Dual polarization transceiver

1. A dual polarization transceiver being switchable between two operation modes,

wherein in a first operation mode an optical QAM—(Quadrature Amplitude Modulation) Signal having a predetermined number (M) of constellation points is generated by said dual polarization transceiver and

wherein in a second operation mode an optical QPR—(Quadrature Partial Response) Signal having a predetermined number (L) of constellation points is generated by said dual polarization transceiver.

2. The dual polarization transceiver according to claim 1 ,

wherein said dual polarization transceiver comprises QAM-encoders each encoding a corresponding bit stream provided by a gearbox.

3. The dual polarization transceiver according to claim 2 ,

wherein each QAM-encoder is connected to an adaptive partial response filter for filtering the encoded bit stream generated by the respective QAM-encoder.

4. The dual polarization transceiver according to claim 3 ,

wherein said adaptive partial response filter is activated in the second operation mode of said dual polarization transceiver.

5. The dual polarization transceiver according to claim 4 ,

wherein each adaptive partial response filter is adapted to generate a controlled intersymbol interference (ISI) in the second operation mode of said dual polarization transceiver.

6. The dual polarization transceiver according to claim 5 ,

wherein the filtered encoded bit streams provided by said adaptive partial response filters in the second operation mode of said dual polarization transceiver or the not-filtered encoded bit streams provided by said QAM-encoders in the first operation mode of said dual polarization transceiver modulate two orthogonal light waves by means of double nested Mach-Zehnder Modulators to generate a complex dual polarized optical signal.

7. The dual polarization transceiver according to claim 6 ,

wherein said adaptive partial response filter is an analogue or a digital low pass filter.

8. The dual polarization transceiver according to claim 7 ,

wherein the cut-off frequency of said adaptive partial response-low pass filter is given by:

f cut-off =c·f symbol,

wherein c is an adjustable factor and

f symbol is the symbol rate, wherein the factor c of said adaptive partial response-low pass filter is in a range of 0,25 to 0,30.

9. The dual polarization transceiver according to claims 8 , wherein said adaptive partial response-low pass filter is formed by a Gauβ low pass filter or by a Butterworth low pass filter.

10. The dual polarization transceiver according to claim 6 ,

wherein the two orthogonal light waves are provided by a polarization beam splitter connected to a continuous wave laser diode,

wherein each orthogonal light wave provided by said polarization beam splitter is applied to a pulse carving unit being connected to a double nested Mach-Zehnder Modulator of said dual polarization transceiver.

11. The dual polarization transceiver according to claim 10 ,

wherein said pulse carving unit comprises a 33% RZ (Return to Zero), a 67% RZ (Return to Zero) or a NRZ pulse carving unit.

12. The dual polarization transceiver according to claim 11 ,

wherein said dual polarization transceiver comprises two pairs of QAM-encoders each encoder having an output connected to a corresponding adaptive partial response filter,

wherein the encoded filter bit streams of two adaptive partial response filters connected to the same pair of QAM-encoders modulate one of the two orthogonal light waves by means of a double nested Mach-Zehnder Modulator.

13. The dual polarization transceiver according to claim 12 ,

wherein said modulated orthogonal light waves generated by said double nested Mach-Zehnder Modulators are applied to a polarization beam combiner comprising a connection interface for connection of at least one optical fiber to said dual polarization transceiver.

14. The dual polarization transceiver according to claim 13 ,

wherein the number (M) of constellation points of the optical QAM-signal generated by said dual polarization transceiver ( 1 ) in the first operation mode comprises M=2 n constellation points, wherein n is an integer number, n≧2 and

wherein the number (L) of constellation points of the QPR-signal generated by said dual polarization transceiver in the second operation mode comprises N×N constellation points, wherein N is an integer number, N≧3.

15. The dual polarization transceiver according to claim 14 ,

wherein said dual polarization transceiver is adapted to provide in the first operation mode

a DP-NRZ-4QAM signal in a 50 GHz grid and in the second operation mode

a DP-RZ-9QPR signal in a 50 GHz grid or

a DP-NRZ 9QPR signal in a 25 GHz grid or

a DP-NRZ 9QPR signal in a 50 GHz grid.

16. The dual polarization transceiver according to claim 15 ,

wherein the bit rate of each encoded bit stream comprises

112

4

⁢

Gbit

⁢

/

⁢

sec

⁢

⁢

or

⁢

⁢

222

4

⁢

Gbit

⁢

/

⁢

sec

.

17. A method for flexible transmission of data via an optical transmission medium,

wherein in a first operation mode an optical OAM-signal having a predetermined number (M) of constellation points generated by a transceiver is transmitted and

wherein in a second operation mode an optical QPR signal having a predetermined number (L) of constellation points generated by said transceiver is transmitted.