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US 6,643,046 B2Granted
Apparatus and method for optical modulation
AssigneeKabushiki Kaisha Toshiba
InventorsHiroyuki Ibe, Masahide Miyachi
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Abstract
An optical modulator includes a phase modulator configured to drive light with an NRZI-coded drive signal for phase modulation and an intensity modulator to modulate the intensity of a phase-modulated NRZI-coded optical signal received from the phase modulator. The operating point of the intensity modulator is set such that the output of the intensity-modulated optical signal is eliminated when the NRZI-coded optical signal is not varied.
Claims20
An apparatus for optical modulation, comprising:
- a phase modulator configured to drive light with an NRZI-coded drive signal for phase modulation;
- and
- an intensity modulator to modulate the intensity of a phase-modulated NRZI-coded optical signal received from said phase modulator, with an operating point set such that the output of said intensity-modulated optical signal is eliminated when said NRZI-coded optical signal is not varied.
A method of optical modulation, comprising:
- driving, at a phase modulator, light with an NRZI-coded drive signal for phase modulation;
- modulating, at an intensity modulator, the intensity of a phase-modulated NRZI-coded optical signal received from said phase modulator;
- and
- eliminating the output of an optical signal intensity-modulated at said intensity modulator when said NRZI-coded optical signal is not varied.
1 more element
Dependencies are inferred from the claim text.