Efficient, tunable, and coherent 0.18-5.27-THz source based on GaSe crystal.

Area of Science:

• Optics and Photonics
• Solid-State Physics
• Terahertz Science

Background:

• Terahertz (THz) radiation offers unique properties for spectroscopy, imaging, and sensing.
• Developing compact, tunable, and high-power THz sources remains a significant challenge in the field.
• Difference frequency generation (DFG) is a viable technique for THz generation, but efficiency and tunability need improvement.

Purpose of the Study:

• To demonstrate a novel, continuously tunable, and coherent THz source.
• To investigate the potential of Gallium Selenide (GaSe) crystals for efficient THz generation via DFG.
• To achieve high output power and broad spectral coverage in the THz range.

Main Methods:

• Utilizing collinear phase-matched difference frequency generation (DFG) in a GaSe crystal.
• Achieving continuous tunability across a wide spectral range (56.8–1618 µm or 0.18–5.27 THz).
• Characterizing the THz source for output power, coherence, tunability, and stability.

Main Results:

• Successfully generated continuously tunable and coherent THz radiation from 0.18 to 5.27 THz.
• Achieved a peak output power of 69.4 W at 1.53 THz (196 µm).
• Demonstrated a photon conversion efficiency of 3.3% with advantages of simple tuning, alignment, and stable output.

Conclusions:

• The demonstrated GaSe-based DFG system is a novel and promising THz source.
• The source offers significant advantages including high coherence, broad tunability, and stable operation.
• Further optimization of the design can lead to a compact and efficient THz generation system.