A tapered parallel plate waveguide for frequency up-conversion of terahertz radiation

Area of Science:

• Terahertz (THz) science and technology
• Plasma physics
• Waveguide engineering

Background:

• Frequency up-conversion is crucial for extending the utility of terahertz (THz) sources.
• Flash ionization offers a promising method for generating and manipulating THz radiation.
• Efficient interaction between plasma and THz waves is key to maximizing conversion efficiency.

Purpose of the Study:

• To develop and evaluate a tapered parallel plate waveguide for THz frequency up-conversion experiments.
• To enhance the interaction between THz pulses and plasma generated by flash ionization.
• To improve the efficiency of THz frequency up-conversion through optimized waveguide design.

Main Methods:

• Fabrication of a tapered parallel plate waveguide.
• Utilizing flash ionization to generate plasma within the waveguide.
• Guiding and converging THz pulses to a narrow plate separation (sub-wavelength).
• Experimental characterization of THz pulse transmission and interaction.

Main Results:

• The tapered waveguide successfully guided p-polarized THz pulses.
• Achieved a narrow plate separation of 50 μm, smaller than the THz wavelength.
• Demonstrated good performance for THz pulse transmission in the optimized gap.
• The design facilitates efficient plasma-wave interaction for frequency up-conversion.

Conclusions:

• The developed tapered parallel plate waveguide is effective for THz frequency up-conversion experiments.
• The sub-wavelength confinement of THz pulses enhances plasma-wave interaction efficiency.
• This waveguide design is suitable for flash ionization-based THz up-conversion applications.