As microelectronics approaches fundamental scaling and energy-efficiency limits, the rapid expansion of generative artificial intelligence, hyperscale data centres, 5 G/6 G wireless networks and quantum technologies is imposing unprecedented demands on hardware bandwidth, power efficiency, parallelism and sensing precision. Integrated photonics has, therefore, emerged as a promising foundation for post-Moore information systems, owing to its intrinsically large bandwidth, low propagation loss and immunity to electromagnetic interference. However, conventional silicon photonics remains constrained by the intrinsic limitations of a single-material platform, most notably the absence of efficient on-chip light sources, the lack of a native Pockels effect for high-speed electro-optic modulation, and weak optical absorption in the near-infrared communication bands. Advanced heterogeneous photonic integration addresses these bottlenecks by incorporating III–V semiconductors, ferroelectric thin films, low-dimensional materials, and specialised optical and atomic components onto common photonic substrates through hybrid integration, bonding, transfer printing and heteroepitaxial processes. This transition extends photonic integrated circuits (PICs) from component-level performance enhancement towards functionally co-integrated system platforms. Here, we review recent progress in heterogeneous photonic integration from devices to applications, organized by device function and system relevance rather than by a single spectral regime. We first discuss representative device-level advances, including short-wavelength lasers, ferroelectric thin-film electro-optic modulators, O- and C-band waveguide-integrated photodetectors, and PIC-integrated Fabry–Pérot cavities and atomic vapour-cell microsystems. We then examine how these device innovations are enabling high-capacity optical transceivers, photonic neural networks, integrated laser frequency stabilisation for microwave photonics, light detection and ranging (LiDAR) and spectroscopic sensing, as well as quantum precision measurement. Finally, we discuss the cross-cutting bottlenecks and enabling directions that will determine the transition from laboratory demonstrations to wafer-scale, manufacturable and reliable heterogeneous photonic system platforms, including interface loss, thermal mismatch, contamination control, long-term reliability, heterogeneous design infrastructure and advanced co-packaging.
Zhao et al. (Wed,) studied this question.