With the development of micro-electr o-mechanical system(MEMS) technolog y,the MEMS-based capacitive sensor has been widely applied in the field of ele ctron components.However,the capacitance of the micromachined sen...With the development of micro-electr o-mechanical system(MEMS) technolog y,the MEMS-based capacitive sensor has been widely applied in the field of ele ctron components.However,the capacitance of the micromachined sensor is so sma ll that the detection of the smaller value change of the capacitance is a great challenge.Based on the principle of charging and discharging of the capacitor,a kind of pulse width modulated differential circuit is introduced in this paper.For subsequent amplification,a modified amplifier is presented.The different ial circuit converts the weak capacitance change to the change of the pulse widt h of the output voltage,and the linear relationship can be obtained.And the mo dified amplifier implements the processes of amplification and filtering synchro nously,and a large DC output voltage can be obtained by the lo w-pass filter.T he designed circuits have advantages as simplified circuit,high voltage stabili ty,perfect linearity and resolution.Besides,it is feasible to be integrated w ith the sensor to largely reduce the transmission error and interference.展开更多
Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for ...Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for increasing the modulating efficiency and alleviating the sensitivity of the extinction ratio （ER） and insertion loss （IL） to the length of the active region. The light behavior and the effect of the taper are explored in detail using the beam propagation method （BPM）. After optimization, the light can nearly be totally confined in the GeSi layer without any oscillation. The modulator with the designed taper can achieve low IL and high ER.展开更多
基金National High Technology Research and Development Program of China ("863"Program) (No.2011AA040404)National Natural Science Foundation of China(No.61127008)
文摘With the development of micro-electr o-mechanical system(MEMS) technolog y,the MEMS-based capacitive sensor has been widely applied in the field of ele ctron components.However,the capacitance of the micromachined sensor is so sma ll that the detection of the smaller value change of the capacitance is a great challenge.Based on the principle of charging and discharging of the capacitor,a kind of pulse width modulated differential circuit is introduced in this paper.For subsequent amplification,a modified amplifier is presented.The different ial circuit converts the weak capacitance change to the change of the pulse widt h of the output voltage,and the linear relationship can be obtained.And the mo dified amplifier implements the processes of amplification and filtering synchro nously,and a large DC output voltage can be obtained by the lo w-pass filter.T he designed circuits have advantages as simplified circuit,high voltage stabili ty,perfect linearity and resolution.Besides,it is feasible to be integrated w ith the sensor to largely reduce the transmission error and interference.
文摘Efficient coupling from the silicon waveguide to the GeSi layer is the key to success in the GeSi electro-absorption （EA） modulator based on evanescent coupling. A lateral taper in the upper GeSi layer has room for increasing the modulating efficiency and alleviating the sensitivity of the extinction ratio （ER） and insertion loss （IL） to the length of the active region. The light behavior and the effect of the taper are explored in detail using the beam propagation method （BPM）. After optimization, the light can nearly be totally confined in the GeSi layer without any oscillation. The modulator with the designed taper can achieve low IL and high ER.
