A waveguide optical monitor is disclosed. The device has an optical input port coupled through a switch to a plurality of input waveguides. A dispersive element disperses light within the input optical waveguides toward a plurality of output waveguides. There are a plurality of photodetectors each optically coupled to an output waveguide. The photodectors are for sensing an intensity of light within the waveguide with which it is optically coupled. An optical switch in optical communication with the optical input port and for switching light received at the optical input port to one of the plurality of input waveguides. Also, an angular dispersive element is present for receiving light from any one of the waveguides and for dispersing the light toward a plurality of output waveguides in dependence upon the input waveguide position and a wavelength of the light such that light directed from the first of the plurality of input waveguides toward the plurality of output waveguides has a first centre wavelength within each of the output waveguides and light directed from the second of the plurality of input waveguides toward the plurality of output waveguides has a second different centre wavelength within each of the output waveguides, the second different centre wavelength different form any first centre wavelength.