A breakthrough for terahertz semiconductor lasers

A breakthrough for terahertz semiconductor lasers: "Working with researchers at MIT and Sandia National Laboratories, Kumar has made a semiconductor laser, also called a quantum-cascade laser (QCL), that emits terahertz (THz) radiation at higher operating temperatures than ever before...

To raise QCLs’ operating temperature, Kumar’s group has harnessed the “relaxation process.” Electrons tend to dissipate their energy in the form of lattice vibrations at higher temperatures, called “non-radiative relaxation,” which is typically detrimental to laser operation.
Kumar’s group used this natural phenomenon in a controlled manner to inject electrons into the correct energy levels. This scattering-assisted injection technique is less sensitive to the thermal energy of electrons and remains efficient at high temperatures as well."