According to the photon statistics theory, the photon distribution for a coherent light source obeys a Poisson distribution, and the photon distribution for an incoherent light source follows a Bose-Einstein distribution. The temporal coherence properties of a random laser were investigated by using a Michelson interferometer [21]. Cao et al. [22] studied the photon statistics of a single-shot random laser mode fit to a Poisson-like distribution upon high-intensity pumping. They also addressed the low spatial coherence of RL emission using double-slit experiments [23]. The RL exhibited a high intensity with low spatial coherence due to the stimulated emission in
many different spatial modes. Optoelectronic and medical applications require low spatial coherence such as for high-resolution speckle-free imaging. Therefore, it has been conceptually demonstrated that RL is superior to conventional lasing Selisistat supplier for speckle-free imaging applications [24]. The RL-related effects have been demonstrated AUY-922 research buy in different ZnO architectures. Most previous studies on RL with ZnO architectures have been accomplished
on ensembles [10–12, 19, 20], meaning the properties of the individual microstructures were missing in the superposition of the ensemble. However, the RL characteristics of single microstructures have not been investigated so far. A detailed investigation on the lasing behaviors of the individual ZnO microstructures is crucial for micro/nanolaser application. In this study, we demonstrated a type of urchin-like ZnO microcrystal formed by oxidizing metallic zinc and revealed the excellent optical quality of these ZnO microstructures. Furthermore, the random lasing behavior of a single urchin-like microstructure was comprehensively examined by employing the excitation power and microstructure size dependence of the photoluminescence emission by pulsed laser excitation. Methods The synthesis of ZnO microcavities was conducted in Diflunisal two steps. First, hexagonal Zn microcrystals
were fabricated using carbothermal vapor-phase transport [14]. This step involved placing a source that contained ZnO powder and graphite powder at a volume ratio of 1:1 into a furnace tube and then placing a Si (100) substrate in a downstream position. After the system was evacuated to a pressure of less than 100 mTorr using a mechanical pump, high-purity argon gas was introduced into the system at a flow rate of 10 sccm. The temperature was kept at 950°C for 1 h, and the pressure in the tube was maintained at 800 mTorr. Then, we conducted an oxidation process. The pressure inside the furnace tube was maintained at 800 mTorr (the same pressure used in the first step) with an O2 flow of 5 sccm, and the oxidation process was conducted at 500°C for 1 h. The synthesized products were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD).