title: Nonlinear polarization dynamics in a weakly birefringent all-normal dispersion photonic crystal fiber: toward a practical coherent fiber supercontinuum laser.
abstract: Dispersion-flattened dispersion-decreased all-normal dispersion (DFDD-ANDi) photonic crystal fibers have been identified as promising candidates for high-spectral-power coherent supercontinuum (SC) generation. However, the effects of the unintentional birefringence of the fibers on the SC generation have been ignored. This birefringence is widely present in nonlinear non-polarization maintaining fibers with a typical core size of 2 µm, presumably due to the structural symmetry breaks introduced in the fiber drawing process. We find that an intrinsic form-birefringence on the order of 10(-5) profoundly affects the SC generation in a DFDD-ANDi photonic crystal fiber. Conventional simulations based on the scalar generalized nonlinear Schrödinger equation (GNLSE) fail to reproduce the prominent observed features of the SC generation in a short piece (9-cm) of this fiber. However, these features can be qualitatively or semi-quantitatively understood by the coupled GNLSE that takes into account the form-birefringence. The nonlinear polarization effects induced by the birefringence significantly distort the otherwise simple spectrotemporal field of the SC pulses. We therefore propose the fabrication of polarization-maintaining DFDD-ANDi fibers to avoid these adverse effects in pursuing a practical coherent fiber SC laser.
authors.affiliation: Biophotonics Imaging Laboratory, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. htu@illinois.edu
authors.forename: Haohua
authors.initials: H
authors.lastname: Tu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Liu
authors.forename: Dmitry
authors.initials: D
authors.lastname: Turchinovich
authors.forename: Jesper
authors.initials: J
authors.lastname: Lægsgaard
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Boppart
mesh_terms: D001718:Birefringence; D003198:Computer Simulation; D005336:Fiber Optic Technology / Q000295:instrumentation* / Q000379:methods*; D007834:Lasers; D008962:Models, Theoretical; D017711:Nonlinear Dynamics; D055100:Optical Fibers