摘要:
A homodyne optical receiver includes a polarization beam splitter for dividing an optical signal into an optical signal with horizontal polarization and an optical signal with vertical polarization. Optical couplers combine two optical signals of the two polarized components with two optical local signals, which signals are almost matched therewith in polarization, and in a state where they are matched with each other in phase. Detectors homodyne-detect respective output optical signals of the optical couplers and two weighting circuits assign output signals of the detectors weights which are approximately proportional to amplitudes thereof, respectively. An adder adds output signals of the weighting circuits.
摘要:
A polarization diversity optical receiving apparatus comprises at least one frequency converter for performing frequency conversion upon an IF signal, an adder for adding two IF signals together, and a demodulator for converting a signal outputted from the adder to a baseband signal.
摘要:
An optical transmitter apparatus comprises a light source for optical signal transmission, an intensity modulator, a transmit signal generator and a signal generator. A transmit signal to be transmitted is supplied from the transmit signal generator to the intensity modulator, while a signal generated by the signal generator is supplied to the phase modulator. A light beam emitted from the light source passes through the intensity modulator and the phase modulator to be subsequently sent out as an optical signal for transmission with intensity thereof being modulated upon passing through the intensity modulator while spectrum thereof being spread by phase modulation which the optical signal undergoes upon passing through the phase modulator.
摘要:
An optical frequency division multiplexing transmission system for sending a large volume of information by a single optical fiber is disclosed. Each of an optical frequency division multiplexing transmitter equipment and an optical frequency division multiplexing receiver equipment has an optical filter having a periodic optical transmission characteristic therein. Each optical filter is stabilized with an absolutely-stabilized standard optical frequency. Each optical signal frequency is stabilized to a periodic transmission characteristic of the optical filter arranged in the optical frequency division multiplexing transmitter equipment, and each local frequency to a periodic transmission characteristic of the optical filter arranged in the optical frequency division multiplexing receiver equipment. Even in the case where no optical signal is applied to the optical frequency division multiplexing receiver equipment due to such causes as a fault of the transmission optical source or the breakage of an optical fiber, the local optical source frequency continues to be controlled in stable fashion.
摘要:
An optical tuning device including a channel designator and an intermediate frequency stabilizer for stabilizing the frequency of a difference signal corresponding to the frequency difference between a transmitted optical signal and a local oscillation optical signal. The channel designator includes a bias control circuit for continuously changing the optical frequency of a local oscillation light source up to a frequency corresponding to a target channel, a channel detection circuit for detecting channel passage on the basis of the difference signal, and a channel counting circuit for storing therein the selected channel and the target channel, detecting the direction of the target channel, counting the number of channel passage times, and detecting arrival at the target channel.
摘要:
An optical frequency division multiplexing transmitter is disclosed, which comprises a plurality of optical transmitters having different optical frequencies; an optical combiner multiplexing optical signals outputted by the different optical transmitters; and an optical filter having passbands, the frequency of each of which is approximately in accordance with the frequency of each of the signals, in which the signal thus multiplexed is inputted.
摘要:
An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.
摘要:
An optical transmission system accomplishes optical transmission over a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission over a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, and with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.
摘要:
An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-to-electric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.
摘要:
An optical transmission system accomplishes optical transmission to a long distance by combining a multiplexing line terminal with optical amplifiers, linear repeaters, and regenerators with optical amplifiers combined together. The system also accomplishes the optical transmission to a short distance by directly connecting the linear terminals therebetween, with an electric-to-optic converter replaced by an electric-to-optic converter having a semiconductor amplifier, with an optic-toelectric converter by an optic-to-electric converter having an avalanche photodiode as light receiver, an with no use of any optical booster amplifier and optical preamplifier in the multiplexing line terminal. With these, the optical transmission system can be easily constructed depending on the transmission distance required.