Ait Austrian Institute of Technology Gmbh

Bernhard Schrenk

Christoph Pacher

Stephan Krenn

Thomas Loruesner

Thomas LORÜNSER

Hannes HÜBEL

A method creates and distributes cryptographic keys for securing communication at two terminals. Signals for creating correlated values in the two terminals are distributed via a first communication channel burdened with error, and the correlated values are present as keys. A checksum is formed on the basis of the first key present in the first terminal and the checksum is transferred to the second terminal via a second communication channel. A second checksum is formed on the basis of the second key present, and information derived from the two checksums is transferred via the second communication channel to a server. Based on the information derived from the checksums, the server determines a correction value, which, when applied to one or both keys, brings the keys into correspondence. The correction value is transferred to one or both terminals via the second communication channel and is applied to one or both keys.

Method for creating and distributing cryptographic keys

A method for receiving a modulated receive signal, with a transmission unit having a laser and an electro-absorption modulator. The received optical receive signal is directed towards the laser; due to the irradiance of the optical receive signal onto the laser, the optical frequency of the light radiated from the laser is adapted to and/or aligned with the optical frequency of the received optical receive signal; the light radiated from the laser and the optical receive signal received via the optical waveguide are overlapped in the electro-absorption modulator; the thus-created overlapping signal from the electro-absorption modulator is converted into an electrical receive signal, in particular into an electrical current signal; and a receive signal is provided which corresponds to the electrical receive signal or is derived from same.

Method for receiving a modulated optical signal and receiver unit

A method detects discontinuities in an optical channel using two laser units that respectively have a laser and an electroabsorption modulator. The reference frequencies of the two lasers have a predetermined reference frequency difference. The optical ports of the electroabsorption modulator are fed to the two inputs of a polarization beam splitter and the output of the polarization beam splitter is connected to the optical channel. A test pulse is applied simultaneously to the two electroabsorption modulators and laser light from the lasers is thus transmitted through the respective electroabsorption modulators during the time of the test pulse. The test pulse is divided into two time periods, and during the first time period the lasers are operated with their respective reference frequency, and during the second time period the emission frequencies of the lasers are detuned with respect to the reference frequencies, by a predetermined detuning frequency difference.

Method and apparatus for detecting discontinuities in an optical channel, in particular a fiber optic line

A system for data transmission has a transmitter and a receiver connected by an optical channel. The transmitter has a transmitter laser and a transmitter-side electroabsorption modulator with an optical output. An electrical data input of the transmitter is connected to an electrical modulation terminal of the transmitter-side electroabsorption modulator. The receiver has a receiver laser and a receiver-side electroabsorption modulator with an optical output forming the input of the receiver. An electrical data output of the receiver is connected to the electrical modulation terminal of the receiver-side electroabsorption modulator. The transmitter and receiver lasers are detunable by specification of a physical variable, each provided by a respective control unit. The control units are synchronized and they specify the same signal at their outputs for establishing the physical variable for establishing the laser frequency.

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Ulrichskirchen, Austria

Bernhard Schrenk