Abstract: It is possible to suppress carrier light with a simple configuration when modulating the carrier light to generate optical sideband components. An optical carrier-suppressed signal generator includes first splitting means used to split input carrier light into two light beams, an optical modulator which modulates one split carrier light beam and outputs light including optical sideband components, a phase modulator which phase-modulates another split carrier light beam, and second or third splitting means used to split the output light of the optical modulator into two light beams. The output light split by the second or third splitting means and the output light of the phase modulator are multiplexed to obtain the amplitude of the signal waveform of optical power, and the optical modulator is controlled such that the obtained value is minimized.

Abstract: The optical frequency comb generating device having two optical modulation parts 41 and 42 independently modulating optical waves propagating in two branch waveguides and a phase regulator 43 controlling a phase difference between the optical waves includes amplitude adjusting means 22 for adjusting a voltage amplitude of the RF signal supplied to at least one of the optical modulation parts, monitoring means 21 for monitoring the intensity Pout of the output light beam, and a bias control circuit 20 that controls the amplitude adjusting means to change a difference in voltage amplitude between the RF signals supplied to each optical modulation part, that detects a variation of the output light beam corresponding to the variation of the difference in voltage amplitude from the output signal of the monitoring means, and that controls the phase regulator on the basis of the detection result to adjust the phase difference.

Abstract: It is possible to suppress carrier light with a simple configuration when modulating the carrier light to generate optical sideband components. An optical carrier-suppressed signal generator includes first splitting means used to split input carrier light into two light beams, an optical modulator which modulates one split carrier light beam and outputs light including optical sideband components, a phase modulator which phase-modulates another split carrier light beam, and second or third splitting means used to split the output light of the optical modulator into two light beams. The output light split by the second or third splitting means and the output light of the phase modulator are multiplexed to obtain the amplitude of the signal waveform of optical power, and the optical modulator is controlled such that the obtained value is minimized.

Abstract: In the electric field measuring device, a DC bias circuit applying a DC bias voltage to an optical intensity modulator is disposed in an area, and a DC bias control portion controlling a DC bias voltage is disposed outside the area. An electrical signal of a DC bias voltage which is output from the DC bias control portion is converted into an optical signal by an electrical-optical converter (E/O) so as to be introduced into the area via an optical fiber, and the optical signal is converted into an electrical signal by an optical-electrical converter (O/E) disposed in the area such that the electrical signal is input to the DC bias circuit.

Abstract: Provided is an optical receiver which accurately demodulates an optical signal obtained by the differential phase shift modulation method. The optical receiver includes: an interferometer which branches the inputted optical signal into two parts and gives a one-bit phase difference to the resultant two optical signals so that the two optical signals after addition of the phase difference are made to interfere each other to output two output lights; reflection means which reflects one of the output lights from the interferometer so as to return to the interferometer; detection means which detects the return light which has been reflected by the reflection means and propagates through the interferometer in the different direction from the inputted optical signal, for output; and phase difference control means which adjusts the phase difference given by the interferometer according to the intensity of the return light detected by the detection means.

Abstract: The optical frequency comb generating device having two optical modulation parts 41 and 42 independently modulating optical waves propagating in two branch waveguides and a phase regulator 43 controlling a phase difference between the optical waves includes amplitude adjusting means 22 for adjusting a voltage amplitude of the RF signal supplied to at least one of the optical modulation parts, monitoring means 21 for monitoring the intensity Pout of the output light beam, and a bias control circuit 20 that controls the amplitude adjusting means to change a difference in voltage amplitude between the RF signals supplied to each optical modulation part, that detects a variation of the output light beam corresponding to the variation of the difference in voltage amplitude from the output signal of the monitoring means, and that controls the phase regulator on the basis of the detection result to adjust the phase difference.

Abstract: An electric field measuring apparatus measures electric field intensity of an electromagnetic wave generated from equipment under test installed in an area in which electromagnetic waves are detected. The apparatus includes an antenna, an RF amplifier amplifying an output signal of the antenna, a signal intensity detector detecting whether intensity of the output signal is higher than a predetermined level, a signal generator generating a detection result signal on the basis of a detection result of the signal intensity detector, a multiplexer multiplexing an output signal of the RF amplifier, the detection result signal, and a DC bias voltage, and an optical intensity modulator having a Mach-Zehnder type optical waveguide performing an optical modulation operation on the basis of an output signal of the multiplexer are arranged inside the area. Arranged outside the area are a light source unit, a receiver unit, a DC bias controller, and a display unit.

Abstract: An optical receiver includes interference means 2 for branching the optical signal modulated in a DQPSK manner into two light beams, delaying at least one branched light beam so that two branched light beams have a predetermined phase difference, rotating the polarization plane of at least one branched light beam so that the polarization planes of the two branched light beams are orthogonal to each other, and coupling the two branched light beams, light separation adjusting means 3 to 5 for separating the output light beam from the interference means and adjusting the polarization planes of the separated light beams, and detection means 6 and 6? for detecting light intensities of the separated light beams output from the light separation adjusting means, wherein an I-component signal and a Q-component signal are generated on the basis of detection signals from the detection means.

Abstract: The present invention relates to an optical receiver, and particularly, to an optical receiver by which a DQPSK-modulated optical signal is demodulated to a multilevel phase-modulated signal.

Abstract: An external cavity semiconductor laser including a first and second input-output section disposed on a common end surface via a center axis, and a semiconductor laser device emitting a first and second laser light from the first and second input-output sections in two directions. The laser device includes a first reflecting unit for reflecting the first laser light emitted from the first input-output section and returning the reflected first laser light to the first input-output section, a second reflecting unit for reflecting the second laser light emitted from the second input-output section and returning the reflected second laser light to the second input-output section, a third reflecting unit provided to a second end surface disposed opposite a first end surface having first and second input-output sections for reflecting laser light returned to one of the input-output sections so as to be emitted from the other one of the input-output sections.

Abstract: Provided is an optical receiver which accurately demodulates an optical signal obtained by the differential phase shift modulation method. The optical receiver includes: an interferometer which branches the inputted optical signal into two parts and gives a one-bit phase difference to the resultant two optical signals so that the two optical signals after addition of the phase difference are made to interfere each other to output two output lights; reflection means which reflects one of the output lights from the interferometer so as to return to the interferometer; detection means which detects the return light which has been reflected by the reflection means and propagates through the interferometer in the different direction from the inputted optical signal, for output; and phase difference control means which adjusts the phase difference given by the interferometer according to the intensity of the return light detected by the detection means.

Abstract: The present invention relates to an optical receiver, and particularly, to an optical receiver by which a DQPSK-modulated optical signal is demodulated to a multilevel phase-modulated signal.

Abstract: A laser beam generating apparatus includes a semiconductor element and a second harmonic generating element that performs a wavelength conversion on fundamental light emitted from the semiconductor element, the laser beam generating apparatus is an external resonance-type laser diode that has an external resonator structure and emits a transversal single mode laser beam, and the second harmonic generating element is a waveguide-type second harmonic generating element that includes a single mode waveguide.

Abstract: An external cavity semiconductor laser is provided with a first input-output section 2a and a second input-output section 2b that are disposed on a common end surface 2 via a center axis 3.

Abstract: A laser beam generating apparatus includes a semiconductor element and a second harmonic generating element that performs a wavelength conversion on fundamental light emitted from the semiconductor element, the laser beam generating apparatus is an external resonance-type laser diode that has an external resonator structure and emits a transversal single mode laser beam, and the second harmonic generating element is a waveguide-type second harmonic generating element that includes a single mode waveguide.