Modern Aspects on Optical Fibers

*Fiber Optics - From Fundamentals to Industrial Applications*

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**Chapter 3**

Fibers

*Monika Bahl*

optical fibers, data communication

**1. Introduction**

**Abstract**

Structured Light Fields in Optical

Structured light, tailored light, sculpted light, or shaped light is a term used for custom light fields and finds enormous use in literature these days. Some of the history's most brilliant researchers, from Newton to Maxwell to Einstein, have studied the nature of light over the centuries. We believe that we know everything about light, its generation, detection, and applications; yet, it continues to surprise us even today. Indeed, one discovery about light's peculiar behavior has offered a new insight into how light works and rendered some intriguing applications. In 1992, physicists mastered a surprising feat—generating light beams that twist like a helical corkscrew. This phenomenon is called twisted light and has led to an altogether new field of optics, known as singular optics. Today, twisted light is being used to build optical tweezers and ultra-powerful microscopes, and it could eventually be used in microscale machinery and for novel spectroscopic analyses. But perhaps the most important use of this structured light is in optical communications, where it moves through optical fibers. This light has the potential to greatly enhance the

bandwidth of data networks and, hence, the speed of data transmission.

**Keywords:** structured beams, tailored light, optical vortex, orbital angular momentum,

Light is an electromagnetic wave, composed of electric and magnetic fields. The fields oscillate in a direction perpendicular to the direction in which the wave is moving. If the electric field is always oscillating in the same plane, the light is said to be linearly polarized. Photons of such light possess a linear momentum. Such photons have the power to propel a boat if the solar sails absorb the linear momentum. If the direction of the plane in which the light's electric field is vibrating is itself rotating as the wave moves, light is said to be circularly polarized. In this case, light is said to possess a spin angular momentum. When such a light hits a floating ball, it will start to spin like a planet, rotating about its own axis. We thus had these two types, and surprisingly, it turned out that these are not the only ways light behaves. Allen et al., in 1992, showed in his seminal paper that light may possess another strikingly different characteristic behavior [1]. It happens when the wave fronts, instead of moving in a straight line or diverging/converging, tend to bend, rotate, and propagate in a helical fashion. This was something unexpected and very different from the already known phenomenon. This implied that the energy propagation direction is not a straight line but that too forms a helical trace
