The first nonlinear optical effect was observed in the 19th century by John Kerr. Nonlinear optics, however, started to grow up only after the invention of the laser, when intense light sources became easily available. The seminal studies by Peter Franken and Nicolaas Bloembergen, in the 1960s, paved the way for the development of today’s nonlinear photonics, the field of research that encompasses all the studies, designs, and implementations of nonlinear optical devices that can be used for the generation, communication, and processing of information. This field has attracted significant attention, partly due to the great potential of exploiting the optical nonlinearities of new or advanced materials to induce new phenomena and achieve new functions. According to Clarivate Web of Science, almost 200,000 papers were published that refer to the topic “nonlinear optic*”. Over 36,000 papers were published in the last four years (2015–2018) with the same keyword, and over 17,000 used the keyword “nonlinear photonic*”. The present Special Issue of Micromachines aims at reviewing the current state of the art and presenting perspectives of further development. Fundamental and applicative aspects are considered, with special attention paid to hot topics that may lead to technological and scientific breakthroughs.

The first nonlinear optical effect was observed in the 19th century by John Kerr. Nonlinear optics, however, started to grow up only after the invention of the laser, when intense light sources became easily available. The seminal studies by Peter Franken and Nicolaas Bloembergen, in the 1960s, paved the way for the development of today's nonlinear photonics, the field of research that encompasses all the studies, designs, and implementations of nonlinear optical devices that can be used for the generation, communication, and processing of information. This field has attracted significant attention, partly due to the great potential of exploiting the optical nonlinearities of new or advanced materials to induce new phenomena and achieve new functions. According to Clarivate Web of Science, almost 200,000 papers were published that refer to the topic “nonlinear optic*”. Over 36,000 papers were published in the last four years (2015-2018) with the same keyword, and over 17,000 used the keyword “nonlinear photonic*”. The present Special Issue of Micromachines aims at reviewing the current state of the art and presenting perspectives of further development. Fundamental and applicative aspects are considered, with special attention paid to hot topics that may lead to technological and scientific breakthroughs.

A robust introduction to real-world nonlinear photonics for students of electrical engineering.

Photonic devices lie at the heart of the communications revolution, and have become a large and important part of the electronic engineering field, so much so that many colleges now treat this as a subject in its own right. With this in mind, the author has put together a unique textbook covering every major photonic device, and striking a careful balance between theoretical and practical concepts. The book assumes a basic knowledge of optics, semiconductors and electromagnetic waves. Many of the key background concepts are reviewed in the first chapter. Devices covered include optical fibers, couplers, electro-optic devices, magneto-optic devices, lasers and photodetectors. Problems are included at the end of each chapter and a solutions set is available. The book is ideal for senior undergraduate and graduate courses, but being device driven it is also an excellent engineers' reference.

The most comprehensive book on waveguide nonlinear optic devices, this volume presents a systematic description of the NLO field, with an emphasis on devices that use ferroelectric waveguides. It ranges from an introduction to the concepts of waveguides to the most recent experimental results.

Nonlinear optical studies of periodic dielectric structures have blossomed in the past two decades. New fabrication techniques are producing fiber grating and multidimensional photonic crystals in materials where the refractive index can be varied by light pulses and beams. Gap solitons that can propagate at any velocity from zero to the speed of light and spatial solitons that prevent the diffractive spread of light in waveguide arrays are two examples of the new phenomena described in this book. Many new materials and structures are being developed that will impact new optical devices with applications in optical communications and optical data processing. All the above topics are addressed in detail in this book.

Nonlinear photonics is the name given to the use of nonlinear optical devices for the generation, communication, processing, or analysis of information. This book is a progress report on research into practical applications of such devices. At present, modulation, switching, routing, decision-making, and detection in photonic systems are all done with electronics and linear optoelectronic devices. However, this may soon change, as nonlinear optical devices, e.g. picosecond samplers and switches, begin to complement optoelectonic devices. The authors succinctly summarize past accomplishments in this field and point to hopes for the future, making this an ideal book for newcomers or seasoned researchers wanting to design and perfect nonlinear optical devices and to identify applications in photonic systems.