Function of laser diode

Answer 1

The question seems to imply that ever since Creation there has always been

a grand cosmic role for the laser diode, and that once our species attained

the ability to invent it, it was then Mankind's holy mission to sally forth and

find its function.

I think it was more like: Once the purification and doping of solid-state materials

had progressed to the point where a diode could be fabricated out of a couple of

pancakes of them, AND someone over in a different lab had succeeded in getting

a laser out of a roomful of flashtubes and a piece of ruby the size of a pencil,

somebody else ... in a job where he didn't have to worry about purpose, profit,

or function but he could get paid to just come in every day and play around with

stuff, maybe at the old Bell Labs ... read about both of those, and figured out

a way to combine them, doping and joining a couple of pure stones in just

the right way that when he connected it to a battery, it would have diode

characteristics AND would lase! And then, he showed it to his boss, wrote and

published report about how he did it, built a few to demonstrate at cocktail

parties and Physics conferences, and went on to play with something else,

while we ... me and the other bottom feeders called engineers ... thought up

neat things to do with the laser diode.

We built the cool laser pointers, that you could hang on your key-chain, put

a red spot on the screen during your high school presentations, do optical

experiments with, and give your cat some great exercise chasing the red spot

on the floor. We built laser diodes and detectors to create and detect microscopic

pits on a high-polished plastic surface, small enough fit into a machine that could

fit in your backpack, run on a couple of skinny batteries, and hold a plastic disk

with an hour of music 'burned' on it. We put laser diodes and detectors into your

computer mouse, that can detect textures so tiny that you can use a sheet of

white paper for a mouse-pad, and we got rid of the clunky potentiometers and

wheels inside the mouse, that used to pick up hair and gunk and get jammed

every couple of months.

But probably the most important bright idea we had that takes advantage of the

laser diode was the method we designed to efficiently couple the light from the

diode into one end of a glass fiber ... the width of a hair and miles long ... and

detect it at the other end. From there, it was a piece o' cake to 'modulate' the

output of the diode, detect the variations at the other end, and kick off the

whole modern fiber phenomenon, that now carries trillions of bits of data

over a single fiber every second. This, at last, solved the cosmic background

requirement that lay unfulfilled since Creation, when finally, subscribers are able

to satisfy their crying need and fundamental human right to stream a different

movie into each room in the house while recording three more to watch later in

case they ever feel like it. Or to have the choice of 300 channels when they plop

down at the TV, even though there's STILL nothing on.