Exciton and electron-hole plasma lasing in ZnO dodecagonal whispering-gallery-mode microcavities at room temperature

Abstract

Dodecagonal ZnO microrods were fabricated by vapor transport method. A dodecagonal ZnO microrod with diameter of 6.35 μm was employed as a whispering gallery mode microcavity, the low threshold exciton lasing was stimulated. In another smaller microrod, the electron-hole plasma lasing was observed under intense excitation as the carrier density was larger than the Mott transition density. The interference condition in the dodecagonal cavity was deduced, and the mode structures were investigated. Compared to the hexagonal microcavity with same diameter, the dodecagonal microcavity has higher lasing performance.

Whispering gallery modes in deformed hexagonal resonators

“…1) have been investigated in various material systems such as (Al,Ga)As/ GaAs [20], GaN [21], (In,Ga)N [22], ZnO [17,23,24], In 2 O 3 [25], and organic materials [26]. Stimulated emission (lasing) has been demonstrated for triangular [15,27], hexagonal [28][29][30][31][32], and dodecagonal [33] cavities.…”

“…In [33], laser modes in a dodecagon had been assigned to 12-WGM, however, other possible modes have not been considered.…”

Controllable fabrication and optical properties of Sn-doped ZnO hexagonal microdisk for whispering gallery mode microlaser

“…[10][11][12][13][14][15][16][17][18][19] Most of the high quality WGM lasing results were observed from ZnO microrod/wires with several millimeters. [12][13][14][15][16] However, the traditional GaAs and GaN WGM microcavities are of disk structures formed by the etching technique. 20,21 It means that high performance thin film deposition system and etching machine are indispensable for fabricating ZnO microdisk WGM cavities.…”

Double threshold behavior in a resonance-controlled ZnO random laser

“…[1][2][3][4][5][6][7][8][9][10][11][12][13] In typical random structures, because localized modes are spontaneously formed and its modal control is difficult due to the multiple light scattering, the lasing peak wavelengths depend mainly on the property of gain materials and their thresholds are determined by the mean scattering property of the structure. Furthermore, the features of the RL (e.g., multimode lasing and high thresholds) make it difficult to realize strong interactions between cavity modes and gain materials and observe cavity-related phenomena, [21][22][23][24] like observed in well-designed resonators, as mentioned above. a fuji@es.hokudai.ac.jp b H. Fujiwara and T. Nakamura contributed equally to this work.…”

“…[18][19][20][21] Although, in most of these ZnO lasers, the gain from electron-hole plasma (EHP) recombination under high excitation intensity condition has typically been reported as the origin of the stimulated emission (photon lasing), 12,13 the lasing originated by excitonic recombination, so-called polariton/exciton lasers, has also been demonstrated in well-designed cavity structures at room temperature. [21][22][23] Random lasers (RLs) based on photon localization due to multiple light scattering have been reported in various materials. In particular, because ZnO has the above-mentioned advantages and high gain, there are numerous studies on RLs so far.…”