Mode Research In Three-core Photonic Crystal Fiber And Generation Of Supercontinuum

Compared with the traditional laser source,the supercontinuum source has the advantages of wide spectrum range and characteristics of good spatial coherence and high brightness.Supercontinuum has great value of application in the fields of hyperspectral imaging,photoelectric resist,biomedicine and so on.At present,high-power supercontinuum has become an important research direction.How to get good output beam quality while maintaining high-power supercontinuum output has become the focus of current research.This dissertation takes the three-core photonic crystal fiber as the object of study.From the coupled-mode theory,the modal property of three-core photonic crystal fiber was analyzed.After that,the visible light enhanced high power supercontinuum was obtained by all-fiber scheme.Finally,the method based on hyperspectral imaging was put forward for measurement of supercontinuum far-field beam quality.The main contents of this dissertation are presented as follows:1.Aiming at the structure of three-core photonic crystal fiber,its modal property was theoretically analyzed.When the gaussian fundamental mode light is incident vertically,the three-core photonic crystal fiber only supports the “in-phase supermode”.Two types of optical fibers were designed and drawn in combination with the dispersion characteristic of three-core photonic crystal fiber.The previous theoretical analysis was verified by the spatial coupling experiment.2.The high-efficient fusion point between three-core photonic crystal fiber and 15/130 double-clad passive fiber was made with the passing efficiency of 90%.Based on the dissipative soliton resonance pulse laser in the laboratory,the study of supercontinuum generation based on three-core photonic crystal fiber was carried out.The visible-band enhanced supercontinuum was obtained with output average power of 4.87 W.The proportion of visible region was 33.86% and the conversion efficiency of light was 34.5%.3.The method of measuring the beam quality out of supercontinuum based on hyperspectral imaging technique was proposed.The divergence angle of single-core photonic crystal fiber with wavelength changing was measured,which is consistent with the theoretical simulation.The spot uniformity in the far field with wavelength changing was measured,which provided important reference for the far-field practical application of supercontinuum.