Segmented‐Electrode Thin‐Film Lithium Niobate I/Q Modulator for Ultra‐High‐Speed Optical Interconnect

ABSTRACT Coherent optical communication offers superior spectral efficiency and substantial transmission capacity, making it indispensable for accommodating the exponential growth of global data traffic. Next‐generation data‐centers demand higher baud rates and improved spectral efficiency, which in turn require optoelectronic devices for both ultra‐broadband operation and high modulation efficiency. However, conventional modulator design commonly faces a fundamental trade‐off between electro‐optic bandwidth and modulation depth. To address this limitation, we present a segmented modulation strategy and fabricate segmented I/Q modulator on the thin‐film lithium niobate (TFLN) platform. It features a 3‐dB bandwidth exceeding 110 GHz while maintaining a high signal‐to‐noise ratio for high‐order signal generation. For high baud rate signal generation beyond the limitation of digital‐to‐analog convertor sampling rate, we achieve 320‐Gbaud single‐polarization quadrature phase shift keying (QPSK) and 310‐Gbaud dual‐polarization (DP) QPSK signal based on polybinary coding scheme. For high spectral efficiency transmission, we demonstrate 2.02‐Tb/s line rate probabilistic shaped (PS) 144‐ary quadrature amplitude modulation (144‐QAM) signal over 125‐km single‐mode fiber, facilitated by the residual carrier‐based phase tracking. The results highlight the potential of segmented IQ modulator, in conjunction with advanced digital signal processing, can pave the way for next‐generation high‐speed coherent optical communications.