Chiral diffraction gratings in twisted microstructured fibers.

We observed dips in transmission spectra of uniformly twisted pure-silica microstructured fibers. The spectral positions of the dips and their insensitivity to the surrounding medium are consistent with Bragg diffraction from the helical structure. The reproducibility of the variation of the dip wavelength with temperature up to 1000 degrees C makes the chiral diffraction grating suitable for high-temperature sensing.