Characteristics of multi-mode lasing in cesium lead bromide perovskite microwires with an isosceles right triangle cross-section

Abstract

The CsPbBr3 microwires with unique isosceles right triangle cross-sections are commonly observed via chemical vapor deposition method. In this work, we study the correlations between measured multi-mode lasing behaviors and the simulation of the mode patterns inside the triangular-rod microcavity. We confirm that lasing action with higher-order transverse modes can well sustain, even when these modes experience large optical loss due to the isosceles triangle cross-section. By comparing the experimental and simulation results, the higher-order transverse modes tend to show up prior to the fundamental transverse modes for wider microwires. We attribute this behavior to the nonuniform field distribution caused by the high absorption efficiency of CsPbBr3. We also elaborate on the difficulties to sustain the whispering gallery mode in the CsPbBr3 triangular-rod microcavity, which implies that the lateral dimension and geometry of the cavity should be considered carefully for the future design of low threshold wire-based laser devices.

Shape‐Controlled Solution‐Epitaxial Perovskite Micro‐Crystal Lasers Rivaling Vapor Deposited Ones

“…This oblique emission direction is likely to cause the high scattering of light at the end facets of the micro-prisms, as observed in Figure 4b (inset). The micro-prisms exhibit further modes, at different wavelengths with similar mode patterns (Figure S14a,b, Supporting Information) Similar modes have previously been obtained for CsPbBr 3 micro-resonators with the same geometry, [41] exhibiting also a rich transverse mode pattern. Higher transverse modes tend to occur due to the relatively large crosssection of the micro-resonators.…”

“…Even under high resolution, no roughness could be observed by secondary electron microscope (SEM, Figure S4, Supporting Information), and the single microstructures look as perfect as those reported in literature from vapor phase epitaxy. [36,41,58] The orientation of the micro-resonators was proven by electron backscatter diffraction (EBSD), as described in the experimental section. EBSD patterns of the MAPbBr 3 micro-crystal showed Kikuchi lines (Figure 1f).…”

“…Metal-halideperovskite based lasers, thus have also been demonstrated by vapor-phase epitaxial growth. [33][34][35][36][37][38][39][40][41] In this case, the vapor-phase epitaxy provides not continuous films, but self-assembled micro-crystallites, providing not only the gain material but also the laser resonators. Most interestingly, however, the lowest laser thresholds reported in literature about perovskites-lasers from micro-crystalline like resonators have not been obtained only by vapor-phase deposition, [42] but also from solution phase, by surface-initiated growth method.…”

Double-Cavity Modulation of Exciton Polaritons in CsPbBr3 Microwire

“…3,12,32 The cross section of the single CsPbBr 3 microwire is an isosceles right triangle, which is difficult to form a stable whispering gallery mode (WGM) due to the leakage of propagating photons. 33 A folded F−P cavity can be formed by partial reflection from two right-angle side walls and total reflection from the bottom wall, as shown in Figure 1b. However, the strong coupling between confined photons and excitons in this kind of self-configuration folded F−P microcavity has been seldom studied in CsPbBr 3 .…”

“…39 In our simulations, the refractive index is a function of energy, 20,30 and the mica has a refractive index of 1.6. 33 Despite the differences in the optimal quality factors Q of the two microcavities, the spectra observed at the end facet can still carry the signals of the two kinds of F−P cavities, which may indicate that double-cavity modulation associated with mode competition can be achieved in SRPL spectral measurements (Figure 3 and Figure S3). The mode competition between the two Fabry−Peŕot cavities may be more evident when stimulated radiation occurs, which needs further study.…”