The generation rate of optical phonons in quantum cascade lasers under different applied field

We have theoretically studied the generation rate of longitudinal optical (LO) phonons in mid-infrared quantum cascade laser so as to learn the effect of phonons on electron transmission characteristics. The LO phonon performance was analyzed by combining the Monte-Carlo simulation with kinetic equations. We have obtained the LO phonon number under different applied field to show that the generating rate and the saturating number of optical phonon increases with applied field. At last we propose the pulsed pumping to point out the importance of LO phonon decaying into two acoustic phonons in electron transmission.