Possible hysteresis loops of resonatorless optical bistability - Ba An, N.; Tuong, L.T.C. (Elsevier)
We qualitatively show that hysteresis loops of intrinsic optical bistability phenomena without any additional feedback may be of various shapes including those of a butterfly and a three-winged bow.
http://linkinghub.elsevier.com/retrieve/pii/0038-1098(90)90980-P
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