Characteristics Of Laser Emission Of Micro-Devices Filled With Dye Doped Liquid Crystal

The tunable dye laser has wide tuning range includeing ultraviolet,visible and infrared regions.Liquid cryestal(LC)as an adaptive flexible material has the characteristics of optical anisotropy and high external field sensitivity.The combination of dye-doped LC and tunable lasers is characterized by small size,flexible structure design,wide tuning range and high optical efficiency.Therefore,it will have broad application in many fields such as:optical communication,sensing,medical diagnosis and others.With the development of a series of dye-doped LC filled droplets,broad spectrum LC light sources,physical sensors,the study of emission characteristics of relative laser based on dye-doped LC is in the ascendant because of new instruments with different characteristics.In this paper,dye-doped LC filled optical devices are proposed with different structure,including dye-doped LC laser,LC lens and LC based broad spectrum fluorescence source.The following four specific dye-doped LC optical devices are investaged:LC cell,capillary,droplet and hollow fiber.By changing specific structural parameters and field conditions,the emission model and characteristic laser are analyzed by theoretical simulation and experimental method.The main contents of this thesis include:Based on the analysis of the present development status of the existing dye-doped LC laser,the laser emission device based on dye-doped LC is designed;the transmission and emission spectrum are experimentally investaged under conditions of different temperatures;voltages,and incidence angles;tuning properties of the distributed feedback mode(DFB)laser under different field conditions are analyzed;and the laser emission threshold characteristics of the silver-nanoparticles doped LC are theoretically and experimentally discussed.The coaxial disk-circle electrode structure is put suggested,and the COMSOL is used to simulate the electric field,optimize the structure of electrode,realize the circular symmetric cone electric field of this structure.We experimentally obtain the director of LC depending on the voltage and the characteristics of the wavelength tuning of the laser emission.Meanwhile,the optical focusing characteristics of the coaxial disk-circle electrode structure filled with LC dependent on the voltage are investigated,and the extensive tunable focal length of the LC based lens is realized.Combined with the cylindrical microcavity structure of the capillary and the anisotropy of the LC,a vacuum coating method is proposed to obtain capillary with the optically controlled polyimide(PI)photo alignment layer on the inner surface.The laser emission device of the capillary filled with dye-doped LC is prepared.The laser emission characteristics of the optical capillary of PI membrane filled with dye-doped LC are investigated.By changing the inner diameter of the capillary and with or without optical PI membrane,the produced Whispering Gallery Modes(WGM_S)and the Random Lasers(RL)modes are annlyzed.The influence characteristics of temperature and voltage on the laser emission wavelength are theoretically and experimentally investigated.At the same time,the WGM lasing modes with low threshold and large free spectral range(FSR)are obtained.Based on the point that the azobenzene photosensitizer chiral part can change the difference of pitch of cholesteric LC,the aniline-phenol synthesis is proposed to make homemade azo photosensitizer and the photosensitive cholesteric phase LC droplets.Since the texture inside the micro droplet ball is a concentric circle from the center to the outside area,the screw pitch of the cholesteric phase LC can be changed by controlling the spiral twisting of the photosensitive chiral agent,and thereby the influences of the droplets density,exposure time under the ultraviolet light,temperature and voltage on the laser emission wavelength are theoretically and experimentally investigated.Therefore,the tuning approach of the lasing emission wavelength is achieved.The fluorescent light source based on the dye-doped LC filled hollow fiber or hollow photonic crystal fiber is proposed,and its lasing emission characteristics are theoretically and experimentally studyed,thus a wide band tunable fluorescence light source is obtained.Then,the characteristics of full width half maximum,the magnification of the light intensity and the changing features of central wavelength of the fluorescent light source are analyzed.The output power and temperature tuning characteristics of two kinds of optical fiber light source filled with dye-doped liquid crystal are studied;the temperature and voltage dependent tunable characteristics of the central wavelength of the hollow fiber and hollow photonic crystal fiber are obtained.Therefore,the preparation and new tuning method of a broadband fluorescent tunable light source based on a dye-doped liquid crystal are provided.