> Electrons are involved as they are an essential part of a non-linear optical medium. But the information being processed is not converted to the electrical do

> Electrons are involved as they are an essential part of a non-linear optical medium. But the information being processed is not converted to the electrical domain That's a matter of hair-splitting. More importantly, it hasn't been used to make practical gates. "Nonlinear optics" has had plenty of important successes in (electrically controlled) amplification and frequency shifting, and those victories make our lives better every day in the way they've improved fiber optics, especially CWDM. However all-optical switching is still pretty much vaporware. I think it's really disengenuous to lump optical switching in with the broader field of nonlinear optics -- this basically just hides the glaring lack of progress in all-optical switching among the victories in neighboring fields. So we get a lot of advocacy of the form "hey you should believe all-optical switching will happen some day because this neigboring field that doesn't make gates is under the same umbrella as us!"