Principles And Applications Of Dissipative Four-wave Mixing

Four-wave mixing is an important nonlinear effect,which has a variety of applications including optical parametric amplification,all-optical wavelength conversion,all-optical signal processing,etc.The efficiency of four-wave mixing is limited by the phase matching condition.It can be satisfied by adjusting wavelength,however the bandwidth will be limited.Quasi phase matching is proposed to break through the restriction of phase matching condition,but conventional quasi phase matching method requires quantitative compensation of phase mismatch.It may be inapplicable when the phase mismatch is unable to be estimated.The idea of harvesting gain through dissipation has attracted interests recently.These schemes introduce dissipation to idler to improve the gain of signal.Distributed loss has been proved to be able to change the phase matching condition,however it is difficult to be implemented.As a supplement,this work propose lumped dissipation scheme introduced by segmented attenuation instead of uniform attenuation,which is proved to be a simple and universal quasi phase matching method.Based on the four-wave mixing model,this work uses analytical method with numerical simulation to study the influence of parameters on the four-wave mixing process,and analyze the characteristics of the coupled mode equations and the nonlinear Schr(?)dinger equation.The principles of distributed loss and lumped loss are revealed,and the influence of dissipation is studied.It is found that introducing loss can change the phase matching condition and increase the bandwidth of the system.The greater the loss,the larger the bandwidth.And it can also improve the efficiency in high-power amplification.The quasi phase matching method based on the introduction of lumped loss is verified by experiments.The 3d B-bandwidth of the gain spectrum is expanded from 22 nm and 8nm to 60 nm and 35 nm in the normal dispersion region and the anomalous dispersion region,respectively.Finally,based on the characteristic that the introduction of dissipation can change the phase matching condition,several applications are studied.In fiber system with dispersion fluctuation,the introduction of loss increases the stability of the system while expanding the bandwidth;the introduction of loss to signal can broaden the bandwidth of wavelength conversion;this scheme can also be applied to improve the phase matching condition of the difference frequency generation process.