摘要:
A data modulator unit generates a DQPSK optical signal in accordance with a data signal. A phase shift unit provides a phase difference of π/2 between a pair of arms. A photodetector converts an output signal of the data modulator unit into an electrical signal. A filter is a low-pass filter with a cut-off frequency lower than a symbol frequency, and filters an output signal of the photodetector. A monitor unit detects power of an output signal of the filter. A phase difference control unit adjusts the amount of phase shift in the phase shift unit so as to minimize power of an output signal of the filter.
摘要:
A variable dispersion compensating unit compensates an optical signal, and changes the compensation amount according to a control signal that has a given frequency. After demodulation of the compensated optical signal, error conditions of the signal are monitored and an error signal is output. A band pass filter filters the error signal for a component having a frequency equal to or less than the given frequency. Based on the component and on the control signal, a synchronous detecting circuit generates a compensation amount modification signal. The compensation amount modification signal is superposed on the control signal.
摘要:
A variable dispersion compensating unit compensates an optical signal, and changes the compensation amount according to a control signal that has a given frequency. After demodulation of the compensated optical signal, error conditions of the signal are monitored and an error signal is output. A band pass filter filters the error signal for a component having a frequency equal to or less than the given frequency. Based on the component and on the control signal, a synchronous detecting circuit generates a compensation amount modification signal. The compensation amount modification signal is superposed on the control signal.
摘要:
A data modulator unit generates a DQPSK optical signal in accordance with a data signal. A phase shift unit provides a phase difference of π/2 between a pair of arms. A photodetector converts an output signal of the data modulator unit into an electrical signal. A filter is a low-pass filter with a cut-off frequency lower than a symbol frequency, and filters an output signal of the photodetector. A monitor unit detects power of an output signal of the filter. A phase difference control unit adjusts the amount of phase shift in the phase shift unit so as to minimize power of an output signal of the filter.
摘要:
An interferometer for demodulating a differential M-phase shift keying signal includes a PLC type interferometer main body, a heating portion that heats the PLC type interferometer main body, and an intermediate member having a higher stiffness than that of the PLC type interferometer main body, for bonding the PLC type interferometer main body and the heating portion with each other while being sandwiched therebetween. A linear expansion coefficient difference between the PLC type interferometer main body and the intermediate member is equal to or smaller than 4.5×10−6/° C., and a thermal conductivity difference between the PLC type interferometer main body and the intermediate member is equal to or larger than 10 W/mK. A phase of an optical signal flowing through the interferometer is adjusted by using the heating portion and a second heating portion.
摘要:
A method and system for transmitting information in an optical communication system includes modulating a non-intensity characteristic of an optical carrier signal with a data signal to generate an optical information signal. The optical information signal is transmitted over an optical link. The optical information signal is amplified over a length of the optical link with a co-launched amplification signal traveling in the optical link in a same direction as the optical information signal.
摘要:
An optical receiver comprises branching units for branching and supplying the signal lights to be inputted to the first to fourth optical waveguides provided on a substrate, second to third optical waveguides for giving delay time differences corresponding to a symbol of the DMPSK modulated signal, a demodulating unit for demodulating two light signals through interference of signal lights between the first to second optical waveguides and between the third to fourth optical waveguides, two optical detectors for converting two light signals from the demodulating unit, and a light path length varying unit for identically varying each light path length of two optical waveguides being arranged through selection of combinations of the first and third optical waveguides, the first and fourth optical waveguides, and the second and third optical waveguides in one region when the wavelength of the signal light is varied.
摘要:
A method and system for demultiplexing non-intensity modulated wavelength division multiplexed (WDM) signals includes receiving a WDM signal having a plurality of non-intensity modulated optical information signals. A plurality of the non-intensity modulated optical information signals are converted to intensity modulated signals while the plurality of non-intensity modulated optical information signals are multiplexed in at least a portion of the WDM signal.
摘要:
A chromatic dispersion monitoring apparatus according to the present invention comprises: a photodetector which photo-electrically converts an optical signal; a low-pass filter which limits a frequency bandwidth of the photo-electrically converted electrical signal to be within a range set according to a modulation format of the optical signal and a bit rate thereof; a DC elimination circuit which eliminates a direct current component of the bandwidth limited electrical signal; and a power detector which detects the power of the bandwidth limited electrical signal to detect the residual dispersion of the optical signal. As a result, it becomes possible to easily realize the chromatic dispersion monitoring apparatus of low cost, which is also capable to be arranged on an in-line.
摘要:
The optical waveform shaper comprises a plurality of interferometers connected in series. The transfer function of each interferometer is either one of a first transfer function, in which the second order derivative of the output optical power in respect to the input optical power is positive when the input optical power is in the neighborhood of zero, or a second transfer function, and the output optical power shows substantially periodical changes to the input optical power, or a second transfer function, in which the second order derivative of the output optical power in respect to the input optical power is negative when the input optical power is in the neighborhood of zero, or a second transfer function, and the output optical power shows substantially periodical changes to the input optical power. At least one of the interferometers uses the second transfer function.