Optically powered telephone system over optical fiber with high service availability and low risk of investment in FTTH infrastructure

The plain old telephone service, POTS, still generates the largest proportion of public network operators' revenues. If optical communications systems are to compete with traditional twisted-pair copper systems in delivering telephony, they must achieve the same levels of cost and service availability, offer low-risk investment in optical fiber infrastructure, and satisfy the same regulatory requirements. Interferometic optical communications system can meet these requirements, in which the laser in the CPE is replaced by an interferometer for the outgoing voice channel, and part of the received optical power is converted to electrical power using photovoltaic cells and an energy storage device to drive the CPE. The reach of the system is similar to locally powered laser systems in the downstream direction, but back reflections and scattering can affect the upstream link if the communications and powering signals share the same path.