PLC-type delay demodulation circuit and PLC-type optical interferometer
AssigneesFurakawa Electric Co., Ltd., Fujitsu Optical Components Limited
InventorsHiroshi Kawashima, Kazutaka Nara, Kohei Shibata
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Abstract
Disclosed are a PLC-type delay demodulation circuit and a PLC-type optical interferometer capable of reducing the size of a PLC chip with respect to the arrangement of various kinds of light output waveguides. In a PLC-type delay demodulation circuit, arm waveguides of a first MZI and arm waveguides of a second MZI are formed so as to overlap each other in the same region of a planar lightwave circuit. The optical paths of the MZIs are arranged such that the propagation directions of two DQPSK signals branched by a Y-branch waveguide are opposite to each other.
Claims16
A Planar Lightwave Circuit (PLC)-type delay demodulation circuit including a planar lightwave circuit that is formed on one PLC chip and demodulates a Differential Quadrature Phase Shift Keying (DQPSK)-modulated optical signal, the PLC-type delay demodulation circuit comprising:
- an optical splitter that branches the DQPSK-modulated optical signal into two optical signals;
- and
- first and second Mach-Zehnder Interferometers (MZIs) that delay the branched optical signals by one bit so as to interfere with each other, wherein
- two arm waveguides of the first MZI and two arm waveguides of the second MZI are formed so as to overlap each other in the same region of the planar lightwave circuit,
- optical paths of the first MZI and the second MZI are arranged such that the propagation directions of the optical signals are opposite to each other,
- a first half-wave plate is positioned in central portions of the two arm waveguides of the first MZI and central portions of the two arm waveguides of the second MZI, and
- a second half-wave plate is positioned at a position that deviates from the central portions of the two arm waveguides of the first MZI and a position that deviates from the central portions of the two arm waveguides of the second MZI.
A Planar Lightwave Circuit (PLC)-type optical interferometer that is formed on one PLC chip, the PLC-type optical interferometer comprising;
- an optical splitter that branches an optical signal into two optical signals;
- and
- first and second Mach-Zehnder Interferometers (MZIs) that delay the branched optical signals by a predetermined value so as to interfere with each other, wherein
- two arm waveguides of the first MZI and two arm waveguides of the second MZI are formed so as to overlap each other in the same region of a planar lightwave circuit,
- optical paths of the first MZI and the second MZI are arranged such that the propagation directions of the optical signals are opposite to each other,
- a first half-wave plate is positioned in central portions of the two arm waveguides of the first MZI and central portions of the two arm waveguides of the second MZI, and
- a second half-wave plate is positioned at a position that deviates from the central portions of the two arm waveguides of the first MZI and a position that deviates from the central portions of the two arm waveguides of the second MZI.
Dependencies are inferred from the claim text.