A method of forming a wavelength detector that includes forming a first transparent material layer having a uniform thickness on a first mirror structure, and forming an active element layer including a plurality of nanomaterial sections and electrodes in an alternating sequence atop the first transparent material layer. A second transparent material layer is formed having a plurality of different thickness portions atop the active element layer, wherein each thickness portion correlates to at least one of the plurality of nanomaterials. A second mirror structure is formed on the second transparent material layer.