Arrayed-waveguide grating with branched outputs for simultaneous multichannel monitoring purposes

We propose an arrayed-waveguide grating (AWG) that has branched output waveguides for simultaneous multichannel monitoring purposes. The transmittances of two adjacent branched output waveguides are slightly different from each other. Thus, we can obtain crossover wavelengths, where the transmittances of adjacent output waveguides are the same with much smaller insertion losses than those of conventional AWGs. As a result, the proposed device can accurately monitor wavelength-division-multiplexed channel wavelengths in the presence of the amplified-spontaneous-emission noise.