ABSTRACT
Nowadays we think nothing of using a laser pointer when giving a presentation (see Figure 1.3), and while magnetic tape is still used for both audio and video recording, compact discs have become standard for audio recording, while DVDs provide high-quality video recording. These devices use tiny solid-state diode lasers made from semiconductor materials to write and read data, but just a few decades ago-before enough was understood about semiconductors and the way they interact with light-the only lasers that existed were huge gas or crystal lasers confined to
laboratories. The next generation of so-called “quantum dot” lasers should be even smaller than solid-state lasers, which could lead to a whole new range of optoelectronic devices and applications. It is also likely that we will see a range of new applications in the future for an existing optoelectronic device-the light-emitting diode (LED). Improvements in the brightness and cost of LEDs are leading us to the point where they are becoming viable as a replacement for conventional tungsten light bulbs for domestic lighting, and can be used for traffic lights.
