Crosstalk can be reduced in optical waveguide bundles(110) by varying the widths of individual waveguides(111-161). Using different width waveguides reduces the growth of crosstalk between the optical waveguides, thereby allowing the waveguides to be placed in closer proximity to increase waveguide density on the chip(200) and/or reduce the routing space required for the waveguide bundle(110). Moreover, varying the width of a waveguide spiral may reduce crosstalk, which can increase power efficiency when implemented in coiled or folded waveguide thermal optical (TO) devices.

Compact optical waveguide arrays and optical waveguide spirals

A process for producing a waveguide, wherein a first layer is deposited on a silicon or glass substrate, a core structure is subsequently structured, and the core structure is protected by a protective layer Prior to each step for depositing a new layer, the layer that has just been applied is fluorinated

Process for producing planar waveguide structures as well as waveguide structure

A planar waveguide structure has, supported on a lower refractive index buffer layer (5), a pair of optical cores (1, 2) that, over at least a portion of their length, are closely spaced. These cores are covered with a layer (6) of cladding material comprising boron and phosphorus doped silica glass deposited by PECVD as a succession of individually annealed layers in order to minimise the incidence of voids in the deposit between the cores.

Waveguide pair with cladding

Annealing a planar wave guide layer is critical because small structural imperfections lead to optical problems. Chemical vapor deposition of the layer tends to leave gaseous substances bonded to the deposit, which on being driven off by initial annealing warm-ups leave cavities requiring densification. Traditional annealing methods take several hours. This invention proposes a rapid heating of the layer to a temperature below the flow temperature, maintaining this temperature for about 30 to 300 seconds, then rapidly heating up further to a temperature close to or above the flow temperature, maintaining this temperature for about 30 to 300 seconds, then allowing the substrate and layer to cool rapidly to room temperature.

Method of fabricating a planar waveguide structure

At least one of two slab waveguides constituting an arrayed waveguide grating is cut and separated together with a substrate on a cross separating face. A slide moving member is arranged over a waveguide forming area formed on the substrate including the separating slab waveguide and a waveguide forming area formed on the substrate including the separating slab waveguide. Temperature dependence of the center wavelength of the arrayed waveguide grating is reduced by slide-moving the separating slab waveguide by the slide moving member along the cross separating face dependently on temperature. The shift of an initial center wavelength is corrected by plastically deforming the slide moving member so that the initial center wavelength is conformed to a grid wavelength.

Arrayed waveguide grating and its method for correcting center wavelength

A method of manufacturing an optical waveguide whose refractive index distribution exhibits a step index profile comprises: forming a first layer (2) of fine glass particles to serve as a lower cladding on a substrate (1) by flame hydrolysis deposition; heat-treating the first layer (2) at 800 DEG C or more; forming a second layer (3) of fine glass particles and a refractive index increasing material e.g. P2O5 or GeO2, on the first layer (2) by flame hydrolysis deposition; heat-treating the first and second layers (2, 3) together, thereby converting the layers into transparent glass layers; applying photolithography and then dry-etching layer (3) to form a core (5) on the layer (2A); burying the core (5) by forming a third layer (6) of fine glass particles to serve as an upper cladding by flame hydrolysis deposition; and a step of heat-treating the third layer (6), to convert it into a transparent glass layer.

Manufacturing method for an optical waveguide

An arrayed waveguide grating optical multiplexer/demultiplexer includes an arrayed waveguide connected to at least one first optical waveguide via a first slab waveguide, a plurality of second optical waveguides connected to the arrayed waveguide via a second slab waveguide. At least one expanding width waveguide has a first end portion and a second end portion having a second width larger than a first width of the first end portion. Each first end portion is connected to each first optical waveguide. The second end portion is connected to the first slab waveguide. The first width of the first end portion is larger than a first optical waveguide width of the at least one first optical waveguide. The first width of the first end portion satisfies a single mode condition. A width of the expanding width waveguide increases from the first end portion toward the second end portion.

Array waveguide raster optical multiplying device and de-multiplying device

PROBLEM TO BE SOLVED: To provide an array waveguide type diffraction grating of which the light transmission central wavelength does not depend on an environmental temperature in use. SOLUTION: A waveguide forming region 10 which is formed by connecting in order a light input waveguide 2, a first slab waveguide 3, plural juxtaposed array waveguides 4 mutually different in length, a second slab waveguide 5 and plural juxtaposed light output waveguides 6 is formed on a substrate 1. The first slab waveguide 3 is cut and separated by a cutting surface 8 which diagonally crosses the central axis in the light advancing direction of the first slab waveguide 3, and a high thermal expansion coefficient member 7 having a coefficient of thermal expansion larger than that of the substrate 1 is provided in such an embodiment as to extend over a first waveguide forming region 10a and a second waveguide forming region 10b which are formed by the cut and separation of the waveguide 3. An interval between the first and second waveguide forming regions 10a, 10b is varied by the high thermal expansion coefficient member 7 in accordance with the environmental temperature in use, the output end 20 of the light input waveguide 2 is moved in the directions of the arrows A', B', and the variation of temperature dependency of respective light transmission central wavelengths of the array waveguide type diffraction grating is reduced.

Array waveguide type diffraction grating

PROBLEM TO BE SOLVED: To make dissolvable temperature dependency of a light transmission central wavelength in an array waveguide diffraction grating and to make the increase of an insertion loss suppressible even under a condition of a high temperature and a high humidity with a simple constitution. SOLUTION: A waveguide forming area 10, wherein a light input waveguide 2, a first slab waveguide 3, plural juxtaposed array waveguides 4 having mutually different lengths, a second slab waveguide 5 and plural juxtaposed light output waveguides 6 are connected in order, is formed on a substrate 1. The first slab waveguide 3 is separated in a cross separating surface 8 which crosses an optical path passing through the first slab guide 3. A matching grease is provided in the cross separating surface 8, and the evaporation of the matching grease is suppressed by providing a thin film member 40 covering the disposing area of the matching grease.

Array waveguide diffraction grating type optical multiplexer/demultiprexer

PROBLEM TO BE SOLVED: To provide an array waveguide diffraction grating type optical coupling/branching device in which the width of 1 dB band is large, an optical loss is small and deterioration of adjacent crosstalk and background crosstalk is controlled. SOLUTION: A waveguide forming part 10, wherein optical input waveguides 12, a first slab waveguide 13, an array waveguide 14 in which a plurality of channel waveguides 14a having mutually different wavelength setting quantities are juxtaposed, a second slab waveguide 15 and a plurality of juxtaposed optical output waveguides 16 are connected in order, is formed on a substrate 11. Trapezoidal waveguides 5 the widths of which are enlarged as they advance to the side of the array waveguide 14 are provided in the exit side of at least one or more optical input waveguides 12. The width of upper bottom 4 of the trapezoidal waveguides 5 is wider than the width of the optical input waveguide 12 and meets a single mode condition.

Kazutaka Nara

Papers

Manufacturing method for an optical waveguide

Array waveguide raster optical multiplying device and de-multiplying device

Array waveguide type diffraction grating

Array waveguide diffraction grating type optical multiplexer/demultiprexer

Array waveguide diffraction grating type optical coupling/branching device and optical waveguide circuit