U.S. patent application number 11/802579 was filed with the patent office on 2008-04-17 for arrayed waveguide grating device.
This patent application is currently assigned to Way-Seen Wang. Invention is credited to Hung-Chih Lu.
Application Number | 20080089646 11/802579 |
Document ID | / |
Family ID | 37012655 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080089646 |
Kind Code |
A1 |
Lu; Hung-Chih |
April 17, 2008 |
Arrayed waveguide grating device
Abstract
A grating device has a waveguide array cyclically arranged. A
horned waveguide is used in a star coupler of the grating device.
An optical signal is divided into streams. The streams are slanted
from original central axes. Or, a waveguide having an asymmetrical
structure is used. Thus, a flat-top pass-band of the optical signal
is obtained. The present invention can be used in any optical
device.
Inventors: |
Lu; Hung-Chih; (Guanyin
Township, TW) |
Correspondence
Address: |
TROXELL LAW OFFICE PLLC
5205 LEESBURG PIKE, SUITE 1404
FALLS CHURCH
VA
22041
US
|
Assignee: |
Wang; Way-Seen
Taipei
TW
|
Family ID: |
37012655 |
Appl. No.: |
11/802579 |
Filed: |
May 23, 2007 |
Current U.S.
Class: |
385/37 |
Current CPC
Class: |
G02B 6/12019 20130101;
G02B 6/266 20130101; G02B 6/12016 20130101 |
Class at
Publication: |
385/037 |
International
Class: |
G02B 6/34 20060101
G02B006/34 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 1, 2004 |
TW |
093215564 |
Claims
1. A cyclic arrayed waveguide grating device using a horned
waveguide, comprising: a first star coupler, said first star
coupler obtaining streams of an optical signal; a waveguide array,
said waveguide array obtaining said streams of said optical signal
having a phase difference between each two neighboring streams; a
second star coupler, said second star coupler transmitting streams
of said optical signal having various wavelengths; and a horned
waveguide, wherein said cyclic arrayed waveguide grating device
using said horned waveguide obtains a flat-top pass-band of said
optical signal through said first star coupler and said second star
coupler coordinated with said horned waveguide.
2. The waveguide grating device according to claim 1, wherein said
first star coupler comprises: a waveguide input, said waveguide
input inputting said optical signal at a first end of said
waveguide input; and a first slab waveguide, said first slab
waveguide being connected with a second end of said waveguide input
at a first end of said first slab waveguide, said first slab
waveguide being connected with first ends of said waveguide array
at second ends of said first slab waveguide, said first slab
waveguide obtaining and transmitting said streams of said optical
signal.
3. The waveguide grating device according to claim 1, wherein said
optical signal has a number of waveguides not less than one.
4. The waveguide grating device according to claim 1, wherein said
waveguide array comprises a plurality of arrayed single-mode
waveguides; and wherein each two neighboring single-mode waveguides
have a length difference.
5. The waveguide grating device according to claim 1, wherein said
second star coupler comprises: a second slab waveguide, said second
slab waveguide being connected with second ends of said waveguide
array at first ends of said slab waveguide to obtain interferential
focuses of said streams of said optical signal having various
wavelengths; and waveguide outputs, said waveguide outputs being
connected with second ends of said second slab waveguide, said
waveguide outputs having said streams of said optical signal having
various wavelengths coupled into various output ends.
6. The waveguide grating device according to claim 1, wherein said
horned waveguide is located between a waveguide input of said first
star coupler and a first slab waveguide of said first star coupler;
and wherein said flat-top pass-band of said optical signal is
obtained through a plurality of compensating central axes of a
plurality of waveguide outputs of said second star coupler
coordinated with said horned waveguide
7. The waveguide grating device according to claim 1, wherein a
plurality of said horned waveguides is located between a second
slab waveguide of said second star coupler and a plurality of
waveguide outputs of said second star coupler; wherein said
flat-top pass-band of said optical signal is obtained by a
complementary asymmetrical two-peak light-field distribution
through compensating central axes of said plurality of waveguide
outputs of said second star coupler coordinated with said horned
waveguide.
8. The waveguide grating device according to claim 1, wherein a
plurality of said horned waveguides is located between a second
slab waveguide of said second star coupler and a plurality of
waveguide outputs of said second star coupler; wherein said
flat-top pass-band of said optical signal is obtained by an
asymmetrical structure of said plurality of waveguide outputs
through a complementary asymmetrical two-peak light-field
distribution coordinated with said horned waveguide.
9. The waveguide grating device according to claim 1, wherein said
horned waveguide has an end of said horned waveguide wider than the
other end of said horned waveguide.
10. The waveguide grating device according to claim 1, wherein said
horned waveguide has a shape selected from a group consisting of a
functional shape a trigonometric-functional shape, a convex-curved
shape, a tapered shape, a tapered-and-straight mixed shape, a
two-sectional tapered shape, a three-sectional tapered shape, a
tapered-and-convex-curved mixed shape, a
taper-and-multimode-interference-structure mixed shape, a multimode
interference structure shape, a directional coupler shape, a
tapered directional coupler shape, a convex-curved taper type
directional coupler shape, a Y branch's shape, a channel waveguide
type branch's shape, a convex-curved taper type branch's shape, a
taper and channel waveguide type branch's shape, a tapered
multimode interference structure shape, a trigonometric-functional
multimode interference structure shape, a convex-curved multimode
interference structure shape, a concave-curved multimode
interference structure shape, a two-sectional taper type concave
multimode interference structure shape, a two-sectional taper type
convex multimode interference structure shape, a two-sectional
curved taper type convex multimode interference structure shape and
a three waveguide type directional coupler shape.
11. The waveguide grating device according to claim 5, wherein,
after said streams of said optical signal are transmitted into said
second slab waveguide, multi-slit interferences are obtained at
first and then constructive interferences are obtained at front
ends of said second slab waveguide.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to an arrayed waveguide
grating device; more particularly, relates to using compensating
central axes or a waveguide having an asymmetrical structure
coordinated with a horned waveguide to obtain a flat-top pass-band
of an optical signal.
DESCRIPTION OF THE RELATED ARTS
[0002] A traditional arrayed waveguide grating device has its
waveguide array and waveguide outputs set along central axes. But,
for a traditional cyclic arrayed waveguide grating device, such an
arrangement produces a non-flat-top pass-band.
[0003] As shown in FIG. 7A and FIG. 7B, a traditional cyclic
arrayed waveguide grating device comprises a first star coupler 61,
a waveguide array 62 and a second star coupler 63. An optical
signal is inputted from a waveguide input 611. After passing
through a first slab waveguide 612, a light field of the inputted
optical signal is scattered and is coupled into the waveguide array
62. Then the optical signal is passed through a second slab
waveguide 631 with multi-slit interferences and is coupled to
waveguide outputs 632 in the end. Because the inputted optical
signal comprises various wavelengths, optical path differences are
different and streams of the optical signal are focused and coupled
to different positions of waveguide outputs 632 after the optical
signals pass through the waveguide array. Thus, streams of the
optical signal having different wavelengths are divided. Owing to
free spectral range (FSR), the cyclic arrayed waveguide grating
device is characterized in a cyclic pass-band with a 3 dB
unevenness in the pass-band distributed as a Gaussian function
curve, as shown in FIG. 8. To deal with this 3 dB unevenness in the
pass-band for a system, optical attenuators are linked after the
waveguide outputs to obtain even optical powers. Yet, in actual
practices, a laser light source having high accurate wavelengths is
demanded; and thus, a cost for fabricating such a system becomes
high.
[0004] In the other hand, there are still some other prior arts for
obtaining a flat-top pass-band, which are grouped into two
categories: one is to put a horned waveguide 7 between the
waveguide input 611 and the first slab waveguide 612, as shown in
FIG. 9A and FIG. 9B; and, the other is to put the horned waveguide
7 between the second slab waveguide 631 and the waveguide outputs
632, as shown in FIG. 10A and FIG. 10B. And the waveguide array 62
and the waveguide outputs 632 are put along a central axis 8 to
obtain the same coupling efficiency between the waveguide outputs
632 and the second slab waveguide 631. However, owing to the 3 dB
unevenness in the pass-band, the pass-band in the outer channel of
the waveguide outputs 632 is deformed, as shown in FIG. 11; thus,
all prior arts for obtaining a flat-top pass-band become useless to
the cyclic arrayed waveguide grating device.
[0005] A prior art to deal with the 3 dB unevenness is revealed,
where an optical coupling loss is generated to uniform the
pass-band through slanting from original central axes 8. Because
the channels closer to the center of the cyclic arrayed waveguide
grating device have a stronger optical power, a bigger optical
coupling loss is required and hence an angle required for slanting
from the original central axis 8 is bigger. On the contrary, an
outer channel have a weaker optical power and hence a smaller angle
is required for slanting from the original central axis 8. In this
way, the pass-band may become even. However, the 3 dB unevenness in
the pass-band can be also made even through using optical
attenuators. The core issue is not to even the pass-band but to
make it flat-top. Furthermore, the prior art can only even the
pass-band, but the deformation of the flat-top pass-band cannot be
modified by this prior art.
[0006] Another prior art is to deal with pass-band deformation
through general horned waveguides as compensating waveguides by
replacing outer waveguides. It is because pass-band at the outer
side of a cyclic arrayed waveguide grating has a more serious
deformation. So, the outer pass-band is deformed to solve the
problem. Yet, this method solves the problem with the outer
pass-band only, but not the inner pass-band, which is a partial
compensation. On the contrary, the present invention uses horned
waveguides having an asymmetrical structure, coordinated with a
central compensating axis, to compensate the whole pass-band. Thus,
the present invention is a complete compensation, totally different
from the prior arts. Hence, the prior arts do not fulfill all
users' requests on actual use.
SUMMARY OF THE INVENTION
[0007] The main purpose of the present invention is to provide a
cyclic arrayed waveguide grating device having a flat-top
pass-band.
[0008] To achieve the above purpose, the present invention is a
cyclic arrayed waveguide grating device using a horned waveguide,
comprising a first star coupler, a waveguide array, a second star
coupler and a horned waveguide, where an optical signal inputted
from a waveguide input of the first star coupler is directed to a
first slab waveguide of the first star coupler for obtaining
streams of the optical signal; the waveguide array comprises a
plurality of single-mode waveguides to obtain a fixed phase
difference of streams of the optical signal between each two
neighboring single-mode waveguides; the second star coupler is
connected at a rear end of the waveguide array to obtain
interferential focuses of the streams at a front end of a second
slab waveguide of the second star coupler to be coupled into
waveguide outputs of the second star coupler for dividing streams
of the optical signal having different wavelengths; the horned
waveguide is located between the waveguide input and the first slab
waveguide or between the second slab waveguide and the waveguide
outputs; and, thus, a flat-top pass-band of the optical signal is
obtained through compensating central axes or a waveguide having an
asymmetrical structure coordinated with a horned waveguide.
Accordingly, a novel cyclic arrayed waveguide grating device using
a horned waveguide is obtained.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The present invention will be better understood from the
following detailed descriptions of the preferred embodiments
according to the present invention, taken in conjunction with the
accompanying drawings, in which
[0010] FIG. 1 is the view showing the present invention;
[0011] FIG. 2A and FIG. 2B are the views showing the first
preferred embodiment of the first star coupler and the second star
coupler;
[0012] FIG. 3A and FIG. 3B are the views showing the second
preferred embodiment of the first star coupler and the second star
coupler;
[0013] FIG. 4A and FIG. 4B are the views showing the third
preferred embodiment of the first star coupler and the second star
coupler;
[0014] FIG. 5 is the view showing the spectrum of the optical
signal outputted;
[0015] FIG. 6A to FIG. 6Y are the views showing the preferred
shapes of the horned waveguides;
[0016] FIG. 7A and FIG. 7B are the views of the first star coupler
and the second star coupler of the first prior art;
[0017] FIG. 8 is the spectrum view of the first prior art;
[0018] FIG. 9A and FIG. 9B are the views of the first star coupler
and the second star coupler of the second prior art;
[0019] FIG. 10A and FIG. 10B are the views of the first star
coupler and the second star coupler of the third prior art;
[0020] FIG. 11 is the spectrum view of the second and the third
prior arts.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0021] The following descriptions of the preferred embodiments are
provided to understand the features and the structures of the
present invention.
[0022] Please refer to FIG. 1 which is the view showing the present
invention. As shown in the figure, the present invention is a
cyclic arrayed waveguide grating device 1 using a horned waveguide,
comprising a first star coupler 11, a waveguide array 12, a second
star coupler 13 and a horned waveguide 2, where an optical signal 3
is divided into a plurality of streams to be slanted from original
central axes, or a waveguide having an asymmetrical structure is
used, for obtaining a flat-top pass-band of the optical signal 3
with the horned waveguide 2.
[0023] The first star coupler 11 comprises a waveguide input 111
and a first slab waveguide 112, where the optical signal 3 is
directed from the waveguide input 111 and is transmitted to the
first slab waveguide 112 to be divided into a plurality of streams.
The waveguide array 12 comprises a plurality of single-mode
waveguides serially arranged to obtain a certain phase difference
between each two streams of the optical signal 3 transmitted in two
neighboring single-mode waveguides. The second star coupler 13
comprises a second slab waveguide 131 and waveguide outputs 132,
where the second star coupler 13 is connected with the waveguide
array 12; and interferential focuses of the streams of the optical
signal 3 are obtained at front ends of the second slab waveguide
131 to be coupled into waveguide outputs 132 for dividing various
wavelengths of the optical signal 3.
[0024] The horned waveguide 2 is located between the waveguide
input 111 and the first slab waveguide 112, or between the second
slab waveguide 131 and the waveguide outputs 132, coordinated with
compensating central axes or with a waveguide having an
asymmetrical structure to modify the pass-band of the optical
signal. Thus, a novel cyclic arrayed waveguide grating device using
a horned waveguide is obtained.
[0025] When using the present invention, the optical signal 3
having a number of waveguide more than one is directed from the
waveguide input 111 into the first slab waveguide 112. Then the
light field of the optical signal 3 is scattered to be coupled into
the waveguide array 12 connected at rear ends of the first slab
waveguide 112. Because the waveguide array 12 comprises a plurality
of serially arranged single-mode waveguides and each two
neighboring waveguides has a fixed length difference, a fixed phase
difference on transmitting a light field in the waveguide array 12
is obtained. Then the light field having the fixed phase difference
is transmitted to the second slab waveguide 131 connected at a rear
end of the waveguide array 12 for obtaining multi-slit
interferences. Then, on a curved surface at a front end of the
second slab waveguide 131, owing to various wavelengths,
constructive interferences are obtained at various positions. And
then the wavelengths are coupled into waveguide outputs 132
connected at a rear end of the second slab waveguide 131 to be
outputted from different output ends.
[0026] The present invention make the streams of the optical signal
3 slanted from the original central axes, or uses a waveguide
having an asymmetrical structure, to modify the pass-band of the
optical signal 3 coordinated with the horned waveguide 2. On
slanting the streams of the optical signal 3 from the original
central axes, the streams of the optical signal 3 transmitted at
channels near center of the second star coupler 13 has a smaller
deformation on the pass-band and thus the slanting angle is
smaller. On the contrary, the streams of the optical signal 3
transmitted at outer channels has a bigger deformation and thus the
slanting angle is bigger. In the other case, when a waveguide
having an asymmetrical structure, the streams of the optical signal
3 transmitted at channels near center of the second star coupler 13
has a smaller deformation on the pass-band and thus the asymmetry
is smaller. On the contrary the streams of the optical signal 3
transmitted at outer channels has a bigger deformation and thus the
asymmetry is bigger. Therefore, a flat-top pass-band of the optical
signal 3 is obtained coordinated with the horned waveguide 2.
[0027] Please refer to FIG. 2A to FIG. 5, which are views showing a
first, a second and a third preferred embodiments of a first star
coupler and a second star coupler; and a view showing a spectrum of
an optical signal outputted. As shown in FIG. 2A and FIG. 2B, to
obtain a flat-top pass-band of an optical signal 3, a horned wave
guide 2 is located between a waveguide input 111 and a first slab
waveguide 112 to obtain a two-peak light-field distribution. Then
the original central axes 5 are slanted to compensating central
axes 5a, where the slanting angles of the compensating central axes
near center of the second star coupler 13 is smaller; and, the
farther the bigger. Thus, the flat-top pass-band is obtained.
[0028] As shown in FIG. 3A and FIG. 3B, to obtain a flat-top
pass-band of an optical signal 3, a plurality of the horned
waveguides 2 are located between a second slab waveguide 131 and
waveguide outputs 132 to obtain a two-peak light-field
distribution. Then the original central axes 5 are slanted to
compensating central axes 5a, where the compensating central axes
near center of the second star coupler 13 have smaller slanting
angles; and, the farther the compensating central axes, the bigger.
Thus, the flat-top pass-band is obtained through a complementary
asymmetrical two-peak light-field distribution.
[0029] As shown in FIG. 4A and FIG. 4B, to obtain the flat-top
pass-band of the optical signal 3, a plurality of the horned
waveguides 2 are located between the second slab waveguide 131 and
the waveguide outputs 132 to obtain the two-peak light-field
distribution, where the waveguide outputs 132 has an asymmetrical
structure. The asymmetry near center of the second star coupler 13
is smaller; and, the farther, bigger. Thus, the flat-top pass-band
is obtained through a complementary asymmetrical two-peak
light-field distribution.
[0030] From a spectrum view of the present invention, as shown in
FIG. 5, the flat-top pass-band is obtained to show that the present
invention is a novel cyclic arrayed waveguide grating device using
a horned waveguide for obtaining a flat-top pass-band.
[0031] Please refer to FIG. 6A to FIG. 6Y, which are views showing
preferred shapes of horned waveguides. As shown in the figures, the
horned waveguides 2a.about.2y are waveguides having narrow front
ends 21 and wider rear ends 22 and further having a functional
shape, a trigonometric-functional shape, a convex-curved shape, a
tapered shape, a tapered-and-straight mixed shape, a two-sectional
tapered shape, a three-sectional tapered shape, a
tapered-and-convex-curved mixed shape, a
taper-and-multimode-interference-structure mixed shape, a multimode
interference structure shape, a directional coupler shape, a
tapered directional coupler shape, a convex-curved taper type
directional coupler shape, a Y branch's shape, a channel waveguide
type branch's shape, a convex-curved taper type branch's shape, a
taper and channel waveguide type branch's shape, a tapered
multimode interference structure shape, a trigonometric-functional
multimode interference structure shape, a convex-curved multimode
interference structure shape, a concave-curved multimode
interference structure shape, a two-sectional taper type concave
multimode interference structure shape, a two-sectional taper type
convex multimode interference structure shape, a two-sectional
curved taper type convex multimode interference structure shape or
a three waveguide type directional coupler shape. Thus, the present
invention is a cyclic arrayed waveguide grating device using a
horned waveguide 2a.about.2y for obtaining a flat-top
pass-band.
[0032] To sum up, the present invention is a cyclic arrayed
waveguide grating device using a horned waveguide, where streams of
an optical signal is slanted from original central axes, or a
waveguide having an asymmetrical structure is used, to obtain a
flat-top pass-band coordinated with a horned waveguide.
[0033] The preferred embodiments herein disclosed are not intended
to unnecessarily limit the scope of the invention. Therefore,
simple modifications or variations belonging to the equivalent of
the scope of the claims and the instructions disclosed herein for a
patent are all within the scope of the present invention.
* * * * *