Theoretical and experimental study of the birefringence of a photonic crystal fiber

Thanks to a magneto-optical method, we have measured the beat length of a photonic crystal fiber (PCF). Our experiments emphasize the singular behavior of the birefringence of a PCF versus the wavelength. We have also studied the birefringence of perfect photonic crystal fibers by means of the finite-element method. We show that detailed attention must be paid to the conditions of simulation for the calculation of the birefringence. Discrepancies between theoretical predictions and experimental results are pointed out and some explanations are proposed.