GB2384320A - Arrayed waveguide grating having opposing waveguide halves - Google Patents
Arrayed waveguide grating having opposing waveguide halves Download PDFInfo
- Publication number
- GB2384320A GB2384320A GB0201263A GB0201263A GB2384320A GB 2384320 A GB2384320 A GB 2384320A GB 0201263 A GB0201263 A GB 0201263A GB 0201263 A GB0201263 A GB 0201263A GB 2384320 A GB2384320 A GB 2384320A
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- United Kingdom
- Prior art keywords
- waveguide grating
- array waveguide
- array
- designs
- symmetrical
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/12007—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer
- G02B6/12009—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides
- G02B6/12011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind forming wavelength selective elements, e.g. multiplexer, demultiplexer comprising arrayed waveguide grating [AWG] devices, i.e. with a phased array of waveguides characterised by the arrayed waveguides, e.g. comprising a filled groove in the array section
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
Abstract
An arrayed waveguide grating 24 has an input side 20 and an output side 28 respectively corresponding in waveguide configuration to opposingly orientated halves 38, 40 of first and second symmetrical array waveguide grating designs 30, 32. The array waveguide grating designs 30, 32 have different relatively high orders but common waveguide configuration along their halfway lines 34, 36. The arrayed waveguide grating 24 may be part of a multiplexer or demultiplexer device having input star coupler 22 and output star coupler 26. The waveguides of the array 24 may also be in the form silicon rib waveguides. In other embodiments a method of designing, and a method of operating a computer to design, an arrayed waveguide grating 24 is disclosed.
Description
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ARRAY WAVEGUIDE GRATING
The present invention relates to an array waveguide grating, a method of designing an array waveguide grating, and to optical devices based on an array waveguide grating.
Array waveguide gratings (AWG) are well-known devices for inducing controlled phase differences between portions of an input optic signal, and have use in optic devices such as demultiplexers and multiplexers. One parameter of an AWG is its diffraction order, m which is defined by m = nAL/, o, where n is the refractive index of the array waveguides, AL is the path length difference of the array waveguides, and Ao is the centre wavelength.
Standard AWGs typically have a symmetrical design as shown in Figure 1.
This design is generally considered as acceptable for relatively high order arrays, but as the diffraction order is reduced, the increasingly low array turn angle makes it increasingly difficult to use such a design whilst maintaining sufficient spacing between consecutive waveguides at a middle portion of the array, which is generally necessary to optimise the performance characteristics of the AWG.
US5212758 and US5943452 describe relative complex designs for low order AWGs.
It is an aim of the present invention to provide an alternative AWG design that can be used to create relatively low order arrays.
According to a first aspect of the present invention, there is provided a method of designing a relatively low order array waveguide grating, the method including the steps of : using as a basis first and second symmetrical array waveguide grating designs having different, relatively high orders but common,
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symmetrical waveguide configurations along their half-way lines, and combining respective halves of said first and second array waveguide grating designs in opposing orientations so as to create an array waveguide grating of relatively low order.
According to another aspect of the present invention, there is provided a method of designing an array waveguide grating having a relatively low diffraction order n, using as a basis first and second symmetrical array waveguide grating designs having relatively high orders separated by 2n, but common, symmetrical waveguide configurations along their half-way lines, and combining respective halves of said first and second array waveguide grating designs in opposing orientations.
According to another aspect of the present invention, there is provided a method of making an array waveguide grating including producing on a substrate an array of waveguides according to a design produced in accordance with the above design methods.
According to another aspect of the present invention, there is provided an array waveguide grating having an input side and an output side respectively corresponding in waveguide configuration to opposingly orientated halves of first and second symmetrical array waveguide grating designs having different, relatively high orders but common, symmetrical waveguide configurations along their half-way lines.
According to another aspect of the present invention, there is provided a method of operating a computer to design an array waveguide grating having a relatively low diffraction order n, the method comprising the steps of : storing in a memory of the computer data for generating a plurality of symmetrical array waveguide grating designs; and inputting at a user interface parameters for selecting first and second array waveguide grating symmetric
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designs having common, symmetrical waveguide configurations along their half-way lines but having different orders separated by 2n; wherein the computer is operable to generate said first and second array waveguide grating designs and to combine respective halves of said first and second array waveguide grating designs in opposing orientations to generate an array waveguide design having a relatively low diffraction order n.
The reference to symmetrical array waveguide grating (AWG) designs does not exclude AWG designs that include minor asymmetries resulting from features, such as tapers at the ends of the array waveguides, that do not substantially affect the path length of each waveguide.
In one embodiment, each of the first and second array waveguide grating designs are characterised in having a centre portion in which the waveguides are parallel, and in that the distance between each waveguide in the central portion is constant.
According to another aspect of the present invention, there is also provided an optical multiplexer/demultiplexer device including an array waveguide grating as described above.
Embodiments of the present invention are described hereunder, by way of example only, with reference to the accompanying drawings, in which :Figure 1 shows the outline of a standard-type symmetric AWG design; Figure 2 shows a multiplexer/demultiplexer design employing an array waveguide grating according to an embodiment of the present invention; Figure 3 shows how the array waveguide grating of the present invention is designed from parts of standard-type symmetric AWG designs; Figure 4 illustrates the geometry of a symmetric AWG design used in the production of a low diffraction order array waveguide grating according to an embodiment of the present invention; and
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Figure 5 illustrates a computer system for designing a low diffraction order array waveguide grating according to an embodiment of the present invention.
Figure 1 shows the outline of a standard AWG design. Only the configuration of the innermost and outermost waveguides 2,4 and the configuration of the arcs 6,8 linking the input and output ends of the array waveguides are shown for the purpose of explanation. In practice, an AWG would typically comprise a large number of waveguides. The design is symmetrical about the half-way line 12, which is the line linking the half-way points of all the array waveguides.
Figure 2 shows a multiplexer/demultiplexer design employing an array waveguide grating according to the present invention. The multiplexer/demultiplexer consists of input waveguides 20, an input star coupler 22, an array waveguide grating 24, an output star coupler 26 and output waveguides 28. Only three input and output waveguides are shown for the purpose of explanation; in practice, a multiplexer/demultiplexer device would have a greater number of input/output waveguides corresponding to the relatively large number of channels desired in communication systems.
Similarly, the array waveguide grating would also typically comprise more than the eleven waveguides shown in the figure. In one embodiment, each waveguide is a silicon rib waveguide.
In use, a wavelength division multiplexed signal is input into one of the input waveguides, and the component channels are each output via a respective output waveguide. The effect of optical reciprocity means that the device can also be used in reverse as a multiplexer. Each channel is input into a respective one of the"output"waveguides for common collection as a wavelengthmultiplexed signal in one of the input waveguides.
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Next, the design of the asymmetric AWG shown in Figure 2 shall be described with reference to Figure 3.
A first standard symmetrical AWG design 30 having an order M1, and a second standard symmetrical AWG design 32 having a different order M2 are selected.
The two AWG designs are selected to have a common number of waveguides and such that their waveguides are arranged in a common manner along the half-way lines 34,36, the common arrangement being symmetrical about the centre point of the half-way line. This can be achieved in one embodiment by selecting first and second AWG designs in which the distance between adjacent waveguides along the respective half-way line is a common constant.
Next, as shown in Figure 3, a half 38 of the first AWG design is combined with a half 40 of the second AWG design about their half-way lines in opposite orientations of curvature, i. e. with the longest array waveguide of the first AWG design coupled to the shortest array waveguide and increasingly shorter array waveguides of the first AWG design coupled to increasingly longer array waveguides of the second AWG design.
The resulting asymmetric AWG has an order M equal to the magnitude of (MI/2 - M2/2). Clearly, the orders of the first and second AWG designs have to be separated by a multiple of 2. For example, if the first AWG design has an order of 50 and the second AWG design has an order of 30, the resulting AWG design has a relatively low order of 10.
In one embodiment, each of the array waveguides of the first and second standard AWG designs includes in the stated order a first straight portion, a first intermediate bend portion, a second straight portion, a second bend portion and a third straight portion, with the second straight (central) portions arranged in a parallel and equidistant manner, as illustrated in Figure 4 which is discussed in detail below. Each waveguide of the resulting S-shaped AWG
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design includes in the stated order a first straight portion, a first bend portion, a second straight (central) portion, a second intermediate bend portion curved in an opposite direction to the first intermediate bend portion and a third straight portion, each of the second straight (central) portions arranged in a parallel and equidistant manner.
An example of a technique for designing such first and second standard symmetric AWG designs with a common distance between adjacent waveguides at the axis of symmetry is described below with reference to Figure 4, which illustrates the geometry of a symmetric AWG design. Only one half of the symmetric AWG design is illustrated in Figure 4; the other half is a mirror image of the half shown about the axis of symmetry.
In Figure 4, - Re is the Rowland circle length (set by the designer).
- be is the angular separation between two consecutive waveguides at the Rowland circle (set by the designer).
- (D is turn angle of the bend on the centre axis of the array, i. e,
Waveguide 0 in the case of an even number of waveguides in the array (set by the designer).
- eN is the angle between the centre axis of the array at the origin"0" and the direction of any waveguide"N"from the origin"0" (calculated).
- Ro is the radius of the bend on the centre axis of the array (set by the designer).
- RN is the radius of the bend for any waveguide"N" (calculated).
- SAo is the length of the straight from the origin"0"to the start of the bend on the centre axis of the array. This length includes the Rowland circle length Rc and the length from the Rowland circle mounting to the start of the bend on the centre axis (set by the designer).
- SAN is the length of the straight from the origin"0"to the start of the bend of any waveguide"N" (calculated).
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- SBo is the length of the straight from the end of the bend to the axis of symmetry on the centre axis of the array (set by the designer).
- SBN is the length of the straight from the end of the bend to the axis of symmetry for any waveguide"N" (calculated).
- AP is the constant separation between two consecutive waveguides on the axis of symmetry (set by the designer).
- PN (XPN, YPN) represents the point of intersection between any waveguide"N"and the axis of symmetry.
- AL (not shown on the figure) is defined as the path length difference between two consecutive waveguides in the full array (set by the designer).
As indicated above, Rc, 88, (D, Ro, SAo, SBo, AP, AL are set by the designer for each of the two symmetric AWG designs, with an identical AP set for both of the two AWG designs and differing AL set for the two symmetric AWG designs according to the diffraction order required for the product AWG. ON
and PN (XPN, YPN) are calculable from the above, and RN, SAN and SBN calculable as follows :
(L-YPj. (cose-a+ (XP-L-aJ- (sm-) ) (Cos (cos < l)-aN). (sme-p + (+sm0). (coseN -aN) (XPN -LN-aN) +SBN. (a-cosC) CON------------- N cosOj-a R- N-SAN-SBN (D + ON Sinq) + sine ., cosC-cosQ., where, < t,'"" L,, =SA, +SB. +t. R. +N 2 The above-described design process can be carried out using a computer. With reference to Figure 5, the memory of a computer 100 is loaded with data for
<Desc/Clms Page number 8>
generating first and second symmetrical AWG designs having differing orders but common, symmetrical waveguide configurations along their half-way lines according to parameters set by the designer. This data could, for example,
include, the equations for calculating PN (XPN, YPN), RN, SAN and SBN in the geometry shown in Figure 4. The parameters set by the designer, such as Rc, 6, C, Ro, SAo, SBo, AP and AL in the example above, are input at a user interface such as a keyboard 102. The computer generates the two symmetric AWG designs according to the data stored in its memory and the parameters input via the keyboard, and generates a low diffraction order AWG design based on the two symmetric designs according to a program for doing so also pre-stored in its memory. The computer displays the generated low diffraction order AWG design on a screen 104 connected to the computer.
Claims (13)
1. An array waveguide grating having an input side and an output side respectively corresponding in waveguide configuration to opposingly orientated halves of first and second symmetrical array waveguide grating designs having different, relatively high orders but common, symmetrical waveguide configurations along their half-way lines.
2. An array waveguide grating according to claim 1 wherein each of the first and second array waveguide grating designs is characterised in having a centre portion in which the waveguides of the respective grating are parallel.
3. A device according to claim 1 or claim 2 wherein each of the first and second array waveguide grating designs is characterised in that the distance between each waveguide at the respective half-way line is constant.
4. An array waveguide grating according to any preceding claim wherein each waveguide of the array is a silicon rib waveguide.
5. An optical multiplexer device including an array waveguide grating according to any preceding claim.
6. An optical demultiplexer device including an array waveguide grating according to any of claims 1 to 4.
7. A method of making an array waveguide grating including the steps of : using as a basis first and second symmetrical array waveguide grating designs having different, relatively high orders but common, symmetrical waveguide configurations along their half-way lines, combining respective halves of said first and second array waveguide grating designs in opposing orientations so as to create an array waveguide grating design of relatively low order ; and
<Desc/Clms Page number 10>
producing on a substrate an array of waveguides according to said array waveguide grating design of relatively low order.
8. A method of designing a relatively low order array waveguide grating, the method including the steps of : using as a basis first and second symmetrical array waveguide grating designs having different, relatively high orders but common, symmetrical waveguide configurations along their half-way lines, and combining respective halves of said first and second array waveguide grating designs in opposing orientations so as to create an array waveguide grating of relatively low order.
9. A method according to claim 8 wherein each of the first and second array waveguide grating designs is characterised in having a centre portion in which the waveguides of the respective grating are parallel.
10. A method according to claim 8 or claim 9 wherein each of the first and second array waveguide grating designs is characterised in that the distance between each waveguide at the respective half-way line is constant.
11. A method of designing an array waveguide grating having a relatively low diffraction order n, the method including the steps of : using as a basis first and second symmetrical array waveguide grating designs having relatively high orders separated by 2n, but common, symmetrical waveguide configurations along their half-way lines, and combining respective halves of said first and second array waveguide grating designs in opposing orientations.
12. A method of operating a computer to design an array waveguide grating having a relatively low diffraction order n, the method comprising the steps of : storing in a memory of the computer data for generating a plurality of symmetrical array waveguide grating designs ; and
<Desc/Clms Page number 11>
inputting at a user interface parameters for selecting first and second array waveguide grating symmetric designs having common, symmetrical waveguide configurations along their half-way lines but having different orders separated by 2n ; wherein the computer is operable to generate said first and second array waveguide grating designs and to combine respective halves of said first and second array waveguide grating designs in opposing orientations to generate an array waveguide design having a relatively low diffraction order n.
13. A method of operating a computer according to claim 12, wherein the computer is operable to display the array waveguide design having a relatively low diffraction order n on a screen.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0201263A GB2384320A (en) | 2002-01-21 | 2002-01-21 | Arrayed waveguide grating having opposing waveguide halves |
| PCT/GB2003/000176 WO2003062888A2 (en) | 2002-01-21 | 2003-01-20 | Array waveguide grating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0201263A GB2384320A (en) | 2002-01-21 | 2002-01-21 | Arrayed waveguide grating having opposing waveguide halves |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0201263D0 GB0201263D0 (en) | 2002-03-06 |
| GB2384320A true GB2384320A (en) | 2003-07-23 |
Family
ID=9929418
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0201263A Withdrawn GB2384320A (en) | 2002-01-21 | 2002-01-21 | Arrayed waveguide grating having opposing waveguide halves |
Country Status (2)
| Country | Link |
|---|---|
| GB (1) | GB2384320A (en) |
| WO (1) | WO2003062888A2 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004083922A1 (en) * | 2003-03-21 | 2004-09-30 | Ignis Technologies As | Optical muliplexer based on arrayed waveguide grating |
| WO2009108757A1 (en) * | 2008-02-28 | 2009-09-03 | Cisparie Group Limited Liability Company | Improved waveguide grating optical router suitable for cwdm |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5212758A (en) * | 1992-04-10 | 1993-05-18 | At&T Bell Laboratories | Planar lens and low order array multiplexer |
| US5943452A (en) * | 1996-08-06 | 1999-08-24 | Nippon Telegraph And Telephone Corporation | Arrayed-waveguide grating |
| GB2362722A (en) * | 1999-12-09 | 2001-11-28 | Hitachi Cable | Array waveguide grating and method of manufacture thereof |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2772145B1 (en) * | 1997-12-08 | 2003-06-27 | France Telecom | GUIDE NETWORK SPECTROGRAPH TYPE OPTICAL COMPONENT WITH CENTER OUTPUT CHANNELS |
| US6219471B1 (en) * | 1999-01-15 | 2001-04-17 | Lucent Technologies Inc. | Optical device having equal length waveguide paths |
| GB2361073B (en) * | 2000-04-05 | 2003-08-06 | Bookham Technology Ltd | Dispersive optical waveguide array device |
-
2002
- 2002-01-21 GB GB0201263A patent/GB2384320A/en not_active Withdrawn
-
2003
- 2003-01-20 WO PCT/GB2003/000176 patent/WO2003062888A2/en not_active Application Discontinuation
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5212758A (en) * | 1992-04-10 | 1993-05-18 | At&T Bell Laboratories | Planar lens and low order array multiplexer |
| US5943452A (en) * | 1996-08-06 | 1999-08-24 | Nippon Telegraph And Telephone Corporation | Arrayed-waveguide grating |
| GB2362722A (en) * | 1999-12-09 | 2001-11-28 | Hitachi Cable | Array waveguide grating and method of manufacture thereof |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2004083922A1 (en) * | 2003-03-21 | 2004-09-30 | Ignis Technologies As | Optical muliplexer based on arrayed waveguide grating |
| WO2009108757A1 (en) * | 2008-02-28 | 2009-09-03 | Cisparie Group Limited Liability Company | Improved waveguide grating optical router suitable for cwdm |
| US7702200B2 (en) * | 2008-02-28 | 2010-04-20 | Corrado Pietro Dragone | Waveguide grating optical router suitable for CWDM |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0201263D0 (en) | 2002-03-06 |
| WO2003062888A2 (en) | 2003-07-31 |
| WO2003062888A3 (en) | 2003-12-18 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |