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Random laser in dye-doped electrospun nanofibers: Study of laser mode dynamics via temporal mapping of emission spectra using Pearson's correlation
摘要： The development of optically active flexible nanostructures has been pursued in the last years owing to their potential application in photonic devices. Herein, we report a random laser architecture based on a flexible Rhodamine B-doped PMMA nanofibers produced via electrospinning technique with 1% and 5% (w/w) of dye. The lower concentrated sample provided only incoherent emission due to the low absorption mean free path. The most concentrated one provided both coherent and incoherent random laser emission depending on the position of the sample the excitation took place. Pearson’s correlation coefficient maps showed a clear correspondence with the already established mode locking transition in random laser. A temporal mapping of successive emission spectra was performed, which provided qualitative information about mode competition dynamic when applied to coherent emission spectra and a highly sensitive way of tracking line widening and red/blueshift in incoherent random laser emission spectra. The developed system can be further employed to design novel miniaturized chemical and temperature sensors.
关键词： Electrospun nanofibers,Random laser,Mode correlation,Temporal dynamics
更新于2025-09-19 17:13:59
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Footprint of plexcitonic states in low-power green–blue plasmonic random laser
摘要： Green–blue plasmonic random laser is attained by two-dimensional plexcitonic structure. The main gain plexcitonic media contained two-dimensional periodic arrays of gold nanowires which is covered by dye layer. Due to the change in the strength of exciton and plasmon coupling in these plexcitonic gain structures, different close loop, and thus random lasing must be takes place. For this purpose, we fabricate six samples with different plexcitonic power and pumped fabricated two-dimensional nanostructures by green nanosecond pulsed laser. Our results show efficient coherent random lasing due to the plexcitonic nanostructure in the blue, because two-photon absorption and also green part of the visible spectral region considering its applicability in the design and fabrication of compact and miniaturized random laser sources.
关键词： random laser,green–blue plasmonic,low-power,plexcitonic states
更新于2025-09-16 10:30:52
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Resonance energy transfer-assisted random lasing in light-harvesting bio-antenna enhanced with a plasmonic local field
摘要： Thanks to the advent of the random laser, new light applications have opened up, ranging from biophotonic to security devices. Here, by using the well-known but unexplored light-harvesting bio-pigment of butterfly pea (Clitoria ternatea, CT) flower extract, generation of continuous-wave (CW) random lasing at ~660 nm has been demonstrated. Furthermore, a wavelength tunability of ~30 nm in the lasing emission was obtained by utilizing the resonance energy transfer (RET) mechanism in a gain medium with a binary mixture of CT extract and a commercially available methylene blue (MB) dye as the gain medium. In the CT extract–dye mixture, the bio-pigments are acting as donors and the MB dye molecules are acting as acceptors. Amplification in intensity of the lasing emission of this binary system has further been achieved in the presence of optimized concentrations of metal (Ag)–semiconductor (ZnO) scattering nanoparticles. Interestingly, the lasing threshold has been reduced from 128 to 25 W cm?2, with a narrowed emission peak just after loading of the Ag nanoplasmon in the ZnO-doped binary gain medium. Thanks to the strong localized electric field in the metal nanoplasmon, and the multiple scattering effects of ZnO, the lasing threshold was reduced by approximately four times compared to that of the gain medium without the use of scatterers. Thus, we believe that our findings on wavelength-tunable, non-toxic, biocompatible random lasing will open up new applications, including the design of low-cost biophotonic devices.
关键词： light-harvesting bio-antenna,resonance energy transfer,random laser,plasmonic local field,biocompatible
更新于2025-09-16 10:30:52
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Rare earth doped PDMS elastomeric random lasers
摘要： We report a very stable elastomeric random laser (SERL) system composed of two stable materials: inorganic Nd:YAB nanoparticles and polydimethylsiloxane (PDMS). Lasing at a wavelength of 1064.5 nm is observed when the samples are exposed to pulsed nanosecond excitation at 808 nm or 532 nm, with long term (days) operation without degradation. Contrary to other RLs based on polymers, this very stable RL is the first elastomeric system, hence tunable, which allows the systematic investigation of its dynamics over a long time, without the complication of gain reduction or deterioration of the polymer. The RL threshold is estimated to be around 1.0 mJ at 808 nm. The measured linewidth decreases from 3.2 nm to 0.5 nm. The spectral peak position as well as the intensity is conveniently tuned by stretching the elastomer polymer composite. As an application which requires long term operation, Levy-like statistics and replica symmetry breaking in this open cavity random laser were also demonstrated. These lasers have been used over several months without noticeable degradation.
关键词： PDMS,Levy-like statistics,YAB nanoparticles,Nd,Elastomeric random laser
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Plasmonic Random Laser with the Embedding of Silver Nanostructure Materials
摘要： In contrast to conventional lasers, random lasers (RLs), without cavity mirrors, were generated based on recurrent light scattering within nano-materials and possessed peculiar properties for practical applications. To date, researchers are not only interested in the novel nano-materials for the generation of RL but also curious in the manipulated property of RL through temperature and electric filed [1]. In addition, plasmonic random laser (PRL)[2] based on the localized surface plasmon resonance (LSPR) of metallic nanoparticles has attracted great interest. In this work, the dye-covered PVA (DC-PVA) film with the embedding of silver nano-particles (AgNPs) was produced to investigate the enhancement of emission spike intensity from PRL and the underlying mechanism by varying the size and shape of AgNPs. Here, the AgNPs were synthesized by a soft solution-phase approach inside the DI water [3]. Depending on the size and shape of AgNPs in colloidal solution, the absorbance spectrum in Fig. 1(a) reveals different peak absorption wavelength (λp) at 404 nm and 610 nm, respectively, and shows deep yellow and navy color (Fig. 1(a)). The PVA film with embedding of AgNPs (PVA/AgNPs) was produced by dropping the mixed solution, comprising PVA powder and AgNPs, onto a glass substrate. After drying, the laser dye (Pyrromethene 597, Exciton inc.) was coated on the top of PVA film (Inset of Fig. 1: the structure of sample). In this work, the coherent back scattering measurement (CBS) measurement [4] was performed to obtain the transport mean free path (lp) of pure DC-PVA film (green squares: Sample-I) and DC-PVA/AgNP film [red triangles: Sample-II (λp at 405 nm), blue circle: Sample-III (λp around 610 nm)]. The solid lines represent the theoretical fitting curves to obtain the lp of three samples around 10.3, 8.7 and 3.6 μm. The value of lp decreases obviously after AgNPs was embedding in the PVA film to illustrate the enhancement of light scattering. In order to generate RL, we excited all the produced samples by a frequency doubling Q-switched Nd:YAG laser with a central wavelength of 532 nm. The 10 Hz pump pulses were focused onto the sample with a long line stripe by a cylindrical lens with focal length f = 7cm. The side emission of the sample was collected by the fiber tip and measured by the spectrometer (resolution about 0.3 nm, Ocean Optics Inc.). Inset of Fig. 1(b) shows the emission spectra of DC-PVA film without (Sample-I, green solid curve) and with (Sample-II: red solid curve and Sample-III: blue solid curve) AgNPs. Even at relatively high pulse energy, the Sample-I (without AgNPs) only reveals broad spontaneous emission spectrum with the maximum intensity at λ = 578 nm. For the sample-II and sample-III (DC-PVA/AgNP film), the discrete emission spikes at around about λ=576 and 583 nm on the top of broad spontaneous emission can be revealed which is the characteristic of RL. In order to qualitatively distinguish the operation state of RL, the α-stable distribution [5] proposed by Uppu et al. was used to analysis the intensity fluctuation (red) of the sample by sampling 1000 spectrum slots. The intensity distribution (red histogram) can be theoretical fitting by the equation (blue solid curves in Figs. 1(c) and 1(d)) to obtain the α=1.99 and 1.58, respectively, which reveals the Gaussian and Levy distribution.
关键词： random lasers,light scattering,localized surface plasmon resonance,plasmonic random laser,silver nano-particles
更新于2025-09-12 10:27:22
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Signature of plasmonic nanoparticles in multi-wavelength low power random lasing
摘要： A multi-wavelength plasmonic random lasing is attained by core-shell nanoparticles and the mixture of metallic nanoparticles in the host dye medium. The plasmonic nanoparticles, fabricated using laser ablation in liquid, were mixed in the corresponding dye medium and pumped with green nano-second pulsed laser. Due to this optical pumping process of plasmonic nanoparticles, amplification of the fluorescence and the lasing activity took place due to the localized surface plasmon resonance and scattering of each nanoparticle, core-shell and mixture nanoparticles. Our results show efficient coherent random lasing due to the interface between two different metallic nanoparticles in the middle part of the visible spectral region considering its applicability in the design and fabrication of compact and miniaturized random laser sources.
关键词： Plasmonic nanoparticles,Dye,Random laser,Core shell,Coherent laser
更新于2025-09-12 10:27:22
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A silicon-based quantum dot random laser
摘要： Herein, a quantum dot random laser was achieved using a silicon nanowire array. The silicon nanowire array was grown by a metal-assisted chemical etching method. A colloidal quantum dot solution was spin-coated on silicon nanowires to form the random laser. The performance of the random laser was controlled by the resistivity of silicon wafers and the length of silicon nanowires. A transition from incoherent random lasing to coherent random lasing was obtained by increasing the resistivity of the silicon wafers. The random lasing threshold increased with an increase in the length of the silicon nanowires. These results may be useful to explore high-performance silicon-based random lasers.
关键词： metal-assisted chemical etching,silicon nanowire array,coherent random lasing,quantum dot,random laser
更新于2025-09-11 14:15:04
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Spectral super-resolution spectroscopy using a random laser
摘要： Super-resolution microscopy refers to a powerful set of imaging techniques that overcome the diffraction limit. Some of these techniques, the importance of which was recognized by the 2014 Nobel Prize for chemistry, are based on the concept of image reconstruction by spatially sparse sampling. Here, we introduce the concept of super-resolution spectroscopy based on sparse sampling in the frequency domain, and show that this can be naturally achieved using a random laser source. In its chaotic regime, the emission spectrum of a random laser features sharp spikes at uncorrelated frequencies that are sparsely distributed over the emission bandwidth. These narrow lasing modes probe stochastically the spectral response of a sample, allowing it to be reconstructed with a resolution exceeding that of the spectrometer. We envision that the proposed technique will inspire a new generation of simple, cheap, high-resolution spectroscopy tools with a reduced footprint.
关键词： super-resolution spectroscopy,random laser,sparse sampling,spectral reconstruction,frequency domain
更新于2025-09-11 14:15:04