Imagine a world without tiny blinking lights. In 1962, the smallest light source was about the size of your thumbnail, and it was really inefficient. Flashlights required several large, heavy batteries just to produce a dim light that was impossible to see in daytime. Electronic calculators were years away, and putting an image on any screen required a huge long vacuum tube.
That was the world that Nick Holonyak, Jr, an engineer working for General Electric, lived in when he demonstrated the world’s first visible light LED fifty years ago today. Infrared LEDs had been around for roughly a year… and they still enable your remote controls. On that day fifty years ago, Dr. Holonyak showed a tiny dim red light and changed the world.
Dr. Holonyak was working at General Electric on laser research and became interested in the search for a visible light LED, which he correctly believed would use many of the same materials as a visible light laser. His initial discovery changed the world.
LEDs are different from regular light bulbs in that they produce light electronically. A regular incandescent light bulb creates light by passing electricity through an inefficient wire. The wire, instead of passing the electricity through, heats up to the point where it glows. Roughly 90% of the energy is lost as heat. LEDs are much more efficient because they release light particles (photons) directly instead of through heat. As a result, LEDs can be very small and still release a lot of light.
LEDs are everywhere. They are the backlight of many TVs and monitors. They are the colored indicators on your devices. They show you that something is plugged in, they flash when there is a problem. Although originally only available in red, they are now available in multiple colors. You may have noticed the blue LED, once a very expensive LED, has taken over in a lot of high-end devices. The white LED (actually a mix of a blue LED and a yellow one) has revolutionized flashlights, turning them from baton-sized behemoths to palm-sized floodlights. They are the mellow, green backlights to our gauges and the flashes to our smartphone cameras. And, all their functions directly point back to one day, 50 years ago when a tiny, dim piece of metal started shining.