A very quick search found these
http://www.elexp.com/opt_rgbc.htm. You might be able to find better, as I am sure there must be others designed for LED based screens.
Interestingly, the output is not the same for each colour but I guess these must be balanced. You might want to synchronously switch them to allow more output, by reducing the duty cycle, which would also have the added benefit of reducing unwanted light.