Figure 2

PBG changes with time and exhibited an asymmetry profile of asymmetry.

(a) PBGs changes with time at an interval of 90 s when they continually adsorbed ethanol gas, dash line is transmittance spectrum of saturated ethanol gas. And, asymmetric profile exists in the PBGs, such as line 11 and 12 (b) shows a clearly asymmetry profile in which the short wavelength photonic band edge is much higher than the long wavelength. Dash line is the fitting curve without PBG.