Co-packaged optics (CPO): status, challenges, and solutions

Abstract

Due to the rise of 5G, IoT, AI, and high-performance computing applications, datacenter traffic has grown at a compound annual growth rate of nearly 30%. Furthermore, nearly three-fourths of the datacenter traffic resides within datacenters. The conventional pluggable optics increases at a much slower rate than that of datacenter traffic. The gap between application requirements and the capability of conventional pluggable optics keeps increasing, a trend that is unsustainable. Co-packaged optics (CPO) is a disruptive approach to increasing the interconnecting bandwidth density and energy efficiency by dramatically shortening the electrical link length through advanced packaging and co-optimization of electronics and photonics. CPO is widely regarded as a promising solution for future datacenter interconnections, and silicon platform is the most promising platform for large-scale integration. Leading international companies (e.g., Intel, Broadcom and IBM) have heavily investigated in CPO technology, an inter-disciplinary research field that involves photonic devices, integrated circuits design, packaging, photonic device modeling, electronic-photonic co-simulation, applications, and standardization. This review aims to provide the readers a comprehensive overview of the state-of-the-art progress of CPO in silicon platform, identify the key challenges, and point out the potential solutions, hoping to encourage collaboration between different research fields to accelerate the development of CPO technology. Graphical Abstract

Scalable On-Chip Optoelectronic Ising Machine Utilizing Thin-Film Lithium Niobate Photonics

“…In the presented works, only a simple set of TFLN modulators and PD is integrated on-chip. Looking ahead, ASICs, DACs, and ADCs�the substituted components of FPGAs, AWGs, and oscilloscopes in the presented demon-strations�as well as light sources all have the potential to be integrated or copacked on the same chip by the copackaged optics techniques 41 to achieve a smaller footprint, higher bandwidth, and lower energy consumption. In Schemes I and II, the use of EO modulations aligns the nonlinear transformation seamlessly with EO signal conversion and multiplication, thereby eliminating the need for additional computational time and energy for nonlinear transformation.…”

High-power tests of expanded beam connectors for co-packaged optics applications

“…The advent of co-packaged optics (CPO) for data centers and high-performance computing, including machine learning and artificial intelligence (AI), represents a paradigm shift which introduces several new connectivity challenges. One such challenge for CPO architectures that incorporate off-chip, external laser (EL) sources [1] is to provide a reliable optical path for the laser power to the modulators on the chip. New ultra high-power continuous wave (CW) lasers demonstrated by Lumentum, operating at over 400 mW at 25 °C [2] enable a more efficient optical solution for the EL source in the CPO application.…”