| 摘要 |
The invention provides a fast variable optical attenuator including a reflective membrane that serves as a varifocal mirror. Electrostatic deflection of the mirror defocuses the optical system and attenuates an optical signal launched to the mirror from an input port to an output port. Since the mirror is generally limited to deflections less than 1 micron, fast attenuation within a small (<5dB) dynamic range is achieved. The dyn amic range is improved by combining the fast attenuator with a slower attenuator. In the preferred embodiment, the slow and fast attenuator are not coupled via optical waveguides, but rather are optically coupled via free space or are integrated in the same device. Advantageously; this compact arrangement reduces the excess loss associated with optical fibre coupling and lowers packaging costs.
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