Ultra-compact primary colors filter based on plasmonic digital metamaterials

Abstract A novel primary colors filter (RGB filter) is designed with ultra-compact size by using the inverse design method. The core size of filter goes to 0.5 μ m × 0 . 55 μ m, and then the chip integration being high enhanced. The transmission characteristics of RGB filtering are simulated by FDTD algorithm. A high performance and high compact coupling region can be obtained by using inverse design method to search a full-parameter space. In addition, we investigate the relationship between the filtering performance and the digital unit size, and prove the good performance tolerance with different digital unit size. The average peak transmission efficiencies are over 70% and the average channel crosstalk are about − 16  dB at 450 nm, 550 nm and 650 nm, for each channel, respectively. High performance is achieved for this RGB filter with a footprint of only 0.5 μ m × 0 . 55 μ m, and is suitable for optical device integration.