| Recent graduate in Optical Communications here :) 1) The fiber is pretty thin, but there are several fibers combined in one transoceanic cable, see here https://en.wikipedia.org/wiki/Submarine_communications_cable. They don't patch them, but splice the fibers. Patching introduces a little loss, so it should be avoided. 2) Not sure how deep they are buried, but I think to remember that the shore end of a submarine cable is better protected than the part in the deep ocean. Due to more ship traffic at the coast etc. 3) Good question. The loss of an optical fiber is roughly 0.2 dB/km. Across the ocean the optical signal must be amplified several times (every 80-100km). Nowadays the amplification is all optical (EDFA or Raman). Before there were electrical regeneration schemes. Check out the history of the field, it's is quite interesting [1]. 4) Not sure how much data such a cable can carry, since it depends on how many fibers are deployed within. However, there are multiple interesting things to look into here. In research labs, people are investigating multicore/multimode fibers (space division multiplexing) [2], these fiber have incredible capacity. Personally, I think the most interesting metric is the spectral efficiency, so how much data can be transmitted per second per Herz. Such a metric is independent of multiplexing schemes over space/wavelength/time, and improvements have to come from better devices, signal processing or signal shaping methods [3]. Another mind-blowing area is using the nonlinear Fourier transform for better signaling methods [4]. Feel free to ask more questions :) and checkout the two biggest conferences for more in depth info. https://www.ofcconference.org/en-us/home/ https://www.ecocexhibition.com/ [1] https://www.osapublishing.org/oe/abstract.cfm?URI=oe-26-18-2... [2] Multicore: https://ieeexplore.ieee.org/abstract/document/7341685 Multimode: https://www.osapublishing.org/abstract.cfm?uri=ofc-2018-Th4C... Multimode+core: https://ieeexplore.ieee.org/document/8535233 [3] https://arxiv.org/abs/1606.04073 [4] https://www.osapublishing.org/optica/abstract.cfm?uri=optica... |