Abstract: An optical waveguide chip includes an output waveguide connected to an optical fiber, an optical fiber array module, or another optical waveguide chip. The output waveguide has a coupling cross-section wider than the core of the optical fiber, the core of an optical fiber of the optical fiber array module, and the waveguide of the other optical waveguide, respectively. The cross-section width of the output waveguide of the optical waveguide chip gradually increases toward an end of the waveguide with a slant angle of 10° or less. Therefore, when the optical waveguide chip is connected to the optical fiber, the optical fiber array module, or the other optical waveguide chip during packaging of an optical waveguide device, an offset of the optical axis of about ±20% of the width of the waveguide guide is allowable.

Abstract: An optical power divider using a beam separator and a beam expander, and a fabrication method therefor. The optical power divider includes an input optical waveguide having an input port for receiving incident light, for guiding the light incident via the input port, a plurality of output optical waveguides having at least two output ports, for outputting the light incident via the input optical waveguide to the output ports, wherein the number of output optical waveguides is equal to that of the output ports, and a beam separator located at a branch area in which the light incident on the input optical waveguide diverges toward the output optical waveguides, the beam separator being made of a material having a refractive index lower than the core of the input and output optical waveguides, for separating the light to the output optical waveguides with a predetermined ratio. Therefore, the length of the optical power divider becomes short and insertion loss can be lowered.

Abstract: A mode shape converter, interposed between an input or output terminal of a function executing unit included in an optical device and an optical fiber and adapted to couple a mode of the optical fiber with a mode of the input or output terminal of the function executing unit, includes a substrate, a lower clad coated over the substrate, the lower clad having an etched portion in a desired region, a lower rib waveguide formed on the etched portion of the lower clad, a core. formed over both the lower rib waveguide and a non-etched portion of the lower clad, an upper rib waveguide formed on the core such that it is aligned with the lower rib waveguide, the upper rib waveguide having a desired shape, and an upper clad formed over both the upper rib waveguide and a portion of the core not covered with the upper rib waveguide.

Abstract: An optical coupler and a method of manufacturing the same are provided. The optical coupler includes an input optical waveguide and N output optical waveguides, and divides an optical signal received from the input optical waveguide into N optical signals.

Abstract: In an optical intensity modulator, and a fabrication method thereof, the optical intensity modulator includes a substrate made of a predetermined material, an arc shaped optical waveguide formed on the substrate, and an electrode formed on the optical waveguide such that the electrode is in alignment with the optical waveguide, the refractive index of the optical waveguide being changed in accordance with an intensity of an electric field applied to the electrode, and an optical wave passing a predetermined location of the optical waveguide being radiated into the substrate due to the changed refractive index. Accordingly, a large modulation depth can be obtained from only a small refractive index variation by using the radiation loss characteristics of the arc shaped waveguide.

Abstract: In an optical power splitter for splitting input light into N equal optical waves, and a manufacturing method therefor, a main waveguide and (N−1) branched waveguides are arranged on one side or both sides of the main waveguide. The main waveguide and the (N−1) branched waveguides form a directional coupler. In each of the directional couplers, the branched waveguide has an appropriate phase mismatch, a proper coupling coefficient, and a suitable coupling length to output 1/N of input optical power in the main waveguide. In the optical power splitter, when the main waveguide is semicircular, a circular substrate can be effectively used when the optical power splitter is manufactured.

Abstract: A method of fabricating a planar optical waveguide in one chamber, comprising the steps of depositing a cladding layer and a core layer on a substrate, depositing an etch mask layer on the core layer, and forming a photoresist pattern on the etch mask layer. An etch mask pattern is formed by etching the etch mask layer according to the photoresist pattern using a first gas which reacts with the material of the etch mask layer, and removing the first gas. An optical waveguide is formed by etching the core layer according to the etch mask pattern using a second gas which reacts with the material of the core layer in the same chamber as the chamber where the above steps were performed, and removing the photoresist pattern and the second gas.

Abstract: An optical fiber passive alignment apparatus for passively aligning an optical fiber with an input/output optical waveguide of an integrated optical device, and a method therefor. The optical fiber passive alignment apparatus includes: an optical waveguide formed on a planar substrate along the longitudinal direction of the planar substrate, having a core which is shorter than the planar substrate; an optical fiber mounting portion formed to a predetermined length on the planar substrate in the longitudinal direction of the planar substrate, such that the optical waveguide and the optical fiber contact each other, for receiving the optical fiber; and a cavity located between the optical fiber mounting portion and a core of the optical waveguide, filled with a material whose refractive index slightly increases on irradiation by UV rays such that the refractive index of the material is not substantially different from the refractive index of a core of the optical fiber.

Abstract: An integrated optical intensity modulator and a method for fabricating it. The integrated optical intensity modulator includes a substrate having spontaneous polarization, cut in an axial direction; an optical waveguide on the substrate; domain-inversion areas having domains reverse from the direction of spontaneous polarization, arranged in a staggered pattern around the optical waveguide; a first electrode on the optical waveguide on a surface of the substrate, and second and third electrodes on the substrate on opposite sides of and on the same surface as the first electrode. When a voltage is applied to the first electrode, a light wave is deflected and scattered in a domain-inversion area in accordance with a change of the refractive index of the domain-inversion area in the optical waveguide and the refractive index of the spontaneous polarization area.