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Thread: Cr:YAG as Q-Switch @1064 nm, how much trouble is it to just add one as a passive Q-Sw

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    Default Cr:YAG as Q-Switch @1064 nm, how much trouble is it to just add one as a passive Q-Sw

    Cr:YAG as Q-Switch @1064 nm, how much trouble is it to just add one in the cavity as a passive Q-Switch? Can it be that simple for an existing ND:YAG at 1064 nm? I'm expecting to hear back it isn't so simple and the cavity would need to be redesigned, or?
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    OK, You buy a bunch of coated CR:YAG disks with differing initial transmissions. You stick them in the cavity on a mount. It either works or it doesn't. Doesn't really matter too much, but usually they go next to the high reflector because generally for grins and giggles spot size wise, that is where they go. If the disk is wrong, it either seriously multi-pulses at low pulse energy, or it doesn't lase very well. There is quite a wide range around the sweet spot. This is true for DPSS and small low rep rate flashlamp pumped lasers. On a big laser the disk will simply saturate open, and heat up, merely reducing power in the laser. . At 70$ US a disk, you can play the lottery a bit. If you don't care and buy the things off Alibaba or what ever, oh well, may work, may not.

    There are always mechanical q-switching methods such as a spinning disk with holes... Problem with that is giant pulsing could in theory fry a mirror coating or long shot if the rear mirror is not perfect, , a pump diode. . But it is the oldest way for CW lasers, other then the spinning self aligning retro prism.

    That is the hobbyist way, and it can be, well, effective.

    Get a laser you don't care about, and try. The old dye based q-switches for the SSY-1 wear out. These days the cheap Q-switch dye used in the SSY-1 gels comes from Russia and is a bit difficult to get with a war on. Kodak stopped making it in the US long ago. Dye based cells using wet solutions in quartz cells or in Brewster Angle dye jets , dye laser style, are fun, trigger easily, difficult to tame, but fun. I got to tune a dye based cell at work once. On a larger high rep rate YAG, the intracavity liquid dye cell had a pump and heat exchanger. Worked fine, classic brute force Eastern Bloc design, but tuning the concentration to be stable took a great deal of experimenting.

    The classic way is check the passive q-switch tuning is with a long SHG crystal, more green = better q-switch.


    The classic Bis (4-dimethylamino dithiobenzil) nickel (BDN) is ~ 300$ for 500 milligrams. The solvents it dissolves in will make you very, very, sick if your exposed to the liquid or the fumes, if you can even obtain them outside of a professional lab. The stuff ain't cheap.

    Steve
    Last edited by mixedgas; 04-11-2024 at 14:11.
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    Quote Originally Posted by mixedgas View Post
    OK, You buy a bunch of coated CR:YAG disks with differing initial transmissions. You stick them in the cavity on a mount. It either works or it doesn't. Doesn't really matter too much, but usually they go next to the high reflector because generally for grins and giggles spot size wise, that is where they go. If the disk is wrong, it either seriously multi-pulses at low pulse energy, or it doesn't lase very well. There is quite a wide range around the sweet spot. This is true for DPSS and small low rep rate flashlamp pumped lasers. On a big laser the disk will simply saturate open, and heat up, merely reducing power in the laser. . At 70$ US a disk, you can play the lottery a bit. If you don't care and buy the things off Alibaba or what ever, oh well, may work, may not.

    There are always mechanical q-switching methods such as a spinning disk with holes... Problem with that is giant pulsing could in theory fry a mirror coating or long shot if the rear mirror is not perfect, , a pump diode. . But it is the oldest way for CW lasers, other then the spinning self aligning retro prism.

    That is the hobbyist way, and it can be, well, effective.

    Get a laser you don't care about, and try. The old dye based q-switches for the SSY-1 wear out. These days the cheap Q-switch dye used in the SSY-1 gels comes from Russia and is a bit difficult to get with a war on. Kodak stopped making it in the US long ago. Dye based cells using wet solutions in quartz cells or in Brewster Angle dye jets , dye laser style, are fun, trigger easily, difficult to tame, but fun. I got to tune a dye based cell at work once. On a larger high rep rate YAG, the intracavity liquid dye cell had a pump and heat exchanger. Worked fine, classic brute force Eastern Bloc design, but tuning the concentration to be stable took a great deal of experimenting.

    The classic way is check the passive q-switch tuning is with a long SHG crystal, more green = better q-switch.


    The classic Bis (4-dimethylamino dithiobenzil) nickel (BDN) is ~ 300$ for 500 milligrams. The solvents it dissolves in will make you very, very, sick if your exposed to the liquid or the fumes, if you can even obtain them outside of a professional lab. The stuff ain't cheap.

    Steve
    Where exactly do you get Cr:YAG disks for $70? They're a few offers of very low transmittance disks (T<=20%) at eBay for $20-$40 but when I searched for higher transmittance cheapest I found were almost $200.

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    mixedgas's Avatar
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    A Lithuanian Optics company. Business to Business quote, order 4 pcs, and let the package come over low and slow.

    Steve
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