  In this paper, we report the design and fabrication of a highly birefringent
polarization-maintaining photonic crystal fiber (PM-PCF) made from chalcogenide
glass, and its application to linearly-polarized supercontinuum (SC) generation
in the mid-infrared region. The PM fiber was drawn using the casting method
from As38Se62 glass which features a transmission window from 2 to 10 $\mu m$
and a high nonlinear index of 1.13.10$^{-17}$m$^{2}$W$^{-1}$. It has a
zero-dispersion wavelength around 4.5 $\mu m$ and, at this wavelength, a large
birefringence of 6.10$^{-4}$ and consequently strong polarization maintaining
properties are expected. Using this fiber, we experimentally demonstrate
supercontinuum generation spanning from 3.1-6.02 $\mu m$ and 3.33-5.78 $\mu m$
using femtosecond pumping at 4 $\mu m$ and 4.53 $\mu m$, respectively. We
further investigate the supercontinuum bandwidth versus the input pump
polarization angle and we show very good agreement with numerical simulations
of the two-polarization model based on two coupled generalized nonlinear
Schr\"odinger equations.
