Method and arrangement for demodulating an optical DPSK binary signal

1. A method for demodulating an optical differentially phase shift keyed (DPSK) binary signal which is phase modulated and in the event of phase changes exhibits amplitude reductions, said method comprising: receiving an optical DPSK binary signal; phase-demodulating the received optical DPSK binary signal; amplitude-demodulating said received optical DPSK binary signal; combining a phase-demodulated signal and an amplitude-demodulated signal to an output signal such that a resulting phase and amplitude information is evaluated; and evaluating the output signal, wherein in addition the amplitude-demodulated signal is combined with the phase-demodulated signal of a non-inverting output of the Mach-Zehnder interferometer and fed to a differential amplifier.

2. The method according to claim 1 , wherein amplitude-demodulated signal is high pass filtered prior to combining.

3. A receiver for an optical differentially phase shift keyed (DPSK) binary signal having amplitude reductions during phase changes, comprising:

a phase demodulator which phase-demodulates the received optical DPSK binary signal;

an amplitude demodulator which amplitude-demodulates the received optical DPSK binary signal;

a first device for combining both demodulated signals to an output signal such that a resulting phase and amplitude information is evaluated; and

a second device for evaluating said output signal, wherein

the phase demodulator is an interferometer that heterodynes a light of a transmitted bit with a light of a subsequent bit in each case and feeds out a first binary signal information at its output,

the interferometer is a Mach-Zehnder arrangement, and

an inverting and a non-inverting output of the Mach-Zehnder interferometer is connected in each case to an optical/electrical converter and to a differential amplifier that produces a first binary signal.

4. The receiver according to claim 3 , wherein the differential amplifier is followed by a first discriminator that produces a second binary signal.

5. A receiver for an optical differentially phase shift keyed (DPSK) binary signal having amplitude reductions during phase changes, comprising:

a phase demodulator which phase-demodulates the received optical DPSK binary signal;

an amplitude demodulator which amplitude-demodulates the received optical DPSK binary signal;

a first device for combining both demodulated signals to an output signal such that a resulting phase and amplitude information is evaluated; and

a second device for evaluating said output signal, wherein

the amplitude demodulator is preceded or followed by a delay element, and a series circuit comprising the delay element and amplitude demodulator is connected to the non-inverting input of the differential amplifier is connected to the electrical side of an optical/electrical converter that is connected to the non-inverting output of the Mach-Zehnder interferometer.

6. The receiver according to claim 5 , wherein the amplitude demodulator or the delay element is preceded or followed by a high-pass filter.

7. The receiver according to claim 6 , wherein a series circuit comprising the high-pass filter, delay element and amplitude demodulator is followed by a second discriminator producing a third binary signal.

8. The receiver according to claim 6 , wherein a series circuit comprising the high-pass filter, delay element and amplitude demodulator is connected to the inverting input of the differential amplifier is connected to the electrical side of an optical/electrical converter that is connected to the inverting output of the Mach-Zehnder interferometer.

9. The receiver according to claim 5 , wherein the output of the first discriminator and the output of the second discriminator are in each case connected to a first and a second forward error correction or FEC unit which determine a bit error rate in each case.