Arrayed waveguide multiplexing/demultiplexing device with phase correction

A method for correcting differences in optical path length in an integrated photonics arrayed waveguide multiplexing/demultiplexing device, the method comprising the steps of:

• providing a free propagation region comprising a first section and a second section;
• providing a first waveguide coupled to the first section;
• providing a plurality of output waveguides coupled to the first section;
• providing an array of waveguides with increasing lengths between consecutive waveguides throughout the array and coupled to the second section, wherein each waveguide comprises:
• an incident light waveguide section comprising a phase correcting region;
• a transmitted light waveguide section;
• a tunable reflector between the incident light waveguide section and the transmitted light waveguide section;
• wherein the tunable reflector is configured to act as a semi-transparent reflector for light propagating between the incident light waveguide section and the transmitted light waveguide section, thereby generating reflected light;
• collecting the reflected light at least partially in the output waveguides;
• for each pair of consecutive waveguides in the array:
• combining light propagating in the transmitted light waveguide sections of the two consecutive waveguides;
• determining therefrom an optical phase difference between the two consecutive waveguides;
• and
• determining therefrom a change in optical path length required for each of two consecutive waveguides in the array to reach a predetermined optical phase difference between the two consecutive waveguides;
• and
• applying the change in each phase correcting region, thereby correcting the optical path length of the respective waveguide.