The purpose of this article is to showcase the role of photonic integration in our interconnected world and to bring to light that there is a ready to scale cost-effective InP PIC ecosystem. The intention of this content is to inform both specialized and non-specialized readers on the topic.
The role of photonic integration in our interconnected world
The Future is Scalable
An interconnected world
Driven by the availability of internet for the masses, that started at the end of the last century, humanity has become increasingly interconnected. While at first, we used dial-up modems and connection was intermittent and expensive, today’s children live in a world where the internet is everywhere and always available through handheld devices and wearables. And we are not just connecting humans together. Machines communicate directly to other machines and sensors are attached to virtually anything, from crops to wildlife. When everything is connected to everything there is quite a lot of technology that is needed to enable this.
The need for speed
Nowadays, most of our (tele)-communication happens wirelessly: either via mobile internet, such as the 4G connection on your phone, or via Wi-Fi when you are at home or at the office. A few years ago, the data carrier of choice for video was a physical medium, such as DVD and for a short time Blu-ray. Nowadays almost all content (video, audio and data) comes to us in a streaming manner. Streaming, especially high definition content like 4K and beyond, requires large amounts of data to be transferred from servers to end-users. And since more and more we watch our videos on the go, global mobile data traffic is skyrocketing. Every quarter one of the leading telecom vendors Ericsson release their Mobility Report, which contains a forecast for global mobile data traffic (in EB per month!). They forecast an astonishing about 60% CAGR between 2015 and 2030. This means that every year the amount of data transferred via mobiles increases by 60%. This increase is mostly driven by the demand for streaming video (75% by 2023). This makes sense when you remember that streaming 4K ultra-HD (UHD) takes about 4 times the amount of data as Full HD. And UHD VR (360-degree) multiplies this number by an astonishing factor of 15.
Without the hot air
While all these new services are very useful and they enrich our lives in many ways, like most things, they come at a cost. Specifically transferring and storing all this data consumes large amounts of energy. Transferring and storing exponentially more will consume exponentially more energy. According to an article in Nature (“The Information Factories”), the ICT ecosystem today is responsible for over 2% of global CO2 emissions, which puts it on par with the aviation industries emissions from fuel. The article continues to predict that by 2030 ICT services could consume as much as 20.9% of global electricity demand. If you zoom into the numbers shown in the graph below, we see the two major contributors to the energy consumption are the data centres and the networks.
So, on our road to interconnect to the world we must come up with a way to make it both economically and environmentally sustainable to do so. That is where photonics integration will play an integral part, to not only make the networks faster and more versatile, but also to enable more efficient data center architectures and make them accessible from all over the world.
Integration is key
In 1965 Gordon Moore, co-founder of Fairchild Semiconductors and CEO of Intel, famously described the doubling every year in the number of components per integrated circuit and projected this rate of growth would continue for at least another decade. We now know that Moore’s prediction proved accurate for several decades. The major enabling technology for achieving this exponential growth is the invention of the integrated circuit: The integration of large numbers of tiny transistors into a small chip. This results in circuits that are orders of magnitude smaller, faster, and less expensive than those constructed of discrete electronic components.
In order to enable the telecommunications networks of the future we now need to undergo the same revolution that electronics went through in the 70s, in the domain of optics. Fully monolithically integrated photonic circuits are the way to enable energy and cost-efficient scalability. By combining all the optical elements needed for an optical transceiver onto a single chip we can create high-power, high-speed, small size devices that can be assembled at low-cost, just like the electronic ICs that are now in every modern device. The chip fabrication technology, where hundreds of chips are fabricated together on a single wafer, is extremely scalable and is starting to follow a similar development curve as the electronic counterparts several decades ago. Wafer sizes have moved from 2” to 3” and 4” and 6” is already on the horizon. This evolution will drive down the cost of the optical chips and therefore their potential applications as well.
Plug and play
Obviously, energy consumption isn’t the only metric when it comes to future telecommunication networks. As already mentioned cost is also an important factor, specifically the cost per bit. This cost per bit does not only include the optical chip price or the purchase price of the transceiver, but also the cost of installing and maintaining it in the network. To reduce this so-called Total Cost of Ownership (TCO) of the network we can create additional flexibility and autonomy at the transceiver level. The InP-platform used for Photonics Integration is the perfect platform for tunable lasers. By using tunable transceivers one module part-number can be used in many different situations, reducing the need for expensive stock and sparing. Additionally, if modules can automatically adjust their channel to the existing Passive Optical Network (PON) after they are plugged in, this removes the need for operator intervention. Less hands-on-tools directly leads to a lower TCO.
InP PIC’s Scalability for Datacenter Applications
InP PIC fabrication platforms have seen an accelerated development over the recent years. Monolithic integration allows novel concepts in packaging and testing technology. Altogether they enable a ready to scale cost-effective InP PIC ecosystem.
InP PIC technology platform is the most versatile monolithic integration platform for photonic circuits. The ability to integrate both high-performance (tunable-) lasers with high-speed low loss modulators, as well as passive functions and detectors, makes the technology very appealing for a wide range of modern telecommunication applications. The technology is currently being used in integrated tunable laser/modulator circuits, both for common 10Gb/s direct detect products by e.g. Finisar, Sumitomo, and Lumentum, as well as for 100+ Gb/s coherent transceivers products by e.g. Oclaro, Neophotonics, and Infinera.
Most commercial products that employ InP PICs are produced in vertically integrated fabrication facilities in which the production line is dedicated to a small set of products, e.g. . This makes the initial investment and therefore the barrier to entry for new products very high. In the last decade, multiple research institutes have pioneered a novel foundry approach to InP PIC manufacturing. Several Multi-Project Wafer (MPW) services have emerged [2,3], allowing new device concepts to be developed at a low cost using standardized building blocks.
Within this framework, the technology readiness of monolithic InP PIC technology is analysed. Particularly, looking at the ability to address the volume and cost requirements as set out by the current datacenter market segment. The opportunities and remaining challenges that monolithic InP PIC’s bring to the packaging and testing technology need to be accounted for.
All of this, with the vision of looking at the applications within the datacenter market that will profit, short and long term, from this scalable cost-effective InP PIC ecosystem. This proposition was shared at the Optical Networking and Communication Conference and Exhibition (OFC) 2019, as an Invited Presentation within “Advances in prototypes and product developments of components and subsystems for data centers and optical networks”.
 G.E. Hoefler, et al., “Tb/s-Class InP System-On-Chip Photonic ICs,” European Conference on Integrated Optics (ECIO), Th.3.1-2, (2018).
 JePPiX, “Technology Roadmap” in JePPIX Roadmap 2018: The road to a multi-billion euro market in integrated photonics, Chap. 5., (2018).
 F. M. Soares et al., “High-Performance InP PIC Technology Development based on a Generic Photonic Integration Foundry,” 2018 Optical Fiber Communications Conference and Exposition (OFC), San Diego, CA, 2018, pp. 1-3.