Method for transmitting at least one first and one second data signal in polarization division multiplex in an optical transmission system

An optical transmission system for transmitting at least one first and one second data signal in polarization division multiplex, comprising:

• a transmitting arrangement including at least one signal generating unit for generating a first and a second carrier signal, differing by a differential frequency, at least one modulator unit following the generating unit for generating a first modulated signal by modulating the first carrier signal with the first data signal and for generating a second modulated signal by modulating the second carrier signal with the second data signal, the first and second modulated signals being polarized orthogonally with respect to one another, and a polarization multiplexer following the modulator unit for combining the first and second modulated and mutually orthogonally polarized signals to form an optical multiplex signal;
• a receiving arrangement connected to the transmitting arrangement via at least one optical fiber link section, the receiving arrangement including at least one polarization control element for adjusting the orthogonality of the polarization of the first and second modulated signals, a polarization splitter following the polarization control element, having first and second outputs for splitting the optical multiplex signal into the first and second modulated signals, a first optoelectrical transducer connected at the first output for converting the first modulated signal into a first electrical signal, and a second optoelectrical transducer at the second output for converting the second modulated signal into a second electrical signal;
• a filter unit provided at at least one of the first and the second optoelectrical transducers for determining a spectral component of at least one of the first and the second electrical signals at the differential frequency;
• and
• a control unit connected to the filter unit for forming at least one control signal from the filtered spectral component for controlling the polarization control element.