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Thread: créer un « SUPERCONTINUUM » avec des fibres de silice de 125; 250 ; 400 et 600 micron

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    Red face créer un « SUPERCONTINUUM » avec des fibres de silice de 125; 250 ; 400 et 600 micron

    i remove the topic !
    Last edited by femtoman; 09-02-2023 at 23:59.

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    Red face Préparation d'une fibre de silice de 1000 microns et réglage de l'optique

    i remove the topic !
    Last edited by femtoman; 09-03-2023 at 00:00.

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    Au foyer de la lentille si l'intensité de focalisation est trop grande il se forme à la face d'entrée de la fibre de 1mm un boule de plasma de silice voir photo
    Last edited by femtoman; 09-03-2023 at 00:01.

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    Quote Originally Posted by femtoman View Post
    Au foyer de la lentille si l'intensité de focalisation est trop grande il se forme à la face d'entrée de la fibre de 1mm un boule de plasma de silice voir photo

    looks interesting. I don’t read French unfortunately. I’m trying similar with a 355nm q switched laser. 360ps 25uj 1khz. Driving single mode telecom fiber. Have not tried it yet. Pulses are 64MW with 25mw average. Hoping that is enough.

    wanT to try my ti Saph too and see if I can do it in the IR

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    Quote Originally Posted by kecked View Post
    looks interesting. I don’t read French unfortunately. I’m trying similar with a 355nm q switched laser. 360ps 25uj 1khz. Driving single mode telecom fiber. Have not tried it yet. Pulses are 64MW with 25mw average. Hoping that is enough.

    wanT to try my ti Saph too and see if I can do it in the IR

    Using your tripled YAG laser (355nm) it will be very difficult or impossible to create a supercontinuum because the spectral width of the laser is too small. The dye laser is 20nm spectral wide.
    The instantaneous power of your laser is not 64MW but 69 kW.
    At the level of the instantaneous power you have more than enough it already works with 1-2 kW it is the spectral width that is too low.
    Send us photos of your montage;

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    Quote Originally Posted by femtoman View Post
    Using your tripled YAG laser (355nm) it will be very difficult or impossible to create a supercontinuum because the spectral width of the laser is too small. The dye laser is 20nm spectral wide.
    The instantaneous power of your laser is not 64MW but 69 kW.
    At the level of the instantaneous power you have more than enough it already works with 1-2 kW it is the spectral width that is too low.
    Send us photos of your montage;
    I guess I’ll try to pump a dye cell with the 355nm laser and see if that works. So far I have not done anything. Waiting for the fiber to arrive. The 64MW is the focused spot size 0.02mm. Came from an on line calculator.

    I’ll post pics once I get everything. Bummer the uv laser can’t drive it direct.

    I also have an old coherent dye laser running r6g. Hat does 2ps pulses at 8mhz after cavity dumper. Might try that too but the source again is not broad after the bifringent filter.

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    Quote Originally Posted by kecked View Post
    Je suppose que je vais essayer de pomper une cellule à colorant avec le laser 355 nm et voir si cela fonctionne. Jusqu'à présent, je n'ai rien fait. En attendant l'arrivée de la fibre. Le 64MW correspond à la taille du spot focalisé de 0,02 mm. Venu d'une calculatrice en ligne.

    Je posterai des photos une fois que j'aurai tout reçu. Bummer le laser uv ne peut pas le conduire directement.

    J'ai aussi un vieux laser à colorant conforme conforme en r6g. Chapeau fait des impulsions 2ps à 8mhz après le dumper de la cavité. Peut-être essayer cela aussi, mais la source n'est pas large après le filtre bifringent.
    Si l'on focalise sur 0.02 mm alors l'intensité est de 64MW/cm2 et pas 64MW. En pompant un laser à colorant avec le 355 nm c'est une bonne solution. Moi j'utilise mon Laser NITROMITE pour pomper une cellule de colorant en enlevant le reseau de diffraction.
    Il ne faut surtout pas utiliser un filtre biréfringent car il limite la largeur spectrale. Le mieux est le pompage longitudinal du colorant http://www.swissrocketman.fr/coloran...2c3%2c277.html et http://s848664668.onlinehome.fr/Wordpress/2020/12/28/ laser-a-colorant-a-pompage-longitudinal/

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    Quote Originally Posted by kecked View Post
    I guess I’ll try to pump a dye cell with the 355nm laser and see if that works. So far I have not done anything. Waiting for the fiber to arrive. The 64MW is the focused spot size 0.02mm. Came from an on line calculator.

    I’ll post pics once I get everything. Bummer the uv laser can’t drive it direct.

    I also have an old coherent dye laser running r6g. Hat does 2ps pulses at 8mhz after cavity dumper. Might try that too but the source again is not broad after the bifringent filter.
    I think the intense UV may well destroy the fiber and conventional wisdom suggests as Femtoman notes, a broad input line-width seems to be required.
    That being said I have read many papers where continuum generation has been achieved with relatively narrow input line-widths, for example the 1064nm from YAG in this paper: https://digital-library.theiet.org/c...49/el_19780556

    The fibers in the paper above were doped (Germanium Oxide) but I would personally encourage experimentation, who knows what dopants are used in modern Fibers!

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    Quote Originally Posted by femtoman View Post
    Démarrage d'une nouvelle expérience !

    Le but de l'expérience est de voir si l'on arrive à créer un « SUPERCONTINUUM » avec des fibres de silice de 125 ; 250 ; 400 et 600 microns de diamètre.

    Une deuxième expérience consistera à faire des essais avec des tubes capillaires de 100 microns remplis avec du soufre de carbone CS2 pour voir si l'on peut créer un « SUPERCONTINUUM ».
    Pour cela j'utilise comme pompe laser mon laser TEA N2 PRA UV1000 qui produit des impulsions de 2000 kW (2MW) en 500 picosecondes. Le colorant sera de la COUMARINE 3 produit des impulsions de 400 ps et 250 microjoules soit 625 kW à 450 nm.
    La cuvette contenant le colorant en quartz fait 30mm de long est de fabrication maison!
    Les fibres de silice ne sont pasdes fibres optiques elles ne se composent pas de 2 indices de réfraction. L'indice n2 =1.000 est l'air.

    Demain je démarre les premiers essais
    This is awesome, I can't wait to see how this turns out!
    I'm sure I saw a supercontinuum video of yours once, where you have a length of PCF? I wonder how it would compare...

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    Default A start

    Mnl106-pd, trigger, power supply, 4 side quartz cuvette, dyes, grating, 2 MM1, baseplate, fused quartz cylinder lens, fiber collimator, and 200M of single 9/125 and multi 50/125 fiber will be all be in Tuesday. Mixedgas dropped me off some oc and hr as well so I plan to try and build a proper cavity for the dye.

    While I’m making the continuum, I am also optimizing the dye laser to see if I can get low ps pulses out of it.
    adding the compressor after a slit and the fiber Ie the continuum might make short tuneable pulses with high energy.
    so two different experiments. One on the dye the other the continuum. Shortening the dye and launching g down the fiber would not be the right idea so separate thoughts for separate use.

    to do this I am using a grating and a mirror plus a telescope in the cavity and tilting the cuvette. This along with curved oc will form a cavity I can optimize for pulse length. None of this is me. I read a paper mixedgas sent me. I’ll be using an auto collimator to measure the pulses.

    if still alive, I’m going to the use two prisms and a mirror to form a compressor and see if I can shorten the dye even further to fs. I have doubts this will work as the dye if I do it right will be ultra tight in bandwidth already. This is done in TiSaph lasers all the time so putting this o. The output of the continuum along with a slit will allow for tuneable short pulses across the spectrum. As femtoman mentioned, I want the wider pulses from the dye for the continuum.

    if I get down to 100ps I’ll be impressed while I know 2 ps is possible as I have a dye laser with cavity dumper that does this but it’s 20 times larger and is driven by a 50k modelocked 532nm millennia. This dye will never match the speed or stability of that dye jet laser.

    last on the dye, I’m going to try and use a 20mm x10mm cell for the dye. If the nitrogen laser can’t drive the whole cell to suoerradiance, I might still make it work with the cavity and see if I get more juice from it. I think the dye will still pump a portion to superradiance that the reflected beam in the cavity and then stimulate for amplification increasing efficiency. I know this is sometimes done in dual dyejets. If I get the uv laser at 1 kHz going this may let me get that higher rep rate too without mixing but I doubt that.

    thanks for starting this line of thought it is a lot of fun. It’s all bs until I post working pictures however.
    Last edited by kecked; 02-04-2023 at 06:34.

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