Time‐Varying Ultrafast Holographic Light Fields Generated by Spatial Frequency Multiplexed Meta‐Holography

In recent years, the emergence of novel spatiotemporal light fields, such as spatiotemporal optical vortices, has significantly advanced the modulation of ultrafast optical fields. However, most ultrafast pulse shaping techniques rely on traditional 4‐f systems with multiple devices, resulting in complex configurations and limited integration and tunability. To address these challenges, here an approach for the generation of time‐varying femtosecond holographic fields based on spatial frequency multiplexed meta‐holography is proposed. This approach involves encoding various holograms into high and low spatial frequency channels of a single meta‐holographic device, thereby facilitating high‐precision control over the temporal evolution of femtosecond holographic light fields can be achieved, and demonstrating advantages of compactness, simplicity, and ease of integration. Experimentally, two examples of ultrafast holographic fields are generated, including a femtosecond vortex field with time‐varying orbital angular momentum (OAM), and a femtosecond holographic pattern varying between different letters over time. The observed temporal dynamics align closely with theoretical predictions. This work offers a new pathway for temporal modulation of ultrafast holographic fields and holds significant potential for applications in ultrafast information processing, optical communication, and integrated photonics.