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The Most Important Subsea Cables Going Live In 2025: Firmina

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 Firmina is a spatial division multiplexing 16 fibre pair cable with initial design capacity of 320 Tbps. It is named after a Brazilian abolitionist, Maria Firmina dos Reis, who was Brazil's first novelist. Google is the owner. Telxius has acquired a fibre pair on the system as part of a complex deal that involves providing landing and back haul in Brazil. Right now Google is selling fibre pair and spectrum capacity to recoup its capex. Cirion Technologies has also purchased a pair. Stonepeak Investments, an  infrastructure investor, purchased Lumen's South American assets which operate today as Cirion. Firmina is substantially complete, but no RFS announcement so far.  Distinguishing Features: 1. It is possible to power the entire cable from either the US or Brazilian landing stations in case the other CLS experiences a black out.  2. Firmina is the third South American hyperscaler subsea cable. Google is the owner of all three.  3. Firmina is the first spatial...

A Key Ingredient Of Modern Fibre Optic Communication: The Semiconductor Laser

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Semiconductor lasers are one of the three building blocks of our modern IT world along with fibre optic cable and the Ethernet protocol. Subsea cables use semiconductor lasers to emit light, fibre optic cable to carry and guide it, and the dominant wrapping for optical wavelengths is an Ethernet format. Finally, the IP/TCP protocols enable different networking technologies to operate together as one network.  Einstein conjectured in 1917 that electrons could be manipulated or stimulated to emit wavelengths at a specific frequency. Later Charles Townes at Bell Labs proposed that light wave intensity could be magnified by passing it through a gas filled cavity. Done in the right way the light would trigger the gas to amplify the light without changing frequency or phase before leaving the chamber. In 1959 at Columbia University he created the immediate predecessor of the semiconductor laser, a maser (microwave amplification by stimulated emission), which used microwaves as both input...

The Birthday Probability Paradox, Subsea Cable Outages, and Russian Sabotage

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In a class of 23 students the probability of at least two having the same birthday is 51%. In a class of 30 students the likelihood rises to 70%. I was introduced to this counterintuitive result in my first graduate school probability course. There were no more than 15 students in the class. Yet  I and another classmate is that course shared a common birthday of March 5, 1962. I will give you the logic behind this result at the end of the post.  This probability calculation is a clear warning human intuition is not likely to be a good guide to whether an event is natural or man-made or a conspiracy. Most people will assume that the chance of a two or more students with the same birthday is 10% to 15%. In case of telecommunications we have at least 450 subsea fibre optic cables in service today. This means that clusters of cable outages like we see now in the Baltic Sea and earlier this year in the Red Sea and off Abidjan are virtually guaranteed to happen due to pure chance al...

Manufacturing Fibre Optic Strands In Space: .001 dB Loss Per Kilometer

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ZBLAN is the acronym for a flouride-based optical fibre that uses a combination of zirconium, lathanum, barium, sodium, and flouride that has a theoretical optical loss of only .001 dB loss per kilometer in the infrared frequencies. Good silicon-based fibre generally lies in the .15 to .20 range. Obviously, if perfected, this would constitute a major fibre optic revolution. The theoretical dB loss of 2000 kilometers of ZBLAN fibre, a French invention, would be equivalent to ten kilometers of standard silica fibre. Optical amplifiers would become obsolete for terrestrial networks and many subsea spans. The challenge is that earth's gravity leads to crystals forming when the glass is drawn and allowed to cool. Unlike standard fibre optic glass which is SiO2, silicon dioxide, ZBLAN is a complex mixture of elements with different molecular weights. Convection during the drawing process results in these elements separating into crystals. The glass also becomes extremely brittle as a res...

The L Band: The Inevitable Destination of Long Haul Optical Networking

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Long haul optical networks are approaching the Shannon limit in the work horse C band raising the inevitable question of how to keep increasing bandwidth. Right now the 64QAM modulation scheme achieves spectral efficiency of 6.5 bit/s/hz. But the upper bound on an optical channel according to the Shannon limit is 6.9 bit/s/hz. In other words, we are getting damn close. Obviously, it is a technological triumph. In very few fields of technology has mankind reached one of Nature's own speed limits. But the practical question is where do we go from here? If you look at the chart, the answer is obvious. The L band (1563-1630) is adjacent to the C band and current long haul DWDM equipment can handle these frequencies without any substantive modification (just software upgrades). Furthermore, as the chart shows, the L band optical loss is only slightly higher than the C band. The line marked 'experimental' showed the actual measured optical loss as a function of wavelength. The C ...

Time To Buy or Lease Equiano Wavelengths or Spectrum

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Equiano is the second highest capacity subsea cable serving Africa at 144 Tbps. It enjoys the lowest latency Lisbon/Capetown. This subsea network is highly resilient with no wet outages since going live in 2022. The cable was buried 2 meters below the sea floor and routed around the subterranean canyons responsible for many subsea cable outages. It is a Platinum Service. 5x 100Gs LS1/CT1. Spectrum IRUs.  Won't last long ...

The Rise of the C Band in Fibre Optic Networks

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The C band is usually defined as consisting of wavelengths in the range from 1530 to 1565 nanometers. Virtually all long haul fibre optic telecommunication transmission uses exclusively this band for data payloads. The graph below shows why. Optical loss or attenuation in the infrared frequencies used by most lasers achieves a global minimum in the C band. The solid bar labelled 'experimental' shows actual measured db loss performance. The other lines represent a theoretical decomposition of overall intensity loss into different factors.  Waveguide imperfections are geometric flaws in the fibre due to the production process. These flaws lead to light scattering. An example are irregular surfaces at the nanoscale. It could be surface of the optical core or the cladding that shields it. Fore example, if the optical core is not perfectly round, and it never is, then some light will either escape or be reflected back down the fibre in the opposite direction. For a detailed analysis...