Finally, in the micropolis corners you can see ring resonators, which are a conventional (non photonic-crystal) way to achieve a resonant cavity for use in channel-drop filters, etcetera.

最后，在光子微域的转角处，你可以看见环形谐振电路，这是用传统的方式（非光子晶体方式）来表示用于滤波器等的谐振腔。