Plasmon-assisted fiber polarizers with high extinction ratio and low insertion loss

Abstract

We propose a compact plasmon-assisted in-line fiber polarizer with metal films selectively coated on the lateral surface of the cladding in a conventional single mode fiber. The polarization-dependent loss mechanism intrinsically originates from the polarization-selective excitation of surface plasmon polaritons (SPPs) at both interfaces of metal films. Both the polarization extinction ratio (PER) and insertion loss (IL) of the plasmonic fiber polarizer strongly depend on the strength of the interaction between the polarized core modes and SPP modes. We numerically demonstrate the performances of an Au-coated and an Al-coated fiber polarizers, respectively. Both of them can achieve a PER at least higher than 10 dB/mm over the whole C- and L-bands. Notably, the PERs at 1550 nm in the Au-coated and Al-coated fiber polarizers can be up to 37.3 dB/mm and 29.4 dB/mm, respectively. The IL in the Al-coated fiber polarizer is about an order of magnitude higher than that in the Au-coated one, but it can still be lower than 0.1 dB/mm over the C- and L-bands. The achievable excellent performance shows that our proposed plasmonic fiber polarizer can provide a promising candidate for compact all-fiber polarizers with a high PER and a low IL.