Optical PON network using passive DPSK demodulation

A passive distribution node for use in a passive optical network, the node comprising:

• an arrayed waveguide grating having at least one input port for connection to a central office;
• and
• a plurality of output ports, each output port being suitable for connection to an optical network unit,
• the arrayed waveguide grating being arranged to provide a passive optical connection between said input port and each of the output ports, and to function as a bandpass filter having a profile and bandwidth such that a differential phase shift key modulated optical signal received on the input port is converted to an intensity modulated signal at a respective one of the output ports.

A method of operating an optical network, comprising:

• generating N differential phase shift key modulated optical signals of different wavelengths at a central office, where N is an integer greater than 1;
• connecting the N signals to at least one optical waveguide for transmission to a passive distribution node located remote from the central office;
• receiving the N signals at the passive distribution node;
• demultiplexing the N differential phase shift key modulated optical signals at the passive distribution node, whilst also converting the differential phase shift key modulated optical signals to intensity modulated signals, each intensity modulated signal being output from a different output port for transmission to a respective optical network unit;
• wherein the demultiplexing and conversion is performed by an arrayed waveguide grating having a bandwidth and profile such that the differential phase shift key modulated optical signal passed to the input port is converted to an intensity modulated signal at the output port.