基于双芯光子晶体光纤的低非线性宽带色散补偿光纤的设计

A Novel Design of a Dual-core Photonic Crystal Fiber for Broadband Dispersion Compensation with Low Nonlinearity

采用矢量光束传输法数值模拟了基于模式耦合的双芯光子晶体光纤的色散和非线性与其结构的关系。结果表明:通过在包层中移除一层空气孔以形成外纤芯并调整内外纤芯之间的距离及包层空气孔的占空比,内外纤芯间的模式耦合可以在宽带范围内发生,导致产生大负色散。同时,由于光场分布在两个纤芯内,增大了模场面积,产生低非线性,可以实现低非线性宽带色散补偿。

Dispersion and nonlinearity are the main adverse factor in modern long-distance and high bit-rate optical transmission systems.Recently,the dual-concentric-core structures,used in conventional dispersion compensation fibers have also been adopted in the design of photonic crystal fibers（PCFs）.Large negative dispersion is always associated with small effective area,which leads to undesirable nonlinear effects during optical signal transmission.By employing the vectorial beam propagation method,a novel dual-core photonic crystal fiber based on pure silica for broadband dispersion compensation with low nonlinearity was proposed.The influence of the air-filing fraction in cladding and the distance between the inner and outer cores on the dispersion and nonlinear coefficient was numerically investigated.The simulation results showed that,by introducing the outer core by removing one air-hole ring in the cladding and adjusting the distance between the inner and outer cores and the air-filing fraction,the mode coupling of the inner and outer cores can take place in a wide wavelength range,which can induce larger negative dispersion.Meanwhile,since the light field is distributed in the two cores,the effective mode field area is larger so that the nonlinear coefficient is lower.These simulation results will be useful for designing broadband dispersion compensation fibers with low nonlinearity.