Multiport tunable optical filters

A self-calibrating optical channel monitoring (OCM) device comprising:

• a tunable multiport optical filter comprising:
• a plurality of optical input ports,
• at least one optical output port,
• a light dispersion element positioned to receive an optical signal from an optical input port of the plurality of optical input ports, and disperse the received optical signal into a plurality of separate wavelength components;
• and
• a reflective beam steering element positioned to receive the plurality of separate wavelength components from the light dispersion element, the reflective beam steering element controllable to redirect any one wavelength component of the dispersed optical signal through the light dispersion element and into the optical output port;
• a photodetector coupled to the optical output port of the tunable multiport optical filter;
• a reference spectrum source that produces a reference spectrum that can be coupled as an optical signal into to the tunable multiport optical filter;
• and
• a controller coupled to the reference spectrum source, the tunable multiport optical filter and the photodetector, the controller configured to:
• control production and/or coupling of the reference spectrum as an optical input to the tunable multiport optical filter, and
• calibrate the tunable multiport optical filter based on a response of the photodetector when the reference spectrum is coupled to the tunable multiport optical filter by determining and storing the positions of the reflective beam steering element associated with predetermined wavelengths in the reference spectrum.