Preparation And Optical Properties Of Disperse Red 1-Doped Organic-Inorganic Hybrid Films

In recent years,some functional dyes have attracted special attention due to their high nonlinear optical coefficient,fast response,and easy preparation.Among them,azobenzene functional dyes are an extremely important class,because azo dye molecules have special photo-induced cis-trans isomerization characteristics.At the same time,organic-inorganic composite optical materials break through the boundary between traditional organic materials and inorganic materials,and can realize the combination of organic nonlinear materials and inorganic substrates at the molecular level.These materials have the advantages of both inorganic and organic materials,such as good flexibility,tunable optical properties,high strength and high wear resistance,etc.As a new type of material in the field of nonlinear optics,they are considered to have great practical application prospects,and they are also hot research objects in the field of material science.In this paper,an improved sol-gel spin-coating technique was used to successfully prepare titanium dioxide（Ti O2）-based organic-inorganic composite film materials doped with azo functional dye Disperse Red 1（DR1）,and UV nanoimprinting technology was used in its The surface is prepared to obtain a microlens array structure.The material has important application value in the fields of all-optical switch,holographic storage,optical filter and optical induction waveguide.The surface morphology and photochemical structural properties of the composite thin film materials were studied by atomic force microscopy,Fourier transform infrared analysis and thermogravimetric analysis.The results show that the composite material has good thermal stability under the condition of lower than 150℃,and the composite film with smooth and dense surface can be prepared,and its surface roughness is small enough.The optical waveguide properties of the composite film under different doping concentrations of disperse red 1 and different heat treatment temperatures were studied by prism coupling technique,including film thickness,refractive index,optical transmission mode and transmission loss.The test results show that the refractive index of the composite film is between 1.51-1.54,and the thickness is close to 2μm.At the wavelength of 1538nm,the optical transmission loss value of the film is about 0.72-0.94d B/cm,which meets the basic requirements of optical waveguides.In addition,based on the photoisomerization properties of small molecules of azo dyes,the effects of disperse red 1 doping concentration and heat treatment temperature on the photoresponse properties of organic-inorganic composite films were studied.The results show that the film doped with disperse red 1 concentration of 1.5wt.%and heat treatment temperature of 50℃has better photoresponse characteristics.At the same time,the photo-induced cis-trans isomerization process of azo dye molecules under the condition of ultraviolet light irradiation was studied.Using the Z-scan technique,the third-order nonlinear properties of the composite film were studied.Combined with test results and theoretical analysis,it is concluded that the nonlinear refractive index of the film is negative,and the nonlinear coefficient is of the order of 10^-8esu,which is 4-5 orders of magnitude larger than common inorganic nonlinear optical materials.It is preliminarily believed that its nonlinear refractive index is the result of the combined effects of thermal effects and molecular reorientation and distribution effects.The nonlinear absorption of the thin film belongs to two-photon absorption,the absorption coefficient is greater than zero,and the order of magnitude is 10⁴cm/GW.In addition,the surface morphology and optical imaging performance of the thin-film microlens arrays were observed by scanning electron microscopy and optical microscopy.The results showed that the hexagonal and circular microlens arrays on the surface of the film were neatly arranged and evenly distributed,and the optical imaging was bright and clear.Finally,it was observed by scanning electron microscope that the strip waveguide arrays on the surface of the film were neatly arranged and evenly distributed.