Patent ID: 11880116
Assignee: NIPPON TELEGRAPH AND TELEPHONE CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 9:
10. The method according to claim 9, wherein:
the first splitter includes (N−1) Y-splitting optical waveguides having a splitting ratio of 1:3;
the Y-splitting optical waveguides are cascade-connected such that each Y-splitting optical waveguide except a most upstream Y-splitting optical waveguide of the (N−1) Y-splitting optical waveguides receives, as an input, a light beam that is output from an optical output port with a lower output intensity among two optical output ports of an upstream Y-splitting optical waveguide; and
a light beam corresponding to a j-th bit counted from the most significant bit of the N-bit electrical digital signal is output from an optical output port with a higher output intensity among two optical output ports of a j-th Y-splitting optical waveguide counted from the most upstream Y-splitting optical waveguide and a light beam corresponding to the least significant bit is output from an optical output port with a lower output intensity among two optical output ports of a most downstream Y-splitting optical waveguide, wherein j is an integer of 1 to N−1.