Nonreciprocal TE-TM mode conversion based on photonic crystal fibre of air-holes filled with magnetic fluids into a terbium gallium garnet fibre

Summary form only given. The nonreciprocal optical effect of Faraday rotation (FR) is widely exploited in optical isolators to suppress back-reflections to protect optical sources and other devices from injection noise, or in optical circulators to route counter-propagating signals in a single physical channel to different ports [1] . The first concept of an integrated isolator was based on nonreciprocal TE-TM mode conversion . However, most proposals of the waveguide type isolators are based on nonreciprocal TE-TM mode conversion [2], the nonreciprocal coupling between these modes is caused by the FR if the magnetization is aligned along the z-axis, parallel to mode propagation . FR effect can be used for magnet sensors, because the Verdet constant of silica fibre is small (~1 .1 rad/(T .m) at 1064 nm) [3] . In this work, we propose to study the nonreciprocal TE-TM mode conversion phenomenon, by the simulation of magneto photonic crystal fibre (MPCF) . It consists of a periodic triangular lattice of air-holes filled with magnetic fluids (Fe
₃
O
₄
) into a Terbium Gallium Garnet (TGG) fibre which is a kind of synthetic garnet with chemical composition Tb
₃
Ga
₅
O
₁₂
. This garnet was chosen as a Faraday rotator material which has excellent transparency properties and is very resistant to laser damage . TGG has also a high Verdet constant which results in the FR effect . We simulated the influence of gyrotropy and the wavelength, and calculated the FR and modal birefringence . In this MPCF fibre, the light is guided by internal total reflection, like classical fibres . However, it was shown that they could function on a mode conversion much stronger than conventional fibres .