Enhancing THz emission from nonlinear metasurfaces by a Bragg perfect absorber

Area of Science:

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

Background:

• Nonlinear plasmonic metasurfaces are ultracompact THz sources emitting single-cycle THz pulses.
• Current metasurface designs show progress in controlled THz wavepacket generation but lack optimized emission strength.

Purpose of the Study:

• To numerically demonstrate a Bragg-assisted perfect absorber for enhancing THz emission from nonlinear metasurfaces.
• To investigate methods for optimizing the coupling of pumping lasers to metasurfaces for stronger THz output.

Main Methods:

• Numerical simulation of a Bragg-assisted perfect absorber integrated with a nonlinear metasurface.
• Analysis of laser-metasurface coupling efficiency.
• Comparison of THz signal enhancement with and without the proposed absorber design.

Main Results:

• Over an order of magnitude enhancement in THz signal strength was achieved.
• The Bragg-assisted perfect absorber improved laser coupling to the metasurface.
• Combined optimization strategies led to over two orders of magnitude THz emission enhancement.

Conclusions:

• Bragg-assisted perfect absorbers offer a viable route to significantly enhance THz emission from plasmonic metasurfaces.
• This approach provides a pathway to developing more powerful and efficient compact THz sources.
• Further optimization can lead to substantial improvements in THz generation for various applications.