Inverse-Designed Narrowband THz Radiator for Ultrarelativistic Electrons.

Area of Science:

• Physics
• Engineering
• Materials Science

Background:

• Terahertz (THz) radiation has diverse scientific and technological applications.
• Current THz generation methods, like optical rectification, often rely on complex setups at free-electron lasers.
• The Smith-Purcell effect offers a more compact and cost-efficient alternative for THz generation.

Purpose of the Study:

• To optimize a structure for single-wavelength Smith-Purcell radiation using photonic inverse design.
• To achieve narrowband THz emission from ultrarelativistic electrons.
• To demonstrate a versatile and adaptable approach for beam-based THz generation.

Main Methods:

• Employing photonic inverse design to optimize a periodic structure for Smith-Purcell radiation.
• Utilizing ultrarelativistic electrons interacting with the designed structure.
• Experimental validation using a 3D-printed model at a 900 μm wavelength.

Main Results:

• The inverse design yielded a highly resonant structure for narrowband THz emission.
• Experiments confirmed coherent enhancement of the generated radiation.
• The designed structure demonstrated adaptability for different electron energies and wavelengths.

Conclusions:

• Photonic inverse design is an effective technique for optimizing Smith-Purcell radiation structures.
• This approach enables efficient, narrowband THz generation using compact setups.
• The method holds promise for advancing beam-based THz sources across various applications.