The Regulation Of Optical Property Of Porous Anodic Alumina Films

Photonic crystal is a kind of periodic structures containing ordered arrays with high and low dielectric constant components. Defect peaks will appear in the photonic band gaps (PBGs), if defects are introduced into photonic crystals. Photonic crystals with or without defects have application prospects in many filelds. The paper aims at solving slant band edge of PBGs, introducing defects and exploring practical use. The main content is as follows:1) A current controlled method was developed to fabricate porous anodic alumina (PAA) films, overcomeing the uneven pore growth in the voltage control mode. The periodic time, the current value, the duty ratio, the temperature and constituents of the electrolyte were investigated in the current control mode to examine their impacts on the optical property of PAA films. By selecting the proper periodic time, we successfully prepared the PAA films with narrow band gaps, of which half-peak width was less than20nrn.2) We have manufactured the PAA films with defects and analyzed the effects of various factors on the defect modes, including defect-introducing voltage waveform, voltage value, voltage duration, voltage sequence and electrolyte concentration. The position and physical thickness of defects played a leading role in determining the transmittance of the defect peak.3) Using PAA films with narrow band gaps as a sensing element for liquids, we studied the relationship between the PBG position or transmittance of PAA films and the liquid refractive index. The chemical modification on the pore surface could shift the position of PBG, which lay the foundation for selective recognition.4) Using the grease as a mask, we created defects in the selected sections of the PAA films. On the basis of this type of PAA films, we proposed an anti-counterfeiting technique working in infrared region.