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.

由此可材料在剩余射线带内折射率小于1特性，我们可以制出中红外区和远红外区存在禁带光子晶体。

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.

同时其远红外线能促进人体血液循环，消除疲劳。