Ah, here's but two interesting and well cited papers regarding an optical "shannon limit", both published in IEEE Journal of Lightwave Technology. The old idea

Ah, here's but two interesting and well cited papers regarding an optical "shannon limit", both published in IEEE Journal of Lightwave Technology. The old idea of a "Shannon Limit" has been split into many types, including linear (old tech) and non-linear (using more modern tech). Both these papers address the non-linear limit (which is not a limit, as both papers show, but more of an artfact of modern tech): [1] "Approaching the non-linear Shannon Limit" : From the abstract "We also discuss the techniques which are promising to *increase* and/or approach the information capacity limit." [2] "Scope and Limitations of the Nonlinear Shannon Limit" : "It is shown that this is a limit (if at all) holding only for conventional detection strategies. Indeed, it should only be considered as a limit to the information rate that can be achieved with a given modulation/detection scheme" These are extensively cited, so use google scholar and read up to see that there is no "Shannon Limit" except for a particular channel technology. The concept has been split into a million directions depending on the underlying technology, each with a different value for "Shannon Limit". [1] https://ieeexplore.ieee.org/abstract/document/5210179 https://ieeexplore.ieee.org/abstract/document/5210179 [2] https://ieeexplore.ieee.org/abstract/document/7637002 https://ieeexplore.ieee.org/abstract/document/7637002