The rapid growth of artificial intelligence and related computing infrastructure has exposed the limited bandwidth of conventional electrical interconnects in integrated circuits as a major bottleneck to system performance. Silicon photonics, which transmits data using photons instead of electrons, has emerged as a promising approach for overcoming bandwidth and latency limitations. The platform is now widely used for photonic integrated circuits (PICs), particularly in telecom and datacom applications.
A major strength of silicon photonics lies in its compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology, enabling scalable PIC fabrication using existing semiconductor infrastructure. However, this also introduces a fundamental limitation. CMOS fabrication infrastructure is highly specialized and optimized and therefore cannot integrate non-standard materials. Conventional group-IV semiconductor materials cannot satisfy all requirements of advanced photonic systems, particularly for functions such as on-chip light generation. Materials such as III–V semiconductors and lithium niobate (LiNbO₃) can provide these capabilities, highlighting the need for heterogeneous integration approaches to expand the functionality of silicon photonics.
A new study published in Journal of Lightwave Technology on April 30, 2026, highlights micro-transfer printing (MTP) as a promising approach for realizing heterogenous integration in silicon photonics. "Among the various approaches being pursued for enabling wafer-scale heterogeneous integration, MTP is an emerging highly versatile technique that combines benefits of die-level assembly with wafer-scale processing," explains Ir. Ye Chen from Ghent University – imec, Belgium.
The study highlights the limitations of existing heterogeneous integration techniques before describing how MTP can address several of these challenges. The MTP process begins with fabrication of thin-film devices, called coupons, on a dense source wafer, followed by selective etching of a sacrificial release layer. An elastomeric stamp is then used to pick up and print multiple devices onto a target wafer. Finally, adhesive or direct bonding secures the devices in place, enabling seamless co-integration of diverse material systems onto large-area silicon photonics platforms.
Notably, one of the main advantages of MTP is its broad material compatibility, which allows multiple material systems to be integrated within a single architecture. This enables individual chiplets to be independently optimized using the most suitable fabrication processes before integration, while maintaining compatibility with CMOS-based photonic platforms.
Recent demonstrations of the MTP process include a fully integrated silicon photonic engine capable of processing both optical and microwave signals using indium phosphide (InP) lasers; gallium arsenide lasers integrated with silicon nitride waveguides for applications in virtual reality, quantum technologies and microwave photonics; widely tunable narrow-line width InP lasers integrated with silicon nitride (Si3N4) waveguides for coherent communications and light detection and ranging; wafer-level integration of LiNbO₃-based modulators with Si3N4 photonic circuits; and heterogeneous electronic-photonic optical receiver platforms.
The study also presents a new pilot line focused on developing key aspects of MTP for large-volume industrial manufacturing. In addition, the authors outline several remaining challenges, including yield, reliability, throughput, and the need for a robust and scalable manufacturing ecosystem, along with possible solutions for some of these issues.
"The MTP technology is still in its early stages of commercial application; however, we believe that consistent advancements will soon lead to large-scale industrial manufacturing, paving the way for advanced silicon photonics that will benefit several industries," concludes Ir. Chen.
Reference
Authors: Ye Chen et al.
DOI: https://doi.org/10.1109/JLT.2026.3689409
Affiliations: INTEC Ghent University, Belgium
