Optical physics is a foundational branch of physics that explores the behavior, properties, and interactions of light with matter. Light, in its various forms, plays a critical role in both natural phenomena and technological advancements. Understanding its fundamental nature is essential for applications ranging from imaging systems to communication networks and quantum technologies. This chapter introduces the basic principles of optical physics, covering the nature and properties of light and the historical development of optical science.

Light exhibits both wave-like and particle-like properties, a duality that has been central to the development of modern physics. As an electromagnetic wave, light consists of oscillating electric and magnetic fields propagating through space. The wavelength and frequency of these oscillations determine the characteristics of light, including its color in the visible spectrum. The wave theory of light explains many optical phenomena such as interference, diffraction, and polarization, all of which are essential in optical technologies. However, light also behaves as a stream of particles called photons, as demonstrated by the photoelectric effect. This particle-like nature of light laid the foundation for quantum optics and photonics, which are crucial for contemporary research and applications.