Can fiber optic cables be used to pipe sunlight into an underground bunker for growing plants?

One major problem with living underground is you lose all of that wonderful energy provided by the sun. This energy is useful for many things including growing plants for food. A window is effectively a very short pipe for sunlight to enter a room in a normal house. Windows clearly allow enough of the right kind of light to enter to allow plants to grow. Could someone in an underground bunker use a bunch of fiber optic cables to pipe enough light into a room to allow plants to grow? Assuming that's possible would it be possible to use the same technique to power a solar oven?

The basic setup would be 144 strand fiber cables ranging from 100 to 300ft long attached to the bunker ceiling to provide overhead lighting. The cables would poke out from the ground to collect sunlight. Some cables would run up trees others would peer out from crevices in rocks, and some would mixed in with low vegetation like grass. The distribution of the cables would be randomized and not point directly back to the bunker in a straight line to reduce the chances of the bunker being found. The cables would have a fish eye lens attached to each end like a borescope. The idea wouldn't be to form a cohesive image but just to collect and pipe the light.

The implementation details described above can be adapted if needed. Some of my concerns relate to the general feasibility of using fiber optic cables to pipe light. Are readily available commercial fiber optic cables tuned to a certain frequency range of light and as a result severely attenuate or filter out the wavelengths I need? Would there be too much loss in the transmission to get the light output I'd need? Some quick googling showed a fiber is 50 microns, and a 144 fiber bundle is a bit under 3/4 of an inch in diameter. That means my "window" is going to have to be roughly 2.5 times bigger than a real window in normal house. This seems workable but I don't know if the losses are going to be so large that the ratio gets significantly worse. That being said I don't know how many watts typical food crops really require out of the roughly 1000 watts per square meter the sun provides (in ideal conditions). I also don't know if I'm missing something obvious and fundamental....

So to reiterate my question could commercially available fiber optic cables pipe enough light under ground to allow food crops to grow? If they can pipe enough light to grow food could they power a solar oven?

posted over 5 years ago

Erik‭

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