The physics of laser action is presented using the quantum photonic basis of spontaneous and stimulated emission, highlighting the limits of Maxwell’s equations in describing quantum behavior. Further, the book shows how the quantum confinement of electrons leads to reduced threshold current on the macroscopic level. Quantum cascade and interband cascade laser structures are analyzed using methods developed in earlier chapters to show how band structure engineering can be applied to access photon emission energies that cannot be achieved using conventional materials. weiterlesen