Corning G-1000 module

[Things]

So, I've got the little G-1000 module here out of a pico projector. I've been doing some looking around, and found the laser driver IC they use for the pico projector: the MAX3600.

On that page, it specifies: "For operation with synthetic green lasers, the driver includes a periodic off function and a fourth output with a random-noise generator."

Now, these little modules have 4 input connections. 2 are for the diode, I am assuming, however there are 2 more that go to a little TEC looking element. I'm not sure if it's actually a TEC or a heater, but the "fourth output" thing described above leads me to think it might be something else. Here is an internal pic, thanks to "impulse" from LPF:



The bottom device is what I assume is the pump diode. Is there a safe current I could start out driving it with, and seeing if I can get anything at all from this module?

The 2nd question, what could the little device at the top be, and it's requirements? I've noticed a slight green output before, just driving the laser diode, but I'm assuming you need to do something with the little element at the top too before it works correctly.

Any help/info/datasheets/thoughts, whatever, are appreciated

[Things]

OK, I just did a little experimenting.

I connected the module up to my Arduino's 3.3V pin. It can source a max of 200mA, so it's pretty safe for testing. I put the entire module ontop of a large TEC with a bit of thermal paste. When I connected the green module to power, it was emitting a smidge of green. I then connected the big TEC up to a 18650 battery, so the module was being cooled, and the green output quickly increased! It then started flickering off to the point where there was no output. Disconnected the TEC, and as its temperature headed back to room temp, the green light came back for a second or 2, then disappeared again. Reconnected the TEC and cooled it again, green light came back!

So, it would appear that maybe the little "element" inside the module is a TEC? If so, what would be the best way to drive it, in terms of current? Last thing I want to do is feed it too much and POP

EDIT: Got a video of my messing around with it. I'll link it here once it's done, but I think this is the first ever picture of one of these lasing outside the projector (by a hobbyist) ever



Cheers,
Dan

[chad]

Dan,

That little thing is a heater. Here is my guess on what is happening.

You fire up the pump diode it warms the silicon plate that it is sitting on, you get a little green. When you cool the assembly down you are changing the pump wavelength slightly and your power goes up. then as it cools more you pass the wavelength match for the pump and dbr crystal then you loose lasing.

I would attach the module to a heat sink so it can get rid of the pump heat. Then apply some power to the heater wires and slowly increase current until you get lasing back. Unless you have a good thermal controller for your tec it will just make things harder. I think that module is rated for about 60 or 70 mw so that is your goal.

The way the pico projector handles this is they turn on the pump diode and set the heater some ware close then they use the photodiode that is mounted on the sled to look at green power and peak it from there. I think.
When I looked at things on the scope they PWM modulate the heater current and you can see it PID hunt for the best light output.

Congrats! As far as I know you are the first to get green out of one of those. I have one sitting here I just have been so busy that I have not had time to muck with it. But thanks you have confirmed the pin out conclusion that I came up with.

*edit, if you look at the pic from "impulse" you can see the resistive element through the crystal. "The "M" looking thing.


chad

[dsli_jon]

Posting for tracking...

...But, 'long as I'm here, I'll take a stab...

...I'm assuming you need to do something with the little element at the top too before it works correctly.

EDIT, after reading Dr Chad's post, *not* an LED nor a sensor / part of an optical-feedback loop... Thx, Chad...

Here's my best-guess, too, of what's goin down, optically...

Picogreen_Optipath.jpg ..still can't quite make sense of the SHG path....maybe someone with a clue can fix my boo-boos?...

...fascinating stuff, this micro-module, eh?! Looking forward to the day when they miniaturize OPSLs... heh.. '..514nm OPSLs the size of pencil-erasers',

Beam me up...
cheers..
j

Ps - Sir Dan - see if you can get some '3/4 or side-view' shots from that LPF'er....

[Things]

Cool, thanks guys!

I know a PID library actually exists for the Arduino, and I have a few DAC's laying around, so I might try an optical regulation system at some stage as well.

It is indeed a really cool little module, the fact you can squeeze 60mW+ out of it is quite amazing!

Though, I can't really find any datasheets on the current ratings for the little heater and the pump diode.

I've been powering the pump diode from 220mA ish, though I have a feeling that's a bit low & I have a lot more headroom yet

Is there any way I can try estimate the max input current for the diode? The heater seems fine running off an Arduino output - limited to about 20mA or so.

EDIT: Just thought I'd also add, I did have a suspicion of the "power hunt" regulation technique, since there is really no other way to regulate it. The crystal on the heater is actually very fast to respond. Infact, the output brightness of the thing almost followed the potentiometer by the second! If we do indeed get these running, but they won't work just setting the heater to a set level, might need to work out a way of "splitting" the beam and shooting some off to a photodiode and reverse engineering the "power hunt" method.

EDIT EDIT: Jon, he's not a very regular poster, but he did post this:



It's quite a beautiful picture actually.

[Things]

Well, managed to get it stable for the first ever beam shot!





It's soo cute!

[dsli_jon]

Great werk, Dan!!

..And yes, that '3/4' shot is brilliant, thanks for the post... but, it raises as many questions in my mind about the SHG path / lateral-components, as it answers...

Here's my 'revised guess'..

Picogreen_Optipath_v2.jpg

...Paging P'fessor Roberts! P'fessor Roberts?

cheers..
j

[Things]

It doesn't like running off the Arduino's power though, I need to build a proper LM317 driver for the diode.

Can anyone give me a rough max current I should keep below? I had a 110mW green module that ran on about 1.2A, so if this module is 60mW, almost half of that, so around 500-600mA max maybe? Not really sure

EDIT: Jon, your diagram looks pretty well right, except I don't think that block is a photo diode, rather just a vertical support for the HR mirror. There are photo diodes in the optical assembly externally

[chad]

Yep looks good!

I have some ideas for you.

1. Use a smaller heat sink. Let it get warmer. don't be afraid of 85-90f or so. These get warm when running and I guarantee they took that into consideration when designing it.

2. Set your current to 300mw for now. Set it and leave it there. Now you can play with current to the heater and see what gives you the most power out. I suspect it will be a range that works. If your porridge is just the right temperature you will get the most green out.
This all about thermal stuff. The pump diode is going to shift wavelength with the temperature of the base of the module then you need to tune the crystal thermally to match *exactly* the pump wavelength. If the base of the module heats or cools then the crystal temp has to change to keep the optimal output.
Remember that this is a battery powered thing so this is going to be the most efficient way of making green there is, minus a direct diode. What I am getting at is don't use typical dpss powers to guess at mw levels. These will be more efficient 600 mw would probably bake it.

3. While you are building a constant current source, build two. Use one for the diode drive and the other for the heater. The heater is just a resistor so get your meeter out and measure the resistance of it. You can then use ohms law and a couple of resistors and a pot and play with temp for the crystal. Start at maybe 50mw for the heater max and see how things go, adjust accordingly.

Once you have a good idea of what kind of power you get out of a fixed diode drive at 300mw and a stable base (warm)temp, then variable current through the heater you can inch up the diode current and play with heater temp and shoot for ~60 mw or so.
Then you can build a smarter driver.

Any way, this is basically what I was planning on doing, if I ever had the time.

Good Luck!
chad

P.s. That is a beautiful pic. And some beautiful engineering and manufacturing. That thing is much smaller than it looks.

[Things]

Yeah Chad, was intending on building some constant current drivers, just needed a current range to aim for! Maybe I'll grab a few resistors. Start off at 300mA like you said, and slowly crank it up.

And yes, the heat thing has had me thinking. If we cool the module itself and keep it at a constant temp, then we should be able to do away with the optical regulation, and just tune the heater.

From what I've already tried, it seems to be pretty stable, but my way of driving it is far from ideal. I don't have a clue on what current I was pumping the diode and heater with, and it has a long way to go before it hits 60mW.

If it's gonna heat up a lot, optical stabilization might be the only way to do. Maybe be able to use one of the optics out of the assy as a "beam splitter" of sorts.

Thanks for the tips.

[polishedball]

Great progress. Thanks for the info.

[holokidd]

i too have two units on order now, im hoping these lil greens will run SLM. I suspect the part in the Photo labled"?"is actually an etalon? an easy test would be to heat the crystal using a hair dryer and some type of cone to direct the heat to the crystal only. this way you could try various temps and make thermal recordings using IR therma camera/probe. my hope is the green will be good for recording holograms ....as the red and blue units work(with some tuning) as well !

[mixedgas]

i too have two units on order now, im hoping these lil greens will run SLM. I suspect the part in the Photo labled"?"is actually an etalon? an easy test would be to heat the crystal using a hair dryer and some type of cone to direct the heat to the crystal only. this way you could try various temps and make thermal recordings using IR therma camera/probe. my hope is the green will be good for recording holograms ....as the red and blue units work(with some tuning) as well !

It might be a etalon, but since it is unheated, and has poor postioning accuracy, I doubt its a very good one. I'd lean towards a tuned element of another sort, or a polarizer but not a BRF.


Steve

[holokidd]

It might be a etalon, but since it is unheated, and has poor postioning accuracy, I doubt its a very good one. I'd lean towards a tuned element of another sort, or a polarizer but not a BRF.


Steve

why would you say if it is a etalon you doubt its a good one?

these lasers need very narrow linewidth to stay in focus over long distances and some how they are doing it. with the advances in micro robotics i dont think alighnments would be an issue ........ as soon as i get my grubby little hands on one we will see! The Coherent sapphire lasers use a block/etalon in the cavity as well, the newer models use two etalons (it sounds like a belt and suspenders to me!)

[vakuum]

some informations for you:

Wavelenght: 530nm
output Power: >46mW
Threshold current: 0.18A
operating current: 0.45A
operating temperature: 20-60°C
beam diameter: 0.1mm
divergence: ~15mrad
Raise and fall time: 10-15ns (the module is made for highspeed modulating at xx MHz!!) it is not made for CW!!
Heater Resistance: 32Ohm (it is a PTC)

drive the Heater with constant VOLTAGE! but the voltage is for every Module individual, so you have to try which value makes best output!
maximal current for the heater is: 50mA
maximal voltage for the heater is: 5V

good luck! :-)

[holokidd]

Good Info Vakuum ! Thank you, how may i ask did you get this info, Corning's been tighter than a clam with thier info on these .............. they said the new G-2000 has 20% better linewidth than the G-1000 (20% of what?LOL)

[mixedgas]

why would you say if it is a etalon you doubt its a good one?

these lasers need very narrow linewidth to stay in focus over long distances and some how they are doing it. with the advances in micro robotics i dont think alighnments would be an issue ........ as soon as i get my grubby little hands on one we will see! The Coherent sapphire lasers use a block/etalon in the cavity as well, the newer models use two etalons (it sounds like a belt and suspenders to me!)

Because its highly irregular to just "glue down" a etalon, and even more highly irregular to not heat one. While I'm used to working on them in one meter cavities, we always heat them, and we can precisely tune their tilt. The amount of tilt is very important, and they are very sensitive to it.

If its just acting as a mode filter, um, maybe its a etalon, but I'm not so sure why one would want such high loss in such a short cavity. Your usually 30-50% down in power when you use one. Besides, its not between the Bragg Grating and the LD. SO it depends on how much 1064 is fed back through the DBG.


I could tell rather quickly if I had a open module here, and could run some tests.

Its not heated, its not on a piezo, so its purely academic at this time. Lets call it a tuning or isolation element, until some one with a mode analyser can mess with it. (Me, Sam Goldwasser , Some of the Europeans, a few of the Holo guys) It really would not surprise me if its a quarter wave plate to get rid of "The Noise Problem" as its known in intracavity frequency doubling.


If that makes extremely stable fringes that shift like crazy while the amplitude of the laser stays basically constant, when just a very slight force is applied to it, its probably a etalon. However the laser video guys want to BREAK coherence before it hits a SLM, so they dont get fringes.

So in other words, I doubt its a etalon, but there is a 10-20% chance I'm wrong.

Steve

[Jem]

Apologies for a 'null' post, but I just *had* to keep a track on this thread

[holokidd]

In the recent past i was able to run thr JDS 532nmn DPSS lasers (@ lower powers) with out any cooling/heating, so its really possible/probable these crystals are warmed slightly (constant) as i see no thermisistor.

yes i too have a Scanning Fabry Peroit Interferometer, But at the present time im lacking Green mirrors to test these so ill revert to my old way to test for SLM by making a hologram w/it.

The main intrest for these lasers is for display technologhy, but if these are used in conjunction w/ a holographic combinder(future systems like Blue Light Optics) it will be nessary to run very narrow-line, i think thats why the new G-2000 has an even finer linewidth.

no doubt these lasers wou'nt stand a chance when the new green direct diodes come out later next year ................. Dave

[mixedgas]

Holokid, if yours is a homemade FP, I can probably dish up some BG mirrors from the box of 250 ion optics.

Steve

[holokidd]

oh cool ! thanks Steve I currently have a pair of concave mirrors Sam gave me for red w/ROC @ 43MM ,and work great for most red diodes and hene , i made my first unit from an old Jodon external mirror HeNe cage. I am now re configuring it into much smaller package ........... its easy to swap out mirrors, and has a very fine focus adjustments.

I can pay you in only gold holograms, you see im just a poor holographer that cant seem to leave the basement !


Corning calls this laser a DFB laser "thru wet processing" it sounds so exciting!....... so it turns out theres a hologram in there dock

im sorry i dont know how to bring this document posted by Pascal if you go to the linked thread and look at post #17 explains quite alot of info Thanks Pascal !

http://www.photonlexicon.com/forums/...ghlight=showwx

[holokidd]

thanks for bringing that post here

[sugeek]

http://www.photonlexicon.com/forums/...chmentid=22566

Fixed the link

1060nmDoublingDiagram.png

im trying to post this Document Pascal placed on another thread...........



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[mixedgas]

Are they 12.5 mm or 15 mm diameter mirrors on your Jodon? If its the usually Jodon 15 I can set you up REALLY GOOD.

Then you can do a contact print for me of a certain grating master I really like. (Legal one, made it by accident one day, not a copy of some one elses grating)
Makes exactly 4 orders and a primary beam, which looks KICKIN with a ion laser.

I used to have access to and maintained a etalon stabilized UV argon with J Lock, and a green argon that was iodine locked. I miss severe coherence.

Steve

[holokidd]

Hey thanks Steve, up till now iv only used the concave mirrors sam gave me, my jodon frame uses the 12.5mm dia. The diameter size dosent matter as i have an edge grinder here ,if i switch to a plano/plano configuration, can I use my dichro mirrors ? Im itching to get that Corning G-1000 in my hands, any day now, any day now.............

Yes i can replicate you Gratings no problem, DCG holograms w/200mw+ Coherent Sapphire 480 nm (yes its SLM)