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Finally, a True Green Laser
dusty writes "Remember those green lasers from Star Wars? Turns out that faking green lasers has been easy for years, but making true green laser diodes has been the stuff of science fiction. Until recently, that is. Now researchers from Japan have created the world's first true green laser diode. Until now, only red and blue laser diodes were available, and now with the addition of green, new TVs and projectors that are more efficient can be produced. And if you were wondering how green lasers pointers are already produced, it is a hack that involved doubling the frequency of an infrared laser. The new true green laser diodes have much higher efficiency than the current 6%, leading many to expect big time laser display breakthroughs in the near future. Ars Technica has a well-written article on this breakthrough."
*head explodes*
"A laser diode is much more robust than (a laser diode and the frequency-doubling package of nonlinear crystals).
Title should read "True green laser diode". 'Green' laser output has been achievable for for more than three decades with Argon ion, Krypton ion, and Copper vapor lasers. This just makes it more 'convenient' to achieve green output.
Sig this!
Let me add to what you have said: Green beams can be obtained from solid-state infrared lasers (e.g., Nd:YAG) by using KTP or KDP crystals, which combine two photons into one (!) with twice the energy/frequency. The resulting beam is collimated and coherent - i.e., the same as the original and any other laser beam. The technique was first demonstrated in 1961, predating this new discovery by almost half a century. Green laser diodes are most definitely interesting and useful, but to suggest that the green lasers from before were "fake" is incorrect. The new part here is having green as the fundamental frequency from a solid-state laser.