Preface

Optics is an old and venerable subject involving the generation, propagation, and detection of light. Three major developments, which have been achieved in the past thirty years, are responsible for the rejuvenation of optics and for its increasing importance in modern technology; the invention of the laser, the fabrication of low-loss optical fibres, and the introduction of semiconductor optical devices. As a result of these developments, new disciplines have emerged and new terms describing these disciplines have come into use; electro-optics, optoelectronics, quantum electronics, quantum optics and lightwave technology. Although there is a lack of complete agreement about the precise usages of these terms, there is a general consensus regarding their meanings.

Photonics

Electro-optics is generally reserved for optical devices in which electrical effects play a role (lasers, and electro-optic modulators and switches, for example). Optoelectronics, on the other hand, typically refers to devices and systems that are essentially electronic in nature but involve light (examples are light-emitting diodes, liquid-crystal display devices, and array photodetectors). The term quantum electronics is used in connection with devices and systems that rely principally on the interaction of light with matter (laser and nonlinear optical devices used for optical amplification and wave mixing serve as examples). Studies of the quantum and coherence properties of light lie within the realm of quantum optics. The term lightwave technology has been used to describe devices and systems that are used in optical communications and optical signal processing.

In recent years, the term photonics has come into use. This term, which was coined in analogy with electronics, reflects the growing tie between optics and electronics forged by the increasing role that semiconductor materials and devices play in optical systems. Electronics involves the control of photons (in free space matter). The two disciplines clearly overlap since electrons often control the flow of photons and, conversely, photons control the flow of electrons. The term photonics also reflects the importance of the photon nature of light in describing the operation of many optical devices.