Optical Communication Systems

Optical Communication Systems refers to the devices used for communicating at a distance using light to carry information. A transmitter, which encodes a message into an optical signal, is used to carry the encoded message to the receiver.
Optical fiber is an example of said system. The transmitters are generally light-emitting diodes (LEDs) or lasers diodes. It transmits information by sending pulses of infrared light. The signal encoding is done by intensity modulation.

Optical Communication Systems such as Optical Fiber are most commonly used by telecommunications companies for internet connections, cable television and telephone signals transmitting.

  • Brightest Source of Entangled Photon

    Optical setup for experiments with entangled photons at IFW Dresden. Photo: Jürgen Loesel

    Scientists at Leibniz Institute for Solid State and Materials Research Dresden (IFW) and at Leibniz University Hannover (LUH) have developed a broadband optical antenna for highly efficient extraction of entangled photons. With a yield of 37% per pulse, it is the brightest source of entangled photons reported so far.

  • First Real-time Test of Li-Fi Utilization for the Industrial Internet of Things

    First real-time test of Li-Fi utilization for the industrial Internet of Things. @ istockphoto.com/3alexd/edit Fraunhofer HHI

    The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

  • Nano Antennas for Data Transfer

    Let there be light – and it was directional: The world's first electrically powered Yagi-Uda antenna was built at the University of Würzburg's Department of Physics. Picture: Department of Physics

    For the first time, physicists from the University of Würzburg have successfully converted electrical signals into photons and radiated them in specific directions using a low-footprint optical antenna that is only 800 nanometres in size. Directional antennas convert electrical signals to radio waves and emit them in a particular direction, allowing increased performance and reduced interference. This principle, which is useful in radio wave technology, could also be interesting for miniaturised light sources. After all, almost all Internet-based communication utilises optical light communication. Directional antennas for light could be used to exchange data between different processor cores with little loss and at the speed of light. To enable antennas to operate with the very short wavelengths of visible light, such directional antennas have to be shrunk to nanometre scale.

  • Quantum processor for single photons

    Quantum processor for single photons | Illustration of the processes that take place during the logic gate operation: The photons (blue) successively impinge from the right onto the partially transparent mirror of a resonator which contains a single rubidium atom (symbolised by a red sphere with yellow electron orbitals). The atom in the resonator plays the role of a mediator which imparts a deterministic interaction between the two photons. The diagram in the background represents the entire gate protocol. Graphic: Stephan Welte, MPQ, Quantum Dynamics Division

    MPQ-scientists have realised a photon-photon logic gate via a deterministic interaction with a strongly coupled atom-resonator system.

    "Nothing is impossible!" In line with this motto, physicists from the Quantum Dynamics Division of Professor Gerhard Rempe (director at the Max Planck Institute of Quantum Optics) managed to realise a quantum logic gate in which two light quanta are the main actors. The difficulty of such an endeavour is that photons usually do not interact at all but pass each other undisturbed. This makes them ideal for the transmission of quantum information, but less suited for its processing. The scientists overcame this steep hurdle by bringing an ancillary third particle into play: a single atom trapped inside an optical resonator that takes on the role of a mediator. “The distinct feature of our gate implementation is that the interaction between the photons is deterministic”, explains Dr. Stephan Ritter. “This is essential for future, more complex applications like scalable quantum computers or global quantum networks.” (Nature, Advance Online Publication, 6 July 2016, DOI: 10.1038/nature18592).