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Thread: Diode Doubled 488 Blue via direct SHG by Melles Griot

  1. #1
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    Default Diode Doubled 488 Blue via direct SHG by Melles Griot

    Checkout this article about didrectly doubling the output of a Telecom 976 laser diode through an SHG to get 488 nM blue up to 40 mW.

    See " http://optics.org/optics/Articles.do...Edou2cor_02-06 "

    1. I wonder why this wasn't tried before ?
    2. I wonder if it's possible to step up the power levels by combining multiple laser diode outputs to pump an SHG crystal using a Star coupler in reverse ?

    Any coments are welcome.

    Rick
    Profile Redacted by Admin @ 04.24.2010

  2. #2
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    I'm wondering what other frequencies could be produced...

    I had actually expected direct injection technology to provide a rainbow of colors by now, but it seems DPSS is ahead of the game, and direct-doubled diodes are right behind...

  3. #3
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    It seems to me that direct doubled diodes are the way to go since there are less components involved it should be easier to produce and far less costly.
    If they can ramp up the power levels and give me analog modulated RGB without mortaging my house then I'd invest more in this money pit hobby.

    Rick
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  4. #4

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    This idea has haunted me strangely...

    In Sam's LaserFAQ there is a question asking why it wasn't done. Answered along the lines of it being inefficient, due to difficulty coupling the high output needed, usually multimode, so wider emitter, and also power density being too low for efficient triggering of the nonlinear doubling process. On alt.lasers he said recently that it is being done, so there seems to be some confusion over time, maybe. Several years ago I brought it up in conversation with a laser enthusiast I found at an astronomy meeting, and I was told it would be too difficult. I couldn't see why, as it was simpler than with extra parts, and what it lost in efficiency it might well gain as it doesn't lose in many optic surfaces, but I let it rest, I didn't know enough to argue the point.

    And now it seems it's being done, and all I can say is where? I want one! :twisted:

    One idea I dreamed up long ago is using a series of doubler stages to take the output of a CO2 laser. Four would give red, and five would give violet or near UV, assuming it worked. The power could be very strong. Is this idea loony, or might it also be one of those which might turn out to be practical, given suitable coatings and crystals?

  5. #5
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    Quote Originally Posted by The_Doctor
    One idea I dreamed up long ago is using a series of doubler stages to take the output of a CO2 laser. Four would give red, and five would give violet or near UV, assuming it worked. The power could be very strong. Is this idea loony, or might it also be one of those which might turn out to be practical, given suitable coatings and crystals?
    Wow... That's a lot of doubling stages! But I see where you're going... You can make a couple kilowatts of 10,600nm IR with a CO2 laser quite easily, so even if you loose an order of magnitude with each doubling stage you'd still be upwards of a watt of red after the 4th stage. (5 doublings would put you well into the UV range and the beam would be invisible.)

    However, finding an AR coating that can handle a kilowatt of input power for that first doubling stage is going to be really hard. Likewise, I don't know if there are any crystals available that can double the long-wave IR.

    While it's a nice idea in theory, I think by the time you get it up and running (assuming it's even possible) you'll have as much or more money invested in the thing as you would if you had simply purchased a big honkin' Krypton ion laser...

  6. #6
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    Ditto on what Buffo said,

    But it would be fun trying.

    More power..........If ya got Lasers " Light Em "


    Rick
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  7. #7
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    Heh Folks,

    Checkout this new product ,a high power 1.5 watt , 976 nM single transverse mode laser diode suitable for direct frequency doubling to 488 nM.

    See " http://www.optics.org/optics/Product...ode=P000000419 "

    More laser beams in my dreams :-)

    Rick
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    How hot was the pump diode on that 40 mw direct-doubled 488nm laser you linked to above? (The article doesn't say...)

    I'm thinking that with 1.5 watts of 976 nm, you ought to be looking at several hundred mw of 488nm out of the doubling stage, yes?

    Next question is cost....

  9. #9
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    Hi Bufo,

    I think the single mode pump laser diode was about 200 mW used by Melles -Griot.
    I emailed the distributor of the 1.5 watt LD but have not heard back anything on pricing yet !.... Guessing about $1,500 in high heat load mount with TEC.
    You would still require a set OC and HR optics and proper AR coatings on all elements within the lasing cavity.

    Rick
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  10. #10
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    So if 200 mw of 976nm gets you 40 mw of 488nm, then with a 1.5 watt pump diode available, we're looking at around 300 mw of 488! That's a lot of blue, even if the pump diode costs $1500...

    Figure $2000 for a complete package, and that still compares favorably with the 473nm blue DPSS solution for the same power level.

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