Tunable photonic devices fabricated by micro-nano machining for optical communication

在光子晶体结构中引入微机电系统，实现了光波的控制。制作了光子晶体波导开关，并对其特性进行了测量。在提出的结构中，光子晶体板分为三部分。波导被连接到一个微型静电致动器上。利用时域有限差分法对所提出的结构进行了理论研究。得到了固定波导与活动波导间隙的最佳条件。利用SOI晶圆制备了二维光子晶体波导。利用电子束拉丝机将周期为400nm、直径为300nm的空穴图案转移到SOI晶圆的顶层硅层上。利用快速原子束和深度反应离子刻蚀机刻蚀出高纵横比的晶体孔。为了去除硅层下方牺牲的二氧化硅层，对氟化氢气相蚀刻机进行了改进。制作了平行板状和梳状静电微致动器。通过改进设计和微加工技术，成功地制造了MEMS光子晶体结构。在开关采用平行板作动器的情况下。用红外摄像机对该装置进行了观察，证实该装置运行良好。通过施加电压，调制光子晶体波导缝隙中的光散射。通过光子晶体开关传输的光被测量为施加在微致动器上的电压的函数。在180V电压下，传输量最小，达到“关断”状态。进一步增加电压，光直接通过输入和输出波导之间的间隙泄漏。制作了带侧梳形作动器的光子晶体波导开关，并对其光学性能进行了评价。

Introducing MEMS into photonic crystal structure, the light wave was controlled. Photonic crystal waveguide switch was fabricated, and the characteristics were measured. In the proposed structure, the photonic crystal slabs were divided into three parts. The waveguides were connected to a micro electrostatic actuator. The proposed structures were investigated theoretically using FDTD method. The optimum conditions of the gap between the fixed and movable waveguides were obtained. Using SOI wafer, two-dimensional photonic crystal waveguides were fabricated. Using electron beam drawing machine, the hole patterns having 400nm period and 300nm diameter were transferred to the top silicon layer of the SOI wafer. Using the fast atom beam and deep reactive ion etching machines, the crystal holes were etched with a high aspect ratio. In order to remove the sacrificial silicon dioxide layer underneath the silicon layer, the hydrogen fluoride vapor etching machine was improved. Parallel plate and comb electrostatic micro-actuators were fabricated. By improving the designs and the micromachining techniques, the photonic crystal structure with MEMS were successfully fabricated. In the case of the switch with the parallel plate actuator. observing the device with an infrared camera, it was confirmed that the fabricated devices operated well. With the application of a voltage, the light scattering from gap of the photonic crystal waveguides was modulated. The light transmitted through the photonic crystal switch was measured as a function of the voltage applied to the micro-actuator. At the voltage of 180V, minimum transmission was obtained, which corresponded to the 'switch-off" condition. Further increasing the voltage, the light leaked directly through the gap between the input and output waveguides. The photonic crystal waevguide switches with the lateral comb actuator were also fabricated, and the optical properties were evaluated.