Generation of terahertz radiation in high-quality diamond samples

A method is proposed for generating terahertz radiation by producing a spectrally limited population inversion between light- and heavy-hole subbands in the valence band of semiconductors. This inversion is achieved by placing a sample in a static magnetic field and pumping it with an alternating electric field resonant with a cyclotron frequency of heavy holes. At a sufficiently low concentration of holes when the energy exchange between them is less effective than the exchange with the lattice, a considerable heating of heavy holes occurs with a nearly constant distribution function of light holes. However, the low hole concentration leads to a small terahertz field gain that can exceed the field loss only in high-quality diamond samples that are almost transparent in the terahertz range. An important advantage of this method for generating terahertz radiation over the previously proposed techniques is the possibility of implementing it at room temperature, which substantially increases its attractiveness, especially for use in biology and medicine.