TABLE OF CONTENTS In Chapter 1, we learned that a light-emitting diode (LED) can be considered to represent a p-n junction semiconductor. By using a variety of semiconductor materials and doping the material, it became possible to generate specific wavelengths of light when a voltage is applied to the LED. In this chapter, we will turn our attention to the fundamental properties of light to obtain a better appreciation for the operation of LEDs and the type of light they produce. Topics we will cover in this chapter include the principal properties of light, light metrics, how light is generated, and how colored light is formed. Because this book is focused on LEDs, we will obviously orient this chapter toward the light-emitting diode.
We can define light as an electromagnetic radiation at a particular wavelength. Depending on the wavelength, light can be visible or invisible to the eye, infrared being a good example of invisible light.
Light has three primary properties. They include frequency or wavelength, intensity or brightness, and polarization or direction of wave oscillation.
If you sat through a high-school physics class, you probably remember discussing the speed of light. When light travels, its speed is governed by the medium, with the speed of light in a vacuum fixed by definition to be 299,792,458 meters per second (m/s). When light travels within an optical fiber or another medium other than a vacuum, its speed is reduced.
Technically, light is carried or...
