Help with SFP Cable

Hello everyone.
My home network basically stretches across my entire property, which could land a plane if needed. Most is wifi, but between my home, barn, and solar array, I have a single Cat6 ethernet cable running (mostly) underground.

I want to electrically isolate that cable from the network inside my home in case of a lightening strike, and I figure the best way to do this is to install a fiber optic cable somewhere between the barn's Cat6 line and my home's main switch. I don't need to worry about my modem or router because they have no physical connection outside the home since I use a cellular ISP. My home's breaker box is already protected by a Siemens FS140 surge protector, but I need to protect the network as well.

In my basement is a Netgear GS728TP 28 port gigabit POE switch. It has four SFP ports. I want to use one of them for that Cat6 cable running to the barn.

I'm shopping Amazon and found this:

The amazon thing look like an adapter to turn an ethernet cable into an SFP cable.. converts the signals?

But when I look at Amazon for the SFP cables and modules, they seem to be copper.. Huh? "High quality oxygen free copper" and bla bla bla.. I thought these cables would be a fiber optic.. What am I missing?

I thought the SFP transiever module would convert the ethernet electrical signals into pulses of light.. Now I'm confused..

You just need an optical SFP module, as opposed to a copper SFP module, something like this:

The above may or may not be exactly what you need, but shows that what you want is on Amazon if you search harder.

For an optical module, you need to match the optical fiber type SM single mode, or MM multi mode, to the SFP module type (SM or MM).

SM fiber is for higher speed (ie, 10Gb+) and/or longer distance (in kilometers), typically blue in color, and more expensive.
MM fiber is for lower speed (100Mb - 1Gb) / shorter distances (in tens or hundreds of meters), typically orange in color, and less expensive.

And a cable something like this:

AK6DN said:

You just need an optical SFP module, as opposed to a copper SFP module, something like this:

Amazon.com

The above may or may not be exactly what you need, but shows that what you want is on Amazon if you search harder.

For an optical module, you need to match the optical fiber type SM single mode, or MM multi mode, to the SFP module type (SM or MM).

SM fiber is for higher speed (ie, 10Gb+) and/or longer distance (in kilometers), typically blue in color, and more expensive.
MM fiber is for lower speed (100Mb - 1Gb) / shorter distances (in tens or hundreds of meters), typically orange in color, and less expensive.

And a cable something like this:

Amazon.com

Click to expand...

That helps a lot.. Thank you.

When searching amazon, everything is copper.. Just figured out that's what DAC stands for.. .. The search has to be specific, and until your post, I didn't know.. Found what I think I need thanks to you.

As a follow on, I purchased these a while back:
SFP optical module: Amazon.com
Wired GIGE adapter: Amazon.com
and use them when I need a very long run (100m) of ethernet connectivity at high bandwidth
where wireless is not acceptable to me. Just plug and play, no configuration needed, inexpensive.

I ended up purchasing these:

Took the cable coming from the barn out of the main 24port switch, plugged in the fiber optical setup, and it works flawlessly. Can't even tell it's there.

Now my outdoor ethernet stuff is electrically isolated from the house. If lightening strikes something out there, the surge might blow the electronics outside, but it won't make it to my main network inside the house.

Thank you AK6DN for the help.. huge help. This was so easy to setup that I'm thinking of doing it again. I figure the more of my network that is isolated, the less damage a surge can do.