Fig. 3: Experimental verification of colour routing response.

a Schematic of the optimised binary pattern of the MBCR with the unit cell size of 2 µm × 2 µm. The top layer Si₃N₄ patterns on a quartz glass substrate with a thickness of 500 µm. b Side view of the unit cell. Parameters of the MBCR are set as: h = 600 nm, a = 125 nm and p = 2 µm. c SEM image of a fabricated sample. d Measured image at the imaging plane of the MBCR array when illuminated by a collimated white beam. e Three colour channels of imaging plane under the illumination of three colour light. f The measured colour collection efficiencies of each channel in the visible region. Each colour curve corresponds to its colour channel. The black line represents the energy utilisation efficiency.