A polarisation-independent coherent optical receiver, comprising - an optical coupler configured to receive a modulated optical signal and an optical signal generated by a local oscillator to create the beat between such signals and to provide on its outputs exactly three optical signals proportional to said beat; - photoelectric conversion means (6a, 6b, 6c) for converting the three optical signals generated by the coupler into three electrical signals; - means (7, 8a, 8b, 8c, 9a, 9b, 9c, 10a, 10b, 10c, 11) for performing an analogue processing of the electrical signals outgoing from the conversion means (6a, 6b, 6c) and generating a resultant electrical signal representing the modulated optical signal; and - a low-pass filter for filtering the resultant electrical signal; characterised in that: - the optical coupler has three inputs and three outputs and is configured so that the three optical signals provided on its three outputs have the same mutual phase shift; - the receiver (100, 200) further comprises optical signal splitting means (5; 5'), which are located on the path of one out of the modulated optical signal and the signal generated by the local oscillator, split the signal applied thereto into two components with orthogonal polarisation and send such components to a first and a second input of the 3x3 optical coupler, respectively, the 3x3 optical coupler being configured to receive at a third input the other out of the modulated optical signal and the signal generated by the local oscillator; - the means (7 to 11) for the analogue processing and the generation of the resultant electrical signal comprise circuitry comprising DC blocking components (8a, 8b, 8c), low pass filters (9a, 9b, 9c), components (10a, 10b, 10c) for squaring signals and an adder, said circuitry being configured to convert the electrical signals outgoing from the conversion means (6a, 6b, 6c) into a resultant electrical signal comprising a baseband component and a replica thereof that is centred on a frequency depending on a frequency difference between the modulated optical signal and the signal generated by the local oscillator and that has an amplitude and a phase depending on the instant states of polarisation of the modulated optical signal and the signal generated by the local oscillator; - said frequency difference is such that the receiver (100; 200) operates under intradyne conditions; and - said low pass filter has a passband such that said replica falls outside said passband or has a minimum spectral overlap with the modulated optical signal. - an optical coupler configured to receive a modulated optical signal and an optical signal generated by a local oscillator to create the beat between such signals and to provide on its outputs exactly three optical signals proportional to said beat; - photoelectric conversion means (6a, 6b, 6c) for converting the three optical signals generated by the coupler into three electrical signals; - means (7, 8a, 8b, 8c, 9a, 9b, 9c, 10a, 10b, 10c, 11) for performing an analogue processing of the electrical signals outgoing from the conversion means (6a, 6b, 6c) and generating a resultant electrical signal representing the modulated optical signal; and - a low-pass filter for filtering the resultant electrical signal; - the optical coupler has three inputs and three outputs and is configured so that the three optical signals provided on its three outputs have the same mutual phase shift; - the receiver (100, 200) further comprises optical signal splitting means (5; 5'), which are located on the path of one out of the modulated optical signal and the signal generated by the local oscillator, split the signal applied thereto into two components with orthogonal polarisation and send such components to a first and a second input of the 3x3 optical coupler, respectively, the 3x3 optical coupler being configured to receive at a third input the other out of the modulated optical signal and the signal generated by the local oscillator; - the means (7 to 11) for the analogue processing and the generation of the resultant electrical signal comprise circuitry comprising DC blocking components (8a, 8b, 8c), low pass filters (9a, 9b, 9c), components (10a, 10b, 10c) for squaring signals and an adder, said circuitry being configured to convert the electrical signals outgoing from the conversion means (6a, 6b, 6c) into a resultant electrical signal comprising a baseband component and a replica thereof that is centred on a frequency depending on a frequency difference between the modulated optical signal and the signal generated by the local oscillator and that has an amplitude and a phase depending on the instant states of polarisation of the modulated optical signal and the signal generated by the local oscillator; - said frequency difference is such that the receiver (100; 200) operates under intradyne conditions; and - said low pass filter has a passband such that said replica falls outside said passband or has a minimum spectral overlap with the modulated optical signal.