Re: DPSS modulation - COMMERCIAL REPLY

[Arrigoni, Marco]

This is a reply from Coherent Inc.

Dear Jens,

OBIS is not a DPSS lasers but an OPSL, i.e. a diode pumping a semiconductor chip designed to emit light at a certain infrared wavelength to be frequency-doubled inside the laser cavity. This is true also for the 532 nm version, specifically designed to replace Nd:YAG lasers. Since the OPSL active medium is a thin semiconductor element, control of the pump wavelength (via the diode temperature) is not as critical as with DPSS active media; furthermore, DPSS active media have a long lifetime (hundreds of microseconds) while the semiconductor chip lifetime is a few nanoseconds, so that modulation does not lead to uncontrolled oscillations or the well-known "green noise" of YAG lasers. Finally, since the frequency doubling takes place in the cavity, with very high conversion efficiency, modulation of the current does not result in non-linear behavior of the modulated output. Additional information is available from or technical sales department or local sales engineer.

Best regards,

Marco Arrigoni
Coherent, Inc.
Director of Marketing
Scientific Market Segment
Office phone [phone]
Cell phone [phone] (Worldwide)

-----Original Message-----
From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of Craig Brideau
Sent: Friday, October 09, 2015 2:17 PM
To: [hidden email]
Subject: Re: DPSS modulation

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The doubling is a non-linear process, and even the efficiency of the process is input-power dependent. As a result, analog intensity modulation may behave strangely. Digital on/off shouldn't be too much of an issue though. The one thing I caution you is that the doubling crystal and the laser diode are usually temperature stabilized. The temperature controller has to be able to deal with the rapidly changing heat load as you attempt to modulate the laser, so you will want to be sure the thermoelectric components are up to the task!

Craig Brideau

On Fri, Oct 9, 2015 at 12:16 AM, Jens-Bernhard Bosse <[hidden email]>
wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Dear Listers,
>
> I have to pick your brains again:
>
> Has any of you experience with the direct modulation (analog-intensity
> as well as digital-on/off) of DPSS lasers? I would be especially
> interested how stable the output is when using direct modulation.
> Coherent claims that their Obis line can be directly modulated. I
> understand that this is pretty easy with diode lasers but how do they
> do it with the classic DPSS lines like 532 nm?
>
> Thanks!
>
> Jens

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