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Preface

A vertical‐cavity surface‐emitting laser (VCSEL) is experiencing rapid growth followed by applications mostly in communication and sensing. This book describes the industrial technologies driven by the rapid expansion of the information age and the extension into rapidly emerging areas of AI (artificial intelligence) and IoT (Internet of Things).

The VCSEL was first conceived in 1977 by Kenichi Iga, one of the authors and while the device itself is smaller than a sesame seed, its impact on the world is profound. The unique advantages of small size, surface normal emission, and scalability into 1D and 2D arrays are hallmarks of the device. The name VCSEL was chosen because the light is emitted perpendicular to the wafer, and the pronunciation as “viksel” is reminiscent of a pixel in the scalability into large 2D structures.

Iga has continued basic research on VCSELs ever since its invention and witnessed commercialization in 1996 as the Internet began its rapid expansion. The first VCSEL products were in optical transceivers used in data centers, which support the modern information age. Along with the spread of the Internet, information‐related companies now own huge information storage centers called the cloud (a mechanism for storing information in memory, such as hard disks, to read and use it). High‐speed optical fiber networks exchange large volumes of information to and from data centers. Each of these data centers may contain many hundreds of thousands of VCSEL‐based optical interconnects. In fact, VCSELs today provide more than 50 Mbps of connectivity for every person on earth.

In addition, many computer users have a mouse, which uses an optical source and a camera to track its position movement. The number of units produced so far is more than 1.1 billion. In 2017, the VCSEL was also adopted by the iPhone X for facial recognition. More recently, a laser RADAR (LiDAR) is being implemented in smartphones and iPads to enable AI and augmented reality. A new era of optical sensing was born taking advantage of the VCSEL’s small volume, low power consumption, and scalability.

It can be said that most of us are using VCSELs even without recognizing them. This small device is becoming a powerful tool that supports the flow of information in everyday life.

The current technological progress has caused many paradigm‐shifts in the information communication world, and we look at the new world of optoelectronics centering on VCSELs because they will be firmly rooted as the devices that enable the IoT and AI smarter. As for the descriptions of the theory and mechanism of the laser, we discuss the VCSEL from the industrial point of view in this book.

Applications of surface‐emitting lasers are expanding, and the numbers of researchers, developers, and manufacturers who handle them are also increasing. The book is intended for a broader audience in industry and introduces the basic ideas and the scope of applications that have not necessarily been written in most of academic papers and textbooks.

We would be extremely pleased if this book could serve as an opening gate for emerging new VCSEL industries.

Kenichi Iga

Tokyo, Japan

July 11, 2021