My (ex) co-worker, Howard, emailed me a link to an article that said that the Nobel Prize in physics has been given to three inventors of the blue LED. As everyone knows, the LED is a major topic of my blog.
This article excerpt says that 2015 is the International Year of Light. We have a whole year to celebrate!!
Frances Saunders, president of the Institute of Physics, a worldwide scientific organization based in London, agreed with those sentiments. Noting in an email statement that 2015 is the International Year of Light, she said, “This is physics research that is having a direct impact on the grandest of scales, helping protect our environment, as well as turning up in our everyday electronic gadgets.”
The reason why blue is so important is that the phosphor that puts out the white light needs to be stimulated with a light that has more energy than white light so that the process, which absorbs light and re-emits light with less energy, can put out light in the visible band. For example, a phosphor that was stimulated with red light would have to emit infrared light, which has less energy than red light, to account for the losses in the process.
However I have some problems with the following excerpt:
Red- and green-emitting diodes have been around for a long time, but nobody knew how to make a blue one, which was needed for blending with the others to create white light. The amount of information that can be packed into a light wave increases as its wavelength shortens, making blue the color of choice for conveying information.
The first sentence says that nobody knew how to make a blue LED. Well, that sentence is not entirely true. The first semiconductor “LED” that was discovered by an Englishman, H.J. Round, and later by a Russian, Oleg Losev, was made of silicon carbide, which emits blue light. So the second half of that sentence is not true, because blue light was emitted from a semiconductor before red or green.
The second sentence isn’t true. The color of choice for transmitting information over optical fibers is red or infrared. Search for GBIC and see for yourself. In the picture shown here, the label says 850 nm, meaning the LED wavelength is just slightly below red, in the infrared part of the spectrum. But it still can be seen as deep red. The single mode GBIC modules are even longer wavelength, typically about 1050 nm.
I had read about Dr. Nakamura back in the early 2000’s when I started building my own white LED flashlights. But I didn’t know about the lawsuit he filed against Nichia. I started buying Nichia white LEDs and they were very good, but for a long time they were more than $2.00 apiece in hundred quantities. Nichia seemed to be very greedy and uncompetitive, more willing to sue than license their patents. It’s quite a shock that he was given so little for such an important invention.
This was a very good article. I hope my corrections were helpful, too. As was noted, many researchers contributed to the process of perfecting the LED. Now if we can get researchers to devote more manpower to perfecting the solar photovoltaic cell. When the sunlight hits the cell, only about 10 to 15 percent is converted into electricity. If we could double that, the amount of power per square meter would double. Also, someone should integrate Peltier devices into the cells so that both the visible light and the infrared that ends up heating the cells could be converted into power. Any more ideas? 😉
