Broadband Black Phosphorus Optical Modulator in the Spectral Range from Visible to Mid‐Infrared

Black phosphorus (BP), a two‐dimensional (2D) material, has a direct bandgap that can be tuned by changing the layers and applied strain, which fills the lacuna left by graphene topological insulators and transition‐metal dichalcogenides. Theoretically, the direct and tunable bandgap should enable broadband applications for optoelectronics with high efficiencies in the spectral range from the visible to the mid‐infrared. Here, a BP broadband optical modulator is experimentally constructed and passively modulated lasers at 639 nm (red), 1.06 μm (near‐infrared), and 2.1 μm (mid‐infrared) are realized by using a BP optical modulator as the saturable absorber in bulk lasers. The obtained results provide a promising alternative for rare broadband optical modulators and broaden the application range of BP in photonics. Based on the special bandgap and saturable absorption property of black phosphorus (BP) a broadband optical modulator is constructed and verified in bulk lasers in the spectral range from the visible to the mid‐infrared. The results promise to broaden the application range of BP and may provide inspiration for further applications of BP in optoelectronics and electronics.