Study On Nonlinear Effects In Specialty Optical Fibers And Their Applications

Photonic devices based on nonlinear effects in optical fibers have great manyimportant applications in numerous fields such as optical communication, opticalsensing, manufacturing, medical and military, et al. Since the silica fibers have lowloss, high mechanical strength and low cost, the majority of optical fiber devices arebased on conventional silica fibers. But the silica fiber has insurmountabledisadvantages, such as relatively narrow optical transmission window (covers only300-2500nm), low third order nonlinear coefficient, high phonon energy whichlimits its application to some extent. In order to overcome the disadvantages of silicafibers and expand the application fields of optical fibers and optical fiber devices;explore new fiber materials, new fiber structures and new types of fiber and itsapplications are of great importance. During the doctoral years, the author has beenworked on this cutting-edge field, focused on nonlinear effects in specialty opticalfibers and its applications and carried out a systematic research on mid-infraredsupercontinuum source, soliton and supercontinuum generation and control, opticalcontrol of group velocity dispersion and their applications and obtained a series ofinnovative research results. Details are as follows:1. By using the professional optical fiber design software Mode-Solutions, wedesigned a series of endless single mode tellurite and fluoride photonic crystalfibers in theory. The numerical results show, when the fiber core becomes smaller,the zero-dispersion wavelength shifts towards the short wavelength, both thenonlinear coefficient and the confinement loss increase as well.2. We theoretically studied the supercontinuum generation in single-mode fluoridefiber pumped by1560nm ultra-short pulsed laser and the pumping condition andfiber length on the mid-infrared energy conversion efficiency. The numericalresults show that when a1560nm laser with pulse width of4ps and peak powerof100kW pumped1-m-long fluoride fiber, the generated supercontinuumspectrum can broadened to5μm, and the mid-infrared energy conversionefficiency can reach44.6%. We further theoretically studied a widely tunable mid-infrared Raman soliton with a tunable range of1.93-3.95μm and provide anew method for generating widely tunable mid-infrared pulsed laser by using aphotonic crystal fiber designed by ourselves. By using a homemade1560nmfemtosecond laser pumped5-m-long fluoride fiber, we experimentally archived asupercontinuum spectrum covering1100-2800nm and an average power of400mW.3. We experimentally realized the soliton self-frequency shift controlled by a weakcontinuous wave laser, from a tellurite photonic crystal fiber pumped by a1560nm femtosecond fiber laser. The control of soliton self-frequency shift isperformed not by changing the pump power but by the cross gain modulation of aweak continuous wave laser and a1560nm femtosecond laser. By varying thepower of the weak continuous wave laser (1560nm) from0to1.17mW, thesoliton generated in the tellurite photonic crystal fiber blue-shifts from1935to1591nm. The dependence of the soliton wavelength on the operation wavelengthof the weak continuous wave laser is also measured. The results show thecontinuous wave laser with a wavelength tunable range of1530-1592nm can beused to control the soliton self-frequency shift generation.4. We experimentally realized supercontinuum generation controlled by a weakcontinuous wave laser in a highly nonlinear silica fiber pumped by a1560nmpicosecond or femtosecond laser. The control is realized through cross lossmodulation and cross gain modulation of a weak continuous wave laser and a1560nm picosecond or femtosecond laser. A1530nm continuous wave laser ofmilliwatt can be used to increase or decrease the supercontinuum bandwidth.When the pump power of erbium-doped fiber amplifier (EDFA) is less than181mW, the1530nm weak continuous laser can be used to increase thesupercontinuum bandwidth. When continue to increase the pump power of EDFAto181mW, the1530nm weak continuous wave laser does not have an obviouseffect on supercontinuum generation. With further increasing the pump power ofEDFA more than181mW, the1530nm weak continuous wave laser inhibit thesupercontinuum generation. We also measured the dispersive wave generationwhen changing the power of weak continuous wave laser. The results show that,when the wavelength of the continuous wave laser with a tunable range of1480-1540nm, it can be used to increase or decrease the supercontinuum bandwidth,when the wavelength of weak continuous wave laser with a tunable range of1540 -1600nm, it can only inhibit the supercontinuum generation.5. We experimentally realized the optical control of group velocity dispersion viaoptical Kerr effect in highly nonlinear tellurite photonic crystal fibers. Thered-shift of the zero-dispersion wavelength is over307nm, measured by solitonself-frequency shift cancellation, when the pump peak power of a1560nmfemtosecond fiber laser is increased to11.6kW. The all-optical control of groupvelocity dispersion not only offers a new platform for constructing all-opticalcontrol photonic devices but also promises a new class of experiments innonlinear fiber optics and light-matter interactions.6. We experimentally discovered the multiple soliton self-frequency shiftcancellation in a highly nonlinear tellurite photonic crystal fiber. In highlynonlinear optical fibers, the fundamental solitons with a certain time interval cangenerate independent dispersion through optical Kerr effect. Each soliton red shiftdue to the stimulated Raman scattering. When they meet their own secondzero-dispersion wavelength, red shifted dispersive waves are formed. Based onthis result, we proposed the concept of temporally dispersion tailored fiber.