[Animats]

The actual fiber joining is done with this device: [1]

"This fusion splicer automatically aligns a pair of optical fibers in both the X and Y (horizontal and vertical) planes and then fuses them together with heat from an electric arc to form a low-loss splice. Improved image processing software of this fusion splicer enables precise core alignment and accurately estimated splice loss. A tensile proof test that is carried out by applying tension to the fusion splice verifies the long-term reliability of the fiber splice. Following a successful proof test, a heat-shrinkable splice protection sleeve is installed over the bare glass fiber and cured in the built-in heater."

Here's a video of a similar fusion splicer for land-based use.[2] The fussy part of aligning the fibers is automated now.

The "universal jointing" thing seems to be more about joining all the outer layers of an undersea cable that give it protection and tensile strength. After the fiber has been spliced, all that outer protection has to be joined, too. Visualize a heavy hose wrapped around a steel strand bridge cable wrapped around a coax cable with a fiber optic strand at the center. Now connect two of those sturdily enough to spend 25 years on the ocean bottom.

[1] https://ujconsortium.com/information/fusion-splicer-ujs-s200

[2] https://youtu.be/JP_C0XLLyR0?t=578

[eternityforest]

Do they not have any power for amplifiers? Or is that done with fiber too, or carried on the same metal layer used for protection?

[adrian_b]

There are optical amplifiers that use erbium-doped fibers (EDFA = erbium-doped fiber amplifier), which are based on the LASER principle, i.e. amplification by stimulated emission.

Their energy source is not electrical, but also optical, i.e. light produced by a laser with a different frequency from the frequencies used for data transmission and which is also sent through optical fibers.

In current speech, laser is used mostly to mean optical oscillators, which generate light, but actually the laser is only the optical amplifier and it must be inserted in an optical resonator in order to make a generator of light. In the amplifiers for optical fibers, only the laser part is inserted in the fibers, without an optical resonator (i.e. without mirrors), so it does not generate light, but it amplifies the light passing through it.

The erbium-doped lasers function exactly like any other solid-state lasers, which typically use crystals of sapphire or of YAG or glasses doped with ions of chromium (ruby lasers) or of neodymium or of titanium, but erbium is chosen instead of the more common dopants because it amplifies light in the frequency band used for optical fibers.

So the cables with optical fibers do not need any electrical connection for providing amplification in intermediate points when the distance between the ends of the cable is too great.

[metadat]

Great video, thanks for sharing!

How does the fusion splice process take place deep under water?

[Animats]

The ends of the cable are on board the cable ship when this is done. For broken cables, cable ships find the ends, catch them with drags, haul the end onboard a ship, and splice in an additional section.

Animated video from a company that does this: [1]

[1] https://www.youtube.com/watch?v=QiwidMEv8CM

[wantoncl]

> How does the fusion splice process take place deep under water?

https://en.wikipedia.org/wiki/USS_Jimmy_Carter