Using the characteristic of refractive index are smaller than 1 in the reststrahlen band,we can produce photonic crystal having forbidden band in the middle infrared and far infrared.

由此知利用材料在剩余射线带内折射率小于1的特性，以制出中和远存在禁带的光子晶体。

It also emits natural phytocide to keep air fresh, and keep people's mind clear, and emit the far infrared ray to improve the blood circulation to relieve the fatigue.

同时其释放的远线能促进人体的血液循环，消除疲劳。