Fiber Optics — Advanced
FTTH/FTTX architecture — bringing fiber to the subscriber
"FTTx" describes a family of fiber-deployment architectures distinguished by how close to the subscriber the fiber actually reaches: FTTH (Fiber to the Home) runs fiber all the way to the subscriber's premises, offering the highest performance and future-proofing but the highest deployment cost; FTTC (Fiber to the Curb/Cabinet) runs fiber to a nearby street cabinet, with the final short stretch to the subscriber typically over existing copper (VDSL or similar), balancing cost against performance; FTTB (Fiber to the Building) runs fiber to a building (common in dense multi-unit residential deployment), with internal building wiring (often existing copper or short internal fiber runs) covering the final distance. The architecture choice is fundamentally a cost/performance tradeoff — FTTH is the clear long-term-capacity winner, but FTTC/FTTB were often chosen historically where full FTTH deployment cost couldn't be justified for the addressable subscriber base.
PON — the dominant FTTH access architecture
Most FTTH deployments use a Passive Optical Network (PON) architecture: a single fiber strand from the operator's central office runs to a passive (unpowered) optical splitter located near a cluster of subscribers, which then splits the signal to individual fiber runs to each subscriber premises. "Passive" is the key architectural property — the splitter itself requires no power and no active electronics, meaning the operator doesn't need to power/maintain equipment out in the field between the central office and the subscriber, substantially reducing both capital and ongoing operational cost compared to an architecture using active (powered) equipment at that intermediate point. Multiple PON standards exist (GPON, XGS-PON, and evolving higher-capacity variants), differing primarily in the capacity offered per subscriber and the split ratio (how many subscribers share one feeder fiber). (needs verification — recheck against current source: specific PON standard capacities and adoption rates continue to evolve as operators upgrade deployed networks.)
Optical network design tradeoffs
Designing a real optical network requires balancing several Advanced-level considerations simultaneously: the DWDM channel plan (how many wavelengths, what spacing, balancing capacity against equipment cost and cross-channel interference risk), amplifier placement (spacing EDFAs closely enough to maintain signal quality without excessive equipment cost), and PON split ratio (a higher split ratio serves more subscribers per feeder fiber, reducing per-subscriber infrastructure cost, but reduces the bandwidth available to each subscriber during periods of simultaneous high demand across the split group). None of these are solved independently — a network architect's actual job is finding the combination that meets a target capacity/reliability/cost profile for a specific deployment's subscriber density and demand pattern.
Why fiber remains fundamental even in an all-wireless-seeming world
5G's radio access network (Wireless Tech) still depends on fiber for backhaul — the connection from each cell site (gNodeB) back to the core network — because radio spectrum alone cannot carry the aggregate data volume a dense 5G deployment generates back to the core; fiber's capacity and reliability make it the default backhaul medium for any cell site where fiber access is available (with microwave backhaul used as an alternative where fiber deployment isn't practical). This is the concrete link between Wireless Tech's radio-access material and Fiber Optics' wired-infrastructure material — they're not competing technologies but two layers of the same end-to-end network.