Time-resolved studies of stimulated emission from colloidal dye solutions

Siddique, Masood; Alfano, R. R.; Berger, G.; Kempe, M.; Genack, Azriel Z.

doi:10.1364/ol.21.000450

Cited by 78 publications

(40 citation statements)

References 4 publications

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“…The real pulse durations might be narrower. In fact, shorter emission pulses of 50 ps or even less were found in other studies devoted to liquid dyes and polymer sheet random lasers following OP excitation [25][26][27]. As it can be seen, the spectral and temporal narrowing of the emission under TP pumping takes place at higher pump densities.…”

Section: Resultssupporting

confidence: 50%

Lasing threshold of one- and two-photon-pumped dye-doped silica powder

et al. 2014

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Section: Resultssupporting

confidence: 50%

Lasing threshold of one- and two-photon-pumped dye-doped silica powder

et al. 2014

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“…In this framework, it is expected that the number of involved modes increases with the pump energy and, correspondingly, the spectrum widens. However, exactly the opposite happens and this is also accompanied by the shortening of the emitted pulse [24,25,26]. In addition, the fact that strong (or Anderson) localization of light sustains the RL action is still debated.…”

Section: Pacs Numbersmentioning

confidence: 99%

Condensation in Disordered Lasers: Theory,3D+1Simulations, and Experiments

et al. 2008

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The complex processes underlying the generation of a coherent-like emission from the multiplescattering of photons and wave-localization in the presence of structural disorder are still mostly un-explored. Here we show that a single nonlinear Schroedinger equation, playing the role of the Schawlow-Townes law for standard lasers, quantitatively reproduces experimental results and threedimensional time-domain parallel simulations of a colloidal laser system. PACS numbers:Random lasers (RL) are a rapidly growing field of research, with implications in soft-matter physics, light localization and photonic devices [1,2]. Since the pioneering investigations [3,4], different groups reported on experimental observations, from paint pigments to human tissue [5,6,7,8,9]. In all of these cases a coherent-like narrow spectral line emerges from the fluorescence as the pump energy is increased and, in some instances, several spectral peaks have been reported [9,10]. In standard single-mode lasers, without structural disorder, the emission linewidth is linked to the electromagnetic energy stored in the cavity by the so-called Schawlow-Townes (ST) law [11,12]. An equivalent law for RL is missing. Nevertheless various issues (like the statistical properties and the link with spin-glass theory [9,13,14,15,16,17]), were theoretically analysed, while the leading model (quantitatively compared with experiments) is that based on the light-diffusion approximation [18,19,20,21], which however overlooks the ondulatory character of the involved photons. Within a different perspective, RL is due to several localized electromagnetic (EM) states put into oscillations in a disordered environment (as, e.g., in [9, 17, 22, 23]). In this framework, it is expected that the number of involved modes increases with the pump energy and, correspondingly, the spectrum widens. However, exactly the opposite happens and this is also accompanied by the shortening of the emitted pulse [24,25,26]. In addition, the fact that strong (or Anderson) localization of light sustains the RL action is still debated. Ab-initio computational studies were limited to 1D and 2D geometries [27,28], not accounting for the critical character of three-dimensional (3D) localization [29]. Monte-Carlo simulations neglect interference effects [30,31,32]. Here we report on an original theoretical formulation; we quantitatively compare its predictions with experiments and with the first ever reported 3D+1 ab-initio MaxwellBloch simulations. We show that the RL linewidth is ruled by a nonlinear differential-equation, which is the equivalent of the ST-law, and is formally identical to the nonlinear Schroedinger, or Gross-Pitaevskii (GP), equation governing ultra-cold atoms [33]. There is hence a strict connection between photons in RL and ultra-cold bosons; the spectral narrowing observed in RL is thus ascribed to a condensation process [34] of the involved electromagnetic resonances. Simulations -We consider a vectorial formulation of the Maxwell-Bloch (MB) equations [35,36]. 21 nonl...

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“…After Lawandy et al reported the random laser, many experimental and theoretical studies have been reported. [6][7][8][9] The dependence of spectral and temporal characteristics of the random laser on dye concentration and density of scattering particles have been studied. 6,7 In a high dye concentration sample, bichromatic emission has been observed.…”

Section: Introductionmentioning

confidence: 99%

Amplification and diffusion of spontaneous emission in strongly scattering medium

Totsuka

Soest²,

Ito

et al. 2000

Journal of Applied Physics

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We experimentally examined the threshold of the spectral collapse in dye embedded in a strongly scattering medium as a function of the excitation beam diameter and the transport mean free path in order to find a condition to minimize the threshold. We found a critical transport mean free path, below which the threshold pulse energy is almost independent of the mean free path. Experimental observations are well explained by a theoretical model based on the rate and diffusion equations, which shows that the luminescence spectra are also dependent on the position in the medium.

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Time-resolved studies of stimulated emission from colloidal dye solutions

Cited by 78 publications

References 4 publications

Lasing threshold of one- and two-photon-pumped dye-doped silica powder

Lasing threshold of one- and two-photon-pumped dye-doped silica powder

Condensation in Disordered Lasers: Theory,3D+1Simulations, and Experiments

Amplification and diffusion of spontaneous emission in strongly scattering medium

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