Abstract

The escalating datacenter traffic emphasizes the need for high-performance, cost-effective, and energy-efficient optical transceivers. We demonstrate barium titanate (BTO) electro-optic Mach-Zehnder modulators (MZMs) integrated on the silicon photonic platform, surpassing all-silicon counterparts in key metrics: modulation efficiency (V_πL = 4.8 Vmm), loss (∼2 dB), and static tuning power (∼100 μW), while maintaining CMOS compatibility. Employing BTO MZMs, we showcase, for the first time, short-reach intensity-modulation and direct-detection (IMDD) transmissions beyond 200 Gbps/λ. In the C-band, over 500 m of standard single-mode fiber (SSMF), we have achieved: (a) a 122 Gbaud PCS-PAM-8 (net 300 Gbps) below the 20% overhead soft-decision forward error correction (SD-FEC) BER threshold of 2.4 × 10⁻², and (b) a 106 Gbaud PAM-4 (net 200 Gbps) below the 6.7% overhead hard-decision (HD) FEC threshold of 3.8 × 10⁻³, with a remarkably 9-fJ/bit electrical power dissipation. In the O-band, we transmit (a) a net 200 Gbps over 10-km SSMF below the 5.8% overhead KP4-FEC BER threshold across wavelengths from 1301 nm to 1321 nm, and (b) a net 250 Gbps over 2-km SSMF below the HD-FEC BER threshold ranging from 1291 nm to 1321 nm. Our research highlights BTO MZMs as potent, power-efficient solutions for next-gen transmitters beyond 200 Gbps/λ for intra- and inter-datacenter applications.