Arrayed waveguide grating multiplexer-demultiplexer and related control method

An arrayed waveguide grating demultiplexer, comprising:

• a first slab waveguide defining a first free propagation region;
• a second slab waveguide defining a second free propagation region;
• an array of optical waveguides ordered in sequence from a shortest optical waveguide to a longest optical waveguide, having first end portions and second end portions, respectively, to receive input optical signals throughout the first free propagation region and to irradiate output optical signals throughout the second free propagation region, with components of a same wavelength of the output optical signals constructively interfering at a respective main focal spot located in a position of the second free propagation region based on the wavelength;
• each optical waveguide, except for the shortest optical waveguide, is longer by a same amount than the optical waveguide that precedes or follows in the sequence;
• and
• a plurality of identical phase shifters coupled to said array of optical waveguides, and configured to be commanded together by a same control signal, with each phase shifter being configured to change an optical path of an optical waveguide of said array of optical waveguides to which it is coupled by a same amount, as determined by the control signal;
• the shortest optical waveguide or the longest optical waveguide having at least one phase shifter coupled thereto, with each of said remaining optical waveguides having a number of phase shifters greater by a constant integer than the number of phase shifters coupled to the optical waveguide that precedes or follows in the sequence.

An arrayed waveguide grating demultiplexer, comprising:

• a first waveguide defining a first free propagation region;
• a second waveguide defining a second free propagation region;
• an array of optical waveguides ordered in sequence from a shortest optical waveguide to a longest optical waveguide, having first end portions and second end portions, respectively, to receive input optical signals throughout the first free propagation region and to irradiate output optical signals throughout the second free propagation region;
• each optical waveguide, except for the shortest optical waveguide, is longer by a same amount than the optical waveguide that precedes or follows in the sequence;
• a plurality of identical phase shifters coupled to said array of optical waveguides, and configured to be commanded together by a same control signal, with each phase shifter being configured to change an optical path of an optical waveguide of said array of optical waveguides to which it is coupled by a same amount, as determined by the control signal;
• the shortest optical waveguide or the longest optical waveguide having at least one phase shifter coupled thereto, with each of said remaining optical waveguides having a number of phase shifters greater by a constant integer than the number of phase shifters coupled to the optical waveguide that precedes or follows in the sequence;
• at least one photo-detector positioned so as not to be illuminated in normal functioning conditions and to be illuminated when the arrayed waveguide grating demultiplexer undergoes a temperature variation greater than a threshold, said at least one photo-detector being configured to generate at least one error signal corresponding to an intensity of an optical signal impinging thereon;
• and
• a control block configured to generate the control signal based on the at least one error signal.

A method for controlling an arrayed waveguide grating demultiplexer comprising a first slab waveguide defining a first free propagation region;

• a second slab waveguide defining a second free propagation region;
• an array of optical waveguides ordered in sequence from a shortest optical waveguide to a longest optical waveguide, having first end portions and second end portions, respectively, to receive input optical signals throughout the first free propagation region and to irradiate output optical signals throughout the second free propagation region;
• each optical waveguide, except for the shortest optical waveguide, is longer by a same amount than the optical waveguide that precedes or follows in the sequence;
• and a plurality of identical phase shifters organized into symmetric arrays and coupled to the array of optical waveguides, the shortest optical waveguide or the longest optical waveguide having at least one phase shifter coupled thereto, with each of the remaining optical waveguides having a number of phase shifters greater by a constant integer than the number of phase shifters coupled to the optical waveguide that precedes or follows in the sequence, the method comprising:
• controlling the plurality of plurality of phase shifters organized into symmetric arrays with a same control signal for each array, with each phase shifter being configured to change an optical path of an optical waveguide of the array of optical waveguides to which it is coupled by a same amount, as determined by the control signal.