An Experimental Study on Wavelength and Polarization Dependences of Fused Fiber Couplers

摘要

Fused fiber couplers were fabricated by controlling the coupler waist profile, and the wavelength and the polarization dependences versus the waist profile were investigated experimentally. In case of the strongly fused coupler whose waist profile is a dumbbell with a thick neck to a circle, the coupling is a little stronger for the x-polarized light than the y-polarized light because of the elliptical deformation of the cores, and the wavelength dependence increases with fusing more strongly in spite of the shorter effective coupler length. In case of the weakly fused coupler having a dumbbell profile with a narrow neck, the wavelength and the polarization dependences increase rapidly with fusing more weakly owing to the longer effective coupler length, and the wavelength dependence and the coupling become much larger for the y-polarized light. The wavelength dependence becomes smallest around a dumbbell profile with a narrow neck and the aspect ratio of 1.94.