Transmission Characteristics Of Tellurite HIC Bragg Fibers And Supercontinuum Generation

The supercontinuum?SC?has attracted much attention in the fields of spectrum,biomedical technology and remote sensing.The supercontinuum generation is due to dispersion and nonlinear characteristics of fiber.High-index-core?HIC?Bragg fiber can overcome the problems of single structure and difficult fabrication of photonic crystal fiber.It provides a new idea for the generation of supercontinuum.In this paper,tellurite solid core Bragg fiber have been put forward as a new type of photonic crystal fiber,we have studied the transmission characteristics and nonlinear characteristics of HIC Bragg fiber through COMSOL simulation software.On the other hand,a flattened dispersion in the 1.064?m of solid core Bragg fiber has been designed based on the study of supercontinuum by numerical simulation and the main achievements include the following aspects:1.The tellurite high-index-core?HIC?Bragg fibers have been put forward as a new type of photonic crystal fiber,which confined modes in the core through total reflection and photonic bandgap?PBG?.The transmission characteristics of high-index-core?HIC?Bragg fiber have analyzed using the transfer matrix method and Bloch theory method.We design the HIC Bragg fiber with flatter chromatic dispersion and low loss than chalcogenide step index fibers on the1064nm.It is numerically demonstrated that flatter chromatic dispersion of HIC Bragg fiber can be generated by the refractive indices at n₁=2.04,n₂=2.02,the radial multilayer period of?=1.2?m,the filling ratio of d/?=0.15,refractive-index contrast of dn=0.02,the core radius of R=5?m and the cladding layers of N=6,the zero dispersion point was also located in 1064nm and the loss only0.775dB/m.Increasing the filling ratio and refractive-index contrast of HIC Bragg fiber or decreasing the core radius can enhance the nonlinear effect of Bragg fiber.The larger nonlinear effect is more favorable for the supercontinuum spectrum with wider spectrum.2.The distribution of ultrashort pulses was numerically simulated by using the distributed Fourier method and the effects of fiber length,peak power and pump wavelength on the spectral broadening were studied.The SC spectrum spanned from 0.28?m to 5?m,when the initial pulse width of T₀=0.25ps,the fiber length is L=15cm,the pulse peak power is 2kw,the pump wavelength of 1.064?m.It demonstrated the ultra-flattened dispersion fibers can be obtained by optimizing the structural parameters of the HIC Bragg fiber,which was useful for generating supercontinuum with high flatness and the spectrum bandwidth is wider.