Abstract: A forward optical intensity modulation signal, generated by optical intensity-modulating a laser signal using a forward microwave phase modulation signal, is transmitted from a base to a remote station. A backward microwave phase modulation signal, in which frequency of the forward microwave phase modulation signal is changed by demodulating the forward optical intensity modulation signal, is generated, and a backward optical intensity modulation signal, generated by optical intensity-modulating the laser signal using the backward microwave phase modulation signal, is transmitted from the remote station to the base. The backward microwave phase modulation signal is extracted by photoelectric converting the backward optical intensity modulation signal, a round trip timing is extracted by demodulating the backward microwave phase modulation signal, and transmission delay is determined from a difference between the timing and the round trip timing.

Abstract: To provide a method for performing phase control of coherent two light wave signals while maintaining coherence in the state of the light signal, and a device which realizes such a method, there is provided, as illustrated in FIG. 1, a phase adjustment device 1 for two light waves including: a two light wave source 3, a wavelength separator 5, a first phase modulator 7, and a second phase modulator 9, whereby coherent two light waves are used as input signals to perform wavelength separation of those input signals thereafter to control optical phases of the respective light signals thereafter to multiplex them by using a multiplexer 11, thus to be able to obtain an output signal of which optical phase has been adjusted.

Abstract: An optical oscillator 10 combines optical signals L1? and L2 to generate an optical signal L3. The optical signal L1? includes light waves W1? and W2? having frequencies spaced apart by a frequency difference ?f1. The optical signal L2 includes light waves W3 and W4 having frequencies spaced apart by a frequency difference ?f2. The optical oscillator 10 separates the optical signal L3 into optical signals L4 and L5, wherein the optical signal L4 includes the light waves W1? and W3 and the optical signal L5 includes the light waves W2? and W4. The optical oscillator 10 compares the frequency differences ?f1 and ?f2 based on frequency difference ?f3 between the light waves W1? and W3 included in the optical signal L4 and frequency difference ?f4 between the light waves W2? and W4 included in the optical signal L5.

Abstract: In an optical synthesizer, a laser source outputs a laser. An optical modulator modulates the frequency of the laser to output a light including a first frequency component. An optical filter extracts the first frequency component from the output of the optical modulator. An optical comb generator generates an optical comb based on the laser and a predetermined driving signal. A variable-wavelength narrowband filter extracts a second frequency component from the optical comb. An optical-electric converter outputs an electric signal based on the frequency difference between the first and second frequency components.

Abstract: An optical oscillator 10 combines optical signals L1? and L2 to generate an optical signal L3. The optical signal L1? includes light waves W1? and W2? having frequencies spaced apart by a frequency difference ?f1. The optical signal L2 includes light waves W3 and W4 having frequencies spaced apart by a frequency difference ?f2. The optical oscillator 10 separates the optical signal L3 into optical signals L4 and L5, wherein the optical signal L4 includes the light waves W1? and W3 and the optical signal L5 includes the light waves W2? and W4. The optical oscillator 10 compares the frequency differences ?f1 and ?f2 based on frequency difference ?f3 between the light waves W1? and W3 included in the optical signal L4 and frequency difference ?f4 between the light waves W2? and W4 included in the optical signal L5.

Abstract: In an optical synthesizer, a laser source outputs a laser. An optical modulator modulates the frequency of the laser to output a light including a first frequency component. An optical filter extracts the first frequency component from the output of the optical modulator. An optical comb generator generates an optical comb based on the laser and a predetermined driving signal. A variable-wavelength narrowband filter extracts a second frequency component from the optical comb. An optical-electric converter outputs an electric signal based on the frequency difference between the first and second frequency components.

Abstract: An optical transmission system includes: a two-lightwave generator for generating optical signals having wavelengths ?1 and ?2 from laser light; a photodetector for detecting a microwave signal M12 from two optical signals distributed by an optical coupler; an optical modulator for frequency-shifting the two optical signals; a Faraday reflector for reflecting the two optical signals; an optical coupler for mixing the two optical signals that have been reflected by the Faraday reflector, frequency-shifted again, transmitted by an optical fiber, and guided by a polarization beam splitter, with two optical signals distributed by an optical coupler; an optical demultiplexer for wavelength-dividing four mixed optical signals into optical signals having the wavelengths ?1 and ?2; photodetectors for detecting respective beat signals of the wavelength-divided optical signals having ?1 and ?2; and a phase difference detector for detecting a phase difference between the beat signals of the optical signals having ?1 and

Abstract: An optical transmission system includes: a two-lightwave generator for generating optical signals having wavelengths ?1 and ?2 from laser light; a photodetector for detecting a microwave signal M12 from two optical signals distributed by an optical coupler; an optical modulator for frequency-shifting the two optical signals; a Faraday reflector for reflecting the two optical signals; an optical coupler for mixing the two optical signals that have been reflected by the Faraday reflector, frequency-shifted again, transmitted by an optical fiber, and guided by a polarization beam splitter, with two optical signals distributed by an optical coupler; an optical demultiplexer for wavelength-dividing four mixed optical signals into optical signals having the wavelengths ?1 and ?2; photodetectors for detecting respective beat signals of the wavelength-divided optical signals having ?1 and ?2; and a phase difference detector for detecting a phase difference between the beat signals of the optical signals having ?1 and

Abstract: The system includes: a two-light wave generator for generating light beams having wavelengths ?1 and ?2 that are spaced apart by a frequency of a signal M1 from a laser; a photodetector for detecting a signal M2 from the light beams transmitted through an optical fiber; an optical modulator for frequency-shifting the light beams by a frequency of a signal M3; a Faraday reflector for reflecting the light beams; an optical coupler for mixing the light beams that have been returned to a polarization beam splitter, with the generated light beams; a photodetector for converting the light beams into microwave signals; an image rejection mixer for frequency-converting the signals obtained through the conversion by using the signal M1 to output a two side bands; and a phase difference detector for detecting a phase difference between the side bands, and controlling a phase shifter so that the phase difference becomes 0.

Abstract: A filter conducts the round trip by using the return optical signal that has been shifted in frequency, and measures the transmission optical signal and the return signal in phase by the principle of the Michelson interferometer at the same time, independently, and splits the two optical signals. A polarization state in which transmission and reception optical signals within an optical phase shifter which enters one route of the two optical signals are made orthogonal to each other is provided, to thereby distinguish the transmission and reception signals of the round trip from each other. The light is allowed to pass the shifter in incoming and returning to remove the polarization rotation of the shifter by using the reversibility of the light. Then, the phases of the transmission signal and the return signal are measured and synchronized with each other to conduct the transmission phase compensation.

Abstract: The system includes: a two-light wave generator for generating light beams having wavelengths ?1 and ?2 that are spaced apart by a frequency of a signal M1 from a laser; a photodetector for detecting a signal M2 from the light beams transmitted through an optical fiber; an optical modulator for frequency-shifting the light beams by a frequency of a signal M3; a Faraday reflector for reflecting the light beams; an optical coupler for mixing the light beams that have been returned to a polarization beam splitter, with the generated light beams; a photodetector for converting the light beams into microwave signals; an image rejection mixer for frequency-converting the signals obtained through the conversion by using the signal M1 to output a two side bands; and a phase difference detector for detecting a phase difference between the side bands, and controlling a phase shifter so that the phase difference becomes 0.

Abstract: A filter conducts the round trip by using the return optical signal that has been shifted in frequency, and measures the transmission optical signal and the return signal in phase by the principle of the Michelson interferometer at the same time, independently, and splits the two optical signals. A polarization state in which transmission and reception optical signals within an optical phase shifter which enters one route of the two optical signals are made orthogonal to each other is provided, to thereby distinguish the transmission and reception signals of the round trip from each other. The light is allowed to pass the shifter in incoming and returning to remove the polarization rotation of the shifter by using the reversibility of the light. Then, the phases of the transmission signal and the return signal are measured and synchronized with each other to conduct the transmission phase compensation.