Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

Buy Site Supporter Role (remove some ads) | LPF Donations

Links below open in new window

FrozenGate by Avery

Sharp GH04955A2G/ The New 495nm diodes

Dr.Laser said:
I sent 4 diodes to CNI and the results came back as following :

494.6nm
494.9nm
494.9nm
494.9nm

All the four tested at 30mW. They are pretty much a spot on 495nm, I was hoping to see a bit of variety in the wl but still can’t complain. I’ll have one built into a GLP as usual and I’m thinking about a PGL running at 300mA.
Click to expand...

Do you know how they measure and define the wave length? Laser diodes emit all internal modes in a 1-2nm wide band. The strength of every mode depends on many factors and changes with time. Do they perform a fit to the data? If yes, than what kind of fit and to what kind of data?

Here two 495nm diodes measured with a high resolution optical spectrometer:

attachment.php


The diode labelled F, has a mode structure with a high variance, while diode J not so much.

Here the same data plotted on a linear scale:

attachment.php



Diode J has one dominant peak, but diode F has multiple ones. They are all spaces by around 0.25nm, which corresponds to the FSR of the bare diode. This is totally normal in every laser diode, but how cni defines a wave length of a diode like the F one with 0.1nm accuracy?

How you want me to specify the wl of the diodes I got?

Singlemode
 

Attachments

  • lin_scale.png
    lin_scale.png
    7.6 KB · Views: 201
  • log_scale.png
    log_scale.png
    7.8 KB · Views: 207





Huh. I found it odd that Dr.Laser got four diodes all so very close to each other. That was not at all what I found, though they were not terribly far apart.
 
jnrpop said:
Really consistent results dr.laser, thanks for sharing :beer:

Just for knows sake, do you get cni to set all your glp's @ 5mw?

J
Click to expand...

Yes, I ask for 5-10mW output.

Singlemode Laser said:
Do you know how they measure and define the wave length? Laser diodes emit all internal modes in a 1-2nm wide band. The strength of every mode depends on many factors and changes with time. Do they perform a fit to the data? If yes, than what kind of fit and to what kind of data?

Here two 495nm diodes measured with a high resolution optical spectrometer:

attachment.php


The diode labelled F, has a mode structure with a high variance, while diode J not so much.

Here the same data plotted on a linear scale:

attachment.php



Diode J has one dominant peak, but diode F has multiple ones. They are all spaces by around 0.25nm, which corresponds to the FSR of the bare diode. This is totally normal in every laser diode, but how cni defines a wave length of a diode like the F one with 0.1nm accuracy?

How you want me to specify the wl of the diodes I got?

Singlemode
Click to expand...

Probably they just report whatever the spectro software shows as the peak value. This is the screenshot they sent me for testing the older 495nm from ebay.

4808e7714233273.jpg


I'm not sure how they report the multi peak diodes.
 
That's an Ocean Optics HR4000 spectrometer on SpectraSuite software. If you look at the peak, it is hardly at 495nm. Looks more like 440nm.
 
Last edited:
Looks to be spot on 488 going of the chart, the increments on the horizontal axis are abit hard to read but 440 is way to the left.

paul1598419 said:
That's an Ocean Optics HR4000 spectrometer on SpectraSuite software. If you look at the peak, it is hardly at 495nm. Looks more like 440nm.
Click to expand...
 
Yeah, that looks about spot on for 488 to me. 400nm is the left-most vertical line on the graph. Resolution makes the numbers a bit hard to read but they're in 20nm increments
 
Oh, the wavelength on the X axis is so small I thought it was between 400nm and 500nm. It is almost unreadable on my laptop.
 
That must be my purchased 488 diode, now happily owned in a one of a kind custom brass host by RB Andrew!

Thank you Dr Laser!
 

Attachments

  • 3BnIU49.jpg
    3BnIU49.jpg
    77.9 KB · Views: 58
Last edited:
Dr.Laser said:
I'm not sure how they report the multi peak diodes.
Click to expand...

Every lasee diode have multiple peaks within its spectral width. In GaN diodes tjeey are separated by >0.1 nm. Herw a picture of a 488nm from the Thorlabs website:

L488P60_OutputSpectrum_450.gif


The amplitude of these peaks changes with time, pressure, temperature and so on.

Ocean optics also shows this on their website:

http://oceanoptics.com//wp-content/uploads/HR4000_Product_Sheet.pdf


The HR4000 has a resolution of 1nm recording to their website and I hardly can see more then 10 data points in a 10nm range of the plot from cni. Specifying the wl of a diode with 0.1nm accuracy with tjia device is just impossible.


Singlemode
 
Are there still some of these diodes available? I've always wanted a cyan color diode.
 
I have 20 diodes and will sell 10 of them. I focus my whole energy now at something that is more important to me, and had no time yet to bin the remaining 10 diodes. Will do it today and open a sell thread.
Plase be patient, I have to work to pay for my bills like most of you. I will prefer honorably members of this forum, who had no chance yet to get one of these diodes and who allready contacted me some days ago.

These diodes are here to stay, so more will come. Just be patient.

Singlemode
 
Singlemode Laser said:
I have 20 diodes and will sell 10 of them. I focus my whole energy now at something that is more important to me, and had no time yet to bin the remaining 10 diodes. Will do it today and open a sell thread.
Plase be patient, I have to work to pay for my bills like most of you. I will prefer honorably members of this forum, who had no chance yet to get one of these diodes and who allready contacted me some days ago.

These diodes are here to stay, so more will come. Just be patient.

Singlemode
Click to expand...

Good to know they are here to stay. I'll keep an eye out for sale threads then. :thanks:
 
Singlemode Laser said:
Every lasee diode have multiple peaks within its spectral width. In GaN diodes tjeey are separated by >0.1 nm. Herw a picture of a 488nm from the Thorlabs website:

L488P60_OutputSpectrum_450.gif


The amplitude of these peaks changes with time, pressure, temperature and so on.

Ocean optics also shows this on their website:

http://oceanoptics.com//wp-content/uploads/HR4000_Product_Sheet.pdf


The HR4000 has a resolution of 1nm recording to their website and I hardly can see more then 10 data points in a 10nm range of the plot from cni. Specifying the wl of a diode with 0.1nm accuracy with tjia device is just impossible.


Singlemode
Click to expand...


This is a great explanation. The graph of the 488nm diode with temperature shows very well how these diodes shift with increasing heat. What I try to do is get the center line at as low at temperature as possible. I keep the temperature at 18 degrees C when I'm testing, though I don't have an active cooling system. I am thinking it would be a great asset to have if I want to continue to measure these diodes.
 
I have everybodys packaged up to go out tomorrow.

Once again I killed my diode. This time, the solder broke off from the driver, shorted out the leads, and killed it. I give up...
 
Man, I had that diode in my hands and could have pressed it and set up the driver before sending it back at no charge. Next time, lets do that. :yh:
 
You must log in or register to reply here.


Back
Top