Terahertz radiation from shocked materials

Distinct physical mechanisms for the generation of temporally coherent, narrow bandwidth optical radiation are few and rare in nature. Such sources, including lasers, have widespread applications ranging from spectroscopy to interferometry. We review the recent theoretical prediction of a new type of temporally coherent optical radiation source in the 1–100 THz frequency range that can be realized when crystalline polarizable materials like NaCl are subject to a compressive shock wave.