Research Of Optical Characteristics Of Composite Polymer Film With Nanoparticles In Terahertz Range

The terahertz region (1THz=1012Hz), being situated between the microwave andmid-infrared range,consists of electromagnetic waves at frequencies from0.1to10THz (corresponding to wavelengths from3mm to30um) and it is widely used notonly for basic science,but also for medical science,imaging, security check,militaryand communication due to its special properties.And the development of Terahertzwave technologies closely depends on various functional THz devices such as opticalfiber,resonator filter, waveguide switch, reflector and so on.Photonic crystal is a kindof structure of dielectric constant changes periodically,And in the electromagneticwave propagation in the structure,photonic band gap can be formed. Theory ofphotonic bandgap is just the basis of functional THz devices. Polyvinylidene fluoride(PVDF) and polymethylmethacrylate (PMMA) are polymer materials with manyexcellent properties such as good chemical resistance,frictional resistance,corrosionresistance and so on,and they have low low absorption against terahertz wave.So theyhave a very wide range of applications in the industrial, electrical and electronicaspects.In this paper, composite films were prepared by using PVDF and PMMA asmatrix.And the refractive index and extinction of PVDF film, PMMA film,compositePVDF films and composite PMMA films in terahertz range were studied.The mainworks of this paper are as follows:1.In the first chapter, the major contents were briefly introduced by these:(1)Thegeneration and detection of terahertz wave, the unique properties andapplications;(2)The main characteristics of photonic crystals;(3)The developmentsabout terahertz reflector.2.In the second chapter,the terahertz time-domain spectroscopy (THz-TDS) andthe ways of extracting optical parameters were mainly presented.3.In the third chapter,the preparation and characterization of compositemembranes were presented.The PVDF film,PMMA film,composite PVDF films andcomposite PMMA films with different ratios of nanoparticles were obtained by spincoating method,and then their surface morphology were observed with SEM. 4.In the forth chapter,the terahertz time-domain spectroscopy system(THz-TDS)has been used to get the transmission spectra of the samples in THz band,from which the optical constants of the samples are extracted. The reflectionspectrum of the reflectors with structure of Si substrate/[HL]nH (H refers to thematerials with high refractive index and L refers to the low refractive index)aresimulated based on transfer matrix method.5.The fifth chapter is the full text summary and work outlook.