A terahertz modulator includes a substrate and an organic semiconductor layer. A material of the organic semiconductor layer is graphitic carbon nitride, and the organic semiconductor layer is coated on a surface of the substrate. The terahertz modulator has a high on-off contrast and is able to reach a high modulation speed. A terahertz spatial light modulator includes a terahertz modulator and an automatic pumped light spatial modulator. The automatic pumped light spatial modulator is optically connected with the terahertz modulator. The terahertz spatial light modulator generates a patterned terahertz light, and the terahertz spatial light modulator has a high on-off contrast and is able to reach a high modulation speed. |