Research On All-fiber Modulators Based On The Micro-structured Fibers

With the development of large-capacity intelligent all-optical networks,highperformance,low-power and low-cost all-optical devices have become key research goals.Optoelectronic devices based on micro-structured fibers are an important support for all-optical networks.They have unique advantages such as large bandwidth,small size,high speed and low loss,providing new ideas for the research of new optoelectronic devices.Optical modulators are one of the core components of high-speed,long-distance optical communication systems.At present,non-fiber structures such as silicon-based and lithium niobate films are widely used in optical modulators.But they have high insertion loss when connected to an all-optical network.In view of the above problems,combined with the major national R&D projects undertaken,this dissertation has carried out a series of in-depth theoretical,simulation and experimental researches on all-fiber modulators based on micro-structured fibers.The main work and innovations of the dissertation are as follows:1.Two kinds of simulation software for performance analysis of microstructure optical fiber devices are proposed.The characteristic analysis of mode field,time delay and spectrum when writing gratings in different types of fibers such as single-mode,multicore,polarization-maintaining,photonic crystal,and multi-cladding is realized.And the analysis of key issues such as transverse mode field,longitudinal energy distribution,comb spectrum wavelength positioning based on coreless fiber devices.The interface is intuitive and visual,and has high efficiency and good applicability.2.An electro-optic polymer fiber modulator based on D-shaped few-mode fiber is proposed.The mechanism of the influence of the external refractive index on the performance of the microstructured fiber modulator is revealed by using the thin-core fiber,and a model with mode interference as the modulation principle is obtained.The bias point of the modulator is shifted by introducing the mode transmission loss difference.The simulation results show the length of the modulator can be reduced by43% with the same extinction ratio,and the insertion loss is less than 2 d B.The modulation depth of the modulator is 22 d B,the optical bandwidth is 6.9 nm,and the Vpi is 2.7 V.3.An all-fiber modulator with graphene interlayer is proposed.Through theoretical analysis,the fitting simplifies the calculation formula of pump light intensity and chemical potential in graphene.The effect of the graphene interlayer structure on the optical field distribution is verified by simulation.The results show that the modulator adopts a bias point with the difference in mode transmission loss,which reduces the length of the modulator to 1.59 ± 0.34 mm.And the insertion loss at a modulation depth of 20 d B is 1 d B.4.An all-optical graphene oxide modulator based on phase-shifted fiber grating is proposed and experimentally proved.Firstly,the mechanism of graphene oxide modulation is revealed using nano fiber.Then,the modulation effect of the nano fiber phase-shift grating is verified using magnetic fluid.Finally,experiments are carried out on the graphene oxide film.The experimental results show that the signal light is regulated by controlling the power of the pump light.And the modulation effect under different powers is consistent with the simulation results.5.A graphene all-optical modulator based on VCSEL is proposed and experimentally proved.The modulator consists of VCSEL to form the first-level electro-optic modulation,and then realizes the second-level modulation through graphene.Through the second-level modulation,the chirp and other problems generated in the first-level electro-optical internal modulation are solved.The modulation experiment is carried out on the signal at low speed,and the feasibility of the system to realize high-speed external modulation is verified.