Research On The Performance Of Photopolymer Based Optical Devices

Polymer based optical devices have many advantages of high integration,low loss and excellent compatibility to various preparation processes.The polymer optical devices have attracted widespread attention in academic and industrial applications.As an important component of modern optical devices,photopolymer materials are inexpensive,rich in variety,and simple to prepare.They are widely applied in volume holographic storage,photoluminescent devices,wearable devices,and biosensing areas.However,the refractive index modulation of the optical diffraction devices fabricated by photopolymer is low because of the limitation of the single component photopolymer itself.On the other hand,the multi-beam interference lithography in the UV and visible spectral region as one of the traditional fabrication techniques of photopolymer optical device can no longer meet the requirements for the fabrication of structures below 100 nm.In this thesis,the first part of research is involved to the research on the refractive index modulation of photopolymer holographic gratings.It is enhanced by doping metal nanoparticles,and the effects of metallic nanoparticles on the photokinetics of photopolymerization during the formation of holographic gratings are also explored.At the same time,we present a straightforward template-assisted method to fabricate a free-standing polymer/colloidal-quantum-dot(CQDs)film with a nanostructured interface,and experimentally demonstrate its ability to control the emission wavelength of the CQDs,towards the use of amplified spontaneous emission.In this thesis,a series of research works is carried out on the improvements of photopolymer based holographic gratings and nanostructure fabrication,in order to conquer the limitations mentioned above.The main contents can be summarized as following:(1)We report a new Ag nanoparticle-dispersed polymer nanocomposite for volume holographic recording through acrylic photopolymerization.This type of holographic grating with high diffraction efficiency was prepared by a one-step synthesis.The refractive index modulation amplitude as large as 0.0069 at 633 nm is seen at the optimum Ag nanoparticle concentration of 1 wt.% with respect to the monomer.The refractive index modulation was increased by nearly two timescorresponding to non-nanoparticle-doped photopolymers.Electron paramagnetic resonance measurements showed that Ag nanoparticles influence both the generation of alkyl radicals and the scavenging of oxygen in free radical photopolymerization.This mechanism intrinsically determines the molecular weight of polymer being formed and,thereby,affects the refractive index modulation amplitude of the formed grating as a function of Ag nanoparticle concentrations.Our results suggest a simple way to control the photopolymerization and,therefore,to tailor polymers for practical uses.(2)In this work,we presented a straightforward template-assisted method to fabricate a free-standing polymer/CQDs film with a nanostructured interface,and experimentally demonstrated its ability to control the emission wavelength of the CQDs.It has been shown the tunability of amplified spontaneous emission by changing the structure of the polymeric interface.The possible relationship among the size of scatters,and the emission wavelength and threshold has been analyzed based on the results obtained by the designed examinations.The applications of photopolymers in structure transferring and quantum dot photoluminescence devices have been expanded.