Fig. 1. (a) Equivalent circuit for the reversed PN junction and (b) relationship between the depletion capacitance and reverse bias voltage.

Fig. 2. (a) Cross-section of a silicon phase shifter based on a vertical PN junction. (b–d) Calculated nonlinear relationships of the optical phase change, absorption coefficient change, and depletion capacitance versus the different reverse bias voltages and the fitting results.

Fig. 3. Simulated spectrum of the EN output Vc(t): (a) power distribution and (b) phase distribution.

Fig. 4. Composition of the spectrum of Pout(t).

Fig. 5. (a) Structure of the simulated MZM, (b) CDR3 under different phase biases for the nonlinear model with EN and the conventional nonlinear model without EN, and (c) SFDR results for the nonlinear model with EN and the conventional nonlinear model without EN.

Fig. 6. (a) Optimized CDR3 under different series resistances and (b) SFDR when the series resistance is 1 or 10  Ω.

Fig. 7. Normalized CDR3 versus the driving frequency (the black line shows that the linearity is frequency-independent without EN).

Fig. 8. Third nonlinear coefficient versus the phase bias.