Coherent optical detector and coherent communication system and method
First Claim
1. A method of an incoming quadrature modulated optical signal receiving, comprising:
- providing an optical device with first, second, third and fourth couplers, the two crossing waveguides, the phase shifter and four photodiodes built on a single planar chip made of an electro-optical material;
wherein the optical device has four optical inputs and two electrical outputs;
applying a voltage to the first, second, third and fourth couplers to maintain a desired power splitting ratio; and
applying offset voltages to the phase shifter to maintain a desired phase relationship between in-phase and in-quadrature electrical signals at an output of the optical device.
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Abstract
An optical device is provided with first and second inputs. A first coupler coupled is coupled to the first input and produces at least a first and second output. A second coupler is coupled to the second input and produces at least a first and second output. A third coupler is coupled to the first output of the first coupler and to the first output of the second coupler. A fourth coupler is coupled to the second output of the first coupler and to the second output of the second coupler. First and second crossing waveguides are provided with an angle selected to minimize crosstalk and losses between the first and second cross waveguides. The first crossing waveguide connects one of the first or second outputs from the first coupler with an input of the fourth coupler. The second crossing waveguide connects one of the first or second outputs from the second coupler with an input of the third coupler. A first phase shifter is coupled to the first and second waveguides. The first and second waveguides connect one of the outputs of the first or second coupler and one of the inputs of the third or fourth couplers. The first, second, third and fourth couplers, the two crossing waveguides and the phase shifter are each formed as part of a single planar chip made of an electro-optical material.
56 Citations
53 Claims
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1. A method of an incoming quadrature modulated optical signal receiving, comprising:
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providing an optical device with first, second, third and fourth couplers, the two crossing waveguides, the phase shifter and four photodiodes built on a single planar chip made of an electro-optical material;
wherein the optical device has four optical inputs and two electrical outputs;applying a voltage to the first, second, third and fourth couplers to maintain a desired power splitting ratio; and applying offset voltages to the phase shifter to maintain a desired phase relationship between in-phase and in-quadrature electrical signals at an output of the optical device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An optical communication system for optical signal transmission in one polarization, comprising:
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a transmitter; and a quadrature modulated optical signal receiver, the receiver including; a first adjustable coupler coupled to the first input and producing at least a first and second output; a second adjustable coupler coupled to the second input and producing at least a first and second output; a third adjustable coupler coupled to the first output of the first coupler and to the first output of the second coupler; a fourth adjustable coupler coupled to the second output of the first coupler and to the second output of the second coupler;
electrodes providing said tuning of the first, second, third, and fourth couplers;first and second crossing waveguides with an angle selected to minimize crosstalk and losses between the first and second cross waveguides, the first crossing waveguide connecting one of the first or second outputs from the first coupler with an input of the fourth coupler, the second crossing waveguide connecting one of the first or second outputs from the second coupler with an input of the third coupler; a first phase shifter coupled to the first and second waveguides, the first and second waveguide being connected to one of the outputs of the first or second coupler and one of the inputs of the third or fourth coupler, photodiodes converting optical signal into electrical signal;
wherein the first, second, third and fourth couplers, the two crossing waveguides and the phase shifter and photodiodes are each formed as part of a single planar chip made of an electro-optical material. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53)
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Specification