How fast is fiber in traditional Kbps/Mbps/Gbps language? 100Gbps?
Theoretically it can go all the way up to Pbps (i.e. petabits per second), I believe.
What you actually get depends on what hardware you have and how much money you want to spend. (And on the type of the fiber line itself – e.g. obsolete OM1 fiber doesn't have anywhere near the same capacity as modern variants.)
So in practice, if you just want a fiber LAN at home, then either 1 Gbps or 10 Gbps will be the most common options. (1 Gbps converters/modules can go as low as $10 each, while 10 Gbps is still a bit more expensive.) And most ISPs providing FTTH will also use 1 Gbps connections.
On the other hand, many ISPs and other large network operators have already moved to 40 Gbps and even 100 Gbps links for the "backbone" connections.
Don't forget that it is possible to send multiple signals over the same fiber simultaneously, using different wavelengths (colors) – just like different radio frequencies. (This is usually called WDM.) So if one 100 Gbps connection isn't enough, you can have two, or five, or a hundred.
Is it possible to set up a private fiber network in an office? What hardware would be required?
Yes. But the hardest part is the actual fiber cabling installation (precisely attaching connectors, etc.) – I know practically nothing about this. You should probably just find an installer and have them tell you what's needed.
(Note that there are different types of the fiber cable itself. "Single-mode" is probably much more future-proof than "multi-mode" especially at long distances.)
You usually plug the fiber connector into a SFP transceiver module slotted into the switch, router, or computer. The transceiver module is what actually has the optics and performs signal conversion & decoding, while the actual switch only sees the electronic data transmission.
There are multiple different module types (SFP for 1G, SFP+ for 10G, QSFP, etc.) and the modules themselves are for different kinds of fiber types – multi-mode, single-mode, single-mode bidirectional. Even for the same kind of fiber, there might be modules for different wavelengths (this obviously must match on both ends).
Is there such a thing as a LAN router or switch that uses fiber optic cable rather than ethernet/twisted-pair cable?
Yes, many switches and routers have slots for "SFP" or "SFP+" modules alongside regular copper Ethernet ports (e.g. 24xcopper + 4xSFP), and there are models which consist entirely of SFP slots as well.
(They use modules instead of having fiber optic ports built in, because different types of fiber connections exist and might even be mixed in the same network, and because the optics sometimes go bad and it's easier to swap a module than a whole switch.)
What sort of networking cards are available for "fiber to the device"?
Again there are PCIe Ethernet cards with SFP or SFP+ slots. There are also dedicated "media converter" boxes, with one copper Ethernet port and one SFP slot (or a built-in fiber optic port).
What is the driver and software support like on various operating systems for fiber?
As far as the OS cares, Ethernet over fiber optic works like regular Ethernet. The PCIe SFP card will have its own driver just like any Ethernet card would, but you don't need any special software other than that.
(Of course, there are other network types that use fiber optics – not just Ethernet – but you usually won't run them directly to your computer. For example, GPON which is used by many ISPs for FTTH probably does need extra configuration.)
When I google for "fiber router"
Well, on a LAN you primarily want a fiber switch anyway. Routers usually don't handle traffic inside the LAN – they just sit between the LAN switch and the WAN connection.
You'll get better results if you google for something like "switch 16x sfp" – most of the time, the product information page specifically mentions the module type (SFP for 1Gbps, SFP+ for 10Gbps, then there's QSFP, etc.)
