Dispersion of photonic Bloch modes in periodically twisted birefringent media

作者：Zang Leyun; Kang Myeong Soo; Kolesik Miroslav; Scharrer Michael; Russell Philip^*

来源：Journal of the Optical Society of America B-Optical Physics, 2010, 27(9): 1742-1750.

We investigate the polarization evolution and dispersive properties of the eigenmodes of birefringent media with arbitrarily twisted axes of birefringence. Analytical and numerical methods based on a transfer matrix approach are developed and used to study specifically helically twisted structures and the Bloch modes of periodically twisted media, as represented in particular by structural "rocking" filters inscribed in highly birefringent photonic crystal fibers. The presence of periodically twisted birefringence axes causes the group velocity dispersion curves to separate strongly from each other in the vicinity of the anti-crossing wavelength, where the inter-polarization beat-length equals an integer multiple of the rocking period. The maximum separation between these curves and the bandwidth of the splitting depend on the amplitude of the rocking angle. We also show that suitably designed adiabatic transitions, formed by chirping the rocking period, allow a broadband conversion between a linearly polarized fiber eigenmode and a single Bloch mode of a uniform rocking filter. The widely controllable dispersive properties provided by rocking filters may be useful for manipulating the phase-matching conditions in nonlinear optical processes such as four-wave mixing, supercontinuum generation, and the generation of resonant radiation from solitons.

• 出版日期2010-9