Chapter 4: explores the interactions of light with structures, or strictly the interactions with the combination of the structure’s dimensions and the materials from which it is fabricated. In general terms we have the large compared to the wavelength, the comparable to and the small. The large includes light from the stars and, often contrived, structures such as lenses mirrors. But the detailed properties of these also depend on the comparable to – in minute imperfections and minute structural detail such as polishing. Even astronomical telescopes are tuned to the order of the wavelength of light! When we get to the tiny there are many strange effects exemplified in colloidal gold used in ancient glassware as permanent colouring. But are even these effects really that strange or unfamiliar? We all are aware that for example a piece of wire behaves very differently depending on it size (especially diameter) and its geometry – most familiar in the induction coil…. The basic ideas are explored here with due recognition of how the very small wavelength and the very high frequency of a light wave can have profound impact on any interaction mechanisms.

Chapter 6: looks into emerging and future technologies and how these techniques for manipulating light may become increasingly important. Super-resolution imaging is already becoming a tool for advanced assessments in, for example, clinical diagnostics. Seeing structure with resolution below the optical wavelength enables new insights. Much is made of ‘entanglement’ and unbreakable quantum codes and the optical frequency integrated circuit is becoming a ‘soon to have’ facility. There’s also much emerging in new materials – graphene (single layer carbon) makes scientific headlines and has intriguing optical properties. Society is also becoming more demanding of technology and many important social and environmental challenges have been identified – there is much potential for photonics as the tool to address these needs. The future looks very optimistic!

Chapter 3: describes the essential principles of light interacting with materials. This includes transmission in both isotropic and anisotropic media and all the material based phenomena which give colour into our lives. This colour also provides insights into the material themselves – spectroscopic signatures! Of course light can also be scattered – sunlight spreading through a room is an everyday example and absorbed through designing surface finishes – a black card heats up much more quickly than a white one when left in the sunshine. There are also materials which have externally controllable optical properties – perhaps liquid crystals are the most familiar example. The absorptive process can of course go backwards – we have light emitters. These range from the centuries old heated ‘black’ body to flame tests for particular materials (sodium – table salt – probably the most familiar) to the lasers. Fluorescent materials and LED’s which are increasing apparent in everyday life.

Chapter 2: explores the nature of light and the much debated question – should we regard light as an electromagnetic wave (including as a current though a conducting material) or as a particle? The key lies in the fact that (usually) light can be regarded as transmitted as a wave and (usually) light can be regarded as detected as a particle. We explore the implications and conclude that the answer lies in the specific question being asked!

Chapter 5: is a brief look into the many and diverse applications of photonics and the essential principles underlying them. Many are familiar – displays and lighting being the most prevalent. Imaging, especially in the era of the mobile phone, is an everyday operation and astronomical telescopes are regulars in publically presented the science and technology reports. Optical communications has also become taken for granted – optical fibre enables the internet! Less familiar perhaps are the use of ultra-violet and other sources in photo-therapy, lasers in surgery and industrial machining and, increasingly important, in environmental analysis and monitoring. And many high street opticians now have subtle probes to assess retinal health based on three dimensional tomographic probes. Photonics has indeed crept into our everyday environment – and will continue to become increasing important as an enabler of technological advances.

Chapter 1: introduces the subject – starting by endeavouring to define what the term ’photonics’ might mean and following this with a very brief exploration of the basic concepts. There is then a brief discussion about applications which impact upon our everyday lives. An outline of the book and the reasons for its being presented in this particular format follows. Finally, there is a very brief mention of the background in other complementary disciplines which complement photonics.