Black silicon with quasi-regular arrays of micrometer-sized spikes, which is obtained by irradiating the surface of a Si wafer with ultrafast laser pulses in the presence of a chalcogen-bearing gas, or prepared by ion implantation and pulsed-laser-melting-induced rapid solidification. This new material has unusual optical and electrical properties, such as strong absorption of light with wavelength between 0.25 μm and 17 μm, nice field emission characteristics and so on, offers silicon many new features. Taking chalcogen as example, the enhancement of light absorption of the microstructured silicon is analyzed under four-level model. A detailed study on the relationship between the light loss and the ionization energy of doped impurities in silicon with two different impurity bands.