Quasi-autocorrelation Measuremnet Based On Carbon-Nanotube Saturable Absorber

Ultrashort pulses play an important role in the field of optical fiber communication and pulse width is an important parameter of ultrashort pulse.The measurement methods have been widely studied and the existing pulse autocorrelation measurement methods have many problems and shortcomings.In order to further promote the high precision and high sensitivity measurement of pulse width,a quasi-autocorrelation measurement technique based on carbon nanotube saturable absorber is proposed and demonstrated.Firstly,we analyzed the parameters of the saturable absorber materials and selected carbon-nanotubes as experimental absorber.Then,the carbon-nanotube polyvinyl alcohol film was prepared by Liquid Phase Exfoliation method.The physical properties of the material were characterized by specific equipment and saturable absorption properties were also measured.Next,we made numerical simulations and built an experimental system.The Gaussian pulse and soliton pulse with hyperbolic secant profile were measured and the results were compared with the standard intensity autocorrelation.The feasibility of the system was verified and the effects of pulse width and pulse peak power were further analyzed.The pulse conversion constant is discussed.At the same time,the system stability and error are tested,and the minimum detectable pulse energy is obtained.In addition,the system is compared with the traditional autocorrelation technology based on second harmonic generation and two-photon absorption,and the improvement scheme of the system is also discussed.Finally,a summary of this paper expounds the innovation of the thesis and the future research direction.We believe this work may pave a new way for autocorrelation measurement and enlighten the subsequent research.