OPEN THREAD 20200113

Basically, all legal free speech is allowed. We will assist the authorities in dealing with illegal speech. You are each other’s moderators. Have fun. And don’t forget to MAGA at nuclear levels.

Citizen U

Day 68 – ERBIUM.

9 thoughts on “OPEN THREAD 20200113

  1. Before I even begin to start thinking about Erbium…..I’m looking at antiseptic soap and it says, “kills 99.9% of bacteria”. I’ve seen the same claim on bleach. What kind of bacteria takes a refreshing 30 second dip in 2% lactic acid, towels off, and is back on top of the wall asserting that your mother was a hamster and your father smelt of elderberries? What kind of bacteria does that with BLEACH?!?!?

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  2. OK, back to erbium. Back in the 90s, I was actually very involved with erbium. I was the VP of Operational Administration for a fiberoptic communications company. Regular optical fiber at the time had two nice windows where it was particularly transparent — 1310nm and 1550nm. If you shot light into the fiber at those wavelengths (or near them…..e.g. 1312nm or 1547nm), it could go for miles and miles before it couldn’t be appropriately detected. Once detected and the signal cleaned up electronically, it could then be retransmitted for miles and miles more.

    But 1550nm had a little trick that involves erbium. If you take a length of fiber and dope it with erbium, it still has the 1310 and 1550 windows. But if you pump the hell out of it with a 980nm laser, the erbiums enter a peculiar excited state. When a 1550 photon hits an excited erbium, it emits two 1550 photons and goes back to its rest state. That allows you to amplify a 1550 signal without converting it to electronics and retransmitting it. This is an erbium-doped-fiber amplifier, or EDFA. We were early commercial producers of these.

    The EDFA concept allows you to do another thing that is kind of cute. When you’re trying to modulate a signal for communications, there are two basic means of amplitude modulation. You either move the power generating the signal up and down; or you impose a “shutter” so that the generated signal can run full on — but the amount released varies. Our early AM laser transmitters modulated the power of the laser, but we developed a way to externally modulate 1550 lasers. Once we had that, we could use a cheap low-power 1550 laser, run it through an EDFA to become a serious laser source, externally modulate that, and potentially run it through another EDFA before running it outside the building.

    We had a variety of fun sidelines we were considering — it was expensive, time-consuming, and largely out of our control to get erbium-doped fiber, so we were considering an erbium-doped slab amplifier where we would do the same physics in a glass brick. We could even illuminate the brick with 980 at right angles to the signal and save the cost of a wave-division multiplexer…..

    So, yeah…..erbium was a large part of my life back in 1996.


  3. Erbium is about the 45th most common element in the earth’s crust, being half again as common as tin — but about 1/3 the prevalence of lead. Like every other fookin’ lanthanide…..mixed up with others, mischmetal, hard to isolate.

    From personal experience, it does magic optical things.

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    1. It may be noted that SFO’s two main runways are 10L/28R at 11,870 feet and 10R/28L at 11,381 feet — it’s the 7th busiest airport in the US. The 12/30 runways at Vandenburg AFB are 15,000 feet…..and they somehow managed to land the Space Shuttle on them. 18,000 foot runways are truly impressive.


  4. A man walks into a Silicon Valley pet store looking to buy a monkey. The store owner points towards three identical looking monkeys in politically-correct, animal-friendly natural mini-habitats.

    ‘The one on the left costs $500,’ says the store owner.

    ‘Why so much?’ asks the customer.

    ‘Because it can program in C,’ answers the store owner.

    The customer inquires about the next monkey and is told, ‘That one costs $1500, because it knows Visual C++ and Object-Relational technology.’

    The startled man then asks about the third monkey. ‘That one costs $3000,’ answers the store owner.

    ‘3000 dollars!!’ exclaims the man. ‘What can that one do?’

    To which the owner replies, ‘To be honest, I’ve never seen it do a single thing, but it calls itself a Consultant.’

    Liked by 2 people

    1. To gain full appreciation, one has to understand that low-level coders (the ones who would be produced by politicians telling manual laborers “learn to code”) are often referred-to as “code monkeys.”

      Liked by 2 people

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