I am about to begin to work on an electronics project that involves the output of red light. After playing around with a bunch of LED’s, I realize that red and yellow are the weakest as far as “luminous” goes, no matter how much current you drive through the LED. How could I make red and yellow more radiant? Like, amplifying the output? I searched “light amplification” and articles about lasers came up, but I’m not sure if that’s what I’m really going for.
You have a few choices. Buy better LEDs and run them at the same current, run more current (assuming that's possible while remaining within ratings) through the same LEDs, or some combination of that and adding more LEDs.
More directional lenses or reflectors may concentrate the light there is into a smaller angle or area, but there is no practical way of getting more total light power from an LED than I mentioned in the above paragraph. Diffused LED packages emit light in all directions so they will have the lowest luminous intensity, all other things being equal. The same die, at the same current and other conditions, in a package that emits with a narrow angle will appear much brighter.