Significance Microwave photonic links (MPLs) serve as a critical physical-layer infrastructure that bridges microwave engineering and integrated photonics, enabling low-loss, high-isolation, and wideband transmission and processing of high-frequency microwave signals. They represent a key enabling technology for next-generation 6G communications, high-resolution radar, and integrated sensing-communication (ISAC) systems. The performance of MPLs is fundamentally governed by two core metrics: working bandwidth and spurious-free dynamic range (SFDR). Working bandwidth determines the link capacity to handle high-frequency and multi-octave signals, while SFDR—comprehensively reflecting system gain, third-order intermodulation distortion (IMD3), and noise floor—quantifies the link's capability to faithfully transmit desired signals in the simultaneous presence of strong interference and weak targets. An inherent design tension exists between these two metrics: broadening the bandwidth typically demands flatter frequency responses from modulators and photodetectors, often at the cost of linearity, while achieving high SFDR requires precise bias control and nonlinear suppression that conflict with low-loss wideband design. Simultaneously realizing ultra-wide bandwidth and large dynamic range therefore remains a long-standing core challenge in this field.

Progress This review presents a systematic survey of recent advances in high-performance MPLs, organized around on-chip integrated micro-nano photonic devices as the central theme.

At the device level, substantial breakthroughs have been achieved across all key enabling components. In on-chip laser sources and optical frequency combs, heterogeneously integrated lasers with fundamental linewidths below 1 kHz and RIN below −160 dB/Hz have been demonstrated; femtosecond pulse generators on thin-film lithium niobate (TFLN) have produced flat-top optical frequency combs with conversion efficiencies an order of magnitude higher than prior integrated sources; and a triple-resonance electro-optic comb on thin-film lithium tantalate (LiTaO₃) has generated over 2000 comb lines spanning 450 nm (>60 THz), while Kerr microcomb sources with conversion efficiencies exceeding 90% provide low-noise multi-wavelength foundations for wideband MPL architectures. In electro-optic modulators, the TFLN platform has advanced the 3-dB bandwidth from 45 GHz in early demonstrations to beyond 250 GHz, supporting 512 Gbps fiber-wireless transmission and 400 Gbps terahertz-band wireless records; a heterogeneously integrated LiTaO₃-on-Si₃N₄ modulator achieved near-100 GHz bandwidth with 333 Gbit/s PAM4 and 581 Gbit/s 16-QAM transmission; and plasmonic modulators extended the modulation bandwidth beyond 1 THz, covering MHz to THz in a single device. In photodetectors, germanium-on-silicon devices achieved 3-dB bandwidths of 265 GHz, while ultrahigh-power Ge-Si photodetectors delivered record saturation photocurrents of 471.4 mA with OIP3 of 32.3 dBm and SFDR of 114.7 dB·Hz^2/3; modified uni-traveling-carrier photodetectors (MUTC-PDs) maintained frequency responses beyond 140 GHz while preserving high linearity.

At the system level, advances are reviewed along three principal directions. For large dynamic range links and nonlinear distortion suppression, three complementary layers of techniques were developed: at the modulator bias and architecture level, schemes including SD-DPMZM, dual-parallel polarization modulator, and DP-DPMZM achieved IMD3 suppression of 20–40 dB and SFDR improvements up to 20 dB; in the optical sideband manipulation domain, a gain-penalty-free IMD3 suppression scheme based on optical single-sideband modulation achieved SFDR exceeding 128 dB·Hz^4/5—the first linearization technique to suppress nonlinear distortion without any link gain sacrifice—while multi-order optical sideband vector manipulation (MOSVM) simultaneously improved SFDR by over 20 dB and system gain by over 12 dB; in the algorithm compensation domain, genetic algorithm-assisted coherent detection enabled stable 100.8 km transmission with SFDR above 122 dB·Hz^2/3 across −40 to 70°C, and deep neural network architectures including complex-biGRU and focal-loss-based networks provided robust nonlinear compensation in ultra-high-speed and long-distance scenarios. For ultra-wideband microwave photonic communication and spectrum sensing, chromatic dispersion compensation strategies spanning optical double-sideband pre-compensation, optical phase conjugation, TFLN differential phase-diversity electro-optic modulators, and silicon photonic neural network equalization were systematically investigated; a dispersion-immune microwave photonic phase shifter achieved continuous 360° phase shifting from 5 to 25 GHz; a TFLN-integrated real-time spectrum sensing system demonstrated 57.5 GHz instantaneous bandwidth with sub-110 ns latency for 6G ISAC applications; photonics-assisted W-band dual-hop radio-over-fiber transmission achieved 80 Gbit/s 16-QAM at 90 GHz over a 21-km fiber link; and a self-injection-locked microcomb-driven silicon photonic transceiver achieved a WDM coherent transmission record of 61.2 Tbit/s with a net spectral efficiency of 8.01 bit/s/Hz. For microwave photonic intelligent signal processing and computing, a programmable TFLN microwave photonic notch filter simultaneously achieved high dynamic range, high link gain, low noise figure, and ultra-high rejection ratio on a single chip; a silicon photonic true-time-delay processor integrated arbitrary waveform generation, tunable filtering, and ultra-broadband beamforming; a silicon photonic analog parallel processor demonstrated simultaneous 6 GHz radar signal processing and 8 Gbps wireless communication on a single photonic integrated circuit; and microcomb-driven optical convolutional accelerators achieved computing speeds exceeding 3 TOPS for tensor convolution, complex-valued convolution, and transposed convolution tasks, while a photonic edge intelligence chip (PEIC) realized multi-modal analog signal sensing and on-chip inference with a response latency of only 1.33 ns and an energy efficiency of 29 fJ/OP.

Conclusions and Prospects On-chip integrated micro-nano photonic devices have substantially advanced the performance boundaries of MPLs in both bandwidth and dynamic range, driving the evolution of MPLs systems from signal transmission conduits toward multi-functional intelligent processing platforms. Looking forward, chip-to-fiber coupling loss, wafer-scale fabrication yield, and heterogeneous integration compatibility remain the primary bottlenecks for TFLN-based systems; topological photonic protection mechanisms offer a promising route to improve fabrication robustness and reduce waveguide losses. The fundamental tension among gain, noise figure, and nonlinearity has yet to be resolved at the system level; deep co-design of device innovations—continuously reducing Vπ and improving linearity and saturation photocurrent—with adaptive wideband digital linearization and online learning algorithms represents the fundamental path to breaking this bottleneck. As wafer-scale multi-layer heterogeneous integration matures, fully integrated MPLs transceiver systems incorporating laser sources, modulators, photodetectors, and signal processing units on a single chip are expected to become the core physical-layer infrastructure for next-generation 6G intelligent wireless networks and integrated sensing-communication-computation platforms.