Optical Computing on the Verge of Becoming Mainstream in Aerospace and Defense
March 24, 2025
The challenges surrounding optical chip-to-chip interconnects are showing signs of resolution thanks to innovative research focused on their development. Optical computing has been heralded as “the next big thing” for decades due to its potential for significant improvements in data transmission rates, enhanced information security, and greater resilience against electronic warfare (EW) interference and electromagnetic disruptions.
By utilizing optical fibers and free-space lasers in place of traditional copper interconnects, optical computing promises advancements across chip-to-chip, box-to-box, and system-to-system applications. While progress has been made in optical connections between boxes and backplanes, the transition to optical computing has been slow.
Challenges in Optical Computing Development
Despite its advantages, optical computing has struggled to gain traction in the industry. The enhancements in data transmission speeds through conventional copper interconnects have provided more economical and lower-risk alternatives compared to optical solutions. Furthermore, the existing infrastructure based on copper offers significant advantages in terms of cost-effectiveness and scalability, making the shift to optical technologies a daunting prospect.
New research initiatives, however, are breaking new ground in optical chip-to-chip interconnects, with an emphasis on quantum computing applications. Recently, the U.S. Defense Advanced Research Projects Agency (DARPA) announced three new contracts aimed at exploring 3D photonic interconnects that enhance information throughput while reducing susceptibility to electromagnetic interference.
DARPA’s Innovative HAPPI Program
The three selected organizations—SRI International, the RTX Raytheon segment, and North Carolina State University—will work on the Heterogenous Adaptively Produced Photonic Interfaces (HAPPI) program. This initiative focuses on the creation of high-density 3D chip optical links and offers various routing options within photonic integrated circuits.
During this project, SRI, RTX Raytheon, and N.C. State will aim to demonstrate the feasibility of low-loss, high-density optical interconnects for 3D chips using a scalable manufacturing process aligned with microelectronics standards. The focus will be on vertical routing connections between layers that can navigate different substrate thicknesses, as well as methods for efficiently coupling light between photonic chips.
Aiming for High-Density Information Transfer
The HAPPI initiative seeks to achieve a staggering 1000-fold increase in microsystem information transfer density through the utilization of photonic signaling. Efficient information processing and transfer across a microsystem necessitate robust signal routing technology that accommodates high data rates and a dense array of access points. Such interfaces must also withstand the common misalignments that occur during the manufacturing and assembly processes.
This two-phase, 36-month program will first aim to validate the practicality of 3D routing in integrated photonics over 18 months, followed by a second phase that will focus on enhancing density and manufacturing scalability of the routing framework.
Advancing Robust and Adaptive Interfaces
These three institutions will also develop interfaces that are designed for optimal stability under various environmental conditions, compatible with standard microelectronics practices. The project will address challenges related to coupling with photonic integrated circuits, incorporating a range of optoelectronic elements like sources, amplifiers, modulators, and filters, all operating within visible or near-infrared wavelengths.
While the funding, which is approaching $20 million, may seem modest, it represents a significant push toward technology breakthroughs capable of bringing optical computing closer to mainstream use in aerospace and defense applications.
About the Author
John Keller serves as the Editor-in-Chief at Military & Aerospace Electronics Magazine, providing in-depth coverage and analysis of vital electronics and optoelectronics technologies applicable in military, space, and commercial aviation sectors. He has been part of the Military & Aerospace Electronics team since 1989 and became the chief editor in 1995.
