Method and arrangement for the optical transmission of data signals via differential phase modulation in a polarization multiplex method

1. A method for the optical transmission of data signals via differential binary

phase modulation in a polarization multiplex method, comprising:

modulating, on a send side, an optical carrier signal with a first data signal via a binary differential phase modulation to form a first polarized transmission signal with two phase states differing by 180° and with a first polarization;

modulating the optical carrier signal with a second data signal via a DBPSK-modulation to form a second polarized transmission signal with a polarization that is orthogonal with respect to the first transmission signal, whose odd modulation sections are transmitted as two phase states differing by 180° and whose even modulation sections are likewise generated as phase states which differ by 180° but which exhibit an additional ±90° phase shift when compared with the odd bits;

combining the first and second transmission signals to form a polarization multiplex

signal;

transmitting the polarization multiplex signal;

splitting the received polarization multiplex signal into a first and a second POLMUX partial signal via an optical splitter;

demodulating the first POLMUX partial signal via a DBPSK demodulator; and

demodulating the second POLMUX partial signal via a π/2 DBPSK demodulator which compensates for the additional phase shift of the carrier signal.

2. The method as claimed in claim 1 , wherein the first DBPSK demodulator and π/2 DBPSK demodulator have symmetrical outputs.

3. An arrangement for the optical transmission of data signals via a binary differential phase modulation in a polarization multiplex method, comprising:

a phase modulator that receives a carrier signal and a first data signal and that modulates the received signals via a binary differential phase modulation to generate a first transmission signal with two phase states differing by 180°;

a π/2 phase modulator that receives the optical carrier signal and a second data signal and that modulates the received signals to generate a second transmission signal such that successive modulation sections of the second transmission signal vary by a phase difference of ±90° compared with the preceding modulation sections;

a polarization controller that sets the polarizations of the first and second transmission signals orthogonally with respect to one another; and

a polarization multiplexer that receives the first and the second polarized transmission signals and combines the signals to form a polarization multiplex signal.

4. The arrangement as claimed in claim 3 ,

wherein that the π/2 phase modulator has a first splitter that splits the carrier signal onto a first signal branch and a second signal branch,

wherein the first signal branch has a first phase modulator and the second signal branch has a second phase modulator which are activated alternately in bitwise fashion and generate phase-modulated signals,

wherein a phase final control element that changes the phase states of the carrier signal between the first and the second signal branch by 90° is arranged at least in one signal branch, and

wherein the first and second signal branches are connected on an output side with inputs to a combiner that combines the phase-modulated signals to form the second transmission signal.

5. An arrangement for receiving an optical data signal that is transmitted via differential phase modulation in a polarization multiplex method and converted back into electrical data signals in phase demodulators, comprising:

an optical splitter splits a received polarization multiplex signal into a first POLMUX partial signal and a second POLMUX partial signal;

a DBPSK demodulator converts the first POLMUX partial signal back into a first data signal;

a π/2 DBPSK demodulator converts the second POLMUX partial signal back into a second data signal, the π/2 DBPSK demodulator has an interferometer structure with a first signal branch and a second signal branch; and

a phase final control element is arranged at least in one signal branch,

whereby a transmission signal modulated by π/2 DBPSK on the send-side is converted into a conventionally DBPSK-modulated signal.

6. The arrangement as claimed in claim 5 , wherein the DBPSK demodulators are balanced and are provided with the signal branches and have symmetrical outputs.

7. The arrangement as claimed in claim 6 , wherein the phase final control element causes a phase rotation of π/2 and is arranged in one signal branch of the π/2 DBPSK demodulator.

8. The arrangement as claimed in claim 6 , wherein a further phase final control element is arranged in a branch of the DBPSK demodulator.