Optical fiber manufacturing (Corning)

Silicon tetrachloride flame-sprayed on a starting rod; graded composition for graded index of refraction; drawn into miles of fiber. Drying step removes moisture (hydroxide formation degrades optical properties).

The next lecture I give is on Tuesday, and I didn't get all the way through the glass stuff I had thought about this morning. If you want to go to YouTube or Corning, they have some videos on making optical glass fibers. I decided optical glass fibers aren't a structural material, but it's a wonderful story. They take silicon tetrachloride gas, because it's so pure, and they flame-spray a starting rod, and they build up something that's like an inch or two in diameter. They grade the composition as they do it, so they get a graded index of refraction. Then they draw it — it's called drawing the glass — they take this precursor and they draw miles and miles of optical fiber.

Lead case for the "real innovations" tour. Flame-vapor-deposited preform, drawn into ten-thousand-mile fibers. Solved New York City's late-1970s copper-wire crisis.

One is optical fibers. Corning worked on something that everyone said was impossible. You know how they make optical fibers? They draw it. It's actually sort of a cleanroom environment of making glass. They start with a very pure quartz fiber that they've drawn down, and then they flame-vapor-deposit layers on this thing as it's rotating. They end up making something that's four or five inches in diameter and three feet long. As they do it, they can functionally grade the composition of the glass.

Functionally graded glass rod made by plasma-spraying glass frit on a lathe, then dieless-drawn using a temperature gradient as the "die". Exploits glass's Newtonian behavior (m = 1).

Now, why is this important? It's important if you think of the longest links that we form by pure stretching, which are in a material that's not metallic. We've talked about it before — glass. It's for making optical fibers. Anybody know how optical fibers are made? Corning has got all the basic patents on this, and this is what keeps Corning alive — they really went after the optical fiber business.

Corning's optical fiber breakthrough — kept Corning in business; transformed transatlantic data transmission from repeater-every-10-km to no-repeater.

Optical glass got better and better, and now they took off on a different tangent because they're changing their metric. They're looking at light going down an optical fiber. If you walk down the Infinite Corridor, almost directly across where we are right now there's some optical fibers, and it shows how they grow the optical fibers. They went from a percent transmission per kilometer of 10 to the minus 100, up to about 96%. This was in 1983. What they did to get these better and better optical fibers at Corning basically kept Corning from going out of business. They perfected making the optical fibers for all the digital communications.