IEEE Study Describes Polymer Waveguides for Reliable, High-Capacity Optical Communication

Researchers discover that glass-epoxy-based waveguides have characteristics ideal for transmitting optical signals in co-packaged optics

PISCATAWAY, N.J., June 6, 2025 /PRNewswire/ -- Co-packaged optics (CPO) technology can integrate photonic integrated circuits (PICs) with electronic integrated circuits like CPUs and GPUs on a single platform. This advanced technology has immense potential to improve data transmission efficiency within data centers and high-performance computing environments. CPO systems require an integrated or external laser source for operation. While integrated laser sources allow for dense CPO integration, ensuring consistent reliability can be challenging, which may affect overall system robustness. The use of external laser sources (ELS) in CPO, in comparison, offers improved system reliability.

Single-mode polymer waveguides are crucial components of many PICs, where they help couple light from an external laser to the PIC. They are cost-effective, mechanically flexible, and highly compatible, showing significant potential for use in CPO systems utilizing ELS.

Now, a team of researchers led by Dr. Satoshi Suda from the National Institute of Advanced Industrial Science and Technology, Japan have tested the stability and reliability of single-mode polymer waveguides fabricated on glass-epoxy substrates. Their findings published in IEEE Journal of Lightwave Technology, suggest that these polymer waveguides have a range of desirable characteristics that make them a promising addition to future CPO systems.

The team fabricated 11-mm-long polymer waveguides using direct laser writing on FR4 glass-epoxy substrates. The waveguides had well-controlled core dimensions (9.0 µm × 7.0 µm), suitable for matching standard single-mode fibers. They exhibited low polarization-dependent loss and low differential group delay, along with excellent uniformity across eight fabricated samples.

The researchers found that the fabricated waveguides possess consistent insertion loss and mode field dimensions. In addition, they exhibited desirable polarization extinction ratio (a critical metric that reflects the ability of waveguides to maintain a specific polarization for the signals they transmit). The testing of waveguides under high-power conditions revealed that the waveguides were resistant to power degradation even after 6 hours of continuous use, while showing minimal heating concerns. The ELS used in these experiments, which enabled stable operation for six hours, was provided by Furukawa Electric Co., Ltd.

"These findings demonstrate the strong potential of polymer waveguides for practical deployment in demanding CPO systems, providing a reliable foundation for next-generation high-density and high-capacity optical communication technologies," concludes Dr. Suda.

Reference

Title of original paper: High-Power Stability and Reliability of Polymer Optical Waveguide for Co-Packaged Optics

Journal: IEEE Journal of Lightwave Technology        

DOI:  10.1109/JLT.2025.3543339

Contact:

Kristen Amoroso 

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SOURCE IEEE Photonics Society