| Summary: | 碩士 === 國立臺灣大學 === 光電工程學研究所 === 94 === Optical communications become more and more important due to the growth of bandwidth requirement. Transparent (O-O-O) MEMS optical switches are applied in add/drop switch modules in WDM systems with relative good performance.
A compact MEMS optical switch with low actuation voltage is demonstrated in this thesis. It is actuated by electromagnetic force. The kernel is a moving micromirror which is perpendicular to the light propagation. The flap is connected by serpentine springs to prevent the stiction problem. The trade-off for stiction-free (or no stopper) is large vibrations. To overcome this difficulty, several techniques are discussed in this thesis. We start from the simulation of magnetic field intensity and find the best position for the magnetic flap. Secondly, we analyze the optical property. To reduce the vibration, the collimator is replaced by a lens fiber with small beam size. Finally, we develop a fast method for finding a special driving waveform to achieve fast switching time based on Fourier transform function. This method also can tolerate the variation in fabrication processes.
Our experimental results show the actuated voltage is 0.5 volts. The switching time is about 3ms. The insertion loss caused by the micromirrors is 0.45 dB, WDL is 0.05 dB. TDL is less then 0.05 dB. PDL is less than 0.1 dB. The size is compact for the integration in optical communications.
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