Downhole fiber optic transmission for real-time well monitoring and downhole equipment actuation

A subsea wellhead system, comprising:

• a hanger comprising a bore and a first fiber optic cable;
• a tree configured to be landed on the hanger, wherein the tree comprises a bore and a second fiber optic cable, wherein the second fiber optic cable is configured to extend from a surface location;
• a seal sub configured to be coupled to the tree and configured to be landed in and engaged with the hanger, wherein the seal sub comprises:
• a bore;
• and
• a fiber optic communications line that is configured to be communicatively coupled to both the first fiber optic cable and the second fiber optic cable;
• a power supply configured to be disposed at a downhole location about a tubing string suspended from the hanger, wherein the first fiber optic cable is configured to be communicatively coupled to the power supply and to extend between the power supply and the seal sub;
• a first photodetector disposed in the seal sub and communicatively coupled to the fiber optic communications line, the first photodetector configured to convert a light signal traveling through the second fiber optic cable from the surface location to an electrical signal communicated to the electrical connection;
• and
• a first optical transmitter disposed in the hanger and configured to be communicatively coupled to the first fiber optic cable, the first optical transmitter configured to convert the electrical signal traveling through the electrical connection into a light signal communicated to the first fiber optic cable.