Preface
We started writing this book in late 2014. At the time, silicon photonics was in a quiet period. The excitement that greeted the early announcements and later a spate of silicon photonics acquisitions had, by then, been replaced by pragmatism as the industry understood not only the technology’s merits but also its challenges. Many in the industry were keeping a watching brief while others remained skeptical, questioning whether silicon photonics was a viable technology [1,2].
Silicon photonics’ quiet period has ended. As we complete the book in late 2016, the year has seen more players enter the marketplace with silicon photonics’ products, more acquisitions, and even a successful initial public offering, by Acacia Communications.
However, in one sense the larger picture has not changed: people have long recognized the potential of silicon, and there have also been voices of pragmatism. Take this view from Simon Sherrington, talking in 2009 about his Light Reading report on silicon photonics: “Silicon Photonics is changing the way vendors do photonic integration and has the potential to disrupt the supply chain.” [3] And a Nature Photonics paper did an important job to dispel some of the myths that were being associated with silicon photonics. The paper also stated this: “The bottom line is that individual silicon devices will probably not outperform single devices based on other material platforms, except in a few particular areas. The applications that will benefit most from the silicon platform are those that require many devices to be strung together into a complex system, just like in electronics.” [4] In late 2016 both statements remain true.
Silicon photonics is coming to market at a time of momentous change. One significant trend is the rise of the Internet content providers and the developments taking place in the data center. These developments are having a knock-on effect for the communications service providers—telcos—which are now undertaking their own transformation. A second change is the end of Moore’s law. The chip industry is currently grappling with a wave of company consolidations, while the end of Moore’s law will have far-reaching consequences. Meanwhile, the optical industry faces its own issues as the bandwidth-carrying capacity of fiber starts to be approached. Optical fiber has been seen as a communications medium of near-boundless capacity. The growth in Internet traffic, the use of smartphones, and subscribers’ appetite for video means that is no longer true.
Each of these developments—the data center, the end of Moore’s law, and the looming capacity crunch—is significant in its own right. But collectively they signify a need for new thinking for chips, optics, and systems, as well as new business opportunities and industry change. Silicon photonics is arriving at a propitious time.
Despite this, the optical industry still has questions regarding the significance of silicon photonics. Meanwhile, for the chip industry optics remains a science peripheral to their daily concerns. This too will change.
As implied by its name, silicon photonics is set to influence both industries. For the optical industry, the technology will allow designs to be tackled in new ways. For the chip industry, silicon photonics may be a peripheral if interesting technology, but it will impact chip design. Silicon photonics may have hurdles to overcome, but it is a technology that no one will be able to ignore.
We felt the timing was right for a book that synthesizes the significant changes taking place in the datacom, telecom, and semiconductor industries and explains the market opportunities that will result and the role silicon photonics can play.
We have cast a wide net across these industries for a reason: we see it as a vital exercise to understand the significance of silicon photonics. Indeed, the book shows that silicon photonics will be a key technology for a post-Moore’s law era, and we argue that it will be the chip industry, not the photonics industry, that will drive optics.
The Reasoning for the Book and Its Organization
Let us start by saying what this book is not. It is not a traditional textbook—there is almost no math. Nor is it a compendium of the latest research work of the leading academics in the field. It is also not a how-to design book. Wonderful examples of such books exist. Nor is it a detailed market research report.
Instead, we have set ourselves a wider brief to look across important industries to tell the story of a key technology that is coming to market. To tell this story, we have broadened the context not just for the optical community but for the chip industry. The book is deliberately written with the assumption that not all the readership is familiar with optics or with the chip industry. We have brought in the voices of key silicon photonics luminaries who have played an important role in bringing the technology to market to tell some of their stories. These individuals have thought deeply about the technology and its likely ramifications.
The book focuses on the telecom and datacom industries, which are and will remain the primary markets for silicon photonics for the next decade at least. But we also note other developments where silicon photonics can play an important role.
A work of this nature must include some technical topics in optical communications, networking, and systems architectures. We have aimed to write these at a level that details what is needed without taking the reader on a detour. Interested readers will find appendices which give a more detailed discussion.
The main audiences for this book include design engineers of components—chips and optical components— as well as systems designers for a range of devices, from optical modules to telecom and datacom equipment. It is also written for sales and marketing executives who want to understand the broader developments in their industry, the changes taking place, and the key technologies. We have also targeted the book at press relations and media executives working in these industries.
Lastly, one of the silicon photonics luminaries, Lionel Kimerling, professor of materials science and engineering at MIT, told us how he is spending most of his time working with AIM Photonics, a US public–private venture established to advance the manufacturing of silicon photonics. Professor Kimerling is putting together educational material to help attract individuals to pursue a career in silicon photonics. Much of the technology is in place, he says; what is required is to make it accessible to people. “I don’t have 40 more years in the industry, but I could influence the next 40 years by creating these instructional materials and career paths, and getting roadmap consensus that can drive the industry,” says Kimerling.
In a very modest way, we hope this book also plays a role in realizing Professor Kimerling’s vision and is read by students considering their engineering options.
The chart shown on the previous page summarizes the book’s content at a glance.
Please visit the book companion website http://booksite.elsevier.com/9780128029756/ for full color versions of the figures in this book.