Broadband light absorption with doped silicon for the terahertz frequency

The broadband absorption effect with patterned doped silicon for terahertz (THz) frequency is investigated. It is achieved by patterning the doped silicon substrate with a two-dimensional grating and covered by a layer of anti-reflective coating. The bandwidth with the polarization-insensitive absorption above 95% covers a frequency range of 0.79–4.115 THz. Moreover the broadband absorption performance can be maintained for the incident angle up to 70°. The electromagnetic field distributions at the resonant frequencies are illustrated to disclose the underlying mechanism of such broadband absorption phenomenon. Last, the influence of geometry parameters on the absorption performance is investigated to provide a guide for practical fabrication. It is hoped that the designed broadband absorber may found applications in the area of thermal emitter, cloaking and biosensor.