Development of 3D-semiconductive photonic crystals with a bandgap in the optical wave region

人们对折射率周期性变化的光子晶体很感兴趣。在晶体中形成光子带隙，所有波矢都禁止电磁波传播。利用光子带隙和人工引入的缺陷态和/或光发射体，有望实现各种重要的科学和工程应用，如控制自发辐射、零阈值激光、非常尖锐的光弯曲、光子捕获等。在这个项目中，我们成功地开发出了在近红外波长(1-2微米)具有足够带隙效应的完整的3D光子晶体，该方法基于III-V半导体条与晶片融合和激光辅助非常精确的对准的方法。详细研究了全三维光子晶体在近红外波段的性质，并讨论了其在超小型光学集成电路(光学芯片)中的可能应用。在本项目中，三维光子晶体的研究经验应用于二维光子晶体，因为即使光的控制受到二维限制，三维光子晶体也可以实现特定(不是万能的，但重要的)功能器件。我们研究了利用二维光子晶体的新型功能器件。一种是在二维光子晶格结构中具有多向分布反馈效应的二维光子晶体激光器。结果表明，该器件可以作为高功率表面发射激光器工作，可以在很大范围内实现单模振荡。另一种是利用二维光子带隙结构中的单个缺陷的器件。缺陷捕获通过二维光子晶片中形成的波导传播的光子，并将其发射到自由空间。基本操作已成功演示。

Much interest has been drawing in photonic crystals in which the refractive index changes periodically. A photonic bandgap is formed in the crystals, and the propagation of electromagnetic waves is prohibited for all wave vectors. Various important scientific and engineering applications such as control of spontaneous emission, zero-threshold lasing, very sharp bending of light, trapping of photons, and so on, are expected by utilizing the photonic bandgap and the artificially introduced defect states and/or light-emitters. In this project, we have succeeded in developing complete 3D photonic crystals with sufficient bandgap effects at near-infrared wavelengths (1-2um) based on a method where III-V semiconductor stripes are stacked with the wafer-fusion and the laser-beam assisted very precise alignment. The properties of the full 3D photonic bandgap crystals at near-infrared wavelengths have been investigated in detail and possible applications to ultrasmall optical integrated circuits (optical chip) have been discussed.In this project, 3D photonic crystal research experience has been applied to 2D photonic crystals, which are also promising since specific (not almighty, but important) functional devices can be realized even though the control of light is limited two-dimensionally. We investigated novel functional devices utilizing 2D photonic crystals. One is a 2D photonic crystal laser with multi-directionally distributed feedback effect in 2D photonic lattice structure. It has been shown that the device can work as a high-output power surface-emitting laser, which can oscillate in very large area with single mode. The other is a device utilizing a single defect in 2D photonic bandgap structure. The defect traps the photons which propagate through a waveguide formed in 2D photonic crystal slab and emits them to free-space. The basic operations have been successfully demonstrated.