Which Transverse Mode has DTR's 9mm 445nm?

[derletztename]

I am using one of DTR's 445nm 9mm Laser Diode (445nm 9mm Diode In V4 Copper Module W/Leads & 405-G-2 Lens) from his Shop for my Masterproject at my University. I am trying to melt steel (with and witout inert gas) with it and it kind of works. To really understand my results I need to know which Transverse Mode they produce. As I just use Lasers and am no expert with them, i don't really understand the details. DTR himself wasn't totally shure about it and made me ask here.

I need to know, which one of these Modes the laser creats. There must be some sort of intensity allocation in the beam and this really affects my results a lot.
File:Laguerre-gaussian.png - Wikipedia, the free encyclopedia

To make shure everybody understand what I try to talk about I added this link
Transverse mode - Wikipedia, the free encyclopedia

Any help would be great

 

[bloompyle]

That's a very interesting question.

None of the TEM modes look like what is produced by these multimode diodes. It is my understanding that this is because those modes are created in unstable resonators. Or resonators in which they are tapping more power than the cavity will allow to lase in TEM00. The most common one in a gas setting is the "doughnut".

I do believe that the multimode output in diodes results in a larger emitter, or multiple emitters side-by-side. So it's the aftermath of of multiple sources lasing at once. Though I could very well be incorrect. I just remember seeing high output 808nm diodes, and 445nm diodes, being listed as having emitters with nonequal dimensions.

You see these sorts of TEM modes a lot in DPSS and gas though, from misaligned cavities. Sometimes they are meant to be non TEM00. They purposely make smaller lasers multimode to get more power from smaller packages.

I hope that at least sort of answered your question...

 

[lazeristasUVISIR]

Laser diode modes are a TM or TE type (mostly the difference in polarization). When power increases modes numbers increase too. The semiconductor (diode) laser has a very specific resonator -a waveguide - a thin layer on one axis (fast axis), and a wide strip on other (slow axis).

When the mode exists the diode it is similar to TEM type with very different divergences on perpendicular axis, and an additional astigmatism, i.e., the starting points are at different locations.

If you want to be sure you might measure the field distribution when it is focused far away, and then scale down to your distance.

I think the datasheet says simple "multimode output" or something like that.

 

[derletztename]

I defocused the laser a lot and the "dot" turns into a rectangle. But I have nothing to measure the intensity or something.
I really would like to see a graph of the intensity distribution or something or be shure about "what it looks like at high power".
For some reason i can see the laser spot through my glasses since today, so i won't go over minimum power till i get new glasses...