Core Viewpoint - Co-packaged optics (CPO) technology is emerging as a promising solution to enhance bandwidth and energy efficiency in data centers, particularly for applications involving generative AI and large language models. However, manufacturing challenges remain, particularly in fiber-to-photonics integrated circuit (PIC) alignment, thermal management, and optical testing strategies [1][20]. Group 1: CPO Technology and Benefits - CPO enables network switches to route signals at speeds of terabits per second while significantly improving bandwidth and reducing power consumption required for AI model training [1][20]. - The technology achieves a bandwidth density of 1 Tbps/mm, optimizing rack space in increasingly crowded data centers [1][6]. - CPO can reduce power consumption associated with high-speed data transmission from approximately 15 pJ/bit to around 5 pJ/bit, with expectations to drop below 1 pJ/bit [6][7]. Group 2: Manufacturing Challenges - Key challenges in CPO manufacturing include achieving precise alignment between fiber and PIC, which is critical for effective optical signal coupling [8]. - The most common passive alignment method is the V-groove technique, which connects the fiber directly to the PIC to minimize loss [8][9]. - Efficient coupling between standard single-mode fibers and silicon waveguides is complicated due to significant differences in size and refractive index, leading to potential light loss [8][9]. Group 3: Thermal Management - CPO systems are sensitive to temperature fluctuations caused by high-power devices like GPUs and ASICs, which can affect the performance of photonic devices [11][12]. - A temperature change of just 1°C can lead to approximately 0.1nm wavelength shift in most photonic systems, necessitating careful thermal management strategies [11][12]. - Advanced thermal interface materials and monitoring circuits are deployed to maintain PIC temperature within predefined ranges [11][13]. Group 4: Reliability Design - Ensuring reliability in CPO systems is crucial, especially with multi-chip integration, requiring known good die (KGD) testing and optical testing solutions [14][16]. - High reliability designs incorporate redundancy, such as backup lasers, to maintain operation in case of component failure [15][16]. - Integrated monitoring and self-correcting features are being developed to detect performance degradation and facilitate quick recovery [15][16]. Group 5: Integration Techniques - Both 2.5D and 3D packaging methods are utilized in CPO, with 2.5D placing electronic ICs and PICs side by side on a silicon interposer [17][18]. - 3D integration allows for optimal manufacturing processes for each chip type, enhancing performance while increasing complexity and cost [18][19]. - The integration of optical features with traditional CMOS processes is becoming more compatible, facilitating advancements in CPO technology [17][18].