High performance fused-type mode-selective coupler using elliptical core two-mode fiber at 1550 nm

In this letter, we demonstrate a high performance fused-type mode selective coupler that couples the LP/sub 11/ mode in one fiber and the LP/sub 01/ mode in another using highly elliptical core two-mode fibers. The phase-matching condition was achieved by etching and prepulling portions of two-mode fibers. The coupling efficiency and the mode extinction ratio of 56% to 80% and 22-32 dB, respectively, were achieved with high temperature stability over 1515- to 1595-nm wavelength range.