Light Disorder as a Degree of Randomness to Improve the Performance of Random Lasers

Influence of the Excitation Light Disorder on the Spatial Coherence in the Stimulated Raman Scattering and Random Lasing Coupled Regime

“…To quantify the degree of spatial coherence, the 2D spatial intensity-correlation function of the speckle patterns generated by the SRS-RL sources was monitored as a function of the pump speckle contrast. The results presented in this paper, in conjunction with those reported in our previous work, 28 demonstrate that the randomness of the light that pumps the scattering gain media is an excellent tool to control and optimize the performance of different classes of RLs. In addition, we mention a recent work showing that complex spatial light patterns can be emitted due to the activation of different spatial domains in heterogeneous RLs, 40 with important applications in sensing, spectroscopy, and structured illumination microscopy.…”

“…36 The emergence of new Raman frequencies that require high RL intensities is promoted by the ability of the disordered light pattern with higher speckle contrast to excite many laser modes with a high photon degeneracy. 28 Based on the demonstration that the random intensity distribution on the excitation laser transverse profile has a strong influence on the efficiency of dual-regime RLs, and knowing that both spontaneous Raman scattering and SRS can present a partial spatial (transverse) coherence depending on their excitation conditions, 37,38 it is important to evaluate how the disordered light patterns affect the degree of spatial coherence in the SRS-RL coupled regime. With this aim, using the experimental setup illustrated by Figure 1, the dependence of the 2D spatial intensity-correlation functions of the light emitted in the SRS-RL regime as a function of the speckle contrast of the excitation beam was analyzed.…”

“…The experimental setup used to study the behavior of RLs based on Ag NWs, pumped by disordered light patterns, is like the one described in ref . Briefly, linearly polarized light pulses, with Gaussian transverse intensity profiles, were obtained by passing the beams emitted by the second harmonic of a Q-switched Nd:YAG laser (7 ns, 532 nm, 10 Hz) through a spatial filter (SF).…”

“…26,27 In a different approach, we recently demonstrated that by introducing a degree of randomness on the intensity distribution of the spatial light pattern that pumps a random lasing medium, it is possible to control and improve the RL efficiency by more than 1 order of magnitude. 28 This new procedure is a better way to pump, with higher intensity, small excitation volumes that result in high-gain regions and give rise to a large number of modes with large populations of photons, required for high-sensitivity applications.…”

“…Due to the interesting characteristics that RLs present for the investigation of new optical phenomena and applications, various studies have been carried out to find new materials or mechanisms that optimize their performance and efficiency. − Actually, the most used strategy consists of managing the scattering strength, for example, from the variation in the scattering particle density, or the excitation volume of the RL medium. This experimental procedure can also be used to tune the spatial coherence of RLs. , In a different approach, we recently demonstrated that by introducing a degree of randomness on the intensity distribution of the spatial light pattern that pumps a random lasing medium, it is possible to control and improve the RL efficiency by more than 1 order of magnitude . This new procedure is a better way to pump, with higher intensity, small excitation volumes that result in high-gain regions and give rise to a large number of modes with large populations of photons, required for high-sensitivity applications.…”