It must lose enough energy to fall past the bandgap into the area where electrons are allowed. 它必须失去足够的能量，属于过去的带隙纳入地方电子获准。
Without changing the period size, the frequency bandgap is varied when the length of the stretching strip is adjusted. 在不改变周期的情况下，通过调整伸长窄带长度可以改变带隙特性频率。
