| 摘要 |
The present invention discloses an optimized optical attenuator device. It includes the design of resonator formed by two identical mirrors, which are made by MEMS process. The structure realizes the minimum insertion loss. The two membranes are chosen to be with high reflection rate. Multiple layer or metal layer or mixture of them can produce membrane of high reflection rate. High reflection rate causes low tuning voltage for one certain attenuation range. To reduce the manufacture error and the cost, the two identical membranes can be formed by bonding two MEMS cells fabricated in the same process face to face. To further reduce the insertion loss, the input mode should match the residual basic mode in the resonator. The basic residual mode is the only one surviving in the resonator. A design of the resonator will guarantee this happen. Ripple is a key specification for present optical component. To achieve very low ripple device, all the interfaces of the MEMS device should be coated with anti-reflection coating. The lower the reflection rate is, the lower the ripple is. Charging will cause the control voltage craze while using the attenuator device. To eliminate the charging effect, the electrode should be attached to the conductive face to face layers during the tuning process, which means between the two electrodes, positive and negative, there should be no dielectric material to trap the charges. However, one or two very thin dielectric layers between the two conductive layer electrodes can improve the electric breakdown voltage. The dielectric material and the thickness are selected without generating severe charging effect, while the safety of MEMS device can be guaranteed. Finally, the device is controlled by a smart control system with the temperature and wavelength compensation functionality. The control system makes the device stable and will keep the attenuation fixed regardless the temperature or wavelength changing. A device should have communication interface with system.
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