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Thread: Dye laser pumping with femtosecond laser

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    Default Dye laser pumping with femtosecond laser

    Hi

    I have femtosecond laser (100fs pulses) and I want to use it as a pump for pulsed dye laser. I know that usually people use ns lasers. I suppose that than your pulses are in ns domain the system (dye laser) is in kind of quasi steady state during the pulse. For fs pulses the pulse duration is much shorter than any processes in the system. I have the filling that this will not work. Somebody has any experience or opinion?

    Thanks
    Last edited by Hispano; 09-12-2012 at 01:43.

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    your first post and you have a question like that...well, you are not providing enough information to even get started to answer the question. If you have a femtosecond laser and you do not know the answer to this question, something is fishy with your post to begin with. With a name like alex it is probably not a language barrier thing. If you are at university, ask your professor. If you are the professor...hmmmmmm. Your question is vague at best, Sorry, not trying to be an ass but regroup, rethink, repost.
    Last edited by Laserman532; 09-11-2012 at 08:52.
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    It depends on what you want to do, but in general something will happen if you shine a femtosecond laser into dye You are right though, unless you modelock the dye as well and sync it up with the pump (not easy to do), your pump will act like a CW source. That said, as long as you have enough power to get over the threshold for your dye system you can still get it to lase, although you will want a dye laser designed for a CW pump as opposed to one designed for a q-switched pump.

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    Ok, you right my question is very general. Lets put it this way:
    1) You have a dye laser (very simple and very general, cell with a dye in a cavity)
    2) Your pump is nanosecond pulsed laser
    3) What you will get? Nanosecond pulses from dye laser with very narrow bandwidth, right?
    4) Now, we will replace the pump laser by femtosecond laser. What now?

    I can guess the answer, I think you will get ASE rather than lasing. So you will not get narrow bandwidth.

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    Ok, what wavelength is the femtosecond laser at? You'll get ASE and some pumping. So if you can pump before any shockwaves form in the dye, you'd get some lasing if your pump is in the dye adsorption band.

    Steve

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    OMG - endless variables

    pump wavelength? Shifted Wavelength? Pulse broadening? Quenching? Saturation? Peak Energy? Halftimes?

    One problem comes to mind immediately. Peak powers in a fempto pulse could vaporize the dye onto the inside of the cell causing a dark spot absorbing pump energy. BUT FUCK...THAT IS JUST A WILD THOUGHT!

    Post your resume before further discussion from me. I have no intention of trying to find out what it is, by finding out what it isn't.



    To answer your original question - can you pump a dye laser with a femto pulsed laser?


    yes.



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    Ok, you right my question is very general. Lets put it this way:
    1) You have a dye laser (very simple and very general, cell with a dye in a cavity)
    2) Your pump is nanosecond pulsed laser
    3) What you will get? Nanosecond pulses from dye laser with very narrow bandwidth, right?
    4) Now, we will replace the pump laser by femtosecond laser. What now?

    I can guess the answer, I think you will get ASE rather than lasing. So you will not get narrow bandwidth.
    Firstly, there is nothing wrong with asking this question. The upper state lifetimes of the Xanthene dyes are on the order of a few nanoseconds. Pumping to a sufficient power level to achieve lasing, but remaining below the peak power levels that will vaporize the volume that will absorb the light based on the irradiated area x the absorption depth will probably work (in my opinion). Depending on the mirror spacing the dye output will probably trail the pump peak and be significantly broadened in duration again depending on mirror spacing as well as the gain.

    Seems like a degradation of the expensive femtosecond beam when a nanosecond pulse works well and for tuning a supercontinum conversion of the femtosecond pulse is a proven technique.

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    planters, you are correct, nothing wrong with asking this question.

    but as a first post on this type of forum was surprising to say the least. The question was vague at best. For someone to join a forum and make his first post with no introduction regarding something that is rarely if never discussed on such a complicated and detailed train of thought with more variables than the limited information supplied, my BS radar malfunctioned and was short with poster.

    he said...I have a "filling" that this will not work. That did not help either.

    Apologies to Hispano for my lack of patience. I hate to have to find out what it is by finding out what it isnt...it is a huge waste of time.
    Pat B

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    Apologies to Hispano for my lack of patience. I hate to have to find out what it is by finding out what it isnt...it is a huge waste of time.
    Oh, I know. And I am done. Now it's his turn. I'll wait for some pics.

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    Laserman532, you don't have to waste your time and answer the question if you don't like it, we are free people.

    I intentionally don't want to go deep into technical details since I don't want to be involved into technical discussion. I want to focus just on one variable: replacing ns pump by fs.

    planters,
    I know that ns laser will work well, but I don't have it, instead I have fs (don't worry I mostly using it for other stuff ). And the core of my question is: can I somehow pump the dye laser with fs or I have to get ns laser.

    Depending on the mirror spacing the dye output will probably trail the pump peak and be significantly broadened in duration again depending on mirror spacing as well as the gain.
    Lets stop here for a second. If the space between the mirrors is smaller than the lifetime (lets say the lifetime is about 1ns and the space is about 3cm, so the light will bounce few times between the mirrors before population inversion will decay). The dynamics will be somewhere similar to 1ns pulse. What do you think?

    supercontinum conversion of the femtosecond pulse is a proven technique
    Sure. We will get some nonlinear effects, but we are interested in absorption and population inversion as a result I don't think any nonlinear effects will interfere with that.

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