Plasmonic Color Filters Integrated on a Photodiode Array

Arrayed plasmonic color filters integrated on Si photodiodes with 21 elements were experimentally demonstrated. The plasmonic color filters consisted of nanodot subwavelength periodic structures. Optical characteristics of the color filters were measured and compared with calculated results. In order to obtain spectrum of an incident light from the signal of photodiodes, spectrum reconstruction using Tikhonov regularization was adapted. In the spectral sensitivity of each photodiode, the peak wavelength was adjusted between 400 and 850 nm in wavelength by the period of nanodot structure on each photodiode. The measured peak wavelengths roughly agreed with calculated values with errors less than 30 nm in wavelength. Spectral characteristics of a monochromatic light were measured by fabricated device and spectrum reconstruction was carried out. The position of the center wavelength could be successfully detected.