Abstract: An optical functional device comprises a dielectric substrate 5, a ferroelectric thin layer 10 provided on the dielectric substrate 5 and comprising a material having electro-optical effect and an electrode 3A, 3B provided on the ferroelectric thin layer 10. A part of the ferroelectric thin layer 10 functions as a core 9 of the optical wave guide and the dielectric substrate functions as a clad for the optical waveguide. The optical waveguide 9 constitutes a multi-mode waveguide in the direction “D” of depth of the ferroelectric thin layer.

Abstract: It is provided an optical waveguide device in which the radius of curvature of a curved part of an optical waveguide can be lowered and the radiation loss of light in the curved part can be reduced. An optical waveguide device 2 has a ferroelectric optical waveguide substrate and an optical waveguide 5 formed in or on the substrate and modulating electrodes 4A, 4B and 4C. The thickness of the optical waveguide substrate is 30 ?m or smaller at least in a region where the optical waveguide is formed. The optical waveguide has curved part having a radius of curvature of 30 mm or smaller.

Abstract: An optical functional device 1 has a slab type two-dimensional photonic crystal layer 29. The layer 29 has a dielectric layer 4 and a plurality of lattice columns 5 each comprising dielectric pillars. A waveguide portion 6 is provided in the photonic crystal layer 29. A ground electrode 8 and a signal electrode 9 are formed on the dielectric layer 4 for applying a modulating voltage on light propagating in the waveguide portion 6. A layer 2 of a high dielectric constant is laminated on the dielectric layer 4. A low dielectric portion is formed direct under the waveguide portion 6 and the lattice columns 7a, 7B and 7C of at least first, second and third orders in distance with respect to said waveguide portion.

Abstract: A first main face 1a of a substrate 1 of a dielectric single crystal is etched to form recesses 4 in the substrate 1. A second main face 1b of the substrate 1 is mechanically processed to form a slab 10, so that the recesses 4 pass through the substrate 1 to form through holes 11.

Abstract: An optical modulator is provided for modulating light propagating in a three-dimensional optical waveguide 5 by applying a voltage thereto. The optical modulator has the three-dimensional optical waveguide 5 including at least one pair of branch optical waveguides 5c and 5d, a multiplexing part 5e of the branch optical waveguides and an emission part 5f provided in the downstream of the multiplexing part, modulation electrodes 3A, 3B and 4 for applying a signal voltage for modulating light propagating in the three-dimensional optical waveguide 5, and guiding waveguides 6A and 6B for guiding primary mode light from the multiplexing part. Thickness of the substrate is 20 ?m or less at least under the modulation electrodes, and an operation point of the optical modulator is controlled by changing, based on light output from the guiding waveguides, DC bias applied onto the modulation electrodes.

Abstract: A voltage is applied on a first branch 3a by a first ground electrode 10 and a signal electrode 11, and a voltage is applied on a second branch 3b by a second ground electrode 12A and the signal electrode 11. A first gap 13 is formed between the first ground electrode 10 and the signal electrode 11, and a second gap 14 is formed between the second ground electrode 12A and the signal electrode 11. The first gap 13 and the second gap 14 are divided into voltage applying portions 13a, 14a, feed-through portions and connection portions 13b, 14b therebetween, respectively, and satisfy the formula: G12/G11?G22/G21<G32/G31.

Abstract: An optical waveguide structure has a slab type photonic crystal and an optical waveguide provided in the photonic crystal. The photonic crystal has a slab of a dielectric film and a plurality of lattice columns each having dielectric pillars. The dielectric pillars included in the lattice columns at least in n'th order (n represents 1, 2, 3, 4 and 5) in distance with respect to said optical waveguide, respectively, has a planar shape of an equilateral polygon or exact circle. At least one of the dielectric pillars included in the lattice columns at least in n'th order (n represents 2, 3, 4 and 5) with respect to the optical waveguide has a size rn different from a fundamental size ro.

Abstract: Major surface of a substrate having an optical waveguide and a modulation electrode is pasted to a base substrate through a thermosetting resin, and then the rear surface of the substrate is machined thus making thin the entirety. Subsequently, the rear surface of the substrate thus rendered thin is subjected to machining or laser machining to form a thin part, which is further subjected to machining or laser machining to form a first thin part at a part, including the optical waveguide, of the thin part and a second thin part thinner than the first thin part contiguously thereto. Thereafter, the rear surface of the substrate is pasted to the major surface of a supporting substrate through a thermosetting resin and the base substrate is stripped thus obtaining an optical modulator.

Abstract: It is provided a practical radio oscillating system for a radar system to alleviate the necessity of a reception filter of severe specification of pass band and an oscillating system and an amplifier of high performance and high reliability. The radio oscillating system has an optical modulator 2 for oscillation; a modulating means 6 for modulating a carrier wave “P” passing through the optical modulator 2 so as to superimpose sideband waves “Q” and “R” onto the carrier wave; an optical receiver 7 for oscillation to receive outgoing light “B” from the optical modulator 2 and to convert the outgoing light into an electrical signal; and a radiating means 8 for radiating radio signal “C” based on the electrical signal.

Abstract: A device 4 has a substrate 5, an optical waveguide 2 and modulation electrodes 1A, 1B, 1C. The substrate 5 is made of an electro-optic material and has a thickness of ?30 ?m at least in a region where the modulation electrode applies an electric field. The device has a ridge generated when the optical waveguide is formed, and the ridge has a height H (angstrom) and a width “W” (?m) whose product (H×W) is 7150 angstrom·?m or smaller to realize single mode propagation of light in the optical waveguide. The waveguide has branched parts in the region where the modulation electrode applied an electric field. The deviation of positions of peaks and bottoms in the extinction ratio curve can be reduced, by increasing the distance of the branched parts of the optical waveguide to ?46 ?m.

Abstract: An optical functional device comprises a dielectric substrate 5, a ferroelectric thin layer 10 provided on the dielectric substrate 5 and comprising a material having electro-optical effect and an electrode 3A, 3B provided on the ferroelectric thin layer 10. A part of the ferroelectric thin layer 10 functions as a core 9 of the optical wave guide and the dielectric substrate functions as a clad for the optical waveguide. The optical waveguide 9 constitutes a multi-mode waveguide in the direction “D” of depth of the ferroelectric thin layer.

Abstract: An object of the invention is to provide an electrode system for optical modulation of an optical modulator to reduce a thickness “E” of an electrode required for velocity matching and for reducing a propagation loss in the electrode. A substrate 2 is made of an electrooptic material and has one and the other main faces 2a, 2b opposing each other. An electrode system 20A is provided on the substrate 2 for applying a voltage for modulating light propagating in optical waveguides 6A and 6B. The electrode system 20A includes ground electrodes 3A, 3B and a signal electrode 4. A ratio “W/G” of a width “W” of the signal electrode 4 to a gap “G” between the ground and signal electrodes is 0.8 or higher. Preferably, the substrate 2 has a thickness “T” of 20 ?m or larger, in a region where the optical waveguides 6A and 6B are provided.

Abstract: It is provided an optical waveguide device in which the radius of curvature of a curved part of an optical waveguide can be lowered and the radiation loss of light in the curved part can be reduced. An optical waveguide device 2 has a ferroelectric optical waveguide substrate and an optical waveguide 5 formed in or on the substrate and modulating electrodes 4A, 4B and 4C. The thickness of the optical waveguide substrate is 30 ?m or smaller at least in a region where the optical waveguide is formed. The optical waveguide has curved part having a radius of curvature of 30 mm or smaller.

Abstract: A voltage is applied on a first branch 3a by a first ground electrode 10 and a signal electrode 11, and a voltage is applied on a second branch 3b by a second ground electrode 12A and the signal electrode 11. A first gap 13 is formed between the first ground electrode 10 and the signal electrode 11, and a second gap 14 is formed between the second ground electrode 12A and the signal electrode 11. The first gap 13 and the second gap 14 are divided into voltage applying portions 13a, 14a, feed-through portions and connection portions 13b, 14b therebetween, respectively, and satisfy the formula: G12/G11?G22/G21<G32/G31.

Abstract: An optical waveguide device has an optical waveguide substrate and a supporting body for supporting the substrate. The substrate has a main body made of an electro-optic material and having a main face and an opposing face, optical waveguides, and electrodes for applying an electrical signal on the optical waveguides. At least a part of the opposing face of the supporting body opposing the substrate is covered with a conductive layer. It is thus possible to reduce the resonance due to substrate radiation leakage of the microwave signal into the whole of the optical waveguide substrate and supporting body.

Abstract: An optical modulator 1C has a substrate 2 of an electro-optic material and having first and second main faces, an optical waveguide formed on the substrate 2 and having first branched part 5 and a second branched part 3, and ground electrodes 4A, 4C and a signal electrode 4B provided on the side of the first main face of the substrate. The first branched part 5 and second branched part 3 are provided between the edges of the ground electrodes 4A, 4C and the edge of the signal electrode 4B, respectively. Microwave electric fields are applied onto interacting parts of the first branched part 5 and second branched part 3, respectively, to modulate light propagating in the first branched part 5 and second branched part 3, respectively. The integral values of field intensities over interaction lengths with electrodes in the first and second branched parts are different from each other so that a predetermined chirp amount is obtained.

Abstract: An optical waveguide device 1 has an optical waveguide substrate 19, a supporting body 2 for supporting the substrate 19 and a joining layer 3 for joining the substrate 19 and the supporting body 2. The substrate 19 has a flat plate-shaped main body 4 made of an electro-optic material with a thickness of 30 ?m or smaller and having first and second main faces 4a and 4b opposing each other, an optical waveguide provided on the side of the first main face 4a of the main body 4, and electrodes 7A to 7C provided on the side of the first main face 4a of the main body 4. The joining layer 3 joins the supporting body 2 at a joining face 4d and the second main face 4d of the main body 4. The joining face 2a of the supporting body 2 is substantially flat. Alternatively, the joining layer 3 has a thickness of 200 ?m or lower.

Abstract: An object of the present invention is to improve the modulation efficiency of an optical modulator in a high frequency band while satisfying the velocity matching condition. An optical modulator is provided having an optical waveguide for propagating light, an electrode for applying a voltage on the waveguide for modulating the light, a signal source electrically connected to the electrode and a terminating resistance electrically connected to the electrode. The signal source has a characteristic impedance Zi and the terminating resistance has an impedance Zl satisfying the formula (Zi<Zl). Alternatively, the signal source has a characteristic impedance Zi and the electrode has a characteristic impedance Zc satisfying the formula (Zi<Zc).

Abstract: A Mach-Zehnder optical waveguide is disposed in a substrate made of a material having an electro-optic effect. Coplanar-waveguide modulating electrodes are disposed on a principal surface of the substrate. A dielectric layer is disposed on a reverse surface of the substrate. A supporting substrate having a recess is disposed in contact with the dielectric layer such that the recess is located at a position corresponding to a modulating region. The relationship: ?r>?s is satisfied where ?r represents the dielectric constant of the supporting substrate and ?s represents the dielectric constant of the dielectric constant of solid, liquid, or gaseous substance in the recess.

Abstract: An optical waveguide device 1A has a substrate 22 and a supporting body 10 for supporting the substrate. The substrate 22 has a main body 2 made of an electrooptic material and one and the other main faces, optical waveguides 3a, 3b and electrodes 4B, 4C provided on the side of the one main face 2a of the main body 2 The supporting body 10 is joined with the substrate 2 on the side of the other main face, and the electrode has a feedthrough portion. The device 1A further has a low dielectric portion 7 provided under the feed through portion and between the other main face 2b of the main body 2 and the supporting body 10.