We report on an all‐dielectric cut‐off perfect absorber and an optical long‐pass filter using a gallium arsenide multi‐nanocylinder array grown on SiO2 in the wavelength from ultraviolet to infrared. A high average absorption of 0.985 is realized in the absorption band and there is a sharp cut‐off between the absorption band and the non‐absorption band, where the extinction ratio is 12.17 dB, the extinction difference is 0.88, and the cut‐off slope is 0.0047 nm−1. Based on the cut‐off absorption mechanism, a transmissive long‐pass cut‐off filter is proposed with extinction ratio of 21.56 dB, extinction difference of 0.86 and cutoff slope of 0.0049 nm−1. The average transmission of only 0.006 in the stop band and 0.967 in the pass band is realized. The demonstrated devices suggest an efficient way of designing cut‐off perfect absorbers and optical filters with metasurface, which is of important applications in advanced nanophotonic devices and integrated photonic systems.
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