Linearity-Enhanced integrated lithium niobate modulator based on carrier separated asymmetric Mach − Zehnder structure

Highly linear electro-optic modulators are key components in analog microwave photonic links that convert analog electrical signals into optical signals. In this work, we present a carrier separated asymmetric Mach–Zehnder modulator (CS-AMZM) based on the thin-film lithium niobate (TFLN) platform. Our strategy enables the suppression of second-order harmonics distortion (SHD) and third-order intermodulation distortion (IMD3). A proof-of-principle experiment result shows an improvement of 11.8 dB for the third-order SFDR and 15.1 dB for the second-order SFDR at 10 GHz compared to the quadrature-biased reference MZM model. No resonant structure is involved in our modulator, and the bandwidth is more than 50 GHz after packaging. The SFDR can be further improved by decreasing the fiber-to-chip coupling loss. Our linear modulator can be further integrated with filters, delay lines, and other devices to play a core role in large-scale integrated microwave photonic circuits.