Generating Angular-Varying Time Delays of THz Pulses via Direct Space-to-Time Mapping of Metasurface Structures

Area of Science:

• Optics and Photonics
• Materials Science
• Terahertz (THz) Science

Background:

• Nonlinear metasurfaces offer unique light-matter interactions.
• Precise control over terahertz (THz) wave generation and shaping is crucial for advanced applications.
• Spatiotemporal control of electromagnetic pulses is a key challenge in ultrafast science.

Purpose of the Study:

• To experimentally demonstrate the generation of double THz pulses with tailored angular-dependent time delays.
• To explore the use of nonlinear metasurfaces for spatiotemporal shaping of THz waves.
• To investigate the potential for generating a full range of elliptical THz polarizations.

Main Methods:

• Excitation of a nonlinear metasurface with a near-infrared femtosecond pulse.
• Utilizing Pancharatnam-Berry phase for symmetric and antisymmetric metasurface configurations.
• Employing parabolic mirrors for collimation and analyzing spatiotemporal profiles.

Main Results:

• Successful generation of double THz pulses with designed angular-dependent time delays.
• Observation of spatiotemporal "X-shaped" emission profiles.
• Demonstration of achieving tunable elliptical THz polarizations through polarization multiplexing.

Conclusions:

• The nonlinear metasurface effectively maps its spatial response to the THz temporal profile for pulse generation.
• Spatiotemporal shaping of THz waves is achievable, offering precise control over pulse characteristics.
• The developed technique holds significant potential for applications in THz spectroscopy and molecular dynamics, especially in pump-probe experiments.