Random laser action under picosecond laser pumping
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Random laser action under picosecond laser pumping R. A. Ejbarah1,2 · J. M. Jassim2 · S. M. Hamidi3 Received: 29 March 2020 / Accepted: 8 September 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract This study was aimed to investigate the effect of scattering mean free path of different concentrations of silver nanoparticles in Rhodamine B (RhB) solution. To get the random lasing, the samples were exposed to Picosecond laser. Our results show a gradual increase in the random lasing emission by increase in the concentrations and thus scattering mean free path until the threshold amount. The emission intensity was enhanced by enhancing the laser power due to an increase in scattering, which cannot make a close loop path in the gain medium to reach the coherence random lasing. Our results showed efficient emission intensity due to the absorption of Rhodamine B with Ag NPs in the pumping wavelength where it has been observed that the lasing threshold is reduced from 0.628 A (without scatterer) to 0.62 A at 9.2 ∗ 1017 cm−3 Likewise, the lowest FWHM (full width at half maximum) for this concentration was 34 nm, while without concentration it was 37 nm, but the clear and important difference is that the first occurred at 72 A, while the second state at 80 A. Keywords Random laser · Picosecond laser · Silver nanoparticles · Scattering mean free path
1 Introduction In recent years, great attention has been paid to random laser (RL) due to miniaturized nature in the comparison with conventional lasers which can be employed in many fields such as medical and electronic ones (Wang et al. 2012; Cao 2009; Wang et al. 2010, 2014). Due to this fact that the lasing action in this kind of lasers depends on the presence of a disordered medium; get more sense about the physical phenomena like as scattering mean free path, scatterer points concentrations, and the pumping source is so important (Haddawi et al. 2020; Firdaus et al. 2012; Kedia and Sinha 2017; van der 2007; Enciso et al. 2010). * S. M. Hamidi [email protected] 1
Department of Petroleum and Gas Engineering, College of Engineering, University of Thi-Qar, Nasiriyah, Iraq
2
Department of Laser Physics, College of Science for Women, University of Babylon, Hillah, Iraq
3
Magneto‑Plasmonic Lab, Laser and Plasma Research Institute, Shahid Beheshti University, Tehran, Iran
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One of the most important parameters to determine the coherent or incoherent operation regime is the scattering mean free path ( ls ) which is define as the average distance of a photon traveled between two successive scattering events (Haddawi et al. 2020). In the case of coherent feedback, the ls is assumed to be close to the emission wavelength while it is much longer than the emission wavelength in the incoherent feedback (Firdaus et al. 2012; Kedia and Sinha 2017). In addition, the concentration of dispersion centers play an important role to increases the chances of random laser occurring signifi
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