Tunable Terahertz Source Based on Near-Infrared Diode Lasers

The figure schematically depicts a heterodyne photonic apparatus built around three continuous-wave, near-infrared diode lasers. This apparatus generates electromagnetic radiation at an adjustable, precisely defined frequency in the terahertz range. The spectral width of the signal is less than about 1 MHz. The apparatus could serve as a prototype of tunable far-infrared sources and heterodyne up- and down-converters for fiber-optic communication systems and for testing infrared systems in general. Other potential uses lie in infrared spectroscopy for remote sensing and in research on low-energy light/matter interactions.