Nanophotonic integrated circuit and fabrication thereof

A nanophotonic integrated circuit comprising:

• an input section, an amplifier section and a multiplexing/demultiplexing unit arranged on a substrate;
• the input section having a plurality of input waveguides, a coupler portion for coupling two of the plurality of input waveguides to the amplifier section, and a remaining input waveguides being connected to the multiplexing/demultiplexing unit,
• the amplifier section having a continuous folded waveguide connected at a first end to the coupler portion of the input waveguide and connected at a second end to the multipiexing/demultiplexing unit;
• the multiplexing/demultiplexing unit having a plurality of input/output waveguides, a slab waveguide, an array waveguide, and a reflective mirror;
• the plurality of input/output waveguides arranged for simultaneously inputting at least one signal to and outputting at least one signal for demultiplexing a multiplexed optical signal in to n different constituent wavelengths and for combining n input optical signals composed of n different constituent wavelengths in to a multiplexed signal;
• the slab waveguide having a first end and a second end, the first end coupled to the plurality of input/output waveguides to focus the at least one input signal to the second end, and the second end coupled to the array waveguide, for focusing the at least one output signal to the input/output interface through the first end;
• the array waveguide comprising a plurality of waveguides for coupling the one or more input signals, separating the one or more input signals into the n different constituent wavelengths and focusing the n different constituent wavelengths back on to the slab waveguide first end coupling to the input/output interface, the plurality of waveguides of the array waveguide being optically coupled at one end with the second end of the slab waveguide, and
• terminated at an opposing end of the array waveguide by the reflective mirror, each waveguide of said array waveguide having a predetermined path difference between successive waveguides, and
• the reflective mirror disposed at the opposing end of the array waveguide for reflecting the one or more signals.