WAVEGUIDE TYPE BRANCHING/COUPLING UNIT

摘要

PROBLEM TO BE SOLVED: To make it possible to save an excess optical part by forming an element branching/coupling device of the first step as a two-input/2-output branching/coupling device and forming all of the element branching/coupling devices of the second and subsequent steps as one-input/two-output branching/ coupling devices. SOLUTION: The element branching/coupling device D1 of the first step is a two-input/two-output directional coupler. The input ports of Y-branch waveguides are respectively cascade-connected to the output ports of the directional coupler D1 to form the group D2 of the element branching/coupling device of the second step having the four output ports. The respective input ports of the Y-branch waveguides are respectively cascade-connected to the output ports of the respective Y-branch waveguides of the group D2 to form the group D3 of the element branching/coupling device of the third step having the 8 output ports. The input ports of the Y-branch waveguides are likewise cascade connected to the respective output ports of the respective Y-branch waveguides of the group D3 to form the group D4 of the element branching/coupling device of the fourth step having the 16 output ports. The one-input/two-output element branching/coupling devices are thus connected in n-1 steps as a whole.