Compact Slow-Light Integrated Silicon Electro-Optic Modulators With Low Driving Voltage

In this work, we report two slow-light enhanced silicon optical modulators with electro-optic (EO) phase shifter lengths of $500~\mu \text{m}$ and $150~\mu \text{m}$ that were fabricated using the AIM Photonics foundry. Tunable power splitters give a threefold increase in the extinction ratio (ER). An eye diagram operating at 10 Gbps was achieved using a very low signal voltage of Vpp = 500mV. The energy per bit is 57.5 fJ/bit and 45 fJ/bit for the $500~\mu \text{m}$ and $150~\mu \text{m}$ modulators, respectively. The nonlinearity of the devices were measured yielding spur-free dynamic range of 113.2 dB/Hz2/3. The $150~\mu \text{m}$ length MZM is among the smallest optical modulators using Bragg gratings for slow light ever reported and results in an estimated modulation efficiency of 0.33 $\text{V}\cdot $ cm.