Most optical oscillator strengths for the transitions between valence band and conduction band are nearly equal to zero.
价带顶和导带底附近的带间跃迁振子强度大部分都近乎为零；
2
The SCH layer can provide optical confinement, but at the same time, it also affects the distribution of the carrier(especially to the electrons in conduction band).
限制层在提供光学限制的同时，对载流子（主要是导带电子）分布也有影响。
3
The light path in the conduction process loss, avoid the traditional cutting bed due to optical transmission problems caused by large attenuation of laser cutting power.