We can see the use of diode lasers in dynamic laser speckle applications, however there is still a doubt concerned with its stability if compared to the HeNe lasers.
I am not an expert at specle, but I expect that as the mode hopping changes the laser frequency/interference phase, it also changes the speckle image. The main advantage of the diode laser can be seen in its wider tuning range (depends on type), compactness and also generated output power. In same cases, the problem of modehopping can be solved by stabilizing/optical isolating of the diode.
Hi Jan Hrabina, thanks. Do you have any document/reference about the "stabilizing/optical isolating of the diode"? I would like to try it.
Hi Roberto, could you descrive your setup/application/type of the laser? I will try to asnwer.
Hi Jan Hrabina, nice to receive your interest. Well, we work with dynamic laser speckle (http://en.wikipedia.org/wiki/Dynamic_speckle) and the speckle boiling is a relevant information from the activity of the material. In turn, we wouldn't like to compromise our results using a diode laser with the mode hopping present. The mode hopping can mask the actual activity. Cheers.
Hi Roberto,
It is very nice to have occasion to talk with you.
Regarding your question. Have you ever tried to compare stability of speckles obtained from this two types of lasers?
I think that in the situation in which we can control parameters of our detector as well as laser diode we are always able to improve stability of laser diodes assuming that mode hopping afects our measurements significantly at all
Best.
Hi Andrzej,
it's my pleasure. Thanks.
Yes, I am planning to conduct an experiment to test it, since if we have the mode hopping influencing the results, we wont be able to separate all the activities, but only those that are very different.
Therefore, the jumping of the diode certainly do not compromise our work, though it could be improved if we reduce the noise created by the phenomenon.
Cheers
Roberto
Hi Roberto, what type of diode do you use? One of the most often reason for mode hopping is backreflection of the laser light back to the diode. Did you mind this during preparing of your setup? Do you use fiber pigtailed/freespace diode? Is it possible that you have some backreflections from any of the element/lenses/mirrors in setup?
Hi Jan, I've been using all sort of diode lasers. The backreflection can be a problem, since it can happens in the lens (beam splitter and neutral filter). I don't use fiber pigtailed diode. I will think about that. I am planning to carry on an experiment to text all those things. Thanks Cheers
- Badges
- Science topic