Methods and apparatus for dual polarisation optical communication

A method for dual polarisation optical reception, the method comprising:

• splitting a received polarisation multiplexed signal onto first and second optical paths, the received polarisation multiplexed signal comprising first and second sub-channels, the first sub-channel having superimposed a first pilot tone and the second sub-channel having superimposed a second pilot tone;
• and
• on each of the first and second paths:
• using maximisation of power of one of the first or second pilot tones for polarisation recovery of one of the first or second sub-channels.

Apparatus for dual polarisation optical transmission, the apparatus comprising:

• a splitter configured to split a continuous wave light source into first and second sub-channels;
• first and second modulation elements configured to optically modulate each sub-channel with a data signal and to superimpose different first and second pilot tones onto the first and second optically modulated sub-channels;
• a polarisation combiner configured to polarisation multiplex the first and second sub-channels to form a polarisation multiplexed signal, in which the first and second sub-channels have orthogonal states of polarisation;
• and
• a transmitter configured to transmit the polarisation multiplexed signal.

Apparatus for dual polarisation optical transmission, the apparatus adapted to:

• split a continuous wave light source into first and second sub-channels;
• optically modulate each sub-channel with a data signal;
• superimpose a first pilot tone onto the first optically modulated sub-channel and a second pilot tone, different from the first pilot tone, onto the second optically modulated sub-channel;
• polarisation multiplex the first and second sub-channels to form a polarisation multiplexed signal, in which the first and second sub-channels have orthogonal states of polarisation;
• and
• transmit the polarisation multiplexed signal.

Apparatus for dual polarisation optical transmission, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operative to:

• split a continuous wave light source into first and second sub-channels;
• optically modulate each sub-channel with a data signal;
• superimpose a first pilot tone onto the first optically modulated sub-channel and a second pilot tone, different from the first pilot tone, onto the second optically modulated sub-channel;
• polarisation multiplex the first and second sub-channels to form a polarisation multiplexed signal, in which the first and second sub-channels have orthogonal states of polarisation;
• and
• transmit the polarisation multiplexed signal.

Apparatus for dual polarisation optical reception, the apparatus comprising:

• a splitter configured to split a received polarisation multiplexed signal onto first and second optical paths, the received polarisation multiplexed signal comprising first and second sub-channels, the first sub-channel having superimposed a first pilot tone and the second sub-channel having superimposed a second pilot tone;
• a first polarisation recovery device configured to receive a signal on the first optical path and a second polarisation recovery device configured to receive a signal on the second optical path;
• and
• a convergence unit configured to use maximisation of power of one of the first or second pilot tones for polarisation recovery of one the first and second sub-channels in the first and second polarisation recovery devices.

Apparatus for dual polarisation optical reception, the apparatus adapted to:

• split a received polarisation multiplexed signal onto first and second optical paths, the received polarisation multiplexed signal comprising first and second sub-channels, the first sub-channel having superimposed a first pilot tone and the second sub-channel having superimposed a second pilot tone;
• and
• on each of the first and second paths:
• use maximisation of power of one of the first or second pilot for polarisation recovery of one of the first or second sub-channels.

Apparatus for dual polarisation optical reception, the apparatus comprising a processor and a memory, the memory containing instructions executable by the processor such that the apparatus is operative to:

• split a received polarisation multiplexed signal onto first and second optical paths, the received polarisation multiplexed signal comprising first and second sub-channels, the first sub-channel having superimposed a first pilot tone and the second sub-channel having superimposed a second pilot tone;
• and
• on each of the first and second paths:
• use maximisation of power of one of the first or second pilot tones for polarisation recovery of one of the first or second sub-channels.

A system for dual polarisation optical communication, the system comprising:

• an apparatus for dual polarisation optical transmission including:
• a splitter configured to split a continuous wave light source into first and second sub-channels;
• first and second modulation elements configured to optically modulate each sub-channel with a data signal and to superimpose different first and second pilot tones onto the first and second optically modulated sub-channels;
• a polarisation combiner configured to polarisation multiplex the first and second sub-channels to form a polarisation multiplexed signal, in which the first and second sub-channels have orthogonal states of polarisation;
• and
• a transmitter configured to transmit the polarisation multiplexed signal;
• and
• an apparatus for dual polarisation optical reception including:
• a splitter configured to split a received polarisation multiplexed signal onto first and second optical paths, the received polarisation multiplexed signal comprising first and second sub-channels, the first sub-channel having superimposed a first pilot tone and the second sub-channel having superimposed a second pilot tone;
• a first polarisation recovery device configured to receive a signal on the first optical path and a second polarisation recovery device configured to receive a signal on the second optical path;
• and
• a convergence unit configured to use maximisation of power of one of the first or second pilot tones for polarisation recovery of one the first and second sub-channels in the first and second polarisation recovery devices.