The researchers at Fraunhofer IZM have developed a glue-free laser welding process for coupling photonic integrated circuits (PICs) with optical fibers, which can also be used in cryogenic environments of up to four Kelvin, equivalent to -269.15°C. This technology offers a more reliable, faster, and cheaper fiber-PIC coupling through a direct quartz-quartz connection, revolutionizing applications in quantum technology.
Low-temperature environments are essential for observing quantum effects, which can greatly improve human quality of life, such as in big data processing for personalized medicine and hospital information management. The development of cryogenic systems for quantum computing is currently being actively promoted. Quantum technological systems with implemented PIC-based modules offer a compact solution for secure communication and networking in quantum computing. Reliable fiber optic connections are, however, a fundamental requirement for such photonic quantum systems.
The focus of the QWeld research project is on realizing this connection technology for applications in cryogenic environments. Standard CMOS-manufactured PICs with a silicon dioxide (SiO2) coating are used, which is necessary for glass-glass laser welding. A vertical coupling of the fiber with the PIC, typically with a specific angle, is a special feature. The laser meets the contact point between the PIC and the fiber on both sides during welding and creates a material-bonding connection within seconds. This manufacturing process offers significant time savings.