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US 2007/0177882 A1Published application
Optical transmitter apparatus
AssigneeFujitsu Limited
InventorYuichi Akiyama
Life of this patent
Estimating the term…
Abstract
An optical DQPSK modulator comprises a pair of phase modulators. Each of the pair of the phase modulators is provided with first and second driving signals. The first and second driving signals are amplified by first and second amplifiers, respectively. An RZ intensity modulator generates an optical RZ-DQPSK signal from an optical DQPSK signal output from the optical DQPSK modulator. A photodetector generates a monitor signal from the optical RZ-DQPSK signal. A gain adjuster unit adjusts the gains of the first and second amplifiers so as to minimize the power of the monitor signal.
Claims12
An optical transmitter apparatus, comprising:
- a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm, which generates a phase-modulated signal by combining the first and second modulation signals;
- an intensity modulator for performing intensity modulation on the phase-modulated signal output from said phase modulator;
- a detection unit for detecting the power of an AC component of an optical signal output from said intensity modulator;
- and
- an adjuster unit for adjusting an amplitude of at least one of the first driving signal or the second driving signal so as to minimize the power detected by said detection unit.
2 more elements
An optical transmitter apparatus, comprising:
- a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm, which generates a phase-modulated signal by combining the first and second modulation signals;
- a DC bias generator unit for generating first DC bias and second DC bias for adjusting an operation point of the first and second phase modulation elements;
- an intensity modulator for performing intensity modulation on the phase-modulated signal output from said phase modulator;
- a detection unit for detecting the power of an AC component of an optical signal output from said intensity modulator;
- and
- an adjuster unit for adjusting an amplitude of at least one of the first driving signal or the second driving signal so as to minimize the power detected by said detection unit.
3 more elements
An optical transmitter apparatus, comprising:
- a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm, which generates a phase-modulated signal by combining the first and second modulation signals;
- a DC bias generator unit for generating first DC bias and second DC bias for adjusting an operation point of the first and second phase modulation elements;
- an intensity modulator for performing intensity modulation on the phase-modulated signal output from said phase modulator;
- a detection unit for detecting the power of an optical signal output from said intensity modulator;
- and
- an adjuster unit for adjusting an amplitude of at least one of the first driving signal or the second driving signal so as to maximize the power detected by said detection unit.
3 more elements
An optical transmitter apparatus, comprising:
- a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm, which generates a phase-modulated signal by combining the first and second modulation signals;
- a DC bias generator unit for generating first DC bias and second DC bias for adjusting an operation point of the first and second phase modulation elements;
- an intensity modulator for performing intensity modulation on the phase-modulated signal output from said phase modulator;
- a detection unit for detecting the power of an AC component of an optical signal output from said intensity modulator;
- and
- an adjuster unit for adjusting an amount of phase shift of the phase shift element as well as adjusting at least one of the first bias or the second bias based on the power detected by said detection unit.
3 more elements
An optical transmitter apparatus, comprising:
- a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm, which generates a phase-modulated signal by combining the first and second modulation signals;
- an intensity modulator for performing intensity modulation on the phase-modulated signal output from said phase modulator;
- a detection unit for generating a power signal representing the power of an AC component of an optical signal output from said intensity modulator;
- first and second amplifiers for amplifying the first and second driving signals;
- a gain adjuster unit for generating a gain adjusting signal adjusting the gain of the first and second amplifiers;
- a superimposing unit for superimposing a low-frequency signal on the gain adjusting signal;
- and
- a detection unit for performing synchronous detection on the power signal by using the low-frequency signal,
- wherein said gain adjuster unit adjusts the gain of at least one of the first amplifier or the second amplifier based on the result of the synchronous detection.
6 more elements
An optical transmitter apparatus, comprising:
- a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm, which generates a phase-modulated signal by combining the first and second modulation signals;
- an intensity modulator for performing intensity modulation on the phase-modulated signal output from said phase modulator;
- a detection unit for generating a power signal representing the power of an AC component of an optical signal output from said intensity modulator;
- first and second amplifiers for amplifying the first and second driving signals;
- a gain adjuster unit for generating a gain adjusting signal adjusting the gain of the first and second amplifiers;
- a first superimposing unit for superimposing a first low-frequency signal on the gain adjusting signal;
- a first detection unit for performing synchronous detection on the power signal by using the first low-frequency signal;
- a phase adjuster unit for generating a phase adjusting signal to adjust the amount of phase shift of the phase shift element;
- a second superimposing unit for superimposing a second low-frequency signal on the phase adjusting signal;
- and
- a second detection unit for performing synchronous detection on the power signal by using the second low-frequency signal,
- wherein said gain adjuster unit adjusts the gain of at least one of the first amplifier or the second amplifier based on the result of the synchronous detection by said first detection unit, and
- said phase shift adjuster unit adjusts the amountof phase shift of the phase shift element based on the result of the synchronous detection by said second detection unit.
10 more elements
An adjusting circuit for adjusting an operation of an optical transmitter apparatus, said optical transmitter apparatus comprising a phase modulator, having a first phase modulation element for generating a first modulation signal on a first arm in accordance with a first driving signal, a second phase modulation element for generating a second modulation signal on a second arm in accordance with a second driving signal, and a phase shift element for providing a phase difference between the first arm and the second arm to generate a phase-modulated signal by combining the first and second modulation signals and an intensity modulator for performing intensity modulation on the phase-modulated signal output from the phase modulator, said adjusting circuit comprising:
- a detection unit for detecting the power of an AC component of an optical signal output from the intensity modulator;
- and
- an adjuster unit for adjusting an amplitude of at least one of the first driving signal or the second driving signal so as to minimize power detected by said detection unit.
Dependencies are inferred from the claim text.