Fiber optics: Learn all about the technology

Thanks to fiber optics, various data can be transmitted in the shortest time possible. In the process, light signals are transferred via a thin thread of glass. The new technology of telecommunication is insensitive to interference from outside and guarantees stable connections. Therefore, it is a secure solution when large amounts of data are to be uploaded or downloaded.

Optical fiber.

Thanks to fiber optics, various data can be transmitted in the shortest time possible. © Deutsche Telekom AG

Optical fiber is the fastest way to transmit digital data via the fixed network internet by transporting optical signals. In this way, customers with a fiber optic home connection by Telekom currently benefit from download speeds of up to 1 Gbit/s. To ensure that more and more people can have access to this technology in the future, Telekom is constantly driving forward the expansion of fiber optics in Germany.

Fiber optics is the technology of the future in telecommunications and is of crucial importance for digitization in Germany. Steadily increasing data traffic due to ever more complex and data-intensive applications – both in the private sector and in industry – is driving demand for fiber optic connections.

Deutsche Telekom is continuously investing in broadband technologies such as optical fiber. Today, Telekom’s fiber optic network already covers more than 600,000 kilometers in Germany alone. Thanks to fiber optic expansion, the network is constantly growing.

What is fiber optics?

In data transmission using fiber optics, information is transmitted in the form of light via the optical fibers. The light signals used in data transmission are produced by fiber lasers. The laser feeds the light signal into the core of the optical fiber via a laser diode.

To ensure that data can be transmitted smoothly using fiber optic technology, the structure and properties of the fiber optic cables are crucial. A fiber optic cable consists of several layers that ensure that the optical signal can be transmitted over long distances.

  • The core: This is where the optical signal is transmitted. The core of a fiber optic cable is at least 9 µm thick and is made of silicon quartz glass.
  • The inner cladding: Around the core is another layer of glass, the so-called inner cladding. This layer of glass has a lower refractive index than the core, which ensures that the light signal is completely reflected in the core and does not leak out.
  • The outer cladding: This is the outermost layer of the fiber optic cable. The outer cladding is made of plastic, which increases the load capacity and resistance to external influences.
  • The different layers of the fiber optic cable ensure that the light signals do not leak out of the cable and guarantee fast and interference-free data exchange. 

The different layers of the fiber optic cable ensure that the light signals do not leak out of the cable and guarantee fast and interference-free data exchange. 

What is FTTH?

There are various methods of connecting a customer to the fiber optic network. 

  • FTTX is the generic term used to describe the different types of fiber optic connection, with the X being replaced in each case by the corresponding end point of the optical fiber:
  • FTTH: This abbreviation stands for "fiber to the home" and enables a direct connection to the customer's home or office. This version offers the best possible data transmission performance, as the connection is made entirely via fiber optics. As a result, transmission speeds of up to 1Gbit/s are possible. Thanks to the continuous fiber optic expansion, already 2,3 million households in Germany have been able to access Telekom’s FTTH network so far. This number is expected to grow to ten million households by 2024.
  • FTTB: This stands for "fiber to the building". The fiber optic line runs into the house but ends in the basement at the demarcation point. The individual subscriber lines are then connected by means of copper or patch cables, which are usually already in place. Depending on the building services, FTTB connections can also achieve maximum speeds of 1 Gbit/s.
  • FTTC: This connection is referred to as "fiber to the curb". The fiber optics ends at the distribution box on the sidewalk where the optical signals of the fiber optics are converted into electrical signals. The final distance to the apartment is then bridged with the copper cable that has already been laid. Thanks to vectoring technology, the connections achieve speeds of up to 100 Mbit/s; with so-called super vectoring, even up to 250 Mbit/s are possible. 
Differences FTTC vs. FTTH

Infographic: Differences FTTC vs. FTTH. © Deutsche Telekom AG

How does a fiber optics house connection work?

Fiber optic technology in the building begins at the so-called house handover point or fiber optic termination point. The house handover point marks the point where the network provider's fiber optic network meets the private fiber optic connection in the building.  This is where the private network is connected to the provider's network. In addition to the house handover point, a so-called fiber optic outlet is also required, as well as a suitable modem and router. Telekom takes care of the installation of the house transfer point and the fiber optic outlet when connecting the building to the fiber optic network. If desired, our experts can also set up the router in the home.

The fiber optic outlet is connected to the house transfer point. In order for the signals to flow into the Telekom network from here, the optical fibers must be interconnected. To do this, the various fibers are linked together by splicing. 

A fiber optic modem is then connected to the fiber optic outlet. The fiber optic modem can be thought of as a kind of translator. It is needed to convert the optical signals into electrical signals, which are then used by the router and the end devices.

Many routers now have a fiber optic modem built in, eliminating the need for a separate modem. Such modern routers can be connected directly to the fiber optic outlet. With the right technology, the customer is connected directly to Telekom's fiber optic network and can surf the Internet at up to 1 GBit/s, depending on the rate.

How fiber gets into the building

Infographic: How fiber gets into the building. © Deutsche Telekom AG

Current status of fiber optic rollout in Germany

Telekom has the largest fiber optic network in Germany which covers more than 600,000 kilometers in total. Thanks to the fiber optic rollout, more than 2.3 million households already have the opportunity to benefit from an FTTH connection by Telekom.  The goal is for all 41.5 million households in Germany to be able to get an FTTH connection by 2030. A large part of this will be provided by Telekom. By the end of 2024 alone, the company wants to enable ten million households to have an FTTH connection, and from that point on, another 2.5 million households per year will be added.

To achieve this goal, Telekom has developed a three-pillar strategy for expansion. In addition to self-financed network expansion and subsidized projects in underserved areas, Deutsche Telekom is relying on cooperative ventures in many places. By cooperating with municipal utilities, regional carriers, or nationwide competitors such as Telefonica, Vodafone or 1&1, fiber optic rollout in Germany is made more efficient and overbuilding of existing line systems is reduced wherever possible. 

You can find the latest news on fiber optic rollout in our media information.



DT invests several billion euros every year in building networks.