Double Green Laser
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How exactly does a DPSS 473nm blue laser work?
I'm looking for a fairly detailed answer. I haven't really found anything useful on google except for ads selling them (for very high prices).
I know that 532nm green DPSS lasers basically have an 808nm IR diode that pumps a solid state Nd:YAG crystal to produce 1.064um IR lasing, which is then frequency doubled in a second harmonic crystal and hence produces 532nm green light. That's the sort of detail I'm looking for (preferably with types of crystal) for 473nm blue lasing action! Thanks!
Perfect answer thanks!
This comes from Sam's Laser FAQ - Solid State Lasers page
http://members.misty.com/don/laserssl.htm#ssldps0
Hope it is of some help!
What is the Difference Between Green and Blue DPSSFD Lasers?
(From: Bob.)
Well, a little, and a lot, depending on how you look at it. Green lasers are doubling the 1064 nm transition of Nd:YAG or Nd:YVO4, or some other similar host medium. The 946 nm line is what is being doubled in blue lasers, and 473 nm light is the result. Often, the choice for a Non-Linear Optical (NLO) crystal is different for the two lines. KTP is the crystal of choice normally for green, and LBO for blue. Also, the 946 nm line has a much smaller cross section for emission. This means lower efficiency and the 1064 line and even the weak 1319 nm line will try to compete with it, stealing energy. On top of that, the 946 line is self absorbing making the device a lot trickier to generate (like ruby, this is a case where the laser medium is actually somewhat opaque to the frequency of light the laser is trying to operate at, where as YAG is almost perfectly transparent at 1064 nm).
So, they start out with pretty much the same structure: High power laser diodes at 808 nm pump a Nd host which lases at 948 nm, and this is inter-cavity doubled. But upon closer examination there are a lot of differences between the mechanisms operating in each laser.
For some of the reasons mentioned above, the brightest commercial source for 473 nm light that I know of is limited to 400 mW, where as you can get a 10 W CW, or higher 532 nm DPSSFD laser with a pulsed beam. (Actually at least 10 times this now. --- Sam.)
Note that to get any sort of efficiency (as these things go) at the 946 nm line requires cooling the YAG rod (but for certain other lines like 1319 nm, ambient temperature is fine). In fact, if you cool YAG enough there are many other lines that will lase, some that can be doubled to nice shades of yellow and orange. 
(From: Jo.)
The doubling crystal is KNBO3 (KN). Temperature stabilization is a big problem for blue DPSS laser. We use modules where YAG and KN are bonded together. The modules are coated ready to use. With TE-control on both the crystal module and laser diode, a very stable beam is possible at about 5 to 15 mW. I think there will be better materials and components next year. Many companies (we too) are working at developing blue lasers.
You can try a KTP-crystal. For extra cavity doubling, output power will maybe not be very high. Better to use the KN crystal. This will cost about $220 at Goldbridge, which is a manufacturer in China or Taiwan. I'ms also developing a range of blue and green lasers. Currently, I get 160 mW CW green when pumping a Nd:YVO4+KTP using 1.5 W of pump power at 808 nm. At the moment I'ms working at temperature control for better stability.
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