A Linear Microwave Electro-Optic Front End With SiGe Distributed Amplifiers and Segmented Silicon Photonic Mach-Zehnder Modulator

The dynamic range of a radio-over-fiber (RoF) link is fundamentally limited by the linearity of electro-optic modulators. Silicon photonic (SiP) processes offer significant potential for integration, but the plasma dispersion effect impacts the realizable spur-free dynamic range (SFDR). This article analyzes the underlying source of nonlinearity in SiP Mach-Zehnder modulator (MZM) and demonstrates fundamental limitations on intermodulation distortion. A SiGe low-noise distributed driver is co-designed for the SiP MZM to linearize and extend the bandwidth over which the SFDR remains high. The RoF transmitter achieves 1-20 GHz bandwidth and an SFDR of 109 dB · Hz2/3 at 11 GHz. To the best of our knowledge, this is the highest SFDR demonstrated for a SiP technology without incorporating predistortion.