High-power terahertz-wave generation using DAST crystal and detection using mid-infrared powermeter

Area of Science:

• Nonlinear optics
• Terahertz (THz) wave generation
• Optical parametric oscillators

Background:

• Accurate power measurement of tabletop terahertz (THz)-wave sources is challenging due to poorly calibrated detectors.
• Mid-infrared (mid-IR) powermeters offer established calibration, unlike typical THz detectors (e.g., Si bolometer, deuterated triglycine sulfate (DTGS)).

Purpose of the Study:

• To construct a high-power THz-wave source for accurate power measurement.
• To overcome limitations of existing THz detectors by utilizing a calibrated mid-IR powermeter.

Main Methods:

• Developed a high-power dual-wavelength optical parametric oscillator using two KTP crystals.
• Employed difference frequency generation for THz-wave production.
• Utilized a well-calibrated mid-IR powermeter (sensitive at ~27 THz) for direct THz energy measurement.

Main Results:

• Achieved dual-wave output powers of 21 mJ at ~1300 nm, a tenfold increase over previous measurements.
• Generated high-power THz-waves with approximately 100 times greater output power than previously reported.
• Measured 2.4 microjoules of THz-wave energy at ~27 THz using the calibrated mid-IR powermeter.
• Estimated THz-wave energy in the lower-frequency range (below 20 THz) to be between submicrojoule and a few microjoules, based on spectral analysis.

Conclusions:

• Successfully developed a high-power THz-wave source enabling more accurate energy measurements.
• Demonstrated the utility of calibrated mid-IR powermeters for measuring THz-wave output.
• Provided a reliable method for quantifying THz-wave energy, advancing research in THz science and applications.