Measurements of mirrors for not red HeNe (for Pr:YLF)

[atomd]

I'm experimenting with Pr:YLF crystal that's capable of lasing at few visible wavelengths (green, orange, red, deep red) and I'm looking for selective mirrors to get specific wavelengths to lase. I have almost same problem as HeNe with red line being the brightness so I'm hoping to reuse existing optics.

Does anyone have any resources or could quickly measure transmittance / reflectance of green or yellow mirrors for HeNe. I'm especially interested with curved OCs as getting dichroic flat mirrors is much simpler than curved ones.

Also any suggestions regarding wavelength selection in resonator would be welcomed.

 

[kecked]

I wonder if a grating might work. There were a bunch of hene mirrors of all kind on eBay few months back. Might see if they are still there

try the grating. I have not seen a tuneable Pr. Not like continuous but between colors. Works for gas lasers like argon.

 

[atomd]

Problem is that all gratings I found have efficiency below 80% so Ill have really high resonator round trip loss.

Exactly because NOS and used HeNe mirrors of all kinds show up from time to time I started wondering if they may be feasible

 

[Mattronium]

As far as I can tell the best option for wavelength selection is using a Brewster prism. This is what is used for tunable argon lasers for example. This way a concave mirror can still be used. Theoretically this setup can have near zero losses at the one specific wavelength.
I've been studying this for a multi-line gas type laser, so I don't know how it would adapt to a dpss setup.

 

[atomd]

In theory it works. Question is where to get prism with good enough coatings for my frequencies of interest? Best I found had around 1.5% reflectivity per side, meaning 6% round trip loss. Not terrible but a bit high concerning typical OC in Pr:YLF has transmitance of 2%.

25mm N-SF11 MgF2 Coated Equilateral Prism | Edmund Optics

TECHSPEC Equilateral Prisms feature three equal 60-degree angles and are ideal for wavelength separating applications. ✓ Shop now with Edmund Optics!

www.edmundoptics.com

I guess I could use typical Littrow prism at Brewster angle but then I have to maintain polarization in entire resonator.

So you're suggesting to stick with something like:

22mm Uncoated, Littrow Dispersion Prism | Edmund Optics

TECHSPEC Littrow Dispersion Prisms are used to disperse light into its component spectrum or deviate the line of sight by 60°. ✓ Shop now with Edmund Optics!

www.edmundoptics.com

 

[Mattronium]

It is called a brewster prism because the light will enter and exit at the brewsters angle, so it will have 0% theoretical losses for one polarization. No coatings are necessary because of this. As long as linearly polarized light works for your application. I can't say the actual real life % loss, but it should easily be <1%.

A littrow prism is 1/2 of a brewster prism (so light will enter at brewsters angle and hit the back surface perpendicularly), so it doesn't really work unless the back surface is coated which would be custom and $$$. The reason brewster is better (at least in my case) is because the prism relatively simple, uncoated and the fancy coated/concave optic is separate. Maybe take a look at my crude diagram (https://laserpointerforums.com/threads/tunable-argon-ion-review-10th-anniversary-post.109813/).

Another drawback to a prism can be that it takes more space, not a whole lot, maybe an inch or two, but for compact dpss it may be an issue to consider. Also, keep in mind that equilateral prisms are not all brewster prism, usually brewster prisme will specifi the apex angle. Dispersive prisme may be the same as brewsters prism, Im not 100% sure. Sorry if its a bit rambling.

 

[kecked]

Where did you get the crystal. Pr:YLF I have been meaning to mess with this for along time and I finally have time.

Diode pumped Pr:Ylf-Laser emitting at 640, 607 and 523nm. — Sci-Projects: Science and engineering at home!

In this article, I describe the design, construction and operation of a DPSS Pr:Ylf Laser which emits green, orange, and red laserlight.

www.sci-projects.org

looks like a good article

 

[atomd]

Where did you get the crystal. Pr:YLF I have been meaning to mess with this for along time and I finally have time.

Diode pumped Pr:Ylf-Laser emitting at 640, 607 and 523nm. — Sci-Projects: Science and engineering at home!

In this article, I describe the design, construction and operation of a DPSS Pr:Ylf Laser which emits green, orange, and red laserlight.

www.sci-projects.org

looks like a good article

I bought it here: https://4lasers.com/en/components/crystals/laser-crystals/pr-ylf-crystals
They're Lithuanian company selling many different laser materials. if it's currently unavailable you may need to wait a bit because as far as i know they produce them in batches