This volume contains five articles presenting reviews of several topics of current research which are likely to be of interest to optical scientists and optical engineers. The first article, by J. Ohtsubo, deals with the dynamics of feedback-induced instability and chaos. The characteristics of semiconductor lasers based on the rate equations, including various laser structures, are reviewed and the effects of optical feedback in semiconductor lasers are then discussed. the general area of the nonlinear interaction of ultrafast pulses with optical and photonic crystal fibres are discussed. In particular, ultrafast pulse measurements, pulse shaping and pulse control are discussed. transient optical phenomena that take place in the spatial-temporal dynamics of ultrashort pulses. The interplay of diffractive and dispersive phenomena is examined. They include coupled processes of amplitude and phase reshaping, spectral variations and polarity reversal for different types of light pulses. Reflection and refraction effects that take place at the interface between media with time-dependent dielectric susceptibilities are also discussed. principles of optical coherence tomography (OCT). This is a relatively new discipline with important potential applications in macropscopic, microscopic and endoscopic imaging. The article begins with a brief summary of the field and then describes various OCT interferometer configurations and discusses basic sample signal extraction techiques. The article also covers subjects such as contrast generation techniques, resolution, signal processing techiques for image display, image enhancement, speckle suppression and OCT detection sensitivity. A description of optical delay lines used in OCT is also presented. concerned with modulation instability (MI) of electromagnetic waves in inhomogeneous and in discrete media. The article pays special attention to the MI of electromagnetic waves in nonlinear optical fibres with periodic amplification, dispersion and birefringence. The MI in random media is also covered. Other topics discussed in this article are discrete nonlinear systems with cubic, quadratic and vectorial interactions and nonlinear optical systems such as tunnel-coupled filters. Some of the readers may note that authors from six different countries have contributed to this volume, thus helping to maintain the international character of this series.