Optics is one of those areas of physics, which finds widespread applications in various scientific and technological applications. Interference, diffraction and polarisation are commonly observed phenomena of wave optics, which have found their way not only in advanced technologies, but also in some of our everyday activities. The concept of thin film is introduced and interference of light in such thin films studied. The application of such thin films is explained for antireflection coating. The phenomenon of diffraction is applied to the case of light passing through a single slit as well as a diffraction grating. The phenomenon of polarisation and double refraction are introduced. An application of these, namely for liquid crystal display is discussed. Lasers find immense industrial as well as scientific applications. Basic physical processes involved in lasing of a medium to emit laser light are discussed. Two main case studies are taken, namely, semiconductor laser and carbon dioxide laser. Optical Fibres are the modern day communication technology. The basics of optical fibre technology are discussed