Wavelength-dependent polarization absorber based on multi-cladding fiber with gold coating

The wavelength-dependent polarization absorber based on multi-cladding fiber (MCF) with surface plasmon resonance (SPR) is proposed and demonstrated. In order to obtain the SPR effect both in the x- and y- polarized direction, the MCF is polished in two sides. The numerical simulations show that the polarization absorber with the wavelengths of 980/1550 nm and 1310/1550 nm can be obtained by adjusting the parameters of dielectric layer. Each wavelength only transmits a single polarization in the wavelength-dependent polarization absorber, and the loss of unwanted polarized mode is more than 95 dB/cm. In addition, when the length of fiber is only 550 µm, the bandwidths of polarization absorber are 29 nm at 980 nm and 413 nm at 1550 nm, respectively; meanwhile, the bandwidth of 1310/1550 nm polarization absorber reaches 102 nm and 302 nm, respectively.