Elliptically polarized THz-wave generation from GaP-THz planar waveguide via collinear phase-matched difference...

Area of Science:

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

Background:

• Terahertz (THz) wave generation is crucial for various applications, including spectroscopy and imaging.
• Gallium phosphide (GaP) planar waveguides offer a promising platform for nonlinear optical processes.
• Efficiently generating and controlling THz wave polarization remains a key challenge.

Purpose of the Study:

• To demonstrate THz-wave generation in GaP planar waveguides.
• To investigate the simultaneous generation of TE- and TM-mode THz waves.
• To explore the control of elliptical polarization of THz waves through waveguide engineering.

Main Methods:

• Collinear phase-matched difference-frequency mixing of two near-infrared sources.
• Utilizing GaP planar waveguides for THz wave confinement and propagation.
• Adjusting the polarization of incident infrared sources to control THz wave modes.
• Varying waveguide length to influence phase shifts and polarization ellipticity.

Main Results:

• Simultaneous generation of TE- and TM-mode THz waves was achieved.
• The phase shift between TE- and TM-modes was dependent on waveguide length.
• Elliptically polarized THz waves were generated, with ellipticity increasing with waveguide length.
• Control over the rotational direction of elliptical THz wave polarization was demonstrated.

Conclusions:

• GaP planar waveguides enable efficient THz-wave generation via difference-frequency mixing.
• Waveguide length is a critical parameter for controlling THz wave polarization.
• The demonstrated control of elliptical polarization opens possibilities for novel THz applications.