Tuyen Le Dac, Lin Jian Hung, Wu Cheng Yi, Tai Po-Tse, Tang Jau, Minh Le Quoc, Kan Hung-Chih, Hsu Chia Chen
Department of Physics, National Chung Cheng University, Ming Hsiung, Chia Yi 621, Taiwan.
Opt Express. 2012 Jul 2;20(14):15418-26. doi: 10.1364/OE.20.015418.
High quality opal photonic crystals (PhCs) were successfully fabricated by self-assembling of monodisperse Eu(3+)/SiO(2) core/shell nanospheres. Angular resolved photoluminescence (PL) spectra of a PhC sample were measured with different pumping powers, and its PL emission strongly depended on spectroscopic position of the photonic stop band and the optical pumping power. Suppression of the PL occurred in the directions where the emission lines aligned with the center of the photonic stop band. Suppression and enhancement of the PL were observed at low- and high-pumping powers, respectively, in the directions where the emission lines were located at the edges of the photonic stop band. When pumping power exceeded 6 µJ/pulse, a super-linear dependence was found between the pumping power and PL intensity. The dramatic enhancement of PL was attributed to the amplification of spontaneous emission resulted from the creation of large population inversion and the slow group velocity of the emitted light inside the PhC. The opal PhC provided highly angular-selective quasi-monochromatic PL output, which can be useful for a variety of optical applications.
通过单分散Eu(3+)/SiO(2)核壳纳米球的自组装成功制备了高质量的opal光子晶体（PhC）。用不同的泵浦功率测量了PhC样品的角分辨光致发光（PL）光谱，其PL发射强烈依赖于光子禁带的光谱位置和光泵浦功率。在发射线与光子禁带中心对齐的方向上发生PL抑制。在发射线位于光子禁带边缘的方向上，分别在低泵浦功率和高泵浦功率下观察到PL的抑制和增强。当泵浦功率超过6 μJ/脉冲时，发现泵浦功率与PL强度之间存在超线性依赖关系。PL的显著增强归因于自发发射的放大，这是由于在PhC内部产生了大量的粒子数反转以及发射光的慢群速度。opal PhC提供了高度角选择性的准单色PL输出，这可用于各种光学应用。
