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Electromagnetic analysis and characterization of photonic crystal fibers with slit-like geometry

We propose a rigorous electromagnetic analysis for a Photonic Crystal Fiber (PCF) geometry consisting of multiple hollow slits that go across the fiber core along the propagation axis z. The slits are regarded as invariant along the transverse dimension x but exhibit multiple sinusoidal bends in the y-z plane, which prevents the transversal profile being constant along the z axis. To analyze and characterize the electromagnetic behavior of the considered PCF geometry, we use a 2D Finite-Difference Time-Domain (FDTD) scheme assuming an ultrashort incident pulse with a polarization angle of 45 degrees as the excitation source. Our analysis focuses on three key aspects for the ultrashort pulse propagation through the slit array: pulse shaping and delay, spatiotemporal dispersion and birefringence features. Numerical FDTD simulations illustrate the effect of the slit array parameters on the previous magnitudes. Our results demonstrate that the proposed structure provides with a wide and deep control over the pulse propagation and wavefront.