Two-threshold silver nanowire-based random laser with different dye concentrations

Abstract

Unlike conventional lasers with reflective mirrors, random lasers without mirrors rely on the multiple scattering of light in a random system to form an optical feedback mechanism. Therefore they have an important theoretical research value in the field of interaction between light and disorder media and in the field of lasers (i.e. the optical amplifying physical mechanism in a mirrorless system) and have potential applications in displays, sensors and biomedicine [1-5]. Generally, it was considered that there are two feedback mechanisms in random lasers: coherent feedback and incoherent feedback. Incoherent feedback leads to a single or two narrow spectral peaks with a bandwidth of a few nanometers [6-8], while coherent feedback will induce several sharp spectral spikes with subnanometer bandwidth [9][10][11][12][13][14][15][16][17]. Generally, the two kinds of feedback have been investigated in different ways. A random laser with incoherent feedback follows the diffusion equations with gain items [18], while a coherent feedback random laser was treated through combining Maxwell's equations and rate equations [19].The correlation between the two kinds of feedbacks has seldom been noticed. In 2000, Cao et al [20] demonstrated the transition from incoherent feedback to coherent feedback in a strong scattering system by changing the pumping energy for the case with some values of the concentrate of scattering particles. Vardeny et al [21] and Noginov et al [22] observed a similar transition in p-conjugated films, in infiltrated opals and in GaAs random laser, respectively. Liu et al [23] achieved a similar transition for a single random system by changing the pulse width of the pumping lasers. These results reveal that there should be inherent relations between incoherent feedback and coherent feedback and under certain conditions the transition between the two kinds of feedbacks can occur for the single disorder system which will demonstrate two-threshold character. Recently, Lopez [24] demonstrated the difference of an incoherent feedback random laser and a resonance feedback random laser by the correlated property of several of the most intense peaks. The smooth random lasing spectrum with a bandwidth of a few nanometers was attributed to the strong correlation of the resonance feedback induced lasing mode Laser Physics Letters

Temporal profiles for measuring threshold of random lasers pumped by ns pulses

“…A typical dual-regime random laser 36 is chosen and its emission characteristics are demonstrated in Fig. 3 under the condition of C R6G  = 2.1 mM with ρ AgNW  = 7.3 × 10 7 mL −1 .…”

“…In our experiment, silver nanowires (Ag NWs) are synthesized by a polyvinylpyrrolidone-assisted reaction in ethylene glycol 11 , 36 . The scanning electron microscope (SEM) image of the Ag NWs in Fig.…”

Pump-Controlled Plasmonic Random Lasers from Dye-Doped Nematic Liquid Crystals with TiN Nanoparticles in Non-Oriented Cells

“…Over the past few decades, plenty of methods have been proposed for controlling the performance of random lasers [27][28][29][30][31][32][33]. Some deals with adjusting the scatterers, others depend on controlling the gain.…”

Magnetically Controllable Random Lasers

“…Mode‐locking and single‐mode random lasers, the longstanding scientific goals, have been demonstrated by the pumping scheme, Raman gain, intentional defect sites, and bioinspired photonic structure . Mode‐transition can also be accomplished by altering the pumping condition, modulating the concentration of gain media or scatterers, and the mechanically induced reformation . Although inherent angle‐free emissions of random lasers are useful for some specific applications, a directional output is also highly desired.…”