More than pins and mirrors

Optical physics underpins a whole revolution in the way we manipulate, transmit and utilize data. Through fibre optics, it provides the backbone for fast telecoms across the world, and through sensitive instrumentation allows for novel imaging especially in medical applications. Optics has also permitted exquisite tests of the most fundamental ideas of quantum physics, for example in demonstrating that the world is not locally realistic through the violations of statistical measures proposed by John Bell.

But it is the impact of optics in industry that has perhaps been of most significance. As a result of the rapid development of fibre-based communications in particular, we have found that students with qualifications in optics are in demand to fuel a worldwide need for manpower. Conferences in this field are overwhelmed with participants, and many have turned into hiring-fair circuses.

Universities and colleges are struggling to meet this demand, both at the undergraduate level and through the provision of postgraduate and masters-level courses. At the same time, developments at the fundamental end of the subject, for example in quantum cryptography and the provision of secure codes, have stimulated incredible student interest in quantum optics. The two books reviewed here are the key references any serious student of optics needs to have to hand if they want to have a reliable guide to both classical and quantum optics. Born and Wolf for long has been the authority on all things classical in optics and developed from Max Born’s much earlier classic text Optik . The first edition of Born and Wolf appeared 40 years ago, one year before the invention of the laser, stimulated by the rapid growth, for example, in statistical optics and coherence. At the time of publication of the first edition, optics had hit an all time low, at risk of disappearing from the undergraduate syllabus entirely. "All pins and mirrors" was the way one distinguished head of my own department once dismissed optics a generation ago. What a contrast this is to the high standing it now has, especially among employers.

Emil Wolf is, of course, the pioneer of coherence theory, as well as of very many novel developments in diffractive optics. This seventh edition of his standard work is the first to be thoroughly revised and expanded. Of course Wolf has retained the standard material on physical optics. His account of the Kirchhoff theory of diffraction remains the best there is and is the source for all other writers in the field. The style remains magisterial and authoritative. But as well as including all the standard material we have come to expect, the new edition includes material on C at scans, tomography and other applications to imaging.

It also has additional material on scattering from inhomogeneous materials, among other new sections. This is not a textbook for beginners, and would not be a primary text for an undergraduate course. But for professionals, and those taking optics beyond the simpler introductory undergraduate courses, this book is essential. It remains the only serious monograph account of physical optics and can be highly recommended. Cambridge University Press ha s done a superb job of production, and deserve s to be congratulated on publishing this updated classic.

This autumn marks the 100th anniversary of Max Planck’s discovery of the quantum, and of the birth of quantum optics. Born and Wolf are not concerned with quantum optics, concentrating on the purely classical optics of wavefronts, interference and diffraction. But Rodney Loudon’s textbook concentrates on optical quanta, particularly on the basic theory of photon physics. Like its predecessors in earlier editions, this third edition is a sympathetic account of the fundamentals: clear, readable and authoritative. A large amount of new material has been added so that about half the book is entirely new, reflecting the many developments in quantum optics since the second edition appeared in 1983. The foundation material is all here: a systematic account of the interaction of radiation with atoms, the nature of electromagnetic fields and their quantization, as well as the basics of laser gain, loss and thresholds.

It is nice to see the phase states of light make a reappearance in this edition, as well as the better-known photon number states and coherent states. As one may have expected from the interests of the author, who has made important contributions to advances in this field over three decades, purely nonclassical effects that require for their explanation full field quantization now feature heavily in the second half of the book. London now presents outstanding accounts of squeezed light with noise properties less than that of the vacuum, of quantum jumps, and of the single photon optics which underpins the new frontier subject of quantum information. Indeed, this is my only criticism: there is little on quantum information. Quantum cryptography, teleportation, quantum gates and so on do not appear here as the author believes these fields are developing too fast for a lasting and coherent account. I think this was a missed opportunity, but it i s nice to know that material exists for a fifth edition. But for a systematic account of the fundamentals of quantum optics, this text remains essential reading for students, and one I will definitely be recommending for my own undergraduate course.
 
Peter Knight is professor of physics, Imperial College, University of London.