Narrow linewidth and wideband tunable continuous-wave terahertz generator based on difference frequency generation...

Area of Science:

• Terahertz (THz) Science and Technology
• Nonlinear Optics
• Spectroscopy

Background:

• Continuous-wave (CW) terahertz (THz) sources are crucial for high-resolution spectroscopy and imaging.
• Existing THz generation methods often face limitations in tunability, linewidth, or output power.
• Developing a versatile and precise CW THz generator is essential for advancing THz applications.

Purpose of the Study:

• To demonstrate a narrow linewidth and wideband tunable continuous-wave terahertz generator.
• To explore the potential of this source for high-precision spectroscopic detection and multispectral imaging.

Main Methods:

• Employed difference frequency generation (DFG) using two narrow-linewidth continuous-wave (CW) fiber lasers as pump sources.
• Utilized a DAST (4-N,N-dimethylamino-4'-N'-methyl-stilbazolium tosylate) crystal for THz wave generation.
• Characterized the THz output by measuring its tunability, output power, and linewidth using CO gas absorption spectra and the Vogit gas model.

Main Results:

• Achieved a continuously tunable terahertz wave in the range of 1.1–3 THz.
• Obtained a maximum output power of 2.79 nW at 2.568 THz.
• Estimated the linewidth of the output THz wave to be 56.5 MHz, with spectra matching air absorption lines and enabling detection of narrow absorption features in 2-Deoxy-D-Glucose.

Conclusions:

• Successfully demonstrated a tunable CW-THz source with a narrow linewidth and wideband tunability.
• The source's performance indicates significant potential for practical applications in THz high-precision spectroscopic detection.
• The generated THz spectra align well with known absorption lines, validating the source's accuracy for spectroscopic analysis and multispectral imaging.