Digital coherent optical receiver
AssigneeFujitsu Limited
InventorsHisao NAKASHIMA, Takeshi Hoshida
Life of this patent
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Abstract
A digital coherent optical receiver provided with a 90-degree optical hybrid circuit for detecting an in-phase signal and a quadrature signal of an input optical signal, includes first through fourth circuits. The first circuit calculates a square of a sum of the in-phase signal and the quadrature signal. The second circuit subtracts a squared value of the in-phase signal and a squared value of the quadrature signal from the calculation result of the first circuit. The third circuit detects a phase error of the 90-degree optical hybrid circuit based on the calculation result of the second circuit. The fourth circuit corrects at least one of the in-phase signal and the quadrature signal according to the phase error detected by the third circuit.
Claims10
A digital coherent optical receiver provided with a 90-degree optical hybrid circuit for detecting an in-phase signal and a quadrature signal of an input optical signal, comprising:
- a first circuit to calculate a square of a sum of the in-phase signal and the quadrature signal;
- a second circuit to subtract a squared value of the in-phase signal and a squared value of the quadrature signal from the calculation result of the first circuit;
- a third circuit to detect a phase error of the 90-degree optical hybrid circuit based on the calculation result of the second circuit;
- and
- a fourth circuit to correct at least one of the in-phase signal and the quadrature signal according to the phase error detected by the third circuit.
A digital coherent optical receiver provided with a 90-degree optical hybrid circuit for detecting an in-phase signal and a quadrature signal of an input optical signal, comprising:
- an amplitude error compensation circuit to generate a second in-phase signal by correcting the in-phase signal in such a way that amplitude information about the in-phase signal coincides with a target value and generate a second quadrature signal by correcting the quadrature signal in such a way that amplitude information about the quadrature signal coincides with the target value;
- a first circuit to calculate a square of a sum of the second in-phase signal and the second quadrature signal;
- a second circuit to subtract a squared value of the second in-phase signal and a squared value of the second quadrature signal from the calculation result of the first circuit;
- a third circuit to detect a phase error of the 90-degree optical hybrid circuit based on the calculation result of the second circuit;
- and
- a fourth circuit to correct at least one of the second in-phase signal and the second quadrature signal according to the phase error detected by the third circuit.
A digital coherent optical receiver provided with a 90-degree optical hybrid circuit for detecting an in-phase signal and a quadrature signal of an input optical signal, comprising:
- a phase error compensation circuit to generate a first signal and a second signal, which represent the in-phase signal and the quadrature signal whose phase error of the 90-degree optical hybrid circuit is compensated for, according to the in-phase signal and the quadrature signal, wherein
- the phase error compensation circuit comprises
- a first calculation circuit to calculate a square of a sum of the first signal and the second signal;
- a second circuit to subtract a squared value of the first signal and a squared value of the second signal from the calculation result of the first circuit;
- a third circuit to detect the phase error of the 90-degree optical hybrid circuit based on the calculation result of the second circuit;
- and
- a fourth circuit to generate the first signal and the second signal by correcting at least one of the in-phase signal and the quadrature signal according to the phase error detected by the third circuit.
Dependencies are inferred from the claim text.