7.1. Introduction

Until recently, the concept of near field has not been extensively exploited in optics. Indeed, since information contained in the signal could only be detected in far field, interest tended generally to be more focussed on the structure of the electromagnetic field in far field.

The advent of near field microscopies and integrated-optical devices first developed in the fields of microtechnology and nanotechnology is now changing this state of affairs. The control of the optical near field is now recognized as a key issue for the qualification of optical nanotechnology devices. The term qualification is used here to denote the control of specific properties of these devices, and the control of their local losses. In the medium term, the efficient development of active near field optical devices based on localized optical interactions will not be possible save through a thorough understanding of near field optics.

This chapter begins with a definition of the notion of near field in certain specific configurations. It then turns to a description of the methods used for detecting the near field, before providing the reader with some examples of applications. Since only a limited number of examples can be described in this chapter, we have chosen to restrict ourselves to a consideration of three: integrated waveguides, photonic crystal cavities and metal perforated with sub-wavelength Hole Arrays. In our opinion, all three types of components are among the key optical devices that will be in used in...