NTT Introduces Invisible Indoor Fiber Optic Cabling Solution


Japanese Telecommunication service provider NTT has developed an innovative solution for indoor fiber optic cabling that takes care of the aesthetic beauty of the indoor walls. The new cable and the fixing accessories are transparent in color sot that they are invisible to view. Installation of this cabling system does not damage the beauty of your interior walls. NTT calls it an invisible indoor cabling solution or transparent indoor cabling solution.

NTT developed the invisible indoor cabling solution based on the inputs from potential customers that the indoor fiber optic cable to be installed in their homes shall be matching to the interior wall color. Different homes may have different colored interior walls. Matching the color of all homes that may have different colors posed a challenge to the operator. Also, the provider learned that there are some sections in the potential subscribers, who delay the installation of indoor cables due to the concern of damage or unpleasant look to their walls. NTT engineers developed transparent cables and transparent fixtures to provide all transparent solution so that it will suit interior walls having different colors. Transparent colored cables and fixtures are invisible after installation and therefore, do not damage the view.

What is Transparent Indoor cable?

The transparent indoor cable is simple in its construction. In fact, it is simply a tight-buffered optical fiber. Tough and weather-resistant jacketing material is extruded over the optical fiber to form the cable. The outer diameter of the cable is 0.9 millimeters. Normal tight buffers used in pigtails and patch cords also have 0.9 millimeters. Since the diameter is less than 1 millimeter, this cable is easy to handle and deploy. The weight of the tight coated cable is around 0.7 kg/km. No special tools are required for installation since the cable is handy.

NTT uses hole-assisted-optical fibers in transparent indoor cables. Hole-assisted fibers (HAF) comply with ITU-T G.657.B3 requirements. In fact, hole-assisted fibers exceed the requirements for bending loss characteristics are stipulated in ITU-T recommendations. Hole-assisted optical fibers are designed with holes in the cladding region surrounding the core so that the escaping light is returned back from going out when bent around small diameters. This makes the fiber suitable for installation at corners and through door gaps. The transparent indoor cable can also be installed through door or window gaps.

Special connectors are required to match the design of hole-assisted fibers. NTT utilizes the design of their field-installable SC connectors and added slight modification so that the connector can be used for hole-assisted fibers.

Solid refractive index matching material for Connector

For normal field assembly SC connectors, a liquid refractive index matching gel is used to ensure the splicing characteristics. The same liquid refractive index matching gel will not work well with hole-assisted fibers. The splice loss characteristics are degraded if the same refractive index matching gel is used. The matching material penetrates the air holes in the hole-assisted fiber and a void is formed between the fiber end faces. NTT solves this problem by using a solid refractive index matching material.

Installation using a transparent indoor cable is not visible to the eyes. However, if looked specifically to find out the cabling route, it is possible to identify and trace. To further improve the aesthetics of the room, NTT uses transparent fixtures. The fixtures are available as pin-point type or protection type, and both of these types are also sorted into two styles. This component is fixed in place with double-sided tape. The multi-type can be fixed to different kinds of walls with double-sided tape, plaster pins, or screws. All the fixtures are transparent in color.


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