CN202614981U - Corrugated type apodization waveguide Bragg grating filter - Google Patents
Corrugated type apodization waveguide Bragg grating filter Download PDFInfo
- Publication number
- CN202614981U CN202614981U CN 201220252086 CN201220252086U CN202614981U CN 202614981 U CN202614981 U CN 202614981U CN 201220252086 CN201220252086 CN 201220252086 CN 201220252086 U CN201220252086 U CN 201220252086U CN 202614981 U CN202614981 U CN 202614981U
- Authority
- CN
- China
- Prior art keywords
- grating
- width
- wave guide
- under
- straight wave
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Optical Integrated Circuits (AREA)
Abstract
The utility model provides a corrugated type apodization waveguide Bragg grating filter including a substrate, a lower cladding, an upper cladding, a straight waveguide, and lower gratings formed by grid strokes. The lower cladding is fixedly connected at the upper surface of the substrate, the lower gratings are fixedly connected at the surface of the straight waveguide, the bottom surface of the straight waveguide is connected to the top surface of the lower cladding, the top surface of the straight waveguide is connected to the bottom surface of the upper cladding, the grid strokes of the lower gratings are bar-shaped, and are parallel to each other, the lower gratings are mutually symmetrical along the vertical center parting line of the straight waveguide, the width of the lower gratings is gradually increased from the two ends to the middle part based on a bell shaped envelope function, and the width of the grid strokes at the end of the lower gratings is less than that of the straight waveguide, the width of the grid strokes at the middle of the lower gratings is greater than that of the straight waveguide, and the width of the straight waveguide is constant. The filter provided achieves the apodization effect with high reflectivity and high side-mode suppression ratio.
Description
Technical field
The utility model relates to a kind of Bragg grating filter, specifically, relates to a kind of pleated and cuts toe waveguide bragg grating wave filter.
Background technology
The waveguide optical grating wave filter is the Primary Component in the wavelength-division multiplex system, has been widely used in waveguide input/output coupler, beam splitter, wave filter, the sensor.Organic polymer because of have loss low, stable and reliability is high, compatible good, cheap, be easy to advantage such as integrated and become the important materials in the integrated optics gradually.Adopt organic polymer material can make designs have bigger dirigibility with making.
The integrated waveguide Bragg grating filter mainly comprises substrate, under-clad layer, top covering, straight wave guide and following grating; Under-clad layer is fixedly connected on the upper surface of substrate; Following grating is fixedly connected on the surface of straight wave guide; And the width of following grating is less than the width of straight wave guide, and the bottom surface of straight wave guide is connected with the end face of under-clad layer, and the end face of straight wave guide is connected with the bottom surface of top covering.The integrated waveguide Bragg grating filter is when being provided with proper parameter; Can obtain high reflectance; But follow the high secondary lobe that also has that high reflectance occurs together, high Bragg grating filter secondary lobe can cause very big crosstalking to adjacent channel in communication system, influence communication quality.If some apodizations with bibliographical information remove the raising side mode suppression ratio with waveguide optical grating wave filter secondary lobe; Part apodization complex process is difficult to realize; And can when improving side mode suppression ratio, suppress the main peak reflectivity, do not reach the requirement of system to high reflectance.Therefore how to guarantee under the big situation of side mode suppression ratio that big degree reduces toe becomes our care to the influence of main peak reflectivity the problem of cutting.
Summary of the invention
Technical matters:The utility model technical matters to be solved is: provide a kind of pleated to cut toe waveguide bragg grating wave filter; Guaranteeing under the big situation of side mode suppression ratio; Reduce significantly and cut the influence of toe the main peak reflectivity, thus reach high reflectance, high side mode suppression ratio cut the toe effect.
Technical scheme:For solving the problems of the technologies described above, the technical scheme that the utility model adopts is:
A kind of pleated is cut toe waveguide bragg grating wave filter, comprises substrate, under-clad layer, top covering, straight wave guide and the following grating of being made up of grid stroke, and under-clad layer is fixedly connected on the upper surface of substrate; Following grating is fixedly connected on the surface of straight wave guide; The bottom surface of straight wave guide is connected with the end face of under-clad layer, and the end face of straight wave guide is connected with the bottom surface of top covering, and the grid stroke in the described grating down is strip; And be parallel to each other between the grid stroke, following grating is symmetrical along the vertical middle separated time of straight wave guide; The width of following grating increases according to bell envelope function from two ends to the centre gradually, and is positioned at the width of the width of the following grid stroke of grating end less than straight wave guide, is positioned at the width of the width of the grid stroke at grating middle part down greater than straight wave guide; The constant width of described straight wave guide.
Beneficial effect:Cut the toe compared with techniques with existing, the beneficial effect that the utlity model has is: reduce significantly and cut the influence of toe under the big situation of side mode suppression ratio guaranteeing the main peak reflectivity, thereby reach high reflectance, high side mode suppression ratio cut the toe effect.Existing waveguide optical grating is cut in the toe scheme; The gamut that raster width changes is all in the straight wave guide width; Lean on the modulation of sandwich layer pattern to realize cutting toe, cut toe after, though secondary lobe is excised; Side mode suppression ratio improves; But because on the whole, the size of effective refractive index poor (
) is limited in the waveguide optical grating cycle, and the main peak reflectivity is suppressed simultaneously after cutting.And the utility model is in order to reach the effect of cutting toe, and the straight wave guide width remains unchanged in transmission direction, and in transmission direction, the bell raised cosine that following raster width is done to narrow down from narrow to wide again changes.Effective refractive index difference in the transmission direction is also done bell variation with following raster width, can realize cutting the effect of optical grating reflection spectrum secondary lobe.The filter construction of the utility model is implemented in the transmission direction, and the toe of cutting that following raster width changes is operated, and the following raster width variation range that is positioned at center section exceeds the width of straight wave guide.Under realizing in the bell variation of raster width; Improved the value of effective refractive index poor (
) on the whole; Lean on the pattern common modulation realization of suddenly dying of sandwich layer pattern and covering to cut toe; Reach the removal secondary lobe and improved side mode suppression ratio; Reduce simultaneously to cut the influence that toe brings for the main peak reflectivity, and do not increase the manufacture difficulty of waveguide optical grating.The wave filter that adopts the utility model is when cutting the toe operation; Raster width changes under guaranteeing; Be when effective refractive index poor (
) is done bell variation in the cycle; Improved the distribution of effective refractive index poor (
) value on the whole again; Finally both can remove secondary lobe raising limit and touch rejection ratio; Reduce to cut the influence that toe causes main peak again, realize that the waveguide bragg grating of high reflectance, high side mode suppression ratio is cut the toe effect.
Description of drawings
Fig. 1 is the longitudinal sectional view of the utility model.
Fig. 2 is the upward view after following grating, straight wave guide and the top covering assembling in the utility model.
Fig. 3 is the reflectance spectrum synoptic diagram of smooth waveguide grating filter in the utility model contrast test.
Fig. 4 is the reflectance spectrum synoptic diagram of the wave filter of the utility model in the utility model contrast test.
Have among the figure: top covering 1, under-clad layer 2, straight wave guide 3, grating 4, substrate 5 down.
Embodiment
Below in conjunction with accompanying drawing, the technical scheme of the utility model is carried out detailed explanation.
As depicted in figs. 1 and 2, a kind of pleated of the utility model is cut toe waveguide bragg grating wave filter, comprises substrate 5, under-clad layer 1, top covering 2, straight wave guide 3 and the following grating of being made up of grid stroke 4.The waveguide optical grating total length of being made up of straight wave guide 3 and following grating 4 generally is millimeter or centimetre magnitude, and the grating cycle generally is the hundreds of nanometer in the following grating 4.Under-clad layer 1 is fixedly connected on the upper surface of substrate 5, and following grating 4 is fixedly connected on the surface of straight wave guide 3, and the bottom surface of straight wave guide 3 is connected with the end face of under-clad layer 1, and the end face of straight wave guide 3 is connected with the bottom surface of top covering 2.Grid stroke in the following grating 4 is strip, and is parallel to each other between the grid stroke, and following grating 4 is symmetrical along the vertical middle separated time of straight wave guide 3.The width of following grating 4 increases according to bell envelope function from two ends to the centre gradually, and is positioned at the width of the width of the following grid stroke of grating 4 ends less than straight wave guide 3, is positioned at the width of the width of the grid stroke at grating 4 middle parts down greater than straight wave guide 3.The constant width of straight wave guide 3.The width size of straight wave guide 3 is constant, is constant value all the time.Bell envelope function can adopt raised cosine, or Gaussian function or the like.
Further; Described grating 4 down is fixed on the bottom surface of straight wave guide 3; And the top of under-clad layer 1 is provided with groove and the step that is parallel to each other, and the step of under-clad layer 1 is embedded in down in the space between the grid stroke of grating 4, and the grid stroke of following grating 4 matches with the groove of under-clad layer 1.Following grating 4 is arranged on the bottom surface of straight wave guide 3, makes that the making of waveguide optical grating is more simple and easy to do.
The Bragg grating filter of the utility model comprises substrate 5, under-clad layer 1, a waveguide optical grating and a top covering 2.Wherein, waveguide optical grating is by grating 4 and straight wave guide 3 constitute down.The whole wave guide optical grating construction wraps between top covering 2 and the under-clad layer 1.In order to reach the effect of cutting toe, straight wave guide 3 width remain unchanged in transmission direction, in the transmission direction, and the bell envelope variation that following grating 4 width work narrows down from narrow to wide again.In conjunction with the complexity of design and actual fabrication technology, the apodizing function in this example is example with the raised cosine, and other apodizing functions also can be used the utility model method.Effective refractive index difference in the transmission direction is also done bell variation with raster width, can realize cutting the effect of optical grating reflection spectrum secondary lobe.Wave-guide grating structure in the utility model is implemented in the transmission direction, and the toe of cutting of following grating 4 change width is operated, and following grating 4 width that are positioned at center section exceed the width of straight wave guide 3.When realizing the bell variation of raster width; Common relatively apodization grating structure; Improved the value of effective refractive index poor (
) on the whole; Lean on the pattern common modulation realization of suddenly dying of sandwich layer pattern and covering to cut toe; Reach the removal secondary lobe and improved side mode suppression ratio, reduced simultaneously to cut the influence that toe brings for the main peak reflectivity, and do not increased the manufacture difficulty of waveguide optical grating.
Above-mentioned pleated is cut the preparation method of toe waveguide bragg grating wave filter, may further comprise the steps:
The first step: in substrate 5, apply under-clad layer 1: utilize sol evenning machine to apply under-clad layer 1 in the upper surface rotation of substrate 5; With ultraviolet curing lamp under-clad layer 1 is cured again; With the drying glue platform under-clad layer 1 is cured then; In vacuum drying chamber, vacuum drying is carried out in the substrate 5 that is covered with under-clad layer 1 subsequently, be 3.5 drying time---24 hours.
Second step: make etch-resistant layer: utilize upper surface vapor deposition one aluminium lamination of vacuum coating equipment, as etch-resistant layer at under-clad layer 1.The method of vapor deposition is the method for vacuum evaporation well known in the art.
The 3rd step: utilize sol evenning machine spin coating negative photoresist on under-clad layer 1, with ultraviolet curing lamp under-clad layer 1 and negative photoresist are cured again.
The 4th step: utilize mask plate and mask exposure machine that negative photoresist is carried out mask exposure, the peripheral contour area of grating 4 under the photoetching.
The 5th step: utilize the ultraviolet wavelength laser instrument in the peripheral contour area of the following grating 4 of the 4th step formation, to interfere the structure of each grid stroke in the following grating 4.The process of interfering is a double beam interferometry well known in the art.
The 6th step: adopt developer for negative photoresist, developed in grating 4 regions down, make each grid stroke structure place in the grating 4 down negative photoresist washed off, corrode washed off the metal level that exposes owing to negative photoresist with acid corrosion liquid again;
The 7th step: the position that utilizes reactive ion etching machine in the 6th step, to erode metal etches grating 4 down.The method of etching is a reactive ion etching method well known in the art.
The 8th step: spend glue and remove remaining negative photoresist, this moment, metal level was positioned at under-clad layer 1 top, with acid corrosion liquid this metal level was carried out erosion removal.
The 9th step: utilize sol evenning machine on the under-clad layer 1 that following grating 4 is arranged after the etching, to rotate the coating core layer material; With ultraviolet curing lamp core material is cured again; With the drying glue platform core material is cured then; In vacuum drying chamber, vacuum drying is carried out in core material, under-clad layer 1 and substrate 5 subsequently, be 3.5-24 hours drying time.
The tenth step: vapor deposition aluminium lamination: adopt vacuum coating equipment at upper surface vapor deposition one aluminium lamination of core material as etch-resistant layer.The method of vapor deposition is the method for vacuum evaporation well known in the art.
The 11 step: carry out the photoetching of straight wave guide 3 with mask exposure machine and mask plate.
The 12 step: adopt developer solution to carry out straight wave guide 3 and develop, with acid corrosion liquid the metal level that exposes after developing is corroded again, utilize reactive ion etching machine that the position of the metal that is corroded in this step is etched straight wave guide 3 then with exterior domain.The method that adopts etching is for being reactive ion etching method well known in the art.
The 13 step: utilize sol evenning machine to apply top covering 2 in the upper surface rotation of straight wave guide 3; With ultraviolet curing lamp top covering 2 is cured; And with drying glue platform post bake; In vacuum drying chamber, substrate 5, under-clad layer 1, top covering 2, straight wave guide 3 and following grating 4 are carried out vacuum drying at last, be 3.5-24 hours drying time.
The 14 step: from vacuum drying chamber, take out the single piece of being made up of substrate 5, under-clad layer 1, top covering 2, straight wave guide 3 and following grating 4, the wave filter preparation is accomplished.
Explain that through test the wave filter of the utility model compares with existing wave filter below, have the premium properties of high reflectance and high side mode suppression ratio.
In conjunction with commercial organic polymer ultra-violet curing ZPU series material, the parameter of the wave filter of the utility model that adopts in the test is as shown in table 1.Consider the manufacture craft problem, we are with in the transmission direction, and the width of the grid stroke of the starting and ending of following grating 4 is designed to 2 μ m.
Table 1
| Design parameters | Title | Numerical value |
 | Resonance wavelength | 1555nm |
 | The refractive index of under-clad layer and top covering | 1.44 |
 | Straight wave guide and following grating index | 1.46 |
 | The cycle of following grating | 0.535 μ m |
 | The total length of waveguide optical grating | 1cm |
 | The thickness of top covering | 3 μ m |
| The thickness of under-clad layer | 9 μ m | |
 | The height of straight wave guide | 6 μ m |
 | The width of straight wave guide | 6 μ m |
 | The height of following grating | 0.6 μ m |
| The width of following | 2 μ m | |
 | In the transmission direction, following raster width changes envelope | Raised cosine changes |
Come the reflectance spectrum of Analysis of Waveguide grating filter with transfer matrix method, the length of whole wave guide grating is L, and waveguide optical grating is made up of straight wave guide 3 and following grating 4.Whole filter is divided into the N section; Every segment length
; Regard each section as uniform structure, with 2 * 2 matrix representations:
(1≤k≤N)
In the following formula; The matrix of
expression k section;
and
representes the coupling constant of k section respectively; Wherein,
;
;
; Resonance wavelength
; Wherein
is the effective refractive index of waveguide optical grating;
is the cycle of following grating 4;
is the average change value of effective refractive index in the k section waveguide optical grating cycle;
is the wavelength of spectrum,
the plural imaginary symbols of expression.
Existing wave filter as a comparison adopts the smooth waveguide grating, and it with the filter construction difference of this patent is: the width of each grid stroke equates in the following grating.In test, the width of the grid stroke of the following grating in the existing wave filter of employing and the width of straight wave guide equate, are 6 μ m, and listed parameter is corresponding identical in other parameters and the table 1.
For the smooth waveguide grating; In transmission direction; Periodic structure begins and finishes with mutant form; Parameter in each matrix equates that then reflectance spectrum can occur with
functional form, and promptly the uniform grating reflectance spectrum has very big secondary lobe.。Cut the toe waveguide optical grating for what the utility model provided; Because the width of following grating is the modulation of bell envelope;
between each matrix is unequal (being bell envelope variation on the whole); Exactly because
is bell envelope distribution on entire device, then cuts toe waveguide optical grating secondary lobe and be suppressed.Every section matrix is multiplied each other successively, can obtain the optical grating reflection spectrum, smooth waveguide optical grating reflection spectrum is as shown in Figure 3, and the reflectance spectrum of the wave filter of the utility model is specifically as shown in Figure 4.
Peak reflectivity
;
is the total length of waveguide optical grating;
expression has average effect refringence in the cycle on the whole, and
is the wavelength in the spectral range.Like Fig. 3 and shown in Figure 4, when light transmitted in the toe waveguide optical grating cutting of providing of smooth waveguide grating or the utility model, the reflectance spectrum scope was all within 1553nm-1557nm.
In actual fabrication, fold formula waveguide optical grating is to realize through etching, and that cuts the employing of toe fiber grating in the very difficult realization bibliographical information realizes cutting toe at depth conversion, can only be through in the change transmission direction, and following raster width realizes cutting the effect of toe.
It is relevant that
changes severe in Sidelobe Suppression effect and the transmission matrix.In the transmission direction; It is strong that
changes Shaoxing opera, and it is good more to cut the toe effect.But; It is big or small relevant to cut behind the toe on the main peak reflectivity size and transmission direction
; Guaranteeing that
distribution is done on the basis of bell variation in the transmission direction;
is big more, and it is just big more to cut behind the toe main peak reflectivity.For the value that improves
when
has acute variation on the whole in assurance; The wave filter of this patent is in transmission direction; Following grating 4 change width are campanula halleri Halleri, and following grating 4 change width scopes exceed the width of straight wave guide 3.Adopt this new design structure, lean on the pattern common modulation realization of suddenly dying of sandwich layer pattern and covering to cut toe, can both obtain high side mode suppression ratio, the high peak reflectivity of getting back.Cladding mode is the pattern in the waveguide optical grating internal transmission, and the mould that suddenly dies is the pattern of in top covering and under-clad layer, transmitting.
Through comparison diagram 3 and Fig. 4, can find out: adopt in the existing wave filter reflectance spectrum of smooth waveguide optical grating construction, reflectivity 33.01dB, side mode suppression ratio 3.2dB, and very big secondary lobe is arranged; And in the wave filter reflectance spectrum of the utility model, reflectivity 27.70dB, side mode suppression ratio 16.67dB, and secondary lobe cut, and the main peak reflectance varies is very little.Under this parameter, the pleated of the utility model is cut toe waveguide optical grating wave filter side mode suppression ratio and is reached 16dB when above, and the main peak reflectivity can satisfy practical application request much larger than 20dB.What the wave filter of the utility model had successfully been realized high reflectance, high side mode suppression ratio cuts the toe effect.
Claims (2)
1. a pleated is cut toe waveguide bragg grating wave filter; Comprise substrate (5), under-clad layer (1), top covering (2), straight wave guide (3) and the following grating of being made up of grid stroke (4), under-clad layer (1) is fixedly connected on the upper surface of substrate (5), and following grating (4) is fixedly connected on the surface of straight wave guide (3); The bottom surface of straight wave guide (3) is connected with the end face of under-clad layer (1); The end face of straight wave guide (3) is connected with the bottom surface of top covering (2), it is characterized in that, the grid stroke in the described grating (4) down is strip; And be parallel to each other between the grid stroke, following grating (4) is symmetrical along the vertical middle separated time of straight wave guide (3); The width of following grating (4) increases according to bell envelope function from two ends to the centre gradually; And the width of the grid stroke of grating (4) end is less than the width of straight wave guide (3) under being positioned at, and the width of the grid stroke at grating (4) middle part is greater than the width of straight wave guide (3) under being positioned at; The constant width of described straight wave guide (3).
2. cut toe waveguide bragg grating wave filter according to the described pleated of claim 1; It is characterized in that; Described grating (4) down is fixed on the bottom surface of straight wave guide (3); And the top of under-clad layer (1) is provided with groove and the step that is parallel to each other, and the step of under-clad layer (1) is embedded in down in the space between the grid stroke of grating (4), and the grid stroke of following grating (4) matches with the groove of under-clad layer (1).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220252086 CN202614981U (en) | 2012-05-31 | 2012-05-31 | Corrugated type apodization waveguide Bragg grating filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220252086 CN202614981U (en) | 2012-05-31 | 2012-05-31 | Corrugated type apodization waveguide Bragg grating filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202614981U true CN202614981U (en) | 2012-12-19 |
Family
ID=47348668
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220252086 Expired - Fee Related CN202614981U (en) | 2012-05-31 | 2012-05-31 | Corrugated type apodization waveguide Bragg grating filter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202614981U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102662218A (en) * | 2012-05-31 | 2012-09-12 | 东南大学 | Wrinkle type apodization waveguide Bragg grating filter and manufacturing method thereof |
-
2012
- 2012-05-31 CN CN 201220252086 patent/CN202614981U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102662218A (en) * | 2012-05-31 | 2012-09-12 | 东南大学 | Wrinkle type apodization waveguide Bragg grating filter and manufacturing method thereof |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102662218B (en) | Wrinkle type apodization waveguide Bragg grating filter and manufacturing method thereof | |
| US7639911B2 (en) | Optical device having optical waveguide including organic Bragg grating sheet | |
| CN103762500B (en) | Asymmetric equivalent apodization sampling optical grating and laser based on reconstruction-equivalent chirp | |
| CN105607186B (en) | Based on SiO2Load the manufacturing method of the waveguide bragg grating of slab waveguide | |
| CN111175896A (en) | High-efficiency grating coupler with large bandwidth | |
| JP6514326B2 (en) | Grating structure and method of manufacturing grating coupler having the same | |
| CN101726769B (en) | Long laminated sub-wave reflection-reducing structure and preparation method thereof | |
| US9874694B2 (en) | Production method for mounting structure for grating elements | |
| CN103645540A (en) | Etched diffraction grating-type wavelength division multiplexing/demultiplexing device | |
| CN101546002A (en) | Sub-wavelength fused silica transmission polarization light-splitting grating at 1064 nano wave band | |
| CN115857091A (en) | MMI polarization beam splitter of lithium niobate thin film | |
| CN116165742A (en) | Double-layer silicon nitride grating coupler integrated with bottom reflecting layer | |
| CN202614981U (en) | Corrugated type apodization waveguide Bragg grating filter | |
| CN104698537A (en) | Aluminum nitride-based guided-mode resonant multichannel light filter and preparation method thereof | |
| JPH0886928A (en) | Manufacture of bragg reflector for waveguide and obtained product | |
| CN110221384A (en) | A kind of silicon substrate Meta Materials multimode curved waveguide and preparation method thereof | |
| CN105207055A (en) | Half-edge apodized sampling grating based on reconstruction-equivalence chirp and DFB laser | |
| CN112415652A (en) | Waveguide grating coupler array | |
| CN216210270U (en) | GaAs-based polarized light beam splitter | |
| CN106483600A (en) | A kind of ultrashort vertical waveguide bonder with tolerance of producing extensively | |
| CN114639745B (en) | Novel optical detector and manufacturing method thereof | |
| CN113866993A (en) | GaAs-based polarized light beam splitter and preparation method thereof | |
| CN115144964A (en) | Silicon-based array waveguide grating based on Euler bending wide waveguide | |
| CN115236799A (en) | Grating type lithium niobate optical filter with apodized transverse amplitude | |
| CN204595252U (en) | A kind of polarization maintaining fiber apodization grating of high Sidelobe Suppression ratio |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20121219 Termination date: 20140531 |