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

The exact power output of a table-top-sized terahertz (THz)-wave source using a nonlinear optical process has not been clarified because detectors for these experiments [Si bolometer, deuterated triglycine sulfate (DTGS), etc.] are not calibrated well. On the other hand, powermeters for the mid-infrared (mid-IR) region are well established and calibrated. We constructed a high-power dual-wavelength optical parametric oscillator with two KTP crystals as a light source for difference frequency generation. The obtained powers of dual waves were 21 mJ at similar to 1300 nm, ten times higher than that of the previous measurement. The device provides high-power THz-wave generation with similar to 100 times greater output power than that reported in previous works. A well-calibrated mid-IR powermeter at similar to 27 THz detected the generated THz wave; its measured energy was 2.4 mu J. Although the powermeter had no sensitivity in the lower-frequency range (below 20 THz), the pulse energy at such a low-frequency region was estimated in reference to the output spectrum obtained using a DTGS detector: the energy would be from about the submicrojoule level to a few microjoules in the THz-wave region. (c) 2007 Optical Society of America.