Abstract: Repeaters for use in amplifying optical data signals transmitted through undersea fiber optic cables are disclosed. Raman amplification schemes using 100 or more pump lasers are integrated into industry standard sized pressure vessels for amplifying optical data signals transmitted through one or more fiber optic pairs. Such repeaters include high density packaging to permit numerous active and passive optical components, as well as significant lengths of optical fiber, to reside within legacy sized pressure vessels.

Abstract: A heating module keeps a length of erbium-doped optical fiber at a constant temperature. The heating module includes the erbium-doped optical fiber, a heating element, and a temperature sensor embedded in a flexible circuit substrate. Insulating and packaging layers may be placed around the flexible circuit substrate.

Abstract: A retainer provides locking and compliance between components. In a first implementation, the retainer includes a non-compliant member and a compliant member. The non-compliant member is configured to expand in a first direction. The compliant member attaches to the non-compliant member and is configured to deflect forces applied to the non-compliant member in the first direction or a second direction opposite to the first direction. In a second implementation, the retainer includes a rail and a group of wedge segments configured to attach to the rail and expand in a first direction. At least one of the wedge segments includes an integrated spring element.