Theoretical And Experimental Study On Sub-wavelength Silica Fiber And Liquid-core Fiber And Their Potential Use

With the rapid development of techniques on optical communication, optical informative analysis and optical sensor, studies on theories of optical waveguides, which focus on light's modulation, coupling, propagation, amplification, GVD controlling and nonlinear interaction in different waveguides including silica fiber used in optical communication, rectangular waveguide used in integration optics, hollow fiber used in energy propagation as well as PCF with most highlights, has become a new industrial field. Recently, the focus of this industry is moving from traditional optical communication system to nonlinear optical field. Most fibers we use nowadays, however, have a relative low nonlinear parameter, which can not meet the increasing needs in experiments and applications of fiber nonlinear optics. We introduce a new kind of fiber: Sub-wavelength liquid core fiber (SLCF) and do some theoretical and experimental research about this new fiber.In theoretical analysis, we firstly set up the model of sub-wavelength liquid core fiber as an ultra-high nonlinear medium. We successfully obtain some important optical parameters of SLCF by solving the Maxwell Equations of a three-layer waveguide in circular cylindrical coordinates. From the results, we simulate its potential use in both supercontinuum generation and polarization control.In experimental research work, by means of optimizing the current fiber dragging method, we successfully manufacture sub-wavelength hollow core fiber (SHCF) with our new dragging method. Furthermore, we managed to seal liquid in the SHCF, which is the last step in manufacturing SLCF. Its propagation properties match the simulation results quite good.The main achievements are shown as follows:The model of SLCF is proposed for the first time. Both theoretical and experimental research is done in our work. The optical properties of SLCF, including propagation constant, propagation energy distribution, propagation efficiency, fiber bending loss, group velocity dispersion and nonlinear coefficient, are obtain by simulation. By comparison to sub-wavelength silica fiber (SSF), this new fiber shows a variety of new optical characteristics, including tighter optical bounding ability, less optical bending loss, flatter GVD region and ultra-higher nonlinear coefficient, which show great potential use in field of nonlinear optics. Meanwhile, we have concluded an effective method of manufacturing SLCF and successfully manufactured low-loss-SLCF with various diameters.By solving the Maxwell Equations, the important optical parameters of two-layer circular cylindrical waveguide model, e.g. SSF, can be obtained. Respectively, by improving this mathematical method, we can also use it in solving three-layer circular cylindrical waveguide model and successfully obtain all these optical parameters of SLCF, which is a good sample of such a model.In our simulation, two potential uses in nonlinear optics of SLCF are given as examples. By solving the Schr?dinger Equation in circular cylindrical coordinates, we stimulate the spectrum broadening process with propagation and an ultra-broadened spectrum is obtained after the input beam propagate a short distance in SLCF. Compared with SSF and other fibers, SLCF has an advantage both in lower power threshold and shorter interacting length. Meanwhile, the polarization instability, which occurs in high-level input light in fiber, can also be found in SLCF with low-level input light and is tunable.We introduced another kind of LCF: hybrid-liquid core fiber (HLCF) and its use in temperature sensing and stimulated Raman scattering (SRS) enhancing. When used as a temperature sensor, HCLF has advantages of ultrahigh temperature sensitivity and wide operating range. This kind of fiber can also greatly enhance the SRS in liquid, which broadens the stimulated peaks.