Can Cheaper Lasers Handle Short Distances?
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The debate rages on about whether cheaper lasers can handle short distances, with commenters diving into the nuances of waveguide technology and the potential of Vertical-Cavity Surface-Emitting Lasers (VCSELs). Some argue that fiber optic cables aren't the only game in town, with alternatives being explored for transmitting thousands of signals in a compact system. VCSEL enthusiasts are excited about the technology's potential in telecommunications, lidar, and even display innovation, with one commenter envisioning a future with VCSEL-powered microLED displays. As the discussion unfolds, it becomes clear that the industry is on the cusp of a significant shift, with cheaper lasers and innovative waveguide solutions poised to revolutionize data transmission.
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Just getting VCELs to 25G per lane would be nice, though, if you can match current prices. Upgrading to 100G-SR4 on the same cable plant would be nice.
not with 4 or 12 core MCF!
And then even after all that, it’s still 1-2 orders of magnitude lower density than waveguides
Huh?
Time scale varies with context. But, its why you have places that "burn in" new computer equipment for days/weeks.
"The lasers typically operate in one of two bands, C or O. The former is centered at 1,550nm wavelength, while the latter is at 1,310 nm. The O band aligns with an optimal low-loss frequency through the fiber channel. The C-band range doesn’t have quite the same low loss, but it’s acceptable"
This is reversed from reality. The C-band (1550 nm) is where optical fibers have minimum losses, which is why this is the only band used for very long-haul links. The O-band (1310 nm) is where optical fibers have minimum dispersion and slightly higher losses.
Minimum dispersion means that data can be transmitted at high speed and at minimal cost (dispersion mixes adjacent symbols, so it limits the bit rate for a given cable length, unless it is compensated). For the 1550 nm band, the higher dispersion requires additional devices for dispersion compensation, but for long-haul links their cost does not matter in comparison with the savings provided by lower fiber losses.
The 1310-band can be preferable for short links because there is no need for dispersion compensation, but nowadays its main role is to provide a second frequency-separated band for bidirectional communication (upload/download) in residential Internet access through optical fibers.
There are limits to the amplifier output power due to how tightly single mode fibers concentrate the beam: if you'd send 1W through a 9μm core, you'd have about 1.5 MW/cm² power density. Even carefully packaged laser diodes break around 12~20 MW/cm² (according to Wikipedia; "catastrophic optical damage"), not to speak of open air patch connectors in a fiber hut.
Don't forget the fiber carries around 100 channels that share this power limit.