New Diode

[catalanjo]

@ "as with the single vs. multimode debate," ....... I take it that you therefore agree that a truckload of single modes (properly trimmed and stacked) can invariably give a better beam than a few multimodes equally (properly trimmed and stacked) !
Cheers

[planters]

No, not at all. I can't answer that. I've always been interested in high power. Elegant little 1W RGB projectors just don't excite me, and so I never worked with the 100+mW single mode diodes. My first projector used 16 of the incredibly unreliable, low powered red diodes extracted from CD burners. Alignment was a nightmare and the space required for all the optics was quite large. I like limiting the number of combined diodes to, at most 6. With PBS this means stacking only three at a time and this is easy to lay out as well.

[VDX]

... I did some testing with fibers and already fibercoupled diodes, what showed pretty interesting results.

It seems, that fiber-coupling into fibers with 0.1mm core-diameter is no problem - I have some IR-diodes with 9Watts or 25Watts @975nm out of a 0.1mm fiber ... and one diode with 1W@808nm out of a 0.05mm-fiber.

When fokussing a 445nm-diode with 15-20mm FL, the focus diameter is as small as 0.05 to 0.03mm, what would easy 'fit' into a 0.05mm fiber - could give pretty good results with the totally circular 'homogenized' output beam ;-)

Viktor

[jors]

Those diodes could be great candidates for Pr:YLF pumping!

[VDX]

... this could be a pretty powerfull pump!



Viktor

[planters]

... this could be a pretty powerfull pump!

You are correct.
There is also a flowing dye laser design that uses visible red diodes to pump a near IR dye with a pump threshold of mW. The trick is to use a near hemispherical cavity with the rear, flat mirror coated with a dichroic which transmits the pump light, but is highly reflective to the laser light. The concave, output coupler with a transmission of close to 5% is adjusted so that the beam waist near the flat is exactly the same diameter as the pump spot on the inner (wet) side of the dichroic.

For pure projection, I'm not excited about fiber homogenizing. The inevitable entropy means the beam quality has to deteriorate as the rays are mixed in the fiber. For pumping, the smooth spot is more important than the highest possible intensity and fiber coupling is very useful. My DPSS required it.

[VDX]

... I'm using the fibercoupled diodes for engraving, where the focus diameter (when refocussing the output of the 0.1mm-fiber) is nearly 0.1mm too -- so could be interesting to test, what's the far-field beam characteristcs, when collimated to 3mm or 5mm beam diameter ...

Viktor

[planters]

what's the far-field beam characteristcs, when collimated to 3mm or 5mm beam diameter ...

I'm going to test this.

[steve-o]

Subscribing with interest to see actual wavelength .. I've read 445 or 462 .. that makes a big difference imho ..

[planters]

Yes, it does. The power alone is exciting, but if the divergence is less as well then that's really good. If the wavelength is around 462 then that's spectacular.