Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!uwmcsd1!uxc!uxc.cso.uiuc.edu!uxg.cso.uiuc.edu!uxe.cso.uiuc.edu!mcdonald From: mcdonald@uxe.cso.uiuc.edu Newsgroups: sci.electronics Subject: Re: Looking for Blue LEDs (Found!) Message-ID: <44300009@uxe.cso.uiuc.edu> Date: 25 Sep 88 14:53:00 GMT References: <1182@nmtsun.nmt.edu> Lines: 25 Nf-ID: #R:nmtsun.nmt.edu:1182:uxe.cso.uiuc.edu:44300009:000:922 Nf-From: uxe.cso.uiuc.edu!mcdonald Sep 25 09:53:00 1988 >Frequency multipliers do exist, though. >One application of their use is to convert the output of a high power >laser; eg: a Nd-YAG laser (IR light); to higher frequency, eg, visible light. >The doubler is grossly inefficient, expensive, and is usable because >the laser gives off lots of watts (large photon flux so multi photon aborption >is more probable). Doublers are not inefficient. 5 mm long potassium titanyl phosphate ( K TiO PO ) crytsals will double 1.064 micron light with typical 4 efficiencies of 60 to 75%. With two in series you can get total 90% efficiency. They are expensive ($2700 for a 5x3x3mm crystal). They do need large powers (say 50 watts to get 60% efficiency). Multiphoton absorption is to be avoided like the plague - if it happens, the crystal EXPLODES! Whoops, $2700 down the drain! These things work on nonlinear index of refraction, not absorption. Doug McDonald