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Analysis wanted on minimum energy losses in very long optical fibres

Launcher poly Australia
Status Vaulted: Jan 29, 2015 08:30


optical fibres energy losses


An analysis is wanted of the minimum attainable energy losses in very long (10,000 km) optical fibres. This should include both the case of what's achievable with the most advanced off-the-shelf materials and ancillary devices (joiners etc) available today, plus an examination of the causes of losses and any theoretical or practical limits to their reduction in the future. No repeaters are involved, and only energy losses are of concern, not signal losses. Special requirements (such as use of monochromatic light) should be noted. (ZBL#138).

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The intention of this zomb was to investigate whether it would be feasible to send daylight along a very long optical fibre cable to another point in the world, perhaps one experiencing night. If feasible, "piped-in" daylight could be used locally instead of generating it at the point of use. The critical factor would be the amount of energy lost in the optical fibre.

The attached report prepared by Michael Mrejen showed that the idea was not practical. Even with the lowest-loss optical fibre available, the light loses half its energy in only 1 kilometre, and another half in the next kilometre. Over any longer distance, the amount of light available becomes negligible.

An alternative approach which might possibly prove workable would be to replace optical fibre with highly-collimated daylight passing along fairly wide evacuated tubes with internally-reflective coating.

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