How photonic ICs are evolving
By Dr. Danny Rittman, chief technology officer, GBT TechnologiesSemiconductors 5G 6G Editor Pick ICs Photonic semiconductors wireless
At a time when data demands are increasing rapidly
First developed in the late 1950s, the integrated circuit (IC) – also known as a chip or microchip – is the key building block in just about every electronic device in use today. Fabricated out of a semiconductor wafer and powered by electricity, most modern IC chips are now measured in square millimeters and can consist of thousands or millions of tiny resistors, capacitors, diodes, and transistors.
However, as chips have become increasingly miniaturized, we are fast approaching the point where it will become physically impossible to fit any more components on a wafer. This post-Moore’s Law world, as it’s been called, may be upon us by as early as the year 2036 and could pose serious challenges for further advances in semiconductor engineering.
Worse yet, current IC chips are already coming under a lot of strain from an exponential increase in data usage through big data, Internet of Things (IoT) devices, and artificial intelligence (AI). Simply put, current IC architecture is not up to the challenge of increasing data demands, which has led to bandwidth bottlenecks and decreased data transmission speeds.
Fortunately, advances in the field of integrated photonics have expanded rapidly in recent years and will likely form the foundation of a new type of IC architecture, one that uses light rather than electricity to send signals and drive components.
What is integrated photonics?
A photonic integrated circuit (PIC), also known as a photonic chip, is a microchip that uses two or more photonic components to form a functioning circuit. What sets a photonic chip apart from an electronic one is that it uses light particles (photons) rather than electricity (electrons) to sense and transmit information.
Photons allow for greater bandwidth than is possible with an electronic chip. Furthermore, photons do not encounter any resistance from one another, as electrons do, which translates into faster data transmission speeds and lower thermal effects.
Another thing that sets photonic chips apart from their electronic counterparts is the substrate material used in their construction. In most electronic chips, silicon is the preferred choice due to its high conductivity, low cost, and well-established processing techniques.
However, with photonics, silicon is not a viable material because it is a poor light emitter. Instead, three different substrates – or “flavors” – have emerged in photonic development, namely indium phosphide (InP), silicon nitride (SiN), and silicon/silica photonics (SiP). Whatever material a chip manufacturer chooses to use will depend on the intended application of the chip, as each substrate has its own strengths and weaknesses. In theory, it may one day be possible to combine all three materials to create the ultimate PIC, but given the limited size of the current PIC market, it doesn’t make economic sense for manufacturers to pursue such an endeavor just yet.
Photonics in data and telecom
One of the key benefits of photonic chips is improved data communications, which has led to many applications for PICs in a diverse range of industry sectors, including autonomous driving, biomedical, astronomy, defense, and aerospace. But the two sectors with perhaps the most to gain from advances in photonics are the data management and telecom sectors. This is where photonic chips are likely to have the biggest effect on data communications in the coming decades.
Integrated photonics in data centers
Between 2010 and 2018, global internet traffic grew more than tenfold, while global data center storage capacity increased by a factor of 25. This vast growth in the amount of data being generated and consumed every day is only set to continue as new possibilities open up from the development of AI, big data, and IoT. As a result of these increasing data demands, the conventional copper cables used to connect servers are suffering from bandwidth bottlenecks that affect the entire system.
While copper cables tend to hit their bandwidth limits within a few Gbps, the limits of an optic fiber are nearly unlimited, allowing for transfer speeds of hundreds of Gbps or Tbps with ultra-low latencies. Moreover, data centers can also integrate photonic chips with onboard components such as high-bandwidth transmitters and receivers, allowing for a significant improvement in system performance and reliability.
Energy use cost savings
One of the consequences of the resistance encountered between electrons when passing through a copper wire is that large amounts of heat are generated. This can be highly problematic for the silicon used in electronic chips, which tends to rapidly break down under heat stress. For this reason, large amounts of cooling are required to keep data centers operational, which in turn leads to heavy energy consumption and high carbon emissions. It’s been estimated that cooling alone accounts for 33 percent of the energy consumed by a data center.
By contrast, PICs generate far less heat. In fact, they generate so little heat that they don’t require any dedicated cooling system. This extreme energy efficiency is likely to become even more important in the coming years as pressure builds for data centers to cut down on their energy consumption as part of the fight to reduce carbon emissions.
Next generation 6G networks
Even as 5G continues to roll out across the world, telecom companies are already discussing potential designs for 6G, which promises to be orders of magnitude faster than 5G. Expected to be launched at the end of the decade, 6G could provide speeds of up to 1 Tbps, opening the doors to new advances in 3D holographic videos, 8K streaming, and improved artificial reality (AR) and virtual reality (VR) devices. Photonics is certain to be the defining technology of 6G, as it can provide a significant improvement over electronics in both bandwidth and transmission speeds.
Over the coming decade, it’s clear that photonic chips will become the preferred choice in the data and telecom sectors. Their ability to provide lightning-fast speeds on a wide bandwidth with low thermal effects makes them the best solution for handling the increasing data demands of a rapidly digitizing society. That said, it must be kept in mind that this is just the beginning for photonics. Increasing data demands are certain to push their development even further, leading to new use cases and an expanded market that could reach new heights within the next five years.
Dr. Danny Rittman is chief technology officer at GBT Technologies, a solution dedicated to enabling the rollout of Internet of Things (IoT), global mesh networks, artificial intelligence (AI) and for applications relating to integrated circuit (IC) design.
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