ECDL setup with custom controller

[paul1598419]

No you missed the point. Errors are not all the same. Typographical errors are not spelling errors. And words that sound the same, but are not aren't either. I've already explained myself on this. Just can't let it go can you?

 

[Unown (WILD)]

No you missed the point. Errors are not all the same. Typographical errors are not spelling errors. And words that sound the same, but are not aren't either. I've already explained myself on this. Just can't let it go can you?

Paul you're hopeless

 

[RedCowboy]

You entirely missed the point that you criticized someone for an error but then proceeded to make them yourself.

Unown..... You gave me a " Time out " for doing exactly what you are doing right here. Going back and forth with paul, even though it was on the thread topic. As a moderator you should be above attacking typos when you are so hypercritical of others. You should not be instigating/attacking.

If you point out a typo then you should spend ( 1 ) sentence to do it politely and then no more, as a proper authority figure.

And you should never, block someone for pointing out your obvious shortcomings, you should say ( Thank you ) and correct the behavior.

If you block me for saying this I will contact Avery and I hope everyone else will too. A moderator should not be a bully !

 

[Unown (WILD)]

Unown..... You gave me a " Time out " for doing exactly what you are doing right here. Going back and forth with paul, even though it was on the thread topic. As a moderator you should be above attacking typos when you are so hypercritical of others. You should not be instigating/attacking.

If you point out a typo then you should spend ( 1 ) sentence to do it politely and then no more, as a proper authority figure.

And you should never, block someone for pointing out your obvious shortcomings, you should say ( Thank you ) and correct the behavior.

If you block me for saying this I will contact Avery and I hope everyone else will too. A moderator should not be a bully !

This coming from someone who wants Paul permabanned. Honestly don't know why you're adding to this pointless argument. You were temp banned for posting seriously inappropriate gifs. I mean you are in no position to start lecturing.

 

[Singlemode Laser]

Sorry, after beeing a long time a scielent reader, I have to put my 50¢. By posting a how to build an ecdl was done 10000 times.

Better than you could here. No results so far, but a lot to say. Modulating the laser within the cavity will give you the most side peaks at the FSR, but this is not a pulsed or a mode locked laser.

Singlemode

 

[Singlemode Laser]

The roundtrip time of this resonator is around 250 ps so 10+ GHz photodiode would useful for analyzing pulse forming in external cavity (but that's foreshadowing future events ). I have access to 28 Ghz 4 channel oscilloscope, so that's not an issue. The best I could find that don't cost an arm and a leg have bandwidth of 3 Ghz max, so I may have to extend cavity length. This would be unfortunate for pulsed experiments though (more foreshadowing).

I can't dig up papers right now, but basically modulating a laser diode with RF at close to cavity round trip time can create spectrum similar to mode locked lasers.

If your cavity is 100mm long, then your fsr is 1.5GHz. not 10GHz. This is easily detectable by a standard pd with a bias and an RF amp.

 

[paul1598419]

If your cavity is 100mm long, then your fsr is 1.5GHz. not 10GHz. This is easily detectable by a standard pd with a bias and an RF amp.

Singlemode, long time no see. It sure is good to see you posting again. Hope you'll post more as time allows.

 

[atomd]

If your cavity is 100mm long, then your fsr is 1.5GHz. not 10GHz. This is easily detectable by a standard pd with a bias and an RF amp.

FSR is 1.5GHz (as you can see I put round trip ~250ps) but to analyze pulse evolution in laser cavity you need much higher bandwidth thanks to highly nonlinear effects in the resonator:

Sci-Hub | Generation and optimum control of picosecond optical pulses from gain-switched semiconductor lasers. IEEE Journal of Quantum Electronics, 24(8), 1519–1523 | 10.1109/3.7078

Sci-Hub | Picosecond pulse generation in semiconductor lasers using resonance oscillation. Electronics Letters, 16(15), 587 | 10.1049/el:19800407

Sci-Hub | On the relationship of light‐output nonlinearities and light‐output spikes in proton‐bombarded stripe‐geometry double‐heterostructure (Al,Ga)As lasers. Journal of Applied Physics, 50(2), 1128–1130 | 10.1063/1.326093

Sorry, after beeing a long time a scielent reader, I have to put my 50¢. By posting a how to build an ecdl was done 10000 times.

Better than you could here. No results so far, but a lot to say. Modulating the laser within the cavity will give you the most side peaks at the FSR, but this is not a pulsed or a mode locked laser.

Singlemode

You can get mode locking in ECDL under certain conditions:

Picosecond Pulse Generation with Diode Lasers

Interest in semiconductor picosecond devices has been stimulated by recent reports of ultrashort pulse generation by modelocking in GaAℓAs diode devices [1–3]. The transferability of this technique to longer wavelengths, where such pulses can be...

link.springer.com

Sci-Hub | Picosecond pulse generation with a cw GaAlAs laser diode. Applied Physics Letters, 33(3), 241–242 | 10.1063/1.90312

Thank you for the "constructive" criticism. If you'd like to add something more, you're very welcome.

 

[kecked]

Quick google turned up this most excellent document

https://www.holographyforum.org/data/pdf/aa-Collection_a_k/aa-Laser/aa_ECDL/Nyamuda-Design_and_development_of_ECDL.pdf

 

[atomd]

Last time I wrote introduction post about optics in the ECDL. Now let's talk about custom driver designed for it. The driver has to do the following:

1. Provide low noise, constant current for driving laser diode
2. drive two Peltier modules with sufficient resolution
3. Measure temperature of important elements
4. stabilize the temperature inside the cavity
5. have some easy adjustment and monitoring

For simplicity, I opted for digital solution. TEC, thermistors and LD river are connected to microcontroller that implements all control algorithms. It also allows to easy adjustment of operating point over USB.


I also printed first, prototype enclosure. Full device currently looks like this:
As always more technical details can be found on my blog: https://sduc6.blogspot.com/2024/04/external-cavity-diode-laser-part-2.html

 

[Singlemode Laser]

FSR is 1.5GHz (as you can see I put round trip ~250ps) but to analyze pulse evolution in laser cavity you need much higher bandwidth thanks to highly nonlinear effects in the resonator:

Sci-Hub | Generation and optimum control of picosecond optical pulses from gain-switched semiconductor lasers. IEEE Journal of Quantum Electronics, 24(8), 1519–1523 | 10.1109/3.7078

Sci-Hub | Picosecond pulse generation in semiconductor lasers using resonance oscillation. Electronics Letters, 16(15), 587 | 10.1049/el:19800407

Sci-Hub | On the relationship of light‐output nonlinearities and light‐output spikes in proton‐bombarded stripe‐geometry double‐heterostructure (Al,Ga)As lasers. Journal of Applied Physics, 50(2), 1128–1130 | 10.1063/1.326093

You can get mode locking in ECDL under certain conditions:

Picosecond Pulse Generation with Diode Lasers

Interest in semiconductor picosecond devices has been stimulated by recent reports of ultrashort pulse generation by modelocking in GaAℓAs diode devices [1–3]. The transferability of this technique to longer wavelengths, where such pulses can be...

link.springer.com

Sci-Hub | Picosecond pulse generation with a cw GaAlAs laser diode. Applied Physics Letters, 33(3), 241–242 | 10.1063/1.90312

Thank you for the "constructive" criticism. If you'd like to add something more, you're very welcome.

Google for 497nm ecdl (Arxiv). They have the simplest design ever and still running at NASA/JPL.


Singlemode