Optical waveguides – With optical coupler – Plural
Reexamination Certificate
2001-08-23
2003-11-04
Lee, John D. (Department: 2874)
Optical waveguides
With optical coupler
Plural
C385S037000, C385S046000
Reexamination Certificate
active
06643427
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wavelength multiplexer/demultiplexer for spatial combination of or split into selected wavelengths, and in particular, to a waveguide-arrayed optical wavelength multiplexer/demultiplexer, and to a manufacturing method of the same.
2. Prior Art
FIG.
1
A and
FIG. 1B
show a conventional waveguide-arrayed optical wavelength multiplexer/demultiplexer using an AWG (arrayed waveguide grating), which has, on a substrate
1
thereof: a plurality of input waveguides
2
for inputting wavelength division multiplexed optical signals; an output waveguide
3
for combining the wagelength division multiplexed optical signals to be output; a waveguide array
5
constituted with a plurality of arrayed waveguides
5
b
having predetermined waveguide length differences &Dgr;L; an input waveguide slab
4
for interconnecting the plurality of input waveguides
2
and the waveguide array
5
, and an output waveguide slab
7
for interconnecting the waveguide array
5
and the output waveguide
3
.
In this conventional waveguide-arrayed optical wavelength multiplexer/demultiplexer, incident light from the input waveguides
2
enters the input waveguide slab
4
, where it radiates, to be coupled to the waveguide array
5
. However, the mode of optical transmission is different in configuration between an output part
4
A of the waveguide slab
4
and input parts
5
A of the waveguide array
5
, such that all the incident light is not coupled, thus resulting in a coupling loss.
FIG.
2
A and
FIG. 2B
show another conventional waveguide-arrayed optical wavelength multiplexer/demultiplexer, in which a waveguide array
5
has narrowed distances L between arrayed waveguides
5
b
, whereby the mode of optical transmission between a waveguide slab output part
4
A and waveguide array input parts
5
A is devised to be matching in configuration, thereby implementing a reduction of loss in the wavelength multiplexer/demultiplexer using an AWG.
However, this conventional waveguide-arrayed optical wavelength multiplexer/demultiplexer has at the waveguide slab output part
4
A an inter-waveguide distance L
1
too narrow for an overclad to be buried thereto without difficulty, as a problem. Failure in burying the overclad would have caused an increased loss.
SUMMARY OF THE INVENTION
The present invention has been made to solve such a problem in the related art. It therefore is an object of the present invention to provide a waveguide-arrayed optical wavelength multiplexer/demultiplexer in which a mode configuration of a waveguide slab output part is matched to a mode configuration of waveguide array input parts, to achieve a reduced loss irrespective of distances between arrayed waveguides, and a manufacturing method of the same.
To achieve the object, according to a first aspect of the invention, there is provided a waveguide-arrayed optical wavelength multiplexer/demultiplexer having, on a base, a plurality of input waveguides for inputting wavelength division multiplexed optical signals, an output waveguide for combining the wagelength division multiplexed optical signals to be output, a waveguide array constituted with a plurality of arrayed waveguides having predetermined waveguide length differences, an input waveguide slab for interconnecting the plurality of input waveguides and the waveguide array, and an output waveguide slab for interconnecting the waveguide array and the output waveguide, wherein one of the input waveguide slab and the output waveguide slab is configured to have an intended refractivity distribution.
According to a second aspect of the invention, in a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the first aspect, the one of the input waveguide_slab and the output waveguide slab is configured with the intended refractivity distribution partially changed by an ultraviolet laser to have an intended refractivity change.
According to a third aspect of the invention, in a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the second aspect, the one of the input waveguide slab and the output waveguide slab is configured to have the intended refractivity distribution and the intended refractivity change by irradiating a portion of the one of the input waveguide slab and the output waveguide slab to be high of refractivity with one of an ArF eximer laser and a KrF eximer laser, subject to a masking over a remainder of the portion of the one of the input waveguide slab and the output waveguide slab.
According to a fourth aspect of the invention, in a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the first aspect, one of the plurality of input waveguides and the output waveguide is configured as a channel waveguide of a single mode with a core formed on the substrate by doping one of Ge, P, and B as a dopant having a photo refractive effect and buried in a clad smaller of refractivity than the core.
According to a fifth aspect of the invention, in a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the first aspect, one of an outpart of the input waveguide slab and an input part of the output waveguide slab is formed with a set of triangular regions higher of refractivity than a remainder thereof.
According to a sixth aspect of the invention, in a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the first aspect, one of an outpart of the input waveguide slab and an input part of the output waveguide slab is formed with a set of rectangular regions higher of refractivity than a remainder thereof.
Further, to achieve the object, according to a seventh aspect of the invention, there is provided a manufacturing method of a waveguide-arrayed optical wavelength multiplexer/demultiplexer having, on a base, a plurality of input waveguides for inputting wavelength division multiplexed optical signals, an output waveguide for combining the wagelength division multiplexed optical signals to be output, a waveguide array constituted with a plurality of arrayed waveguides having predetermined waveguide length differences, an input waveguide slab for interconnecting the plurality of input waveguides and the waveguide array, and an output waveguide slab for interconnecting the waveguide array and the output waveguide, wherein one of the input waveguide slab and the output waveguide slab is configured to have an intended refractivity distribution.
According to an eighth aspect of the invention, in a manufacturing method of a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the seventh aspect, the one of the input waveguide slab and the output waveguide slab is configured with the intended refractivity distribution partially changed by an ultraviolet laser to have an intended refractivity change.
According to a ninth aspect of the invention, in a manufacturing method of a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to the eighth aspect, the one of the input waveguide slab and the output waveguide slab is configured to have the intended refractivity distribution and the intended refractivity change by irradiating a portion of the one of the input waveguide slab and the output waveguide slab to be high of refractivity with one of an ArF eximer laser and a KrF eximer laser, subject to a masking over a remainder of the portion of the one of the input waveguide slab and the output waveguide slab.
According to a tenth aspect of the invention, in a manufacturing method of a waveguide-arrayed optical wavelength multiplexer/demultiplexer according to any of the seventh aspect, one of the plurality of input waveguides and the output waveguide is configured as a channel waveguide of a single mode with a core formed on the substrate by doping one of Ge, P, and B as a dopant having a photo refractive effect and buried in a clad smaller of refractivity than the core.
According to an eleventh aspect of the invention, in a manufacturing method of
Antonelli Terry Stout & Kraus LLP
Hitachi Cable Ltd.
Lee John D.
Lin Tina M
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