Low power diode collimating lens wavelength range

[techygrizz]

Hey y'all,

I've got a 5mW 1310nm TO-56 diode I am trying to power for a scientific measurement application. When I run it up near its max current, I appear to get only 0.1 mW output when it should be approaching 10mW. I'm using a cheap fibre optic power meter (-7 to 10 dbm) for communications and the voltage across the diode is reasonable so I think the issue is the beam being to divergent for the measurement method. I measured by placing the meter directly up against the diode.

Safety note:
I have laser safety training and work with UV lasers up to 11W while doing high power beam path measurements and low power alignment. I have more than sufficient safety glasses for my SWIR diode, OD 5+ for my wavelength. But if there is something else I should know about IR at this power, I am all ears.

The question:
So, I need a collimating lens. I have found several examples the right size on AliExpress but they all state a limit like 200-1100nm which doesn't include my wavelength. At this low power, does that matter? I do not know enough about optics to know. Where do I look for lens and free-space couplers?

 

[RedCowboy]

The acrylic lenses are non coated IINM but in order to fiber couple you need a narrow angle of approach as well.
That is your divergence needs to be low.

Redirect Notice

Take a look at these

Here

and here

 

[RedCowboy]

Light to Fiber Couplers/Collimators

Product PortfolioFor collimation or focusing tasks, a very broad and complete line of fiber optic components is available for coupling light into and out of optical fibers. Depending on the fiber’s core and cladding diameter and the required optical perf…

shop.amstechnologies.com

 

[kecked]

Measure the absorbance of the lens…..it might be eating your power.