Understanding Light

Is light a wave or a particle? We are often asked this question but are seldom given the answers.

Light is actually an electromagnetic wave that propagates in the form of two mutually perpendicular vector waves ( an electric wave and a magnetic wave). However, most of the phenomena in our daily life can be described using a scalar wavefunction. This theory is called scalar wave optics or simply wave optics. Applications of wave optics include microscopy, spectroscopy, interferometers, Liquid Crystal Displays(LCDs), optical discs, and many more.

Ray optics is a special case of wave optics. This model of light is taken into consideration when dimensions of objects through or around which light waves propagate are much larger than the wavelength of light. Unlike wave optics, ray optics cannot explain phenomena like interference and diffraction. Ray optics is only valuable for explaining reflection, refraction which has applications in light guides, graded-index optical components, and optical resonators.

Electromagnetic optics encompasses both wave optics and ray optics. It explains all the phenomena within these two aspects using basic principles of electromagnetic radiation. Although electromagnetic optics provides a detailed explanation of light that is within the confines of classical optics, some optical phenomena are quantum mechanical in nature and can be explained through quantum mechanics and quantum electrodynamics only. These properties are considered in the domain of quantum optics. Applications of quantum optics include quantum entanglement, quantum teleportation, quantum communication systems, and quantum information processing or quantum computing.

Quantum optics and photonics are closely related. However, quantum optics is more theoretical and photonics involves the design of practical applications. Utilizing their talent for manipulating light, photonics engineers have revolutionized the telecommunications and energy sector. The median salary of a photonics engineer in the US is $99,980 with $158,000 as the highest salary.

We would discuss the individual topics separately in the subsequent posts.

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