Abstract

Fiber-optic couplers are the key components in many sensor and communication applications, including wavelength multiplexing and polarization beam splitting. Due to the deviation of the coupler geometry from circular symmetry, the difference in the coupling characteristics between x and y polarization states is usually called the form birefringence. Zheng [1] used the finite-element method to analyze the influence of the coupler’s degree of fusion on the form birefringence. His results showed that weakly fused couplers are non-birefringent, or isotropic (i.e., the coupling coefficients C_ϰ=C_y) when the degree of fusion is 1.8 and 2.0 under the assumption that the normalized frequency V = ∞. However, for couplers with longer elongation the V-value in the waist region would not be large.

© 1995 Optical Society of America