Study On Preparation And Optical Characterization Of One Dimensional Defective Photonic Crystal

One dimensional photonic crystals(1D PCs) were paid attention to scientists early because of its simple structure and easy preparation. Different media with different refractive index deposit periodically to form the1D PCs which exhibit an essential forbidden energy band in a differential frequency range called photonic band-gap(PBG). By employing a defect mode into the PC structure, sharp narrow resonant peaks appeared within the PBG which is called transmittance peak(TP). In relative researches, electricity, mechanics and optics method are used to modulate the intensity of TP. VO2is a kind of thermotropic phase transition functional material which could transform from monoclinic insulating phase to the rutile metal phase at about68℃, concurrently with a drastic change in electrical, mechanics and optical properties as well. In this paper, a temperature tunable defective1D PC was designed whose tunability is achieved by employing vanadium dioxide(VO2) as the defect layer. The main work as follows:Firstly, VO2thin film was fabricated using sputtering oxidation coupling(SOC) method. The technological parameters and its properties were studied. The thickness measuring instrument was used to investigate the optical thickness of the film; the four-probe method was applied to test sheet resistance of all samples to determine the phase transition temperature and electric properties; The Fourier Transform Infrared Spectroscopy (FTIR) was introduced to test the optical transmittance curve in different temperatures. The technological parameters of other optical thin film materials involved in this paper were also optimized.Secondly, the defective1D PC was designed using the theoretical data and adopted the matrix method to calculate the spectrum of the structure. For designing to obtain theoretical parameters, the thickness of each layer was optimized the thickness of each layer in the multi-layer film and then the the preliminary experiment was prepared. The X-ray diffraction(XRD) experiments were introduced to characterized the composition of each layer and the transmittance of all samples were measured. The refractive index(n) and extinction coefficient(κ)in various light-wave length(λ) could be fitted by Film Wizard software. Compared the obtained optical parameters with theoretical optical parameters, we obtained the theoretical optimized multi-layer structure thickness.Finally, the1-D PC with VO2defect layer was prepared and characterizations using FTIR and Field Emission scanning electron microscope(FESEM) to investigate the infrared spectrum and morphology of the cross-section and surface, respectively. The results showed that the transmission peak intensity of the designed structures was temperature tunable and the transmission peak position almost no change when the temperature up and down. Compared with the theoretical structure, the change amplitude of the experimental preparation structure transmission peak intensity is smaller than the theoretical calculation resultsIn this paper, a temperature tunable ID defective PC was designed theoretically and fabricated practically. This structure was low-cost, high productive rate and easy-manipulate. It can be widely used in laser protection, optical switch and optical communication and so on.