Mode Control of Random Laser Action Assisted by Whispering-Gallery-Mode Resonance

Abstract

Whispering-gallery-mode (WGM) resonance manipulated random laser action has been proposed. To illustrate our working principle, lasing characteristics of ZnO nanorods decorated with SiO2 nanospheres have been investigated. It is found that with the assistance of SiO2 nanospheres the emission spectrum exhibits a very narrow background signal with a few sharp lasing peaks and a very small full width at half-maximum of less than 0.3 nm. The differential quantum efficiency (ηd) of random laser action can be greatly enhanced by up to 735%. More interestingly, the wavelength of laser action of ZnO nanorods can be controlled by the decoration of different-size nanospheres. The underlying origin is attributed to the fact that the decorated nanospheres not only enable the generation of WGM resonance and enhance the peak emission intensity but also can serve as scattering centers. Cathodoluminescence mapping images of nanorods decorated with nanospheres and theoretical calculation based on the spherical cavity were utilized to confirm our proposed mechanism. These intriguing features manifest the tunability of mode-controlled random laser action by WGM resonance of nanospheres. Our discovery shown here may open up a new approach for the creation of highly efficient optoelectronic devices.

Whispering-Gallery-Mode for Coherent Random Lasing in a Dye-Doped Polystyrene Encapsulated Silica-Glass Capillary

“…It has been reported that random lasings (RLs) are generated by WGM resonance in disordered systems. Chen et al [19] modified SiO 2 nanospheres on the surface of ZnO nanorods, pumping out random laser light with the aid of WGM resonance effect of spherical particles. As for a glass capillary, WGM resonance easily occurs in the wall of the capillary if the refractive index (RI) of the filling medium in the capillary is greater than the RI of the glass capillary.…”

Random lasing realized in n-ZnO/p-MgZnO core–shell nanowire heterostructures

“…[1][2][3][4][5][6] Many efforts have been devoted to develop random lasers, and optically pumped random lasers have been reported extensively. [7][8][9][10][11][12][13] Realizing electrically pumped lasing has been one of the most challenging issues of random lasers, and zinc oxide (ZnO) has been considered as one of the most active materials for electrically pumped random lasers. [14][15][16][17][18][19] Although many reports have demonstrated electrically pumped random lasing from ZnO, most of them are realized in metal-insulator-semiconductor (MIS) structures.…”

Whispering Gallery Mode Lasing from Self-Assembled Hexagonal Perovskite Single Crystals and Porous Thin Films Decorated by Dielectric Spherical Resonators

“…Over the past few decades, the optical processes associated with various reasonable micro/nano cavities, such as photonic crystals cavity, Fabry–Perot (F–P) optical cavity, and whispering-gallery-mode (WGM) resonator have been considered as an attracting platform for micro or nanolaser systems . Amidst them, the WGM induced laser action is of present scrutiny by the reason for inherently high quality ( Q ) factor, small mode volume, low-lasing threshold, and relatively simple fabrication . One of the advantages of WGM oscillations arises from the underlying working principle of the strong coupling between confined light beam and the cavity.…”

“…17 Amidst them, the WGM induced laser action is of present scrutiny by the reason for inherently high quality (Q) factor, small mode volume, low-lasing threshold, and relatively simple fabrication. 18 One of the advantages of WGM oscillations arises from the underlying working principle of the strong coupling between confined light beam and the cavity. Attributable to the total internal reflections (TIRs) of light at the hexagonal or circular boundary, there exists possibility of high-quality factor (Q) of WGMs, which enables low threshold microcavity lasers.…”

“…The value of the lasing threshold is approximately 85.5 μJ/cm 2 , implying that the laser action can be easily achieved as compared with previous reports. 14,18,43 A plot of integrated emission intensity and fwhm as a function of pumping energy density is shown in Figure 7b. We can clearly see the occurrence of threshold behaviors, which provides a firm signature of laser action.…”