Optical up-conversion-based cross-correlation for characterization of sub-nanosecond terahertz-wave pulses

Area of Science:

• Nonlinear optics
• Terahertz (THz) wave technology
• Optical characterization

Background:

• Terahertz (THz) wave pulses are crucial for various scientific applications.
• Characterizing the temporal profiles of ultrashort THz pulses is challenging.
• Nonlinear optical mixing offers potential for THz wave detection.

Purpose of the Study:

• To demonstrate an optical cross-correlation technique for sub-nanosecond THz-wave pulse detection and characterization.
• To utilize frequency up-conversion for sensitive THz-wave measurements.
• To analyze the temporal characteristics of THz pulses generated by an injection-seeded THz-wave parametric generator (is-TPG).

Main Methods:

• Employed a frequency up-conversion process involving nonlinear optical mixing.
• Mixed monochromatic THz-wave pulses with near-infrared (NIR) pump pulses in a MgO-doped lithium niobate crystal.
• Utilized noncollinear phase-matching conditions for efficient frequency conversion.

Main Results:

• Successfully demonstrated an optical cross-correlation technique for sub-ns THz-wave pulse detection.
• Showed that frequency up-conversion enables sensitive detection and intensity cross-correlation characterization.
• Revealed a slightly frequency-dependent pulse width (150-190 ps FWHM) for THz pulses in the 0.95-2.00 THz range.

Conclusions:

• The developed optical cross-correlation technique is effective for characterizing sub-ns THz-wave pulses.
• Frequency up-conversion is a viable method for sensitive THz-wave detection and temporal analysis.
• The study provides insights into the temporal properties of THz pulses from is-TPGs.