Mode Field Characteristics And Applications Of The Tapered Micro-nano Fiber

ABSTRACT:The micro-nano-fiber (MNF) with the core-diameter of micro-nanometer is drawn from ordinary optical fiber through the tapered transition region, and the entire structure is compact and small in size. Through the design of its parameters of the transition region, the tapered MNF can be used to achieve mode transfer and as a near-field scanning optical microscope probe. It has a smaller bending loss and high nonlinear coefficient in the MNF, which makes it have also been widely used such as pulse compression, supercontinuum generation in nonlinear optical fields.This paper carried out theoretical and computer simulation studies mainly focusing on the tapered MNF transmission characteristics, particularly in the nonlinear characteristics and the application of supercontinuum.First, we analyzed the basic transmission characteristics of MNF and fiber tapering related theories. Because of the core and cladding refractive index large difference and the diameter of the micro-nano-scale, the MNF shows a large evanescent wave, a strong binding capacity of the field, a large waveguide dispersion and a high non-linear and so on. And we derived the tapered transition zone radius function. Then applying the theory of local models the tapered transition zone model is analyzed. It has important significance that ensuring the adiabatic condition along tapered transition region.Then using the FDTD method in Meep simulation environment, the tapered MNF carried out the computer simulation. First we did the analysis of mode transfer and loss characteristics of the tapered transition. By observing the simulation results shows that in this area there were two distinct scattering region. Through simulation of the tapered MNF with different beam waist diameter, we did mode field of the waist region and the loss characteristics of the entire structure for data analysis. Finally the analysis of the pulse signal transmission characteristics and supercontinuum along the MNF were presented, while the applications of such as pulse compression and supercontinuum generation in nonlinear optical fields in the tapered MNF were presented.