Abstract: An optical modulator has a ridge optical waveguide and a modulation electrode. The modulation electrode is composed of a signal electrode to which a modulation signal is supplied, a first ground electrode, and a second ground electrode, the signal electrode has a wide portion having a width wider than the width of the uppermost portion of the ridge optical waveguide, the first ground electrode has a central portion ground electrode component provided on a first surface so as to extend along a first direction, and the second ground electrode has a central portion ground electrode component provided on a second surface so as to extend along the first direction. The central portion ground electrode components respectively have a first and a second through-holes, and these through-holes overlap the wide portion of the signal electrode as seen in a planar view.

Abstract: [Task] Reduction in crosstalk between signal electrodes. [Means for Resolution] An optical modulator 1 includes a relay substrate 3 including a substrate portion 30, and signal electrodes 31 and 32, and a ground electrode 33 which are provided on the substrate portion 30, and an optical waveguide substrate 4 including an electrode-optical substrate 40, signal electrodes 431 and 432, and an optical waveguide 42 which are provided on the electro-optical substrate 40.

Abstract: Provided is an optical control device including first and second optical waveguides, a first control signal electrode including a first input-side signal electrode, a second control signal electrode including a second input-side signal electrode, an inter-signal-electrode ground electrode, a first ground electrode, and a second ground electrode. The substrate has a first groove that is provided between the first input-side signal electrode and the inter-signal-electrode ground, a second groove that is provided between the first input-side signal electrode and the first ground electrode, a third groove that is provided between the second input-side signal electrode and the inter-signal-electrode ground electrode, and a fourth groove that is provided between the second input-side signal electrode and the second ground electrode.

Abstract: [Task] Reduction in crosstalk between signal electrodes. [Means for Resolution] An optical modulator 1 includes a relay substrate 3 including a substrate portion 30, and signal electrodes 31 and 32, and a ground electrode 33 which are provided on the substrate portion 30, and an optical waveguide substrate 4 including an electrode-optical substrate 40, signal electrodes 431 and 432, and an optical waveguide 42 which are provided on the electro-optical substrate 40.

Abstract: An optical modulator has a ridge optical waveguide and a modulation electrode. The modulation electrode is composed of a signal electrode to which a modulation signal is supplied, a first ground electrode, and a second ground electrode, the signal electrode has a wide portion having a width wider than the width of the uppermost portion of the ridge optical waveguide, the first ground electrode has a central portion ground electrode component provided on a first surface so as to extend along a first direction, and the second ground electrode has a central portion ground electrode component provided on a second surface so as to extend along the first direction. The central portion ground electrode components respectively have a first and a second through-holes, and these through-holes overlap the wide portion of the signal electrode as seen in a planar view.

Abstract: Provided is an optical waveguide element including a first interactive part, a first EO substrate line, a second interactive part, and a second EO substrate line. A relay substrate unit includes a first relay substrate line, a second relay substrate line, and a loss adjusting part. The loss adjusting part is provided to the relay substrate line in a combination in which an electrical loss is low so that an electrical loss in a combination of the first EO substrate line and the first relay substrate line, and an electrical loss in a combination of the second EO substrate line and the second relay substrate line become approximately the same as each other.

Abstract: Provided is an optical control device including first and second optical waveguides, a first control signal electrode including a first input-side signal electrode, a second control signal electrode including a second input-side signal electrode, an inter-signal-electrode ground electrode, a first ground electrode, and a second ground electrode. The substrate has a first groove that is provided between the first input-side signal electrode and the inter-signal-electrode ground, a second groove that is provided between the first input-side signal electrode and the first ground electrode, a third groove that is provided between the second input-side signal electrode and the inter-signal-electrode ground electrode, and a fourth groove that is provided between the second input-side signal electrode and the second ground electrode.

Abstract: An aspect of the present invention is an optical modulator including a substrate, a plurality of optical waveguides, and a plurality of modulation electrodes provided on the substrate in order to modulate light propagating through the optical waveguides. The modulation electrodes include signal electrodes, to which modulation signals are supplied, and ground electrodes. The signal electrodes include first and second signal electrodes. The ground electrodes include a first ground electrode provided between the first and second signal electrodes, a second ground electrode provided on the opposite side of the first signal electrode from the first ground electrode adjacent to the first signal electrode, and a third ground electrode provided on the opposite side of the second signal electrode from the first ground electrode adjacent to the second signal electrode. A concave groove is formed in each of the first to third ground electrodes.

Abstract: Provided is a transmission line used to transmit high-frequency electrical signals which can remove a dip-shaped (S21) loss of transmission characteristics due to wall surface resonance, furthermore, can further decrease the size, and can suppress the manufacturing cost at a low level. The transmission line used to transmit high-frequency electrical signals (1) is made up of a signal line (3) used to transmit high-frequency electrical signals which is formed on a front surface (2a) of a dielectric substrate (2), GND electrodes (4) formed outside the signal line (3) and in vicinities of end portions of the front surface (2a), a GND electrode (6) that is electrically connected to the GND electrodes (4) through via holes (5) formed across an entire rear surface (2b) of the dielectric substrate (2), and band-shaped resistors (7) that are formed outside the GND electrodes (4) and in the end portions of the surface (2a) and are electrically connected to the GND electrodes (4).

Abstract: An object of the present invention is to provide an optical 90-degree hybrid circuit which is capable of easily adjusting the optical power ratio between signal and local oscillator and suppresses an optical system of an optical receiver becoming complex and optical receivers using the same.

Abstract: Provided is a transmission line used to transmit high-frequency electrical signals which can remove a dip-shaped (S21) loss of transmission characteristics due to wall surface resonance, furthermore, can further decrease the size, and can suppress the manufacturing cost at a low level. The transmission line used to transmit high-frequency electrical signals (1) is made up of a signal line (3) used to transmit high-frequency electrical signals which is formed on a front surface (2a) of a dielectric substrate (2), GND electrodes (4) formed outside the signal line (3) and in vicinities of end portions of the front surface (2a), a GND electrode (6) that is electrically connected to the GND electrodes (4) through via holes (5) formed across an entire rear surface (2b) of the dielectric substrate (2), and band-shaped resistors (7) that are formed outside the GND electrodes (4) and in the end portions of the surface (2a) and are electrically connected to the GND electrodes (4).

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: 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: 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.