Research On Nonlinear Fiber Optics Conversion Controlled By Modes

Propagation of ultra-short pulse in photonic crystal fiber(PCF)is extremely easy to cause the nonlinear effect in optical fiber.The nonlinear phenomena produced by PCF have achieved many research achievements in ultra-microscopy,micro-fabrication,micro imaging,surface and interface technology,etc.The supercontinuum generation(SCG)and frequency conversion,as the nonlinear phenomenon involved a number of nonlinear effects,has been developing greatly since appearance of PCF.But there is still some issues needing us to explore or resolve.In terms of frequency conversion,acquiring deep ultra-violet(UV)continuous wide spectrum by frequency conversion has not been achieved.Besides,SCG based on multi-core PCF which is a process needing optimization of multigroup parameter and the results is still need to promote.In this paper,the following research work is carried out on the issues above.The broadband deep UV third harmonic radiation transported in the very high order UV modes has achieved and the UV frequency conversion rate of the ultra short pulse transmitted in PCF is optimized.The research focuses on the seven-core PCF and conduct a series of comparative experiments including detailed study about the influences produced by the difference of fiber structure,fiber length,pulse coupling angle and pulse polarization parameters on the transmission modes,output beam quality and SCG.It provides more comprehensive solutions for generating output beam of better quality and obtaining SCG of wider band,higher power and better flatness.Put forward a suppose that collapsing the end face of the multi-core PCF can effectively improve the capacity of withstanding high power,the quality of supercontinuum output and the quality of the output beam and prove it through a series experiments.Relative experimental results can provide some references for the further development of high power SCG in multi-core PCF based on ultra-short pulses.