Non-silicon Micro-mechanical Optical Switches And Tunable Optical Attenuator Design, Production And Analysis

This thesis presents a study on the non-silicon based MEMS optical switch and variable optical attenuator. By fully utilizing the available micro-machining capability, we developed a series of devices based on Electrical Discharge Machining technique. The content of the thesis is classified into three parts. The first part summarizes the modern tecchnoligies for optical switches and variable optical attenuators, analyzes the pros and cons of the techniques involved. The second part contributes to the design of a novel structure of the micro-machinging based unit driving cell, based on which a 1 X 4 and 1 X 8 optical switch were designed and fabricated. A detailed description of their working principle was provided also. We tested and analyzed the translation and angular misalignment sensitivity of the collimators for the switch assembly. The characteristics of switching speed was compared with that of a numerical solution by using finite element analysis (FEA) and a good agreement was obtained. The switch allows fast switch (<2 ms) and features a small size (50 X 25 X 10mmfor 1X8 switch).The third part introduces the design, fabrication, analysis and testing of serveral types of variable optical attenuators. We have designed a micro-machining based VOA that consists of an electromagnetically actuated gold-coated silicon mirror rotating around a 100 #am diameter shaft and a miniature driven coul. The VOA is capable of fast dynamic response (<2ms), great dynamic range (0~35dB), and low return loss (<55dB).Through persistant improvement of the structure, we successfully designed and fabricated a VOA as small as 25x10x7 mm3. The attenuation was introduced by a micro-silicon mirror, with its direction can be fine tuned through the balance of a pair of electromagnetic forces. The fabricated VOA was able to privide a wide attenuation range of 40dB with an insertion loss of 0.8dB and back-reflection of-50dB.The last part of the thsis presents a novel fast response digital variable optical attenuator. This device is driven by two electromagnetic driving units rather notstepper motors. A wide attenuation (40dB) was fully digitized and can be set by a certain number of driving pulses.