Thin‐Film‐Lithium‐Niobate Photonic Chip for Ultra‐Wideband and High‐Precision Microwave Frequency Measurement

Abstract

Integrated photonic‐assisted instantaneous frequency measurements (IFMs) have been extensively explored and widely used in 5G/6G communications, navigation, automotive control, and radar systems. They offer significant advantages such as wide frequency, low power consumption, and immunity to electromagnetic interference compared to electrical solutions. As data traffic in high‐speed wireless communication systems and the operation bandwidth of advanced radar systems continue to grow, there is an urgent need for large instantaneous bandwidths and accurate frequency measurements to ensure signal integrity and efficient bandwidth utilization. However, achieving wide‐bandwidth and high‐precision measurements simultaneously with photonic IFMs remains challenging. Here, an integrated photonic IFM system based on a thin‐film lithium niobate (TFLN) platform is demonstrated that can dynamically identify signals with wide‐band frequency changes. The system incorporates a wide‐bandwidth Mach–Zehnder modulator (MZM) and a high‐Q Mach–Zehnder interferometer (MZI)‐coupled microring resonator (MRR) for double‐sideband suppressed‐carrier (DSB‐SC) modulation. Additionally, it includes dual‐stage frequency discriminator based on asymmetric MZIs (AMZIs) for both coarse wide‐band and accurate narrow‐band measurements. The proposed IFM system operates over a wide‐band frequency up to 67 GHz with a low root mean square (RMS) error of less than 123 MHz. This work opens up a path for high‐performance broadband microwave photonic applications using TFLN platform.