High group birefringence in photonic crystal fibers with both positive and negative phase birefringences

A novel index-guiding holey fiber, which features positive phase birefringence at short wavelength and negative phase birefringence at long wavelength, is proposed for achieving group birefringence as high as 0.015. High group birefringence of >0.014 is obtained over a 380 nm wide wavelength range. Other properties of such fibers, such as confinement loss and dispersion, are examined as well. The potential tunability and fabrication tolerance of the induced group birefringence are discussed.