On-chip net-amplified modulator in erbium-doped thin-film lithium niobate with 110-GHz bandwidth

The electro-optic modulator (EOM) converts electronic signals into the optical domain. EOM cascading is a key technology in modern wireless communication, microwave photonic systems, and photonic computing. However, the scalable cascade of EOMs is hindered by the accumulation of modulator insertion losses, which critically degrade system performance. Erbium-doped waveguide amplifiers (EDWAs) have emerged as a pivotal technology recently, enabling efficient optical loss compensation and facilitating large-scale photonic integration. Here, we demonstrate an amplified Mach-Zehnder modulator (MZM) enabled by the erbium-doped thin-film lithium niobate-on-insulator (Er:LNOI). The presented device achieves a net on-chip optical amplification of over 6 dB and a measured electro-optic (EO) bandwidth of over 110 GHz. The modulator enables a high-speed data modulation rate of up to 144 Gbit/s. The device demonstrated here allows for the seamless integration of electrical-to-optical conversion and optical amplification, which paves the way for future high-speed, high-density, and ultra-large-scale integrated photonic systems.