Experimental and theoretical study of a novel input polarization-independent nonlinear optical loop mirror with elliptical birefringence

We present an experimental and theoretical study of an input polarization-independent power-imbalanced nonlinear optical fiber loop mirror (NOLM) with elliptical birefringence. We found physical parameters of linear and circular induced birefringences to eliminate the input polarization dependence of the nonlinear polarization rotation effect due to self-and cross-phase modulation. Experimental results for a NOLM including a 60/40 coupler and a 100-m fiber loop with 1 turn m-1 twist ratio, and 4.5 cm bend radius are presented. The polar-ization dependence was reduced to less than 3 %25 for any input polarization ellipticity state in contrast to a common power-imbalanced NOLM which has 30 %25 input-polarization dependence. We corroborate the exper-imental results by solving the nonlinear Schro center dot dinger equations for elliptical birefringence fibers with numerical simulations made by the transfer matrix method and solved by the split-step Fourier method. These novel NOLM results could impact multiple present-day applications, such as optical communications, soliton switching, mode -locking pulsed lasers, among others.

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