Abstract: The arrayed waveguide grating (AWG) is a known prior art optical multiplexer used in WDM optical communication systems. In the prior art flat-type AWG, the pulse waveform is distorted due to the dispersion in the AWG itself, and this forms a serious problem that makes it impossible to use the AWG as a multiplexer.

Abstract: It is an object of the present invention to provide an optical filter which allows parameters to be easily adjusted, which allows birefringence and temperature dependence to be easily compensated for, and which is essentially free from dispersion. The optical filter includes an optical coupler that splits light into two beams, optical couplers connected to outputs of the optical coupler, a first group of two optical waveguide delay lines connected to the coupler, a second group of two optical waveguide delay lines connected to the coupler, an optical coupler that combines lights from the first group of the lines, an optical coupler that combines lights from the second group of the lines, and a multimode interference optical coupler that combines lights from the couplers together.

Abstract: An optical signal processing apparatus includes a first optical waveguide and a first slab waveguide configured to equally distribute an output light of the first optical waveguide. A first arrayed waveguide includes an aggregate of optical waveguides changing in optical length by a constant interval for dividing the output light. A second slab waveguide focuses the optical output of the first arrayed waveguide. A spatial filter receives incident light focused by the second slab waveguide and distributes the incident light on a straight line. The spatial filter also modulates the light into a desired amplitude according to the position on the straight line. The apparatus also includes a second arrayed waveguide and an aggregate of optical waveguides changing in optical length by a constant interval for applying light modulated by the spatial filter to the second arrayed waveguide. Structure is provided for converging the output light of said second arrayed waveguide to a single point.

Abstract: An optical fiber including a core having an area of about several times an optical wavelength and composed of a hollow hole, and a cladding having a diffraction grating which is arranged at least in a peripheral area adjacent to the core and has a grating period equal to ½ the optical wavelength.

Abstract: In a light waveguide circuit including a plurality of waveguides having different length, a material (10) having a temperature coefficient of a refractive index including a symbol different from that of a temperature coefficient of an effective refractive index of the waveguide (4) is charged into a groove (12) formed by removing the upper clad and the core from the waveguide (4), or a groove (12) formed by removing the upper clad, the core and the lower clad from the waveguide (4). A difference in length of the removed portions between adjacent waveguides is proportional to a difference in length of the waveguides which were not removed and remained.

Abstract: A polarization maintaining optical fiber is formed by using a core in a cross sectional shape having different diameters along two orthogonal axes defined on a plane perpendicular to an optical axis, or a photonic crystal structure cladding having a diffraction grating with lattice intervals for realizing confinement of lights within the core which are different along two orthogonal axes defined on a plane perpendicular to an optical axis, or the photonic crystal structure cladding that is divided into four divided portions along a circumferential direction, where at least a part of lattice holes in a first pair of divided portions that are facing each other along one direction have a diameter larger than that of lattice holes in a second pair of divided portions that are facing each other along another direction orthogonal to the one direction.

Abstract: In the disclosed optical signal processing device, the digital-to-analog conversion of the input optical signals is realized in an optical region, without converting the input optical signals into electric signals for the purpose of signal processing, by splitting input optical signals into plural sets, delaying the split optical signals for mutually different delay amounts while adjusting amplitudes of these optical signals, combining these optical signals, and gating these optical signals on a time axis. It is also possible to realize the processing of the optical signals that are multiplexed on a time axis such as interchanges of time-slots similarly.

Abstract: A wavelength division multi/demultiplexer multi/demultiplexes incident light to emit demultiplexed lights from each of a plurality of light output ends and includes a first wavelength division multi/demultiplexing circuit having at least one light input end and a plurality of light output end; and second wavelength division multi/demultiplexing circuits of AWG type formed on a substrate, including a plurality of light input and output ends, one or two light multiplexing and demultiplexing sections, and a plurality of arrayed waveguides, and having a transmission bandwidth different from that of the first circuit, the transmission bandwidth indicating the width of a light frequency that can pass through each light input and output end, wherein the first circuit and at least one of the second circuits are optically connected together, and wherein the light output ends of the final second circuit are used as the light output ends of the wavelength division multi/demultiplexer.

Abstract: An optical CDMA encoder-decoder is constructed by combining arrayed-waveguide gratings, matrix optical switches, and delay lines, otherwise by combining arrayed-waveguide gratings and variable delay lines, thus providing an encoding process that a wavelength change with respect to time in optical pulses.

Abstract: The present invention relates to an optical signal processing apparatus and optical signal processing method which enable generation, waveform shaping, waveform measurement, waveform recording, correlation processing, and the like of optical pulses of 1-10 ps. A basic construction of the optical signal processing apparatus includes an optical waveguide, a first structure for equally distributing output light of the optical waveguide, an optical waveguide comprising an aggregate of optical waveguides changing in optical length by a constant interval, a arrayed waveguide for dividing the output light, second structure for focusing optical output of the arrayed waveguide, and a mirror for receiving and reflecting incident light focused by the second structure.

Abstract: An arrayed waveguide grating including an input waveguide or input waveguides, an input side slab waveguide lens, arrayed waveguides, an output side slab waveguide lens, and an output waveguide or output waveguides, wherein an optical length of the arrayed waveguides monotonically increases or decreases by a constant value between adjacent waveguides; the arrayed waveguides include an input side waveguide block, an intermediate waveguide block, and an output side waveguide block; the intermediate waveguide block includes at least one fan-formed waveguide block, the fan-formed waveguide block is coaxial, equal in vertical angle, and monotonically increases or decreases by a constant value in radius between adjacent waveguides; and the input side waveguide block and the output side waveguide block are line symmetrical about a bisector of the vertical angle of the intermediate waveguide block.

Abstract: An integrated optical waveguide circuit includes a substrate; an optical wavelength multiplexer and an optical power splitter formed on a same surface of the substrate. The optical wavelength multiplexer is composed of a first slab optical waveguide, a second slab optical waveguide, a single or a plurality of input optical waveguides connected to the first slab optical waveguide at one end of the first slab optical waveguide, a plurality of arrayed optical waveguides arranged in parallel and having different lengths and connected to the first slab optical waveguide and the second slab optical waveguide, and a plurality of output optical waveguides arranged in parallel and connected to the second slab optical waveguide. The optical power splitter is composed of the second slab optical waveguide, one or more input optical waveguides, and the plurality of output optical waveguides arranged in parallel and connected to the second slab optical waveguide.

Abstract: In a single mode optical waveguide having a substrate, a cladding layer formed on the substrate, a core portion embedded in the cladding layer, and an elongated member for applying a stress to the core portion or a stress relief groove for relieving a stress from the core portion in the cladding layer along the core portion. The position, shape and material of the elongated member or the groove are determined in such a way that stress-induced birefringence produced in the core portion in accordance with a difference in thermal expansion coefficient between the substrate and the single mode optical waveguide is a desired value.

Abstract: In a single mode optical fiber comprising a core made of glass and a cladding surrounding the core and made of glass, when a difference .DELTA. between refractive indices n.sub.1 and n.sub.2 of the core and cladding is expressed by (n.sub.1 -n.sub.2)/(n.sub.1).times.100%, the refractive indices n.sub.1 and n.sub.2 are determined to satisfy a relation 1.0<.DELTA.<3.6 and a diameter of the core is determined according to this value of .DELTA..

Abstract: A single-polarization single mode optical fiber of the type comprising an elliptical core, a pair of stress applying parts on both sides of the minor radius of the elliptical core for applying asymmetrical stress thereto and a clad embedding therein the core and the stress applying parts, the stress applying parts being made of B.sub.2 O.sub.3 wherein a relative refractive index difference .DELTA. between the core and the clad satisfies a relation 0.004.ltoreq..DELTA..ltoreq.0.05, an ellipticity .epsilon. satisfies a relation 0.01.ltoreq..epsilon..ltoreq.0.9, the B.sub.2 O.sub.3 has a molar concentration of 1 to 25 mole %, ratio of thickness of the stress applying parts and the core is 5 to 15, a modal birefringence B expressed by an equation B=(.beta..sub.x -.beta..sub.y)/k satisfies a relation B=1.times.10.sup.-6 where (.beta..sub.x -.beta..sub.y) represents a propagation constant difference between HE.sub.11.sup.x and HE.sub.11.sup.

Abstract: In a single mode optical fiber of the type comprising a core, a cladding surrounding the core and an intermediate layer, the refractive indices n1, n2 and n3 respectively of the core, the cladding and the intermediate layer are selected such that the following relations are satisfied0.5<.DELTA.1<1.5-0.3>.DELTA.2>-1.