A study on the three-dimensional optical circuits and technology

该项目的目的是发展三维光学电路和技术，其沿传播轴具有逐渐的折射率变化。所开发的电路具有以下新功能：辐射波的应用；天线耦合y结波导；锥度和相干锥度的应用；模式匹配装置；反射与共振的应用；abrupt-bend波导。基于上述概念，提出了以下新器件，并对其进行了分析和部分制作。天线耦合y结波导；为了减少y结的辐射损失，降低了分支区附近的折射率。实际得到了宽、低损耗的y型结。一种不同光波导间的光纤模式匹配装置制作了一端为矩形芯，另一端为圆形芯的单模锥形光纤，并对其基本性能进行了验证。新型波导弯曲结构；一个结构在角的外面有一个低折射率的区域。基本性能得到确认。三维光波导的微加工技术介绍了一种电子回旋共振反应离子刻蚀系统。连续制备了离子刻蚀LiNb <O_3>和Si <O_2>脊波导。完全速度匹配LiNb <O_3>行波调制器由脊波导组成的调制器具有约1太赫兹的调制带宽和低驱动电压。实验验证了20 GHz调制的可行性。光开关;(1)制备了小型化LiNb <O_3>定向耦合器。(2)研究了载流子注入型<III> - <V>化合物半导体开关。利用自制的LPE设备，计算折射率变化，制备外延生长薄膜。采用相板进行波束变换的分支电路；进行了设计和基础实验，并确定了基本性能。

The purpose of the project is the development of 3-dimensional optical circuits and technology, which have gradual refractive index variations along the propagation-axis. The developed circuits have new functions as follows:1. Application of radiation-wave; antenna coupled Y-junction waveguides,2. Application of taper and coherent taper; mode matching device,3. Application of reflaction and resonance; abrupt-bend waveguides.Following new devices have been proposed, analized and partially fabricated based on the above mentioned concepts.1. Antenna coupled Y-junction waveguides; To reduce radiation losses of Y-junctions refractive index near the branching region was reduced. The wide and low loss Y-junctions were actually obtained.2. A fiber mode matching device between dissimilar optical waveguides; A single-mode tapered fiber with a rectangular core at one end and a circular core at the other was fabricated and basic performance was confirmed.3. New waveguide-bend configuration; A structure has a low refractive-index region at the outside of the corner. Basic performance was confirmed.4. Microfabrication for the 3-D optical waveguides; An ECR (electron cyclotron resonance) reactive ion etching system was introduced. Ion-etched LiNb <O_3> and Si <O_2> ridge waveguides were successively fabricated.5. Perfect velocity matching LiNb <O_3> traveling-wave modulators; The modulator that comprises of a ridge-waveguide has about 1 THz modulation band-width and low driving voltage. 20 GHz modulation was confirmed experimentally.6. Optical switches; (1) Miniaturized LiNb <O_3> directional-coupler was fabricated. (2) Carrier injection type <III> - <V> compound semiconductor switches are investigated. Refractive index changes was calculated and epitaxial growth films were fabricated by using a hand-made LPE equipment.7. Branching circuit by beam transformation using phase plates; Design and fundamental experiments were made, and basic performance was confirmed.