Laser power levels in SFP's/GBIC's

[FutureOne]

Hello guys.

IT related question. I was putting together some Fiber Channel cables for a server install.

By accident I looked into a live SFP module with the cable unplugged (had that IR very dim red color)

Now I've worked with this kind of equipment for a while, but I don't think I've ever gotten a direct hit from one of these like today.

Some google searching seems to yield that these modules tend to be anywhere between 0.3mW and 1.6mW at wavelengths of 808nm to 1500nm

Here's a link of common Cisco modules:

Cisco SFP Modules for Gigabit Ethernet Applications Data Sheet - Cisco

Seems that data on actual mW output of these is very hard to find.

I can't imagine that these diodes are large enough to cause any serious damage, but being a paranoid freak, I am mildly worried now lol

Anyone have knowledge/experience with these?

 

[H2Oxide]

From what I can find, Cisco modules use a class 1 laser. Though I'd be interested to see where you got the 0.3mW-1.6mW figures.

From Wiki:
"A Class 1 laser is safe under all conditions of normal use. This means the maximum permissible exposure (MPE) cannot be exceeded when viewing a laser with the naked eye or with the aid of typical magnifying optics (e.g. telescope or microscope)."

So basically, if you pointed it in your eye there shouldn't be any damage whatsoever. Of course, that's assuming it actually was a class 1 laser.

 

[Benm]

You should probably not be worried. A disconnected fibre output doesnt produce a very narrow beam at all, so if you were at any distance from it most of the light would probably have missed your eye in the first place.

You shouldn't put an optical ouput up to your eye to check if any light is coming out, but at arms length everything is probably just fine - i'm sort of surprised you noticed it at all. Perhaps it was 808 nm which is visible to some degree, whilst 1500 nm would be invisible at power levels that, literally, set things on fire.

 

[Cyparagon]

The datasheet for this 8gb fibre channel transceiver uses <1W for one channel, so maybe 100mW? Not sure if laser output power correlates with input power in this case.

From what I can find, Cisco modules use a class 1 laser.

The class is only an indication of power output if the beam is accessible. A Bluray burner with a 600mW laser inside is also a class 1 device, because there is no way the user can peer into the beam without major modification. Some infiniband optical cables have the transceivers build into the cable. As such, it could be anything between 1mW and 10W and still be labeled class 1.

 

[H2Oxide]

The datasheet for this 8gb fibre channel transceiver uses <1W for one channel, so maybe 100mW? Not sure if laser output power correlates with input power in this case.



The class is only an indication of power output if the beam is accessible. A Bluray burner with a 600mW laser inside is also a class 1 device, because there is no way the user can peer into the beam without major modification. Some infiniband optical cables have the transceivers build into the cable. As such, it could be anything between 1mW and 10W and still be labeled class 1.

Yep, my bad. Cyp is right as usual.

 

[FutureOne]

The datasheet for this 8gb fibre channel transceiver uses <1W for one channel, so maybe 100mW? Not sure if laser output power correlates with input power in this case.



The class is only an indication of power output if the beam is accessible. A Bluray burner with a 600mW laser inside is also a class 1 device, because there is no way the user can peer into the beam without major modification. Some infiniband optical cables have the transceivers build into the cable. As such, it could be anything between 1mW and 10W and still be labeled class 1.

Hmm, very interesting. Thank you guys.

Well, 2 days later and my sight is still ok, and I seem to still have 20/20 vision

So I guess I'm good to go.

I don't make a habit of staring into transceivers lol. If I have to troubleshoot connectivity, I like to just do it thru the switches themselves.

In this case, I unplugged a cable, as I wanted to replace with another one, and happened to stare directly into the open transceiver. Saw the reddish color, and remembered these could potentially be higher wattage IR laser diodes, and got a bit worried.

Anyway, I did a bit of searching and found the exact SFP that I was working with:

https://www.finisar.com/optical-transceivers/ftlf8529p3bcv

Looks like frequency is 850nm on that one, which explains the dull reddish color.

And the datasheet says it's class 1 laser, but no power specs that I can see, but it does say it's 50-62.5 Multi Mode Fiber, which I know are typically much lower power than Single Mode (phew!!)

So my understanding is that frequencies in the IR range are absorbed mostly by the cornea. Is that the way it is?

EDIT: Multiplying the supply voltage of 3.46v by the current of 290mA, gives us almost exactly 1W of power. So it is essentially identical to the HP transceiver in Cyaragon's link.

I also found this link:

http://media.digikey.com/pdf/Data Sheets/Finisar/HFE7192-xxx.pdf

That looks like the actual VCSEL diode used in these SFP+. It says a max output of 10mW, and classified as Class 1M (large diameter beams)

Man I thought I knew a bunch, but I've learned a ton more haha

 

[Benm]

You were right to be concerned about the 'dull red color'. Seeing that can be a clear sign of danger, though it is very hard to estimate how much power is actually there.

It's a similar thing with 808 nm pump diode light: very dangerous when looking directly into a diode, but also visible from a meter away when shining onto a matte piece of paper (no danger there provided it's actually matte).

If in doubt, avoid