发信人: chuckle (现在你是我的人了), 信区: Physics
标 题: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Tue May 20 11:52:27 2008)

小弟最近用一个YAG pulse laser pump一个OPA，但输出光的profile很不均匀（最强最
弱可差10倍），而且功率随时间涨落很大（1s内总功率可变2倍），请问大牛，这通常
是什么原因引起的，有没有什么办法可以解决这个intensity空时变化太大的问题？
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发信人: woodknife (小木飞刀), 信区: Physics
标 题: Re: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Thu May 22 21:56:22 2008)

偶不是大牛，没怎么做过非线性的试验，不过pump得什么晶体啊？是怎么做得opa啊？
估计是没有align好。
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发信人: bozeman (bozeman), 信区: Physics
标 题: Re: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Wed May 28 20:26:57 2008)

more details needed....
it is very likely due to the misalignment of the cavity
what is pulse width of YAG?
what is the upstate life time of the crystal?

【 在 chuckle (现在你是我的人了) 的大作中提到: 】
: 小弟最近用一个YAG pulse laser pump一个OPA，但输出光的profile很不均匀（最强最
: 弱可差10倍），而且功率随时间涨落很大（1s内总功率可变2倍），请问大牛，这通常
: 是什么原因引起的，有没有什么办法可以解决这个intensity空时变化太大的问题？



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发信人: booker (书生~旅程), 信区: Physics
标 题: Re: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Thu May 29 17:27:21 2008)

First, are you sure of your laser output? Is the laser output itself
stable enough? OPA is based on nonlinear effect, so 10% fluctuation in
laser pulse may lead to 100% fluctuation of your OPA output.

Second, what is your output wavelenth? 1550 nm is always more stable
than 1200 nm output, because of the nonlinear crystal used.

Third, what OPA you are using? OPA from Newport is not as good as
a former soviet union company (EKSPLA or something).

Last, alignment and protection. Even air flow has effect on your OPA
output. The key point is to generate a stable white supercontinum
first - that depends on the incident pulse energy, the saphire
plate you are using, and the alignment.

Overall, OPA is tough to deal with. Commersial one always gives you
~5% fluctuation, I am very happy when my home-made OPA gives me
20% of fluctuation.

【 在 chuckle (现在你是我的人了) 的大作中提到: 】
: 小弟最近用一个YAG pulse laser pump一个OPA，但输出光的profile很不均匀（最强最
: 弱可差10倍），而且功率随时间涨落很大（1s内总功率可变2倍），请问大牛，这通常
: 是什么原因引起的，有没有什么办法可以解决这个intensity空时变化太大的问题？



--

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发信人: chuckle (现在你是我的人了), 信区: Physics
标 题: Re: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Sat May 31 01:17:27 2008)

3X a lot, here are some details.I use 355nm laser from YAG laser as the pump
source, use BBO serve as the OPA nonlinear crystal. Single pulse has a
100ps pulse width.
The 355nm pump laser should has a 15% fluatation as our technichian said.
But how to measure the fluatation of the YAG laser and the OPA? Normally
what kind of powermeter should I use, and how long should I take the average
?
And for the non-uniformity, how to find the cause of the pheonormena?
【 在 booker (书生~旅程) 的大作中提到: 】
: First, are you sure of your laser output? Is the laser output itself
: stable enough? OPA is based on nonlinear effect, so 10% fluctuation in
: laser pulse may lead to 100% fluctuation of your OPA output.
: Second, what is your output wavelenth? 1550 nm is always more stable
: than 1200 nm output, because of the nonlinear crystal used.
: Third, what OPA you are using? OPA from Newport is not as good as
: a former soviet union company (EKSPLA or something).
: Last, alignment and protection. Even air flow has effect on your OPA
: output. The key point is to generate a stable white supercontinum
: first - that depends on the incident pulse energy, the saphire
: ...................



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发信人: booker (书生~旅程), 信区: Physics
标 题: Re: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Tue Jun 3 13:49:33 2008)

This is pretty standard ps-OPA set-up.

I would suggest you use a pulse energy meter (I am using one from Laser
Probe),
which can give you the average, standard variation, etc., of your pulse
energy. Those are useful information for OPA alignment.

Spatial non-uniformity is mostly due to miss-alignment. I would suggest
you first check your white super-continuum, it should be a co-centered
ring with different colors - and in most case you won't get that (I never
get that), but you should do the best you can.

【 在 chuckle (现在你是我的人了) 的大作中提到: 】
: 3X a lot, here are some details.I use 355nm laser from YAG laser as the
pump
: source, use BBO serve as the OPA nonlinear crystal. Single pulse has a
: 100ps pulse width.
: The 355nm pump laser should has a 15% fluatation as our technichian said.
: But how to measure the fluatation of the YAG laser and the OPA? Normally
: what kind of powermeter should I use, and how long should I take the
average
: ?
: And for the non-uniformity, how to find the cause of the pheonormena?



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发信人: shell (空雀彳亍), 信区: Physics
标 题: Re: 问tunable laser 同OPA大牛
发信站: BBS 未名空间站 (Tue Jun 3 17:34:01 2008), 转信

Ophir的powermeter可以测standard deviation.你们既然有这样的laser
应该相应有类似的powermeter可以测single pulse energy的。

【 在 chuckle (现在你是我的人了) 的大作中提到: 】
: 3X a lot, here are some details.I use 355nm laser from YAG laser as the
pump
: source, use BBO serve as the OPA nonlinear crystal. Single pulse has a
: 100ps pulse width.
: The 355nm pump laser should has a 15% fluatation as our technichian said.
: But how to measure the fluatation of the YAG laser and the OPA? Normally
: what kind of powermeter should I use, and how long should I take the
average
: ?
: And for the non-uniformity, how to find the cause of the pheonormena?



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