Amplified Spontaneous Emission in Semiconductor‐Nanocrystal/Synthetic‐Opal Composites: Optical‐Gain Enhancement via a Photonic Crystal Pseudogap
Amplified Spontaneous Emission in Semiconductor‐Nanocrystal/Synthetic‐Opal Composites: Optical‐Gain Enhancement via a Photonic Crystal Pseudogap
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DOI：
10.1002/adma.200500875
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发表时间：
2006-02
影响因子：
29.4
通讯作者：
G. Maskaly;M. Petruska;J. Nanda;I. Bezel;R. Schaller;H. Htoon;J. Pietryga;V. Klimov
中科院分区：
文献类型：
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作者：
G. Maskaly;M. Petruska;J. Nanda;I. Bezel;R. Schaller;H. Htoon;J. Pietryga;V. Klimov
对紧凑、低阈值激光器的可能性的兴趣激发了对嵌入光子晶体（PC）结构中的活性材料的发射的研究。光子带边缘处光群速度的急剧下降增加了光与增益介质的相互作用时间，从而增强了光学增益。 [1,2] 这种增益增强已在各种 PC 系统中观察到，包括一维 (1D)、[3] 二维 (2D)、[4] 和三维 (3D) [5] 结构。我们重点关注蛋白石，它是面心立方 (FCC) 晶格中球体的 3D 排列。虽然胶体纳米晶体 (NC) 已渗透到蛋白石中 [6]，并且此类材料已证明可以改变 NC 的自发发射，但 [7,8] 胶体 NC/蛋白石材料的放大自发发射 (ASE) 此前尚未得到证实。我们提出了由二氧化钛溶胶-凝胶/CdSe 或 PbSe NC 纳米复合材料 [9,10] 组成的新型材料，渗透到聚苯乙烯蛋白石 PC 中。我们证明，尽管光子结构中NC的体积负载较低，但相对于参考溶胶-凝胶/NC材料，这些溶胶-凝胶/NC/PC复合材料在较低的阈值下表现出高效的ASE。这一观察结果表明，由于蛋白石中第一个 L 点间隙边缘的影响，光学增益有效增加。该 L 点间隙对应于光在 FCC 蛋白石结构内的方向传播的最低能隙（简称为 L 点间隙）。
Interest in the possibility of compact, low-threshold lasers has motivated investigations of the emission of active materials embedded in photonic crystal (PC) structures. The sharp decrease in the group velocity of light at the photonic band edge increases the interaction time of the light with the gain medium, enhancing optical gain. [1,2] Such gain enhancements have been observed in a variety of PC systems, including one-dimensional (1D), [3] two-dimensional (2D), [4] and three-dimensional (3D) [5] structures. We focus on opals, which are 3D arrangements of spheres packed in a face-centered cubic (FCC) lattice. While colloidal nanocrystals (NCs) have been infiltrated into opals [6] and such materials have demonstrated modification of the spontaneous emission of the NCs, [7,8] amplified spontaneous emission (ASE) from a colloidal NC/opal material has not been demonstrated before. We present novel materials consisting of a titania sol–gel/CdSe or PbSe NC nanocomposite [9,10] infiltrated into polystyrene opal PCs. We demonstrate that these sol–gel/NC/PC composites exhibit efficient ASE at decreased thresholds relative to the reference sol–gel/NC materials despite the lower volume loading of NCs in the photonic structure. This observation indicates an effective increase of the optical gain as a result of the influence of the first L-point gap edge in the opal. This L-point gap corresponds to the lowest energy gap for light traveling in the direction within the FCC opal structure (referred to as simply the L-point gap).