Q.E.D:
I have to disagree with this to an extent. The ability to make a blue LED is absoultely a prerequisite to the ability to make a blue diode laser since the emitted wavelength is dependent upon the semiconductor chemistry. The light-emitting p-n junction is, for all practical purposes, identical in both devices; the main difference between an LED and an injection-type diode laser is the optical cavity–and that’s entirely mechanical.
It took two years of work to go from blue LED to blue LASER, and commercial viable blue lasers took a decade more. So, I stand by my statement.http://archive.sciencewatch.com/jan-feb2000/sw_jan-feb2000_page4.htm
Green lasers are a whole lot easier to see, which is why I waited for a 25mW green for my AR. Price has come down so I suspect we’ll be seeing a lot more