How? I have no idea. I don't think anybody ever actually implemented the 1Gbps physical protocol.

Yeahhhhhh. Nice dreamin', folks.

The fastest I recall being implemented was the 4Mbit FIR:

https://www.amazon.com/Compex-iRE201-Infrared-Wireless-Access/dp/B00006B74G

Though evidently common palmtops couldn't take advantage of it:

http://www.palminfocenter.com/news/4504/review-compex-ire201-ir-access-point/

I assume the 4Mbps hardware would've been more common in laptops. Hmm. I wonder if any of mine in the basement have IrDA. I remember it being everywhere for a while, but I don't know if I bought anything new during that era.

I've gotten SFP's to link over a few inches of free space, I haven't been willing to drop the coin at Thorlabs to do more. ;)