固体激光器的四能级系统密度矩阵元的演化特性

固体激光器是一个四能级系统。本文基于量子力学和Kraus算子理论,针对能级间存在跃迁的情况,利用约化密度矩阵方法,得到四能级系统密度矩阵元的演化特性。结果表明:当粒子的跃迁概率满足一定条件时,能在第二激发态与第一激发态之间形成粒子数反转,为产生激光作准备;当粒子以大概率从第二激发态辐射到第一激发态和从第一激发态辐射到基态时,产生激光。

The transformation of density matrix of four-level system in solid laser

Solid laser is a four-level system.This paper utilizes theories of quantum mechanics and Kraus operator,to analysis the four-level system which in the case of absorption as well as radiation.The object of the research is to probe into the transformation properties of density matrix.The result shows that probability of absorption and radiation condition is satisfied,between the second excited state and the first excited state forms reversion of particles and prepares for producing laser.It also shows that when particles transform from the second excited state to the first excited state and the first excited state to the ground state at very high probability,the system produces laser.