Fig. 1. Normalized transmission spectra of the modulator. Black line: transmission spectrum with 0V applied on the p-i-n junction. Blue line: transmission spectrum with 1.8V on the junction. The dc current at this voltage is 58μA. Inset: schematic of the device structure.

Fig. 2. Calculated dynamics of the micro-ring modulator. (a): NRZ driving signal at 5 Gbit/s; V ₁ = V ₂ = 4V. (b): Total charge in the junction with driving voltage of (a). (c): Optical transmission of the ring resonator; t_r = 192 ps; t_s = t ₁- t ₂ = 114 ps. (d): Pre-emphasized NRZ signal at 5Gbit/s; V ₁ = 6V; V'₁ = 2V; V ₂ = 4V. (e): Total charge in the junction with driving voltage of (d). (f): Optical transmission of the ring resonator; t_r = 110 ps; t_s = t ₁ - t ₂ ≈ 0 ps. In all the calculations, we used the experimentally measured serial resistance R = 7.7 kΩ

Fig. 3. Schematics of the experimental setup showing the generation of the NRZ driving signal with pre-emphasis. PG: pattern generator. IGN: impulse generator network. PC: power combiner. DUT: device under test.

Fig. 4. (a). square-wave driving signals with (red line) and without (blue and green lines) the pre-emphasis. (b): the output optical power when the modulator is driven by voltage signals shown in (a).

Fig. 5. The waveform and eye-diagram of the electrical driving signal with pre-emphasis at 12.5 Gbit/s.

Fig. 6. Eye-diagrams of the modulated optical output at 12.5 Gbit/s with PRBS 2¹⁰-1.