In SMF, the optical signal propagates in an area of about 10 µm, so to connect the fiber, it must be positioned with a high precision of better than about 1 µm.
On the other hand, in an optical connector, external forces may act through the optical cable. Especially in the optical communication network, the optical connectors are installed on the terminal board at a high density, and the telephone office performs line switching work every day, so the cables of the existing lines are often contacted during the work. Connection performance must remain stable even when force is applied to the cable.
The optical connector housing is also elastically deformed through physical contact technology, pressing the ferrules together to maintain a stable connection. This deformation can reach several tens of μm, and it is difficult to ensure the positioning accuracy required for the above-mentioned SMF. To avoid this problem, a floating mechanism is employed, in which the ferrule holding the optical fiber floats, and the deformation of the outer casing does not affect the positioning of the optical fiber.
As mentioned above, the physical contact technology and floating mechanism developed in Japan became the basis for subsequent optical connector technologies, which are used in the currently mainstream SC-type and LC-type optical connectors.
