µJ-level multi-cycle terahertz generation in a periodically poled Rb:KTP crystal

Area of Science:

• Nonlinear Optics
• Terahertz (THz) Photonics

Background:

• Efficient generation of multi-cycle terahertz (MC-THz) radiation is crucial for various applications.
• Periodically poled crystals are key nonlinear optical materials for THz wave generation.

Purpose of the Study:

• To demonstrate MC-THz generation in a rubidium (Rb)-doped potassium titanyl phosphate (Rb:PPKTP) crystal.
• To evaluate the performance and potential of Rb:PPKTP for high-energy THz applications.

Main Methods:

• Utilized a 15.5 mm long Rb:PPKTP crystal with a 300 µm poling period.
• Cryogenically cooled the crystal to 77 K to optimize THz generation.
• Investigated the crystal's performance under high optical fluences.

Main Results:

• Achieved up to 0.72 µJ of THz energy at 0.5 THz with a 3 GHz bandwidth.
• Obtained a maximum internal optical-to-terahertz conversion efficiency of 0.16%.
• Observed no photorefractive effects or damage up to 900 mJ/cm².

Conclusions:

• Rb:PPKTP is a promising material for efficient MC-THz generation.
• The crystal demonstrates robustness and potential for multi-millijoule-level THz output.
• Performance is comparable to established materials like periodically poled lithium niobate.