Patent ID: 8213752
Filing Date: 2012-07-03
Classification: G02B

Abstract:
1. A planar lightwave circuit (PLC) coherent mixer chip having a longitudinal and a lateral central axis in the plane of the chip, wherein the chip comprises: a first and a second input port for receiving a first and a second portion of an input signal, respectively; a third input port disposed between the first and the second input ports for receiving a local oscillator (LO) signal; a Y-coupler for separating the LO signal into first and second LO sub-signals, wherein the Y-coupler has an input optically coupled to the third input port, and a first and a second output; a first, a second, a third, and a fourth input waveguide for inputting light, optically coupled to: the first input port, the first output of the Y-coupler, the second output of the Y-coupler, and the second input port, respectively; a first, a second, a third, and a fourth coupler each having an input for inputting light and a first and a second output for outputting light, wherein the inputs of the first, the second, the third, and the fourth couplers are optically coupled to the first, the second, the third, and the fourth input waveguides, respectively; a fifth, a sixth, a seventh, and an eighth coupler each having a first and a second input for inputting light, and an output for outputting light; a first waveguide path for optically coupling the first output of the first coupler to the first input of the fifth coupler; a second waveguide path for optically coupling the second output of the first coupler to the first input of the sixth coupler; a third waveguide path for optically coupling the first output of the second coupler to the second input of the fifth coupler; a fourth waveguide path for optically coupling the second output of the second coupler to the second input of the sixth coupler; a fifth waveguide path for optically coupling the first output of the third coupler to the first input of the seventh coupler; a sixth waveguide path for optically coupling the second output of the third coupler to the first input of the eighth coupler; a seventh waveguide path for optically coupling the first output of the fourth coupler to the second input of the seventh coupler; an eighth waveguide path for optically coupling the second output of the fourth coupler to the second input of the eighth coupler; a first, a second, a third, and a fourth output waveguide for outputting light, optically coupled to the outputs of the fifth, the sixth, the seventh, and the eighth couplers, respectively; a first output port optically coupled to the first output waveguide, for outputting a first phase component of the first portion of the input signal; a second output port optically coupled to the second output waveguide, for outputting a second phase component of the first portion of the input signal; a third output port optically coupled to the third output waveguide, for outputting a first phase component of the second portion of the input signal; and a fourth output port optically coupled to the fourth output waveguide, for outputting a second phase component of the second portion of the input signal; wherein the first waveguide path is symmetrical about the longitudinal central axis with the eighth waveguide path; wherein the second waveguide path is symmetrical about the longitudinal central axis with the seventh waveguide path; wherein the third waveguide path is symmetrical about the longitudinal central axis with the sixth waveguide path; and wherein the fourth waveguide path is symmetrical about the longitudinal central axis with the fifth waveguide path.