Design of photonic crystal fibers with flat dispersion and three zero dispersion wavelengths for coherent supercontinuum generation in both normal and anomalous regions

• Published in: Results in physics Vol. 23; p. 104033
• Main Authors: Huang, Ying, Yang, Hua, Zhao, Saili, Mao, Yucheng, Chen, Shuyuan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-04-2021; Elsevier
• Subjects: Direct soliton spectrum tunneling; Photonic crystal fiber; Supercontinuum generation; Three zero dispersion wavelengths; Waveguide dispersion; Three zero dispersion wavelengths; Supercontinuum generation; Photonic crystal fiber; Direct soliton spectrum tunneling; Waveguide dispersion
• ISSN: 2211-3797; 2211-3797
• DOI: 10.1016/j.rinp.2021.104033

•A regularity was revealed to design the PCF with three zero dispersion wavelengths (ZDWs) and flat dispersion.•A quantitative methodis established to fix ZDWs and vary dispersion slope for PCF design.•Direct soliton spectral tunneling (DSST) is caused by the mismatch between SPM and gradually decreasing dispersion.•DSST produces the coherent supercontinuum (SC) and avoids the generation of the redshifted DWs.•The flat-dispersion PCF with three ZDWs is conductive to the width and the flatness of coherent SC.
A photonic crystal fiber (PCF) structure with three-zero dispersion wavelengths (ZDWs) and a flat dispersion curve was designed by adjusting the structural parameters (the diameters of small air holes inserted between standard lattices in the first and third rings) and fiber core size to obtain the required shape, number of extreme points and the dynamic range of waveguide dispersion (Dw) curve. A quantitative method which was realized by fixing the positions of the ZDWs and tailoring different dispersion slopes was proposed to design another PCF with the same ZDWs and a slightly larger dispersion slope. Both of the designed PCFs were used for contrast experiments of supercontinuum (SC) generation. The simulation results show that the flat dispersion can produce the coherent SC in both normal and anomalous dispersion regions for the designed two PCFs. The degree of flatness and the wavelength range of coherent SC are determined by the great time-domain compression due to the direct soliton spectrum tunneling (DSST) resulting from the mismatch between self-phase modulation and gradually decreasing dispersion. A wide, flat, and coherent SC with a wavelength range of 1281–2200 nm and power range of −14.8 ~ −9.4 dB was obtained for the PCF with flatter dispersion by pumping in the anomalous dispersion region with 50 fs incident pulse. This study is instructive for PCF design in different application scenarios and finds a new way for the generation of wide flat coherent spectrum.