Color sensing by optical antennas: Approaching the quantum efficiency limit

Color image sensing is commonly carried out by an array of color pixels. Each of the color pixels consists of at least three sensing elements in combination with optical filters for red, green and blue. The filters are arranged side-by-side limiting the total quantum efficiency of a color pixel to 1/N, where N is the number of color channels per color pixel. Hence, in the most basic filter arrangement, just consisting of a red, green, and blue filter, the upper limit of the quantum efficiency is equal to 1/3, limiting the dynamic range and color contrast of the detected optical input signal. In order to increase the quantum efficiency and improve the image quality, an alternative sensor device is proposed, which can be realized by using current semiconductor technology. The proposed sensor uses silicon optical antennas to detect the incident light. The sensor allows for detecting the color information, with quantum efficiencies approaching unity. The design of the optical antennas is described, and optimi...