Study On The Characteristics Of 3D Photonic Crystal Of Blue Phase Liquid Crystal With Continuously Adjustable Photonic Band-gap

Photonic crystal(PC)with periodic modulation of dielectric constant is a new type of artificial microstructured material and its most fundamental feature is the photonic band-gap.The three-dimensional photonic crystal realizes the ability for controlling and manipulating the flow of light due to its complete photonic band-gap.Therefore,researching on three-dimensional photonic crystal is particularly important.Blue phase liquid crystal(BPLC)with self-assembled three-dimensional periodic cubic structure can be regarded as artificial three-dimensional photonic crystal.As soft three-dimensional photonic crystal,BPLC undergoes a change in dielectric constant and refractive index under the influence of external electric field,thereby causing the movement of photonic band-gap.BPLC is a good stimuli-responsive three-dimensional photonic crystal material with a wide range of application.In this paper,by changing the electric field driving modes and experimental conditions,the BPLC three-dimensional photonic crystal with reversible tuning of the wide photonic band-gap range is obtained.In the first chapter,the development of photonic crystals is introduced.Starting from the characteristics and classification of photonic crystals,photonic crystals in nature and the application of stimuli responsible photonic crystals,we introduce the research value and development prospects of photonic crystals as an emerging artificial microstructured material.Next,we introduce the development of BPLC and the research progress as artificial three-dimensional photonic crystal mainly from the aspects of lattice stretching and photonic band-gap tuning of BPLC three-dimensional photonic crystal under electric field excitation.Then we introduce the wide application of BPLC as stimuli responsive three-dimensional photonic crystal.In the second chapter,we introduce the experimental materials,experimental equipment and fabrication methods for the preparation of BPLC three-dimensional photonic crystals,and record the whole process of its formation.Next,by applying the direct-current field and alternating-current field to the pure BPLC samples and the polymer stabilized blue phase liquid crystal(PS-BPLC)samples respectively,we investigate the effects of different driving modes on the photonic band-gap tuning of blue phase liquid crystal three-dimensional photonic crystal.By comparing the different driving methods,the optimal driving conditions for inducing the tuning of the photonic band-gap range are obtained.In the third chapter,the extension effect of the alternating-electric field on the tuning range of photon band-gap of pure BPLC three-dimensional photonic crystal is introduced in detail.The effects of different experimental conditions such as the orientation and thickness of the liquid crystal cells and the frequency of alternating-current field on the tuning range of BPLC photonic band-gap are also studied.By changing different experimental conditions,the tuning range of the photonic band-gap can be extended to nearly 200 nm,covering almost the entire visible spectrum while showing a vivid color change.Finally,the response time of the BPLC three-dimensional photonic crystal under the action of the alternating-current field is obtained by directly applying the threshold field strength to the sample,and the wide range of fast reversible tuning of the photonic band-gap is also realized.