| 摘要 |
The present invention relates to a micro-electromechanical optical attenuator and a method of operating the same. In prior art attenuators, the attenuation obtained from a deflection angle does not change uniformly over a range of interest. In addition, over a range of interest the required voltage to obtain a desired deflection changes as a nonlinear function. The cause of the poor control of prior art attenuators can be viewed graphically by examining the attenuation as a function of deflection, and the angle of deflection as a function of voltage. These functions combine to produce a very unstable voltage to attenuation response function. The present invention has found that by operating an electrostatic drive of a reflective optical attenuator in order to attain a low loss state with the mirror in a fully deflected position, the drive voltage can be reduced to increase attenuation in a very stable nearly linear attenuation vs. drive voltage response. The non-linearity of the attenuation vs. deflection function is countered by a deflection vs. voltage response that becomes increasingly stable with decreasing voltage. A resulting attenuation vs. voltage curve gives a superior, stable and nearly linear response. To achieve the novel drive method in accordance with the present invention, an adjustable substrate is provided for supporting the mirror drive which can be positioned to support the mirror at a maximum deflection position in a neutral, unpowered state.
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