上转换发光机理图1(A)的过程是稀土元素处于中心先接受足以传递的能量跃

上转换发光机理图1（A）的过程是稀有元素处于中心先接受分解传递的能量跃迁到中间激发态的供体离子，然后它再吸收一个供体离子的能量跃迁到达到发光能级，图1（B）过程是稀土元素在中心吸收一个光子跃迁到中间激发态之后再吸收一个激发光子跃迁到更高的激发态而发射短波光子，称为激发态吸收。图1（C）表示的是两个处于激发态的稀土离子同时跃迁回到基态后，令中心具有更高的发光激发态，这个激发态会发射短波光子，这种情况则被称为图1（D）为合作发光分析过程，也就是通过两个于激发态的稀有金属离子在第三一个离子不参与的情况下能够回到基态和发射一个短波长的光，它具有一个很明显的特征是发射光的能量是退激发离子能级能量的2倍，并且没有能级 和图1（E）所示的为双光子吸收激发过程，它与过程（B）的明显不同是它和和发射光子相匹配，这也是一个重要区别，是它与（A）和（C）的。没有中间激发态的参与，与过程（D）的不同在于不用两个处于激发态的离子，同时存在真实的发光能级。

[1][][]，[]，[]，[]，[]，[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][]，[][][][][][][]，[][]，[][][]，[][][B]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[[1]，[]，[]，[A]。1[D]，[[2]，[，[，[A][，[C]。[1]，[B]，[D]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]，[]

The process of up conversion luminescence mechanism in Fig. 1 (a) is that the rare earth elements in the center first receive enough energy to transfer to the donor ion in the intermediate excited state, then it absorbs a donor ion to make the energy transition enough to the luminescence level, and emits a photon of short wavelength. Fig. 1 (b) is a process in which rare earth elements absorb a photon in the center to transition to the intermediate excited state, then absorb an excited photon to transition to a higher excited state and emit short wave photons, which is called excited state absorption. Fig. 1 (c) shows that after two rare earth ions in the excited state jump back to the ground state at the same time, the center has a higher excited state, which emits short wave photons, which is called cooperative sensitization. The difference between this process and (a) process is that it does not need the participation of intermediate excited states. Figure 1 (d) is a cooperative luminescence analysis process, that is, through two rare earth metal ions in the excited state that can return to the ground state and emit a short wavelength light without the participation of the third ion, it has a very obvious feature that the energy of the emitted light is twice that of the de excited ion, and there is no matching between the energy level and the emitted photon, which is also an important difference, It's with (a) and (c). Fig. 1 (E) shows a two-photon absorption excitation process, which is significantly different from process (b) in that it has no intermediate excited state. The difference from process (d) is that it does not need two ions in the excited state, and there are real emission levels at the same time.<br>