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US 7,957,652 B2Granted
Optical FSK/SSB modulator having intensity balance function
AssigneeNational Institute of Information and Communications Technology
InventorsTetsuya Kawanishi, Masayuki Izutsu, Takahide Sakamoto, Masahiro Tsuchiya
Life of this patent
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Abstract
It is an object of the present invention to provide an optical modulator which is capable of adjusting optical intensity of optical signals which contains non-desired components so that the intensity of the components become at a similar level, whereby the optical modulator is capable of effectively suppressing the non-desired components when the optical signals are combined.
Claims11
An optical modulator comprising:
- a first sub Mach-Zehnder waveguide (MZA) (2);
- a second sub Mach-Zehnder waveguide (MZB) (3);
- a main Mach-Zehnder waveguide (MZC) (8) including:
- an input part (4) of an optical signal;
- a branching part (5), wherein the optical signal is branched at the branching part to the first sub Mach-Zehnder waveguide (MZA) and the second sub Mach-Zehnder waveguide (MZB);
- the first sub Mach-Zehnder waveguide (MZA);
- the second sub Mach-Zehnder waveguide (MZB);
- a combining part (6) being configured to connected to the first sub Mach-Zehnder waveguide (MZA) and the second sub Mach-Zehnder waveguide (MZB), wherein the optical signal outputted from the first sub Mach-Zehnder waveguide (MZA) and the optical signal outputted from the second sub Mach-Zehnder waveguide (MZB) are combined at the combining part;
- an output part (7) outputting the optical signal combined at the combining part, the output part being configured to be connected to the combining part;
- a first electrode (RFA electrode) (9) for inputting radio frequency (RF) signals to two arms composing the first sub Mach-Zehnder waveguide (MZA);
- a second electrode (RFB electrode) (10) for inputting radio frequency (RF) signals to two arms composing the second sub Mach-Zehnder waveguide (MZB);
- a main Mach-Zehnder electrode (electrode C) (11) for applying voltage to the main Mach-Zehnder waveguide (MZC), thereby controlling a phase difference between an output signal from the first sub Mach-Zehnder waveguide (MZA) and an output signal from the second sub Mach-Zehnder waveguide (MZB);
- a first intensity modulator (12), the intensity modulator being provided on waveguide portion between a combining part of the first sub Mach-Zehnder waveguide (MZA) and the combining part (6) of the main Mach-Zehnder waveguide (MZC), the intensity modulator modulating intensity of the optical signal propagating through the waveguide portion;
- an asymmetric directional coupler provided at the branching part (5) of the main Mach-Zehnder waveguide (MZC) (8), the asymmetric directional coupler controlling intensity of the optical signal branched to the first sub Mach-Zehnder waveguide (MZA) so that intensity of the optical signal branched to the first sub Mach-Zehnder waveguide (MZA) becomes higher than intensity of the optical signal branched to the second sub Mach-Zehnder waveguide (MZB);
- and
- an intensity modulator provided on a waveguide portion between a combining part of the second sub Mach-Zehnder waveguide (MZB) and the combining part (6) of the main Mach-Zehnder waveguide (MZC), the intensity modulator modulating intensity of the optical signal propagating through the waveguide portion.
13 more elements
An optical modulator comprising:
- a first sub Mach-Zehnder waveguide (MZA) (2);
- a second sub Mach-Zehnder waveguide (MZB) (3);
- a main Mach-Zehnder waveguide (MZC) (8) including:
- an input part (4) of an optical signal;
- a branching part (5), wherein the optical signal is branched at the branching part to the first sub Mach-Zehnder waveguide (MZA) and the second sub Mach-Zehnder waveguide (MZB);
- the first sub Mach-Zehnder waveguide (MZA);
- the second sub Mach-Zehnder waveguide (MZB);
- a combining part (6) being configured to connected to the first sub Mach-Zehnder waveguide (MZA) and the second sub Mach-Zehnder waveguide (MZB), wherein the optical signal outputted from the first sub Mach-Zehnder waveguide (MZA) and the optical signal outputted from the second sub Mach-Zehnder waveguide (MZB) are combined at the combining part;
- an output part (7) outputting the optical signal combined at the combining part, the output part being configured to be connected to the combining part;
- a first electrode (RFA electrode) (9) for inputting radio frequency (RF) signals to two arms composing the first sub Mach-Zehnder waveguide (MZA);
- a second electrode (RFB electrode) (10) for inputting radio frequency (RF) signals to two arms composing the second sub Mach-Zehnder waveguide (MZB);
- a main Mach-Zehnder electrode (electrode C) (11) for applying voltage to the main Mach-Zehnder waveguide (MZC), thereby controlling a phase difference between an output signal from the first sub Mach-Zehnder waveguide (MZA) and an output signal from the second sub Mach-Zehnder waveguide (MZB);
- a first intensity modulator (12), the intensity modulator being provided on waveguide portion between a combining part of the first sub Mach-Zehnder waveguide (MZA) and the combining part (6) of the main Mach-Zehnder waveguide (MZC), the intensity modulator modulating intensity of the optical signal propagating through the waveguide portion;
- an asymmetric directional coupler provided at the branching part (5) of the main Mach-Zehnder waveguide (MZC) (8), the asymmetric directional coupler controlling intensity of the optical signal branched to the first sub Mach-Zehnder waveguide (MZA) so that intensity of the optical signal branched to the first sub Mach-Zehnder waveguide (MZA) becomes higher than intensity of the optical signal branched to the second sub Mach-Zehnder waveguide (MZB);
- and
- an intensity modulator (13) provided on one of two arms composing the first sub Mach-Zehnder waveguide (MZA) or one of two arms composing the second sub Mach-Zehnder waveguide (MZB) or two or more of the waveguides, the intensity modulator (13) modulating intensity of the optical signals propagating through the waveguides.
13 more elements
An optical modulator comprising:
- a first sub Mach-Zehnder waveguide (MZA) (2);
- a second sub Mach-Zehnder waveguide (MZB) (3);
- a main Mach-Zehnder waveguide (MZC) (8) including:
- an input part (4) of an optical signal;
- a branching part (5), wherein the optical signal is branched at the branching part to the first sub Mach-Zehnder waveguide (MZA) and the second sub Mach-Zehnder waveguide (MZB);
- the first sub Mach-Zehnder waveguide (MZA);
- the second sub Mach-Zehnder waveguide (MZB);
- a combining part (6) being configured to connected to the first sub Mach-Zehnder waveguide (MZA) and the second sub Mach-Zehnder waveguide (MZB), wherein the optical signal outputted from the first sub Mach-Zehnder waveguide (MZA) and the optical signal outputted from the second sub Mach-Zehnder waveguide (MZB) are combined at the combining part;
- an output part (7) outputting the optical signal combined at the combining part, the output part being configured to be connected to the combining part;
- a first electrode (RFA electrode) (9) for inputting radio frequency (RF) signals to two arms composing the first sub Mach-Zehnder waveguide (MZA);
- a second electrode (RFB electrode) (10) for inputting radio frequency (RF) signals to two arms composing the second sub Mach-Zehnder waveguide (MZB);
- a main Mach-Zehnder electrode (electrode C) (11) for applying voltage to the main Mach-Zehnder waveguide (MZC), thereby controlling a phase difference between an output signal from the first sub Mach-Zehnder waveguide (MZA) and an output signal from the second sub Mach-Zehnder waveguide (MZB);
- a first intensity modulator (12), the intensity modulator being provided on waveguide portion between a combining part of the first sub Mach-Zehnder waveguide (MZA) and the combining part (6) of the main Mach-Zehnder waveguide (MZC), the intensity modulator modulating intensity of the optical signal propagating through the waveguide portion;
- an asymmetric directional coupler provided at the branching part (5) of the main Mach-Zehnder waveguide (MZC) (8), the asymmetric directional coupler controlling intensity of the optical signal branched to the first sub Mach-Zehnder waveguide (MZA) so that intensity of the optical signal branched to the first sub Mach-Zehnder waveguide (MZA) becomes higher than intensity of the optical signal branched to the second sub Mach-Zehnder waveguide (MZB);
- wherein the main Mach-Zehnder electrode (electrode C) (11) comprises a first main Mach-Zehnder electrode (MZCA electrode) (14) and a second main Mach-Zehnder electrode (MZCB electrode) (15), the first main Mach-Zehnder electrode (MZCA electrode) (14) being laid along at least a part of the waveguide between an output part of the first sub Mach-Zehnder waveguide (MZA) and the combining part, the second main Mach-Zehnder electrode (MZCB electrode) (15) being laid along at least a part of the waveguide between an output part of the second sub Mach-Zehnder waveguide (MZB) and the combining part.
12 more elements
Dependencies are inferred from the claim text.