Rotary spinner apparatuses, systems and methods for producing fibers from molten materials are disclosed. Certain exemplary embodiments include substantially net shape single pattern rotary spinner castings that include gussets extending radially inward from a side wall and axially upward form a lower wall to an upper wall. A dispenser may be structured to supply molten material in a downward direction through a hollow interior of the casting to the lower wall. A plenum may be structured to direct elevated temperature glass toward an exterior surface of the casting.

A coupled-core multi-core fiber in which an inter-core distance is stabilized is manufactured. A method of manufacturing a coupled-core multi-core fiber includes forming a second cladding base material by depositing glass particulates on an outer periphery of a first cladding base material and sintering the glass particulates. The first cladding base material has a hydroxyl group concentration that is less than or equal to 10 ppb; obtaining a ground rod by grinding an outer periphery of the second cladding base material; and forming holes in the first cladding base material in the ground rod, inserting a core base material into each of the holes, and obtaining an assembly.

An internal combustion burner including a combustion chamber supplied with fuel and with oxidant and at least two combustion devices supplied with oxidant and with fuel. Combining two combustion devices of distinct configurations, which respectively generate two distinct types of flames with a system for cooling the walls of the burner by introducing air along the walls, makes it possible to obtain a burner that supplies a combustion gas temperature of up to 1700 C., while at the same time being easily cooled and occupying very little space so that it can, for example, be housed in an existing installation used in the manufacture of rock wool or glass wool.