A system for transmitting differential optical signals comprising: an optical modulation device (20,120) comprising at least one optical input port and multiple optical output ports (128,130), wherein an optical input signal having an input power is received at the at least one optical input port and the optical modulation device transforms the optical input signal into multiple complimentary modulated optical signals that are transmitted from the multiple optical output ports (128,130) each having an output power, and wherein a sum of the output power of each of the multiple complimentary modulated optical signals is substantially equal to the input power of the optical input signal that was received by the at least one optical input port of the optical modulation device; and a balanced optical receiver (60,160) comprising multiple photo-detectors, wherein each of the multiple photodetectors transforms at least one of the multiple complimentary modulated optical signals into an electrical signal, and wherein the electrical signal of the multiple photodetectors of the balanced optical receiver is combined to form a pulse amplitude modulated signal; characterised by a multi-core optical waveguide (40,140,240,340,440,540,640) optically coupled to the multiple optical output ports (128,130) of the optical modulation device, the multi-core optical waveguide comprising multiple cores (142, 144, 146, 148, 150, 242, 244, 246, 248, 250, 342) disposed within a cladding material, wherein the multiple cores, the cladding material, or both are configured to mitigate exchange of optical energy between the multiple cores; and wherein the balanced optical receiver is communicatively coupled to the multiple cores of the multi-core optical waveguide. an optical modulation device (20,120) comprising at least one optical input port and multiple optical output ports (128,130), wherein an optical input signal having an input power is received at the at least one optical input port and the optical modulation device transforms the optical input signal into multiple complimentary modulated optical signals that are transmitted from the multiple optical output ports (128,130) each having an output power, and wherein a sum of the output power of each of the multiple complimentary modulated optical signals is substantially equal to the input power of the optical input signal that was received by the at least one optical input port of the optical modulation device; and a balanced optical receiver (60,160) comprising multiple photo-detectors, wherein each of the multiple photodetectors transforms at least one of the multiple complimentary modulated optical signals into an electrical signal, and wherein the electrical signal of the multiple photodetectors of the balanced optical receiver is combined to form a pulse amplitude modulated signal; characterised by a multi-core optical waveguide (40,140,240,340,440,540,640) optically coupled to the multiple optical output ports (128,130) of the optical modulation device, the multi-core optical waveguide comprising multiple cores (142, 144, 146, 148, 150, 242, 244, 246, 248, 250, 342) disposed within a cladding material, wherein the multiple cores, the cladding material, or both are configured to mitigate exchange of optical energy between the multiple cores; and wherein the balanced optical receiver is communicatively coupled to the multiple cores of the multi-core optical waveguide.