Aluminum and silicon hybrid nano-cavities for four-band, near-perfect light absorbers

Multi-band light perfect absorbers formed by metal-semiconductor materials are desirable for optoelectronics and have been long pursued. In this work, we numerically propose and demonstrate a four-band resonant near-perfect light absorption by utilizing the aluminum ring intercalated with silicon disk array, which can support strong plasmonic resonances and optical cavity modes. The multi-band near-perfect absorption can be tuned by the structural parameters and the maximal absorption is exceeding 99.8%. These features lay a foundation for low-cost optoelectronic technologies since the semiconductor silicon cavities are currently very important elements in the field of photonics.