What is Photonics?

Photonics is the physical science of light waves. It deals with the science behind the generation, detection and manipulation of light.

Light has a dual nature known as the wave-particle duality. That is to say that light has characteristics of both a continuous electromagnetic wave and a particle (photon). Which nature of light is operative depends on the kind of interaction being observed. For example, light bending through a lens or diffracting at the edge of an aperture is exhibiting its wave nature. Light being created or absorbed by a solid-state device such as a laser diode or charge-coupled device (CCD) detector is exhibiting light’s particle nature.

The term “photonics” came into wider use in the 1960’s with the invention of the laser and later the laser diode. It was originally intended to describe a field where the goal was to use light to perform functions traditionally accomplished using electronics, thus the name. The term came into more popular use with the advent of fiber optic communications in the 80s.

Today, photonics refers to the creation, manipulation and detection of light in the service of practical applications where the particle nature of light is important.

Optics is a general area of physics covering a wide range of topics related to the study of light. Optics includes such subfields as geometrical optics, physical optics, and quantum optics. Photonics is a subset of the optics discipline.

Geometrical optics, sometimes referred to as classical optics, is primarily concerned with the manipulation of light using devices such as lenses, mirrors and prisms. In geometrical optics, light is modeled using the ray approximation. In the ray approximation, light wavefronts are approximated as a collection of rays, each perpendicular to the wavefront of light and representing the energy flow through the system. A typical application of geometrical optics would be the design of an imaging lens for a camera.

Difference Between Photonics and Optics?

Physical optics is the study of light where the wave nature is predominant. In physical optics the ray approximation is not valid since interference and diffraction effects must be accounted for. Physical optics tends not to include effects caused by the particle nature of light. A typical application of physical optics would be the production of holographic images.

Quantum optics is the study of light phenomena where the particle, or quantum, nature of light is important. Quantum optics and photonics are closely related, but quantum optics tends to be more theoretical and photonics is more concerned with the design of practical applications. A typical area of study for quantum optics would be theoretical study of the physics of light creation at the p-n junction inside an LED.

Why Photonics is Important ?

We are at the beginning of a photonics revolution. Photonic devices have become ubiquitous in everyday life but often go unnoticed. Light sources such as LEDs and laser diodes have found their way into countless applications where light must be created. These devices are relatively cheap, extremely lightweight and compact, and are quite rugged with a long usable life span. In addition, these solid-state sources generate less heat and require less power compared with more traditional light sources. LEDs are being deployed widely as a replacement source technology due to their significant energy and replacement cost savings.

Photonics represent a growing opportunity for designing and manufacturing devices, systems and integrated circuits for applications in high-speed data communications, advanced sensing, and imaging. Photonic technologies promise orders-of-magnitude speed improvements with reduced power consumption for data transmission and ultrasensitive sensing capabilities in multiple domains.

Photonic-based detectors such as CMOS image sensors (CIS) have transformed how we take photographs and have all but replaced film as a media for capturing images. CIS share some of the same benefits as solid state sources in that they are small, rugged, and lightweight. One of the biggest advantages over traditional film is their light sensitivity and compact size. This allows for much smaller optics to create a usable image on the detector. This has enabled compact, high-quality cameras being added to everything from cell phones to automobiles.

By combining sources and detectors with other means of manipulating light, photonics engineers have transformed our digital world with fiber optic communications, scanners, medical devices, agricultural advances and a whole host of other applications.