Terahertz vector beam generation using segmented nonlinear optical crystals with threefold rotational symmetry

Area of Science:

• Physics
• Optics
• Terahertz Science

Background:

• Cylindrical vector beams (CVBs) are crucial for advanced optical applications.
• Generating CVBs in the terahertz (THz) frequency region presents unique challenges.
• Existing methods for THz CVB generation are often complex or limited in tunability.

Purpose of the Study:

• To propose and demonstrate a simple, efficient method for generating broadband terahertz cylindrical vector beams.
• To enable easy switching between radial and azimuth modes for THz CVBs.
• To directly observe the longitudinal electric field components of THz CVBs.

Main Methods:

• Utilizing optical rectification in segmented nonlinear crystals with threefold rotational symmetry.
• Employing segmented Gallium Phosphide (GaP(111)) plates for THz CVB generation.
• Employing a terahertz camera for beam visualization and terahertz time-domain spectroscopy (THz-TDS) for field component analysis.

Main Results:

• Successful generation of a broadband terahertz cylindrical vector beam.
• Clear experimental evidence of beam generation confirmed by terahertz camera imaging.
• Demonstrated capability for easy switching between radial and azimuth modes.
• Direct observation of longitudinal electric field components at the focal point using THz-TDS.

Conclusions:

• The proposed method offers a simple and effective route for generating tunable terahertz cylindrical vector beams.
• The technique facilitates the study of THz fields, including their longitudinal components.
• This advancement holds potential for applications in THz imaging, spectroscopy, and material science.