Note: Coherent detection of terahertz radiation employing a continuous wave optical parametric source

Area of Science:

• Optics and Photonics
• Terahertz Spectroscopy
• Materials Science

Background:

• Optoelectronic terahertz (THz) sources are limited in frequency.
• Coherent detection of THz waves is crucial for advanced applications.
• All-optical approaches offer potential for overcoming current limitations.

Purpose of the Study:

• To present an all-optical terahertz (THz) source for coherent detection.
• To overcome frequency limitations of conventional optoelectronic THz sources.
• To demonstrate a proof-of-principle application in materials characterization.

Main Methods:

• Generation of Gaussian-shaped, linearly polarized THz waves using a continuous wave optical parametric oscillator (CW-OPO) at 1.4 THz.
• Coherent detection of THz waves utilizing the infrared signal light from the CW-OPO with a photoconductive antenna.
• Phase shifting interferometry for determining the thickness profile of a plastic lens.

Main Results:

• Successfully generated THz waves with an all-optical setup.
• Demonstrated coherent detection capability using the OPO's infrared signal.
• Obtained the thickness profile of a plastic lens, validating the technique.

Conclusions:

• The presented all-optical THz source combined with coherent detection is a viable alternative to conventional methods.
• This approach effectively overcomes frequency limitations inherent in optoelectronic THz sources.
• The technique shows promise for non-destructive characterization and imaging applications.