Analysis of ultra-high birefringent fully-anisotropic photonic crystal fiber

Abstract

Highly birefringent photonic crystal fiber (PCF) is proposed and analyzed using full vectorial finite element method. The reported design has a central large core filled with nematic liquid crystal (NLC) which provides tunability with the external electric field and temperature. In addition, the full permittivity tensor of the NLC material is taken into account when we study the modal properties of the proposed PCF. The effects of the geometrical parameters, rotation angle of the director of the NLC, and temperature on the modal properties of the reported design are investigated. The suggested design offers high birefringence of 0.191 at the operating wavelength of 1.55 lm with NLC diameter of 3.4 lm with low losses of the two polarized modes. As the NLC diameter decreases to 1.0 lm, high birefringence of 0.08 is obtained with single mode NLC PCF design, which is significantly large birefringence to maintain polarization state.

Ultra-Short Polarization Rotator Based on Flat-Shaped Photonic Crystal Fiber Filled with Liquid Crystal

“…This is due to the fact that the extraordinary refractive index ne of the liquid crystal decreases from 1.7096 to 1.6438 as the temperature rises from 15–50 °C in the 1.55 μm band; its ordinary refractive index decreases from 1.5034 to 1.5017 from 15–35 °C, and its no increases from 1.5017 to 1.5089 as the temperature rises from 35–50 °C. From the law of change of liquid crystal birefringence, we can see that the birefringence effect becomes smaller as the temperature rises, and the conversion length of PR is inversely related to birefringence, so it makes the conversion length gradually become larger as the temperature rises [ 26 ]. Although the mixing degree of the rotator will increase with the increase of temperature, it can be seen from Figure 7 b that when the fiber length is 3.99 μm instead of Lπ, the crosstalk value and conversion ratio are the same as Lπ at 25 °C.…”