Large‐Range Beam Steering through Dynamic Manipulation of Topological Charges

Abstract Dynamic tuning of light properties by external stimuli is at the core of various applications such as electro‐optical modulators, beam steering, and spatial light modulators. The conventional mechanism involves fine‐tuning the eigenmode of an optical system through adjusting the effective refractive index. However, the weak nonlinearity results in low modulation efficiency, leading to devices with poor performance and large size. Polarization topological charge is a significant concept that has facilitated the development of innovative optical devices like low‐threshold lasers and vortex generators. But the devices reported so far are static in nature. Here, a method for dynamically controlling light by actively manipulating the evolution of topological charges in momentum space is first presented. By switching between integer and half‐integer states of topological charges, the device's radiation properties undergo a significant transformation. The beam direction can be tuned up to 160°, which, to the best of the authors' knowledge, is the largest tuning angle among similar beam steering devices. Furthermore, the device demonstrates high radiation efficiency while maintaining a compact device size. This light controlling method can be applied in various fields, including optical communication, tunable lasers, and light detection and ranging.