All-fiber Brewster windows made with extremely weakly fused asymmetric coupler

New type of fiber-optic Brewster windows made with extremely weakly fused asymmetric couplers is reported. The first polarization modulation waist point in the power transfer curve of the asymmetric coupler was taken as the stopping point in the coupler drawing process. A 20-percent power with 26.4-dB extinction ratio at the coupled port and a 80-percent power with 2.5-dB extinction ratio at the throughput port at the designated wavelength have been achieved, with the Brewster bandwidth being 38 nm.<>