Broad-band LP02 mode excitation using a fused-type mode-selective coupler

Abstract

We demonstrate a novel fused-type directional coupler that couples the LP01 mode in one fiber and the LP02 mode in another using a few-mode fiber. The phase-matching condition was satisfied in the coupler waist by initially etching and prepulling portions of the fibers based on simple numerical calculation. A coupling efficiency of about 70% was maintained over 1515-1595-nm wavelength range, and the mode extinction ratios with LP01, LP11, and LP21 modes were measured to be 35, 20, and 7 dB, respectively.