Investigation On Photonic Crystal With Tunable Refractive Index And Experimental Chatacteristics

Nowadays, photonic crystal(PC) as a positive periodical device, has extensive practicalvalue and application prospect at laser, communication and information processing, and so forth.The PC technique has already been an independent field with decades'development, which leadsto the improvement of related field. Photonic crystal forms three typical structures:one-dimensional PC, two-dimensional PC and three-dimensional PC.There are a lot of research methods of theoretical and application to use on one-dimensionaland two-dimensional PC, but not for three-dimensional PC because of the limitation, like thefabrication process. However, with the improvement of nano technology, the enhancement ofphotonics and further increasing of the technology for precision machining, the theory andapplication of photonic crystal must be developed more deeply. In research of PC, thedescription of structure and theoretical model of PC are hotspot. The investigation of my workincludes:On the basis of Maxwell equation, the basic theory of PC is studied, the propagationcharacteristic of electromagnetic wave in PC is obtained and the band gap and eigen equation ofPC are derived; some commonly used methods in the study of PC is discussed aiming at the oneson the characteristic of PC, such as Finite-Difference Time-Domain(FDTD), planar waveexpansion and scattering matrix, moreover, we established corresponding mathematical model.In contrast to the research methods commonly used on PC, the finite element method isemployed to describe the theoretical mechanism of PC. In addition, the square lattice, trianglelattice and hexagonal lattice are described quantitatively as well as brillouin zone, respectively,moreover, the finite element combination of PC is expressed with different lattices based onderivation of function, region discretization and unit different.In this thesis, the finite element model is established, and the effect of dielectric constant,fill rate and media fill ratio on the band gap of two-dimensional PC for TE and TM are studied for square-, triangle- and hexagonal-lattice structure, respectively. The band gap curves of PC forthree constructions are calculated by finite element. Meanwhile the defect concept is introducedfor researching the transmition characteristic and band gap of PC whose material is KTP basis,on which the AC electrical field is applied aiming at modulating the refractivity.The influence of temperature on band gap for square-, triangle-, point defect square- andpoint defect triangle lattice of PC is analyzed, respectively. Whereas the refractivity and gaincharacteristic of KTP basis PC with tunable refractivity is researched. Furthermore, thecombination of band gap and refractivity are obtained for one-dimensional doped andtwo-dimensional PC for tunable refractivity is calculated.On the basis of model of PC, the multiple samples of PC are fabricated andexperimentalized. The SEM images with different magnifying parameters for periods of PC arecaptured and detailed analyzed.In this paper, the PC LED and the gas concentration measurement system on the basis of PCare designed due to the unique advantagement of PC. It widens the application of PC, which iscondition for PC filter, PC laser and PC sensor.