High linearity silicon modulator capable of actively compensating input distortion

In this Letter, we demonstrate an ultra-high linearity silicon carrier-depletion-based modulator by integrating a dual-parallel Mach–Zehnder modulator (DP-MZM) with a 1 × 2 thermo-optical switch. The operation principle is to manipulate power distributions of RF and optical signals among the two sub-MZMs, so their third-order nonlinearities can cancel each other. Spurious-free dynamic ranges (SFDRs) for the third-order intermodulation distortion (IMD3) are measured to be 123 / 120 d B ⋅ H z 6 / 7 at 1/10 GHz, which represents a record-high linearity achieved with silicon-based modulators. As a contrast, SFDRs of a reference single MZM are 113 / 108 d B ⋅ H z 4 / 5 at the same frequencies. Furthermore, we first demonstrate that this device is able to actively compensate nonlinear distortions of RF driving signals in the optical domain. Carrier-to-distortion ratios (CDRs) of deliberately distorted two-tone signals are improved from 40/50 dB to 45/72 dB after the modulation.