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  • The Future of Photonics/Optics in Data Centers

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    As high-performance computing, artificial intelligence, and machine learning algorithms need more and more data, hardware struggles to keep up. In addition, an increasingly hands-free world is

    dependent on the availability of real-time evaluations of moving data points. These evaluations are required for tasks such as the precise mapping of other objects’ velocities in autonomous systems and facial recognition to enhance security measures. The most recent research from IDTechEx, titled “Semiconductor Photonic Integrated Circuits 2023-2033,”explor es the companies responsible for technological innovations that aspire to satisfy the aforementioned needs across numerous markets. The potential of semiconductor photonics can be summed up in four words, More Data, More Quickly. To respond effectively to the ever-in-creasing demand for data usage around the world, the global technology industry faces several issues. Today, the typical size of a data center is comparable to that of a football field, and some of these facilities demand as much power as a small city. With the increase in demand for these high-speed data centers, it is
    more important than ever to ensure that data centers are built and maintained in a secure, reliable, and efficient way. Embedded optics at the board module are not new, but a necessary shift toward optical options is sweeping the industry. The trend toward data-intensive usage models and resource disaggregation continues within nextgeneration applications hosted within data centers. In order to fulfill the requirements of the next generation of applications, it is necessary to take into account the cost,power consumption, latency, and overall bandwidth of each component, not only for the applications that already exist but also for any new use cases. Many industry leaders anticipate that developments in photonics/optics will play a significant
    role in optimizing these integral highspeed data centers. Photonics/optics is a rapidly growing field of research and technology that has the potential to revolutionize how data centers operate in the future. However,the vast majority of semiconductor chips in use today are electrical in nature. These chips come in small packages (most of which are measured in square milli-
    meters) and are made up of billions of transistors, which are switches that can either be “on” or “off.” These chips can be used to store and process data; electricity is required to run them.
    The rapidly growing need for high- speed data has resulted in an Input/Output (I/O) bottleneck in these traditional systems and is being tackled head-on by the communications industry through the development of photonic systems as one of the potential solutions. This bottleneck occurs when data cannot be transported into or out of a chip or chiplet at the same or a faster pace than
    the rate at which processing occurs. This is referred to as a data bottleneck. Because of this, a backlog is produced in the data

    stream, and the processing and storing that is being done in other chips and chiplets is halted while those chips and chiplets wait for the data. Systems like neural-language programming algorithms, which deal with vast amounts of potentially unstructured input, but have low-latency requirements in order to function properly, have a significant challenge as a result of this
    issue. Several different companies are hard at work on solutions for optical I/O that will cut down on latency, permit high bandwidth, and use the least amount of power possible. Although it is likely to have some electrical components as well, such as a laser diode source that is electrically pumped and as a result emits photons, a photonic integrated circuit uses light (photons
    being the quanta of light) to transmit data. Photonics, or Optics, can provide higher bandwidth and faster transmission speeds for data center networks by using light signals instead of electrical signals. Because they possess different properties, photons do not come into contact with resistance like electrons do. Photons are more likely to be lost as a result of the material’s absorption, scattering, or other effects, all of which can be minimized by selecting the appropriate materials. However, photonic systems can facilitate long-distance transmissions of considerable volumes Energy Consumption Forecast for Data Centers1 of data when injection and propagation losses are appropriately reduced. This is useful in situations where transferring data by electrical means is cumbersome due to the resistance in the conductive material. The field of photonics is now being investigated in two distinct areas: Co-Packaged Optics (CPO) and Optical Printed Circuit Boards (OPCBs). The CPO tile and flyover optical cable are the two primary components used in the production of CPO and include a short-reach optical interconnect between the physical optical fiber and the photonic engine. On the other hand, optical PCB is primarily utilized at the full rigid board level.

    Dupont’s Industry-Leading Photonics Research

    As a corporation, Dupont has a robust portfolio of materials relevant to photonics/optics such as automotive systems and components for consumer electronics. In developing these materials, they have made innovations to create more energy-efficient systems that reduce dielectric and signal loss. In fact, during their research, they have discovered that partially replacing copper
    interconnect systems in high-speed data centers with optics will improve the overall energy efficiency by an impressive 70 – 80 percent, lowering overall energy consumption and improving speeds -which offers operational cost savings as well. With more efficient processes and increased energy efficiency, introducing optics into data centers can potentially reduce the need for expansion, and therefore the eco-footprint. The use of optics in data centers is a great way to increase the capacity of a network while maintaining speed and efficiency. Options include con-
    verting rigid laminate materials at the switchboard level with polymers that conduct optics (Optical PCB, or OPCB), or Co-Packaged Optics (CPO) with a polymer waveguide, which can enhance
    the overall bandwidth through optical fan out. A reduction of copper length is possible by using polymers that are either directly connected to the face plate of the switch box (OPCB) or connected between the optical fiber and the photonics engine (CPO), getting optical units closer to the chip’s computing power. Replacement of Cu to Optics in both approaches allows the system to have ultimately lower insertion loss and improved signal integrity at a higher data rate. Using optics to reduce the copper length also reduces thermal loss, providing more efficient cooling and power consumption, leading to more cost savings. With these benefits combined, photonics could become a staple in the future of data center operations. However, there are still barriers to the widespread adoption of photonics in data centers, such as the cost associated with implementation and system replacement when needed. Nevertheless, with continued research and development, photonics could become a major part of the data center landscape in the years to come. In fact, since optical pluggables have been removed from the faceplate of these units,
    there is now an opportunity to re-evaluate the design configuration of the faceplate in terms of optical connections, heat management, and power into a network switch or data center server.
    Multi-Chip Module (MCM) configurations have the potential to leverage significant advantages in terms of electrical power and signal integrity, particularly in contexts requiring high bandwidth and a high baud rate. Therefore, to increase the scorecard for the bandwidth/power

    consumption ratio, it is necessary to carry out co-design to optimize the chips’ functions. Power consumption is integral to today’s data center architecture design, and effective thermal management is required due to the large amount of energy needed to power up and cool these systems. In an optical multi-chip module, also known as an OMCM, we have to take into consideration the fact that the laser,which must be cooled in order to maintain optical stability and efficiency, will be in close proximity to an application specific integrated circuit that produces
    heat (ASIC). The design of the packaging is therefore an essential component in the process of supplying the required heat isolation and dissipation solution. If the appropriate photonic packaging solutions can be created, the integration of electrical and optical capabilities could usher in a new era of device shrinking and cost-efficiency. This would be made possible by the reduction of the size of the device. Moving transceivers closer to the data-generating chips can significantly impact the amount of power consumed per bit and the latency experienced by the system. This is especially true when considering the electronic overhead and regeneration that are associated with long-distance electrical lines.
    Looking Ahead

    The CPO option has the benefit of covering both data center (ether-net) connections & Optical Compute Interconnect. Compared to what would be achievable with separate photonics and ASICs components, co-packaging enables a system that is more cost-effective, smaller, consumes less power, and has a higher bandwidth. The rise of (CPO) devices has brought about a new era of high-speed, low-latency data transfer and communication within computing systems. CPO technology integrates optical components directly onto silicon substrates, enabling efficient interconnects at the chip level. While CPO devices hold tremendous promise for enhancing performance and energy efficiency,they also present significant challenges.The miniaturization of optical components, the coexistence of electrical and optical components, thermal management, and ensuring reliable signal integrity are just a few of the complex hurdles that must be overcome.

    Conclusion

    The industry’s requirements for enhanced performance, optical loss budget, power, and cost are driving the deployment of new optical component technologies and, eventually, the widespread application of such technologies. Thankfully, various photonic packaging technologies are flexible and compatible with integration into the assembly of microelectronics. As a result, they provide the framework for the packaging co-de-sign of photonics with ASICs and other electronic components. Co-packaging allows for a solution that is more compact, less expensive, lower
    in power consumption, and higher in bandwidth than would be possible with separate photonics and ASICs components. Embedded photonics are quickly moving from the category of “good to have” to “absolutely necessary” as the movement toward bringing the light as close as feasible to the ASICs and CPUs gains momentum. The industry is looking forward to a growing presence of optical connectivity in the world’s data centers. To complement this new technology, Dupont also has a plethora of system-level solutions to increase efficiency in data centers: Advanced chip designs, innovative thermal materials, rigid substrates, new optical dielectrics, rigid and flat circuits, and frequency/non-frequency dependent signal transmission systems.

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