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Single Mode Diodes

obabo

obabo

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Jun 9, 2022
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Hey everyone, I've been reading the forums for a while and I haven't found many mentions of single mode diodes. Can anyone help me find some companies that sell single mode diodes? Preferably under 5 mw, but if that isn't possible for some reason that's fine.
 





obabo said:
Hey everyone, I've been reading the forums for a while and I haven't found many mentions of single mode diodes. Can anyone help me find some companies that sell single mode diodes? Preferably under 5 mw, but if that isn't possible for some reason that's fine.
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Here's some from a reputable seller: https://www.ebay.com/sch/m.html?_ss...p2046732.m570.l1313&_nkw=single+mode&_sacat=0

If you need it under 5mW then you could just regulate the driving current lower as long as the threshold current is in that vicinity.
 
Shmackitup said:
If you need it under 5mW then you could just regulate the driving current lower as long as the threshold current is in that vicinity.
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I don't have a power meter, is there a way for me to verify that the output is under 5mW?
 
Do you need a diode or could you use a pre built laser pointer for your application?
 
I prefer a diode because I'm practicing building lasers from parts and I like being able to adjust the focus, but if there are cheap pre-built pointers I'll take that too.
 
For pre-builts I would contact sales at Laserglow and see if they can offer you anything. Or even diodes for that matter.

If you go the route of lowering the driving current of a higher power diode, you should at least invest in safety goggles and refer to guides like this or this. Otherwise I would invest in an affordable power meter like a LaserBee
 
It seems clear to me that I'm way out of my depth here. I built my first laser a few weeks ago and it's becoming more clear that I have no idea what I would use a single mode laser for. Do you have any recommendations for beginners? If there's a beginner project recommendation thread I'd like to look at that too.
 
obabo said:
I prefer a diode because I'm practicing building lasers from parts and I like being able to adjust the focus, but if there are cheap pre-built pointers I'll take that too.
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Single mode lasers are more about quality of the light, not quantity. A 5 to 10mW He-Ne can be built easily at home with a surplus tube, and run all day and night with the best beam ever.

Single mode lasers get real expensive real fast as the power increases, but they can be used to make holograms and do lots of other sciencey things. Multimode lasers are good for burning, cutting, etching, and drilling. If you're really ambitious, build an extended-cavity diode laser to give you a stable single mode beam.
 
obabo said:
It seems clear to me that I'm way out of my depth here. I built my first laser a few weeks ago and it's becoming more clear that I have no idea what I would use a single mode laser for. Do you have any recommendations for beginners? If there's a beginner project recommendation thread I'd like to look at that too.
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If you built a laser already that’s a good sign. What did you build? There are lots of threads about what to do/learn as a beginner, you can use search or look through various threads on the home page.

Why did you want single mode in the first place?
 
julianthedragon said:
If you built a laser already that’s a good sign. What did you build?
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I built a 5mw 650nm laser from an Aixiz diode and an lm317 current regulator, with a 9v battery as a power source. I know the beginner thread recommends using something other than 9v, but it was all I had on hand.
julianthedragon said:
There are lots of threads about what to do/learn as a beginner, you can use search or look through various threads on the home page.
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I read some of them along with a textbook on the fundamentals of light, lasers, and laser safety.
julianthedragon said:
Why did you want single mode in the first place?
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I wanted to try making an interferometer and observing the interference pattern it makes, but beyond this I have no idea what I would use it for.
 
Many diode lasers will run single mode when just above threshold current. Look for interference fringes in the reflections from a piece of glass ( a simple form of what's called a "shear plate" or "shearing interferometer") to know if it's running that way. Most applications needing a single mode laser need it to be stable, so they are usually bolted down and plugged in. That's why there's little mention of them here. If you really want to experiment with interferometers, get a cheap He-Ne and cruise the holography forums.
 
Hi,
Single mode diode have great divergence to start with, and can be made for lower powers. I made many for customer in the past .
Hope you find what you want.
Rich:)
 
Any laser over 5mw has the potential to damage our eyesight and accidents do happen, so if you do work with anything over 5mw make sure to get the correct laser safety glasses for the wavelength you will be working with and make laser safety a good habit.

Glasses can be found here and here.

Laser power meters here.
 
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Also single mode diodes can be combined in several ways to increase the power and give you a better beam profile than a multimode. But again, the higher the power the more complicated doing it and more expensive.

Knife edging, Cubes, Dichroics (am I missing any?)
 
Did anyone mention coherence length for laser in an interferometer?
 
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