employed the Pearson correlation method in a set of emission spectra obtained by pumping the sample with same excitation energy and sample position and acquiring a emission spectra each excitation pump. For monitor those spectra, we used the Pearson correlation coefficient of the emission intensities for every pair of wavelength in a subset of the emission spectra. This method results in intensity correlation maps. By comparing those maps, we could characterize random laser emission line widening and blue or redshift for the incoherent emission. In addition, for the coherent random laser, it was possible to monitor the lasing modes competition as function of time.
Referências
1 WIESRMA, D. S. The physics and applications of random lasers. Nature Physicsv. 4, p.359–367,2008.doi:10.1038/nphys971.
2 CAO, H. et al. Random laser action in semiconductor powder. Physical Review Letters,v.82, p.2278–2281, 1999.doi:10.1103/PhysRevLett.82.2278.
| Apresentação do trabalho acadêmico para o público geral | Não |
|---|---|
| Subárea | Óptica e Lasers |
