Four-wave mixing and direct terahertz emission with two-color semiconductor lasers

The four-wave mixing in a semiconductor laser configured to emit on two wavelengths simultaneously was analyzed. It was shown that the four-wave mixing sidebands exist up to 4 THz stemming from a modulation of the carrier plasma at the difference frequency of the two laser modes. The tunable THz radiation at the difference frequency from the laser device itself suggesting a scheme for a tunable THz source was generated and detected. The results show that the corresponding difference frequency in the THz regime is emitted directly out of the laser diode.