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The dispersion on a half wave plate- polarizer combination should be
lower. But do
remember that they are very wavelength specific. You probably need one
for every 25 nm.
Sudipta
On Fri, 15 Feb 2008, Ann
Haberman wrote:
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> Dear List,
>
> Thank you all for the many helpful suggestions.
>
> One of the manufacturers of a Faraday isolator feels that a rotator by itself
> would be insufficient to reduce the reflected laser and indicated that a
> isolator would be necessary. Given the amount of dispersion I would get with
> just a rotator, I'm loathe to get an isolator. Their assumption is that the
> polarization of the reflected laser will be identical to the laser output. Is
> likely that it would be different ?
>
> The suggestion of using a 1/2 or 1/4 waveplate sounds like a good idea. Would
> there be less dispersion in this arrangement? What would be disadvantages of
> this compared to the rotator?
>
> Many thanks again for this helpful advice,
> Ann
>
>
>> Search the CONFOCAL archive at
>> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal A Faraday rotator
>> isolator is a large chunk of crystal. It will cause a lot of dispersion to
>> your pulses if you are using a femtosecond laser. Our own laser went from
>> 70fs to 300fs after passing through ours. This effect can be minimized by
>> getting as short a crystal as possible in your isolator.
>> EOT <http://www.eotech.com/>http://www.eotech.com/ has decent isolators
>> although it can be hard to tell which one has the shortest crystal. We
>> originally selected ours based on the assumption that the smallest entrance
>> aperture will have the shortest crystal. This turned out to not be the
>> case, so check with the company before buying. Last I heard recently that
>> their 8mm aperture unit:
>> <http://www.eotech.com/store/products.php?categoryParentName=Faraday+Rotators+%26+Isolators&categoryName=Broadband++%28Ti%3ASapphire%29+Rotators+%26+Isolators>http://www.eotech.com/store/products.php?categoryParentName=Faraday+Rotators+%26+Isolators&categoryName=Broadband++%28Ti%3ASapphire%29+Rotators+%26+Isolators
>> actually had the shortest crystal, but make sure to check with the company
>> first.
>> Regarding the utility of an isolator, if you have any reflections at all
>> having one is critical for the stability of your laser. In some laser
>> designs the reflected light can actually be physically harmful to the laser
>> as well!
>>
>> Craig
>>
>>
>> On Thu, Feb 14, 2008 at 11:51 AM, Ann Haberman
>> <<mailto:[log in to unmask]>[log in to unmask]> wrote:
>>
>> Search the CONFOCAL archive at
>> <http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal>http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>>
>> Dear List,
>>
>> I am considering placing a Faraday rotator or isolator in front of a
>> two-photon laser and am wondering what others have experienced with
>> such a configuration.
>>
>> I am currently experiencing a lot of "feedback", ie return reflected
>> laser, that is wrecking havoc with my laser's stability. When it
>> senses the reflected light, it can not maintain a mode locked state
>> and can only lase in CW.
>>
>> I'm heard that a Faraday rotator should be sufficient, but I am
>> wondering if an isolator is necessary to stop the reflected light
>> from entering the cavity of the laser source. Also, I would love to
>> get a recommendation for a reliable company that makes them.
>>
>> Many thanks for any advice,
>> Ann
>> --
>>
>> Ann Haberman, PhD
>> Department of Laboratory Medicine
>> Yale University School of Medicine
>> 1 Gilbert St.
>> TAC S541
>> New Haven, CT 06510
>>
>> 203-785-7349
>> 203-785-5415 (fax)
>> <mailto:[log in to unmask]>[log in to unmask]
>
>
>
--
Sudipta Maiti
Dept. of Chemical Sciences
Tata Institute of Fundamental Research
Homi Bhabha Road, Colaba, Mumbai 400005, India
91-22-2278-2716
www.tifr.res.in/~biophotonics
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