Chapter 6 discussed devices that convert light to electricity. In this chapter, we discuss devices that convert electricity to light. These devices vary widely in size and shape from tiny Light Emitting Diodes (LEDs) and semiconductor lasers to large high power gas lasers. In addition to LEDs and lasers, lamps and optical amplifiers are also discussed.
We take lamps for granted now because they are present in practically all buildings. However, their invention dramatically improved human productivity because lamps allowed people to constructively use indoor spaces at night. Similarly, lasers have improved productivity in many activities. We encounter them almost daily in our use of communications networks, DVD players, medical devices, and in other applications.
Thumbnail: Six commercial lasers in operation, showing the range of different colored light beams that can be produced, from red to violet. From the top, the wavelengths of light are: 660 nm, 635 nm, 532 nm, 520 nm, 445 nm, and 405 nm. Manufactured by Q-line. (CC BY-SA 3.0 Unported; Sariling gawa via Wikipedia)