Novel optical single-mode asymmetric Y-branches for variable power splitting

Single-mode asymmetric Y-branches using microprisms are proposed. With a bend prism designed by the bend phase compensation rule (bend PCR) and a pair of Y-branch prisms designed by the Y-branch PCR, the phase front mismatch at the branching point is greatly eliminated, resulting in wide-angle low-loss 3-dB asymmetric Y-branches. Furthermore, control of power-splitting ratios is fulfilled through varying the lengths of prisms for a fixed branching angle and a fixed prism index. Finally, cascades of the proposed structures are studied. It is shown that the construction of a satisfactory 1/spl times/N tree power divider based on the cascaded structures is possible.