Numerical optimization of large-scale fiber-optic splitting tree uniformity

In order to split the optical power of a signal into many fibered outputs, large-scale optical splitting trees (splitters) are used. In most applications, the optical power should remain constant from output to output. Large-scale splitting trees (typically 1 : 32 or 1 : 128) may be composed of a single-stage or of cascaded small splitters (typically 1 : 2). In the former case, power uniformity is determined by the design and manufacturing tolerances. In the latter case, considered here, uniformity may be optimized by a proper choice of the positions of the small splitters in the tree. Simulations show that less than 1-dB uniformity may be reached.

I. Introduction

Large-Scale splitting trees (also called splitters or couplers depending on the direction in which they are used) are required for many low-cost optical network concepts or for broadcasting a signal [1], [2].