Probing the terahertz wave distribution inside a crystal in a terahertz wave parametric source

Area of Science:

• Nonlinear Optics
• Terahertz (THz) Photonics
• Quantum Electronics

Background:

• Terahertz (THz)-wave parametric sources are crucial for THz generation.
• Experimental validation of THz-wave development during parametric generation is limited.
• Understanding spatial THz-wave dynamics is key for source optimization.

Purpose of the Study:

• To experimentally investigate the spatial distribution and development of THz-waves during parametric generation.
• To validate simulation predictions regarding THz-wave amplification and pump depletion effects.
• To explore novel THz-wave phenomena under high-intensity conditions.

Main Methods:

• Utilized a probe beam injected from the crystal's z-face to upconvert THz-waves to the near-infrared.
• Measured the spatial distribution of THz-waves inside a nonlinear optical crystal by scanning the probe beam injection position.
• Observed THz-wave amplification, generation position shifts, and interference patterns.

Main Results:

• Successfully captured experimental evidence of THz-wave amplification dependent on seed beam intensity.
• Observed shifts in THz-wave generation position attributed to pump depletion, consistent with simulations.
• Discovered a fringe pattern from higher-order THz-wave interference under high-intensity seed conditions, a phenomenon not included in current simulations.

Conclusions:

• The study provides unprecedented experimental insight into the physical processes governing THz-wave parametric generation.
• Results support the development of more accurate numerical models for THz sources.
• Findings facilitate the optimal design of advanced THz-wave parametric sources.