| As a new model of artificial optical compound material,photonic crystals have got a periodic variation of dielectric constant in space.Due to its characteristics of photonic band gap and photon localization,it can be used to manipulate the propagation of electromagnetic waves.One-dimensional photonic crystals can be used as optical switches,optical waveguide couplers,band-stop filters,omnidirectional reflectors and so on.In this paper,a(Si/SiO2)ND(Si/SiO2)N structure with filter characteristics is designed by stacking two kinds of dielectric materials Si and SiO2.The one-dimensional photonic crystal filter characteristics is studied in the visible band and near-infrared band by transmission matrix method,and one-dimensional photonic crystal films are prepared by the method of radio frequency magnetron sputtering deposition.The main contents are summarized as follows:(1)Based on the transmission matrix theory,the transmission characteristics,energy band characteristics and the transmission and reflection properties in the TE and TM modes of the one-dimensional periodic and defective photonic crystals are studied.The error of the film thickness monitor in the magnetron sputtering instrument is corrected.The effect of the sputtering power on the surface morphology of the films and the argon pressure on the thickness of the films in experiment are studied.Then the optimum process parameters are obtained.(2)The filter properties of one-dimensional(Si/SiO2)ND(Si/SiO2)N structure photonic crystals in the visible band and near-infrared band are studied theoretically.The study shows that with the increasing of the number of periodicity,the cut-off degree of the band gap edge is getting better,and the band gap becomes clearer.With the increasing of the incidence angle,the blue-shift of the band gap in the short wave length is larger than the long wavelength in the TE mode,while in the TM mode,it is opposite.The photonic crystal with the low refractive index defect of SiO2,the peak value of the trapping mode is higher.When the thickness of the defect material increases,the defect mode has a red-shift.When the thickness of the defective medium is constant,with the increasing of the incident angle,the defect mode in the transmission spectrum is blue-shift,and the peak of the defect mode is decreased in the band gap in the TE mode,and the full width at half maximum(FWHM)is decreased.In the TM mode,the peak value of the defect mode got a increase at first and then decreases,the peak value reaches the maximum at 0.99 when the incident angle is 60 degrees,and the FWHM increases.(3)The photonic crystal films of three(Si/SiO2)N structures when N is 5,7,9 and three(Si/SiO2)ND(Si/SiO2)N structures when the defective medium D was SiO2,MoO3 and TiO2 were prepared by magnetron sputtering.And their transmission spectra were tested.The results show that as the number of periodic increases from 5 to 9,the reflectivity in the band gap increases gradually and reaches the highest 95%when N is 9.Due to the fact that photonic crystal is more sensitive to the incident angle in the TM mode,the gap width changes as the incident angle increases,and the band gap width increases with the number of TE and TM modes as the number of period increases.The variation of band gap width is smaller and smaller with the increased angle,which indicates that increasing the number of period can weaken the sensitivity of photonic crystal band gap to the variation of angle.When the defect medium D is SiO2,MoO3 and TiO2 with different thickness,the peak value of the defect mode decreases.It indicates that the increase of refractive index of the defect medium could lead to the reduce of the peak of the defect mode in the band gap.The photonic crystal film of(Si/SiO2)11 structure was prepared and the transmission spectrum was tested.The idea of widening the band gap can be achieved when the number of period increases to 11. |
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