Multi-waveguding type photonic functional devices for WDM systems

为了应用于先进的波分复用系统，本课题通过理论分析和实验研究，提出并实现了一种新型的多模或多波导光器件，以期在小型化的同时具有新的功能。主要成果如下：1)提出了多模干涉(MMI)光开关。分析表明，在器件长度约为50um的情况下，MIPS对于-20dB或更小的低串扰等具有良好的特性。实际制作了器件，并演示了基本的光子开关。还证实了MIPS可以在多种功能中运行，例如为同一设备切换和分配光线。2)提出了多模干涉波长转换器，它的优点是器件结构简单，不需要额外的元件来分离信号和转换后的L…更多的枪声。对其制作工艺进行了研究，并从实验上证实了波长转换所必需的交叉增益调制特性。这些结果显示了有源MMI作为有效波长转换器的潜力。3)对于窄带光分插复用器，理论研究表明，通过引入合适的密度调制光栅，可以获得较低的旁瓣特性，抑制比约为-30dB。4)提出了一种结构紧凑的多次反射阵列波导，并从理论和实验两个方面对其有效性进行了验证。5)提出了激光二极管与多模干涉光波导(MILD)集成的方案，从理论上证明了适合于单模光纤耦合的窄光束特性，耦合损耗低至-4db。通过本项目，多模和多波导器件被证明是非常有效的高性能多功能光子开关，并计划进行进一步的研究，以实现实际器件和系统评估。较少

For the application to advanced wavelength-division multiplexing systems, this project was carried out to propose and realize the novel multi-mode or multi-waveguide photonic devices, which were expected for new functions as well as compactness, through the analyses and experiments. The main results during the two-year term are as follows :1) Multi-mode interference (MMI) photonic switches (MIPS) were proposed. The analyses suggest that an MIPS is capable to show good characteristics for a low cross-talk of -20dB or less and so on with a device length of about 50mum. Actually the devices were fabricated, and fundamental photonic switching was demonstrated. It was also confirmed that the MIPS could operate in versatile functions such as switching and distributing of the light for the same device. 2) Multi-mode interference wavelength converters (MIWC) were proposed, which have the advantage of a simple device structure without additional components to separate a signal and a converted l … More ights. Fabrication process was investigated, and cross-gain modulation characteristics which was a necessary effect to show wavelength conversion was experimentally confirmed. These results shows the potential of the active MMI for effective wavelength converters. 3) As for the narrow-band optical add-drop multiplexer, the theoretical investigations clarified that low side-lob characteristics with about -30dB suppression ratio can be attained by introducing appropriate density-modulated grating. 4) Quite a compact arrayed waveguide with multiple reflection structure was invented, and fundamental theoretical and experimental investigations clarified its effectiveness. 5) Laser diodes integrated with a multi-mode interference waveguide (MILD) were proposed, and narrow beam characteristics suitable for easy coupling to a single mode fiber was demonstrated theoretically with as low as -4dB coupling loss.Through this project, multi-mode and multi-waveguide devices were shown to be quite effective for high-performance versatile photonic switching, and further research is planned to undergo for realization of practical devices and system evaluation. Less