High performance silicon modulator with extremely low loss

For RF-/microwave-applications, the loss of the current optical silicon modulator (typical ~1 dB/mm) is still too high for commercial using compared with that of Lithium Niobate modulator. Approaches for reducing the loss often compromise with the degradation of the other two key performance parametric including modulation efficiency and switching speed. In this work, we achieved the reduction of the phase shifter loss by optimizing the doping level of the modulator while keeping the modulation efficiency and switching speed still at a high level. 10Gbit/s silicon modulator is realized with 0.7 dB/mm phase shift loss and phase shift efficiency V_πL_π= 3.4V·cm. The phase shift loss can also be reduced to 0.45 dB/mm with efficiency V_πL_π= 4.3V·cm. Compensated doping method is utilized to optimize the doping level along the cross section of the phase shifter.