Supercontinuum Generation In 2?3 ?M Band Based On Normal Dispersion Optical Fiber

Supercontinuum(SC)has been widely used in many fields such as the generation of ultra-short pulses in nonlinear optics,spectral analysis,optical coherence tomography,optical metrology,optical communication and so on.High energy pulse fiber lasers and nonlinear medium for SC generation are the hot areas of research.The all-normal-dispersion SC generation in 2?3?m wavelengths has excellent degree of coherence in time domain and relatively flat spectra.The main works are as follows:Firstly,the mode-locked fiber lasers which generate high energy pulses are numerically investigated.An experimental model consisting of single-mode fiber,gain fiber,dispersion compensation fiber(DCF)and saturable absorber is analyzed.The effects of group velocity dispersion(GVD),nonlinear coefficient and small signal gain on output pulses are discussed.Secondly,an optical fiber with a highly nonlinear liquid-filled core and air-hole cladding structure is proposed.By tuning the diameter of the core,the diameter of the air hole and the space between the core and air hole,GVD with a flat dispersion curve(-20ps/nm/km?-50ps/nm/km)and highly nonlinear coefficients in 2?3?m wavelengths can be obtained.Consequently,when the pump wavelength is 2000 run,the generated spectra can be broad and flat.The SC generation in fibers is analyzed.By varying parameters such as pulse energy,fiber length and number of air holes,the outputting SC is analyzed.When the core diameter dl=2.2pm,the air holes diameter d2=0.5?m,the spacing of core and air hole A=2.5?m,the wavelength bandwidth of SC spectrum in fiber with quadrilateral air-hole structure is 2184nm(20dB)with 793-2977nm.The wavelength bandwidth of SC spectrum generated in the fiber with hexagonal air-hole structure is 2207?n(20dB)with 785?2992nm.The wavelength bandwidth of SC spectrum generated in the fiber with octagonal air-hole structure is 2218nm(20dB)with 778?2996nm.