Reducing temperature drift of an arrayed waveguide grating

A wavelength selective device comprising:

• an input port for inputting an optical beam;
• a tiltable MEMS mirror optically coupled to the input port, for reflecting the optical beam;
• a focusing element optically coupled to the MEMS mirror, for focusing the reflected optical beam into a focal spot displaceable by varying an angle of tilt of the MEMS mirror;
• an arrayed waveguide grating comprising an input slab having an elongate aperture for receiving the focal spot, and a plurality of output waveguides for outputting wavelength sub-beams of the optical beam, wherein the input slab is disposed so that when the angle of tilt of the MEMS mirror is varied, the focal spot is displaced along the elongate aperture;
• a temperature sensor thermally coupled to the arrayed waveguide grating, for sensing a change of temperature thereof;
• and
• a controller electrically coupled to the temperature sensor and the tiltable MEMS mirror, and configured for varying the angle of tilt upon sensing the arrayed waveguide temperature change by the temperature sensor, so as to lessen a wavelength drift of the wavelength sub-beams induced by the temperature change.