Abstract: An optical directional coupler (1) comprises first and second straight optical waveguides (2, 3) having respective cores (2a, 3a) extending longitudinally close to each other to form an optical coupler portion, and a tapered optical waveguide (4) having a core (4a) connected to the core (2a) of the first straight waveguide (2). The core (2a) of the first straight waveguide (2) has a centerline (2d). A width of the core (4a) of the tapered waveguide (4) becomes narrow toward the first straight waveguide (2) and a profile of the tapered waveguide (4) is asymmetric relative to the centerline (2d) of the core (2a) of the first straight waveguides (2).

Abstract: The present invention provides an optical system with waveguides, which comprises first, second and third optical input/output means (12, 14, 16), fourth and fifth multi-mode optical waveguides (20, 22) each capable of propagating light with plural propagation modes, and optical-filter mounting means (26) for mounting an optical filter (24) between the fourth and fifth multi-mode optical waveguides (20, 22) across a traveling direction of light in the fourth and fifth multi-mode optical waveguides (20, 22). The first optical input/output means (12) is connected to an end face of the fourth multi-mode optical waveguide (20) on a side thereof opposite to the optical-filter mounting means (26). Each of the second and third optical input/output means (14, 16) is connected to an end face of the fifth multi-mode optical waveguide (22) on a side opposite to the optical-filter mounting means (26).

Abstract: The invention is directed to an optical waveguide that reduces an excess loss caused in a curved waveguide region by a deviation of the center axis of a beam propagating mode from the center axis of the optical waveguide. The optical waveguide has its part curved, and assuming that the shortest distance from a certain point of a convex edge of the curved portion to a concave edge is a waveguide width at that point, the optical waveguide has its width progressively reduced from the maximum waveguide width in the midst of the curved portion toward the opposite ends of the curved portion.

Abstract: The present invention relates to a curved optical waveguide which is free of any axis-deviation structure in the middle of the waveguide and which has a sigmoidal core shape, wherein the curvature thereof at one end is zero and the curvature thereof at the other end is finite (>0) and the use of such a curved optical waveguide permits the reduction of optical loss at the connected portions to the lowest possible level even when it is applied to, for instance, an optical splitter or a directional coupler and the curved optical waveguide of the present invention can provide an optical waveguide which never requires the use of any offset.

Abstract: Provided is a light branching optical waveguide including: at least one incident light waveguide (A) optically connected to one end of a multi-mode optical waveguide; and output light waveguides (B) larger in number than the incident light waveguide (A) optically connected to the other end thereof, the light branching optical waveguide being characterized in that: an intensity distribution of light incident from at least one optical waveguide (a) out of the incident light waveguide (A) on the multi-mode optical waveguide at a connecting surface of the incident light waveguide (A) and the multi-mode optical waveguide is asymmetric with respect to a geometrical central axis of the optical waveguide (a); and an extended line of the geometrical center axis of the optical waveguide (a) does not coincide with a geometrical central axis of the multi-mode optical waveguide.

Abstract: An optical waveguide structure has a single port 10 on one input/output side, a plurality of ports 12 on another input/output side and an S-bent optical waveguide portion 20 arranged on the outermost side of the waveguide structure. Tangential lines at opposed ends of the S-bent waveguide portion are parallel to each other. The S-bent optical waveguide portion includes a first circular arc optical waveguide portion 24 and a second circular arc optical waveguide portion 26 connected thereto at a first inflection point 22 where a curvature of the S-bent optical waveguide portion 20 is inverted. The first circular arc optical waveguide portion 24 has a first splitting/coupling point located on a single-port side relative to the first inflection point 22. The waveguide portion also has a third circular arc optical waveguide portion 32 extending from the first splitting/coupling point 30 toward the plural-ports 12 side and having a curvature inverted relative to the first circular arc optical waveguide portion 24.

Abstract: The present invention provides a polymeric optical waveguide film whose core and clad are constituted from polymer materials and which is characterized in that a protective layer of a polymer material having resistance to solvent attack higher than that observed for the clad is arranged on at least one of the surface and back face of the waveguide film. The present invention thus permits the preparation of such a film, the clad of which is hardly damaged, which is excellent in the resistance to solvent attack and which never undergoes cracking even when it is bought into contact with a commonly used solvent such as acetone.

Abstract: The present invention provides a polymeric optical waveguide film whose core and clad are constituted from polymer materials and which is characterized in that a protective layer of a polymer material having resistance to solvent attack higher than that observed for the clad is arranged on at least one of the surface and back face of the waveguide film. The present invention thus permits the preparation of such a film, the clad of which is hardly damaged, which is excellent in the resistance to solvent attack and which never undergoes cracking even when it is bought into contact with a commonly used solvent such as acetone.

Abstract: A method of producing optical elements using a substrate having a recess, which is capable of easily removing a film in the recess, and optical elements formed. The optical element comprises a substrate 1, an optical waveguide structure layer 10 of resin disposed in a part of the region on the substrate 1, and a recess 21 formed in the region where the optical waveguide structure layer 10 is not disposed. The optical waveguide structure layer 10 includes an optical waveguide 4 and a clad layer. A coupler layer is disposed between the substrate 1 and the optical waveguide structure layer 10, and the film thickness distribution range of the coupler layer in the region below the optical waveguide 4 is such that the minimum film thickness is not more than 30 angstroms and the maximum film thickness is not less than 20 angstroms.

Abstract: A method of producing optical elements using a substrate having a recess, which is capable of easily removing a film in the recess, and optical elements formed. The optical element comprises a substrate 1, an optical waveguide structure layer 10 of resin disposed in a part of the region on the substrate 1, and a recess 21 formed in the region where the optical waveguide structure layer 10 is not disposed. The optical waveguide structure layer 10 includes an optical waveguide 4 and a clad layer. A coupler layer is disposed between the substrate 1 and the optical waveguide structure layer 10, and the film thickness distribution range of the coupler layer in the region below the optical waveguide 4 is such that the minimum film thickness is not more than 30 angstroms and the maximum film thickness is not less than 20 angstroms.

Abstract: The present invention herein provides an optical waveguide which comprises a cladding and a core formed on a substrate, wherein a refractive index of a material constituting the cladding on the upper side of the core is smaller than a refractive index of a material constituting the cladding on the lateral side of the core and a refractive index of a material constituting the cladding on the lower side of the core; an optical waveguide (an optical waveguide for coupling) which is used for coupling with an optical waveguide (an optical waveguide to be coupled) having a refractive index distribution within a core in the vertical direction, wherein a cladding has a refractive index distribution in the vertical direction; and a method for the preparation thereof. The optical waveguide of the present invention permits the reduction of the coupling loss observed when it is coupled with an optical waveguide whose core is formed by the diffusion technique such as a lithium niobate optical waveguide.

Abstract: The present invention provides an optical module using optical waveguides which permits easy fabrication of a PLC type optical multiplexer/demultiplexer with reduced loss. The optical module comprises cores which are contiguous to each other through a dicing groove adapted to position and fix an optical functional part such as a wavelength selection filter and a core branched from the said cores. A slight gap is present between the former and the latter core and both cores are narrower in width in the vicinity of the dicing groove than the other portions.

Abstract: The present invention disclosed is an optical waveguide structure that has a first waveguide provided with the opposite ends A and B, a second waveguide with the opposite ends C and D, a third waveguide with the opposite ends E and F, and a coupling waveguide having its first beam incoming/outgoing end connected to the end B of the first waveguide and its second beam incoming/outgoing end connected to the end C of the second waveguide and the end E of the third waveguide. The optical waveguide is characterized in that the first waveguide and the coupling waveguide are longitudinally dimensioned so that light beam at its peak of light intensity can transit the point of axial mal-alignment at the end A of the first waveguide and further transit the axial zone at the second beam incoming/outgoing end of the coupling waveguide.

Abstract: The present invention provides a polymeric optical waveguide film whose core and clad are constituted from polymer materials and which is characterized in that a protective layer of a polymer material having resistance to solvent attack higher than that observed for the clad is arranged on at least one of the surface and back face of the waveguide film. The present invention thus permits the preparation of such a film, the clad of which is hardly damaged, which is excellent in the resistance to solvent attack and which never undergoes cracking even when it is bought into contact with a commonly used solvent such as acetone.

Abstract: A method of producing optical elements using a substrate having a recess, which is capable of easily removing a film in the recess. An optical element comprises a substrate 1, and optical wavefuide structure layer 10 of resin disposed in a part of the region on the suvstrate 1, and a recess 21 formed in the region where the optical waveguide structure layer 10 is not disposed. The optical wavefuide structure layer 10 includes an optical wavefude 4 and a clad layer. A coupler layer is disposed vetween the substrate 1 and the optical wavefude structure layer 10, and the film thickness distribution range of the coupler layer in the region below the optical wavefuide 4 is such that the minimum film thickness is not more than 30 angstroms and the maximum film thickness is not less htan 20 angstroms.

Abstract: The present invention relates to an electrode structure, which comprises a substrate provided with an electrode formed thereon, wherein the substrate comprises a layer of a fluorine-containing polyimide and a layer of a fluorine-free resin is interposed between the polyimide layer and the electrode and, in particular, to the foregoing electrode structure, wherein the electrode comprises a gold layer as the outermost or surface layer and an aluminum layer interposed between the substrate and the gold layer. The electrode structure of the present invention never causes any peeling off of the electrode due to insufficient adhesion of the electrode to the substrate, the structure has sufficiently high strength and therefore the boundary between the substrate and the electrode formed thereon is not destroyed by the energy of ultrasonics applied thereto.

Abstract: The present invention relates to an electrode structure, which comprises a substrate provided with an electrode formed thereon, wherein the substrate comprises a layer of a fluorine-containing polyimide and a layer of a fluorine-free resin is interposed between the polyimide layer and the electrode and, in particular, to the foregoing electrode structure, wherein the electrode comprises a gold layer as the outermost or surface layer and an aluminum layer interposed between the substrate and the gold layer. The electrode structure of the present invention never causes any peeling off of the electrode due to insufficient adhesion of the electrode to the substrate, the structure has sufficiently high strength and therefore the boundary between the substrate and the electrode formed thereon is not destroyed by the energy of ultrasonics applied thereto.

Abstract: The invention provides an optical element comprising a substrate having provided thereon a coating of an organic zirconium compound, a coating of a fluorine-free polyimide resin and a coating of a fluorine-containing polyimide resin, in this order. The element has increased adhesive property with the substrate and reliability.

Abstract: Related to a liquid-crystal alignment film that can align liquid-crystal molecules without resort to the rubbing.The liquid-crystal alignment film of the present invention comprises a resin (e.g., a polyimide) containing a photoisomerizable and dichroic structural unit (e.g., a stilbene derivative), and is furnished with the ability to align liquid-crystal molecules when a film formed of the resin is irradiated with linearly polarized light; the ability to align liquid-crystal molecules being held and fixed.The liquid-crystal alignment film of the present invention is used in electric-filed driven type liquid-crystal display devices.

Abstract: An alignment film for liquid crystal is provided which comprises a polyimide comprising a repeating unit of the general formula (I): ##STR1## wherein n is an integer of from 2 to 16 and R.sup.1 represents a divalent organic group. This polyimide is obtained for example, from a reaction between ethylene glycol bis(trimellitate dianhydride) and 4,4'-diaminodiphenyl ether. This polyimide or a varnish of a precursor thereof is coated on a plate, and dried to obtain an alignment film for liquid crystal, which stably exhibits a high pretilt angle, irrespective of curing temperatures. The present invention further provides a liquid crystal-sandwiched panel and a liquid crystal display module prepared using the alignment film as well as a material for the preparation of the alignment film.