CA2379077A1 - Narrow-band optical interference filter - Google Patents
Narrow-band optical interference filter Download PDFInfo
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- CA2379077A1 CA2379077A1 CA002379077A CA2379077A CA2379077A1 CA 2379077 A1 CA2379077 A1 CA 2379077A1 CA 002379077 A CA002379077 A CA 002379077A CA 2379077 A CA2379077 A CA 2379077A CA 2379077 A1 CA2379077 A1 CA 2379077A1
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- 230000003287 optical effect Effects 0.000 title claims abstract description 27
- 239000010410 layer Substances 0.000 claims description 99
- 238000000034 method Methods 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 5
- 239000002356 single layer Substances 0.000 claims description 4
- 230000003247 decreasing effect Effects 0.000 claims description 2
- 230000005540 biological transmission Effects 0.000 description 17
- 239000000463 material Substances 0.000 description 14
- 238000000576 coating method Methods 0.000 description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 125000006850 spacer group Chemical group 0.000 description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- -1 Ta 20 5 Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000007740 vapor deposition Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/515—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using pulsed discharges
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/28—Interference filters
- G02B5/281—Interference filters designed for the infrared light
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/28—Interference filters
- G02B5/285—Interference filters comprising deposited thin solid films
- G02B5/288—Interference filters comprising deposited thin solid films comprising at least one thin film resonant cavity, e.g. in bandpass filters
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- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Optics & Photonics (AREA)
- General Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Plasma & Fusion (AREA)
- Optical Filters (AREA)
Abstract
The invention relates to a narrow-band optical interference filter for a wavelength (.lambda.0) comprising a plurality of dielectric layers, whereby said dielectric layers alternately have a high (nH) and a low refractive ind ex (nL) and a first number of dielectric layers has an optical layer thickness of .lambda./4 or .lambda./2 or an integral multiple thereof. The invention is characterized in that a second number of layers in the layer system has an optical layer thickness differing from .lambda./4 and .lambda./2 resulting i n a minimized overall layer.
Description
Interference-optical narrowband filter The invention relates to an interference-optical narrowb~and filter for a wavelength of ~,o with a great number of dielectric layer;~, as set out in the preamble of Claim 1, as well as to the use of such filter and a plasma-activated CVD process for the production of such narrowband, interference-optical filters.
Narrowband, dielectric filters of Fabry-Perot design are known in prior art from a large number of publications.
Reference is made in this respect to the following patent specifications:
The subject-matter of these patent specifications is included to the full extent in the specifications of this application.
Interference-optical narrowband filters are produced by i:he alternating application of high and low-refractive-index layers of a precisely defined thickness of layer. The Fabry-Perot design has a symmetrical buildup composed of 7~I4 layers around a so-called spacer layer (~,I2 or n*~,12 layer) - a so-called cavity -, which means that the arrangement of the layers in the first half of a cavity is repeated in the second half in a mirror-inverted manner. The narrow-band filter consists of several cavities, for example of three cavities. The expansion of the 7~I2 or ~,,I4 layers is monitored and controlled during the production preferably with the help of optical methods. The increase of the layer may be purposively controlled, for example, by an extreme-value turn-off that interrupts the coating process at precisely the point when the transmi:~sion or reflection of the layering system reaches an extreme value, i.e. when the coating thickness corresponds to a a,14 layer or an integral multiple thereof. In order to produce a specified filter characteristic with the help of the traditional deposit, i.e. from a great number of ~,,I4 layer's and a specified selection of materials (i.e. a specified refractive index), an "oversizing" of the layering system is frequently necessary. This means that very many layers or very thick layers have to be used. This in turn means an extension of the production time of the filters and, consE:quently, results in most cases in less profitability.
An optical narrowband filter is known from US 4 756 60;2 in which the spacer layers are separated into thinner layers by breaking them down into equivalent layers of the same optical thickness in total.
The interference filter, as set out in US 4 756 602, was produced with the help of a continuous vapor deposition technique by way of laser ellipsometric layer-thickness control wherein, after the preposition of the layer, its precise thickness was determined and the subsequent layer was re-optimized. Such layer-thickness control is very expensive and can only be used conditionally in practical operation.
It is the task of the invention to make available a very narrowband Fabry-Perot filter with specified transmission characteristics without having to tolerate the disadvantages according to the state of the art. The aim is to
Narrowband, dielectric filters of Fabry-Perot design are known in prior art from a large number of publications.
Reference is made in this respect to the following patent specifications:
The subject-matter of these patent specifications is included to the full extent in the specifications of this application.
Interference-optical narrowband filters are produced by i:he alternating application of high and low-refractive-index layers of a precisely defined thickness of layer. The Fabry-Perot design has a symmetrical buildup composed of 7~I4 layers around a so-called spacer layer (~,I2 or n*~,12 layer) - a so-called cavity -, which means that the arrangement of the layers in the first half of a cavity is repeated in the second half in a mirror-inverted manner. The narrow-band filter consists of several cavities, for example of three cavities. The expansion of the 7~I2 or ~,,I4 layers is monitored and controlled during the production preferably with the help of optical methods. The increase of the layer may be purposively controlled, for example, by an extreme-value turn-off that interrupts the coating process at precisely the point when the transmi:~sion or reflection of the layering system reaches an extreme value, i.e. when the coating thickness corresponds to a a,14 layer or an integral multiple thereof. In order to produce a specified filter characteristic with the help of the traditional deposit, i.e. from a great number of ~,,I4 layer's and a specified selection of materials (i.e. a specified refractive index), an "oversizing" of the layering system is frequently necessary. This means that very many layers or very thick layers have to be used. This in turn means an extension of the production time of the filters and, consE:quently, results in most cases in less profitability.
An optical narrowband filter is known from US 4 756 60;2 in which the spacer layers are separated into thinner layers by breaking them down into equivalent layers of the same optical thickness in total.
The interference filter, as set out in US 4 756 602, was produced with the help of a continuous vapor deposition technique by way of laser ellipsometric layer-thickness control wherein, after the preposition of the layer, its precise thickness was determined and the subsequent layer was re-optimized. Such layer-thickness control is very expensive and can only be used conditionally in practical operation.
It is the task of the invention to make available a very narrowband Fabry-Perot filter with specified transmission characteristics without having to tolerate the disadvantages according to the state of the art. The aim is to
2 produce especially a narrowband interference filter of small total thickness, if possible.
The problem is solved, according to the invention, by the fact that in an interference-optical narrowband filter for a wavelength crf ~,o a number of layers of a multilayered system have an optical thickness of layer that deviates from 7~I2 or 714.
Such optical narrowband filter comprises, therefore, altE:rnately arranged dielectric layers consisting, for example, of materials such as titanium dioxide and silica, preferably nioboxide and silica, and wherein the optical thickness of the individual layers can be any fraction or multiple of ~,/4.
Such design, according to the invention, has the advantage that at a smaller total thickness than in designs consisting only of ~,/4 layers, a respective transmission characteristic that conforms to predetermined specifications can be achieved.
Preferred materials to be used for high-refractive-index layers are Nb20 5, Ti0 2, Ta 20 5, Zr02 as well as Hf02.
For designs, according to the state of the art, with mirror coatings of (HL)-stacks (H: coating made of a high-refractive-index material, L: coating made of a low-refractive-index material), as well as spacer layers consisting of n*~,/2 layers for which the coating materials have been specified, it is not possible to adapt at will the transmission characteristic to predetermined specifications since the ratio of the rE:fractive values, the minimum reflection of the mirror coatings and the position of the band-pass on the wavelength scale are very limited.
The designs, according to the invention, overcome this disadvantage.
Furthermore, by using layers whose optic thickness deviates from x,14 or multiples thereof, the so-called non-x,14 layers, it is possible to vary and particularly to minimize recesses in the transmission characteristic of the band-pass filter, the so-called "ripples".
Provision has been made in a preferred embodiment of the invention to the effect that the optical thickness of layers that deviatE: from ~,/4 or from x,12 is selected in such a way that the total thickness of layer of the interference-optical narrowband filter is minimized when the transmission characteristic is specified.
It is especially preferable if the interference-optical narrowband filter has a great number of stacks with several alternating high and low-refractive -index layers. In a first embodiment provision can have been made for the arrangement of a large number of reflecting ~,/4 layers in a stack and for at least one layer whose optical layer of thickness deviate:> from x.14 or 7~,I2.
It is also possible to provide a stack in which the optical thickness of almost all layers deviates from ~,/4.
In a particular embodiment spacer layers have been prcwided between the stacks that can comprise one or several ?~/2 layers but ~~Iso layers of an optical thickness that deviates from 7~I2.
Since the designs, according to the invention, are produced in production processes, using customary measuring methods, such ~~s optical moni-toring or the extreme-value turn-off, and thus lack the required accuracy, a process is also indicated that makes the production of such narrowband filters possible. According to the invention, a plasma-activated CVD
(PICVD) process is used for this purpose wherein the production parameters are selected in such a way that per microwave pulse, on average, clearly less than one monolayer of the dielectric layer is deposited on a substrate. Thus, by counting the pulses it is possible to set a specified thickness of layer.
In such plasma-activated CDV process, for example, it is possible to de-termine first of all the number N of the plasma pulses in order to obtain a x,14 or x,12 layer. Furthermore, to produce a layer of an optical thickness that deviates from ~,/4 or ~,,I2 , the number of plasma pulses in relation to the predetermined number N can be increased or decreased by n, so that a slightly thicker or thinner layer than a ~./4 layer is creai:ed.
Alternatively to this, the material used for the production of a 714 layer in a plasma-activated CVD process can be replaced by a material with slightly deviating optical constants in order to produce a layer o~f a thickness that deviates from ~,/4 and without negatively affecting the edge steepness of the filter since, the change-over to the other material can be made during a pulse interval.
It is especially preferable when per plasma pulse, on average, clearly less than one monolayer of the dielectric layer is deposited. A specified thick ness of layer can then be very precisely set by counting the pulses.
A modification of the optical thickness of layer is possible by changing the process parameters, such as the temperature of the substrate and/or the gas pressure of the process or the coating rate.
By changing the temperature of the substrate andlor the. gas pressure of the process or the coating rate, differences in refractive values of 0.05 and more can be obtained.
Described below are exemplified embodiments of Fabry-Perot narrow-band filters that comprise one or several layers of a thiclkness deviating from x,14.
Figure 1 shows a first, desired transmission curve of a layered system.
Figure 2 shows the refractive-value path of a system that fulfills the first, desired transmission curve with a total of 112 layers, including a great number of layers whose ~nptical thickness of layer deviates from x,14.
Figure 3 shows a second, desired transmission curve for a narrow-band interference filter.
Figure 4 shows a transmission curve with a layered system of a total of 66 layers, including a great numbE:r of layers whose thickness of layer deviates from 7,.I4, and Having a total thickness of approximately 16 pm, which almost meets the desired values according to Figure 3.
Figure 5 shows the refractive-value path of the sysi:em according to Figure 4.
Fig. 6 shows the transmission curve of a layered system based on ~,/4 and ~./2 layers which almost meets the desired values according to Figure 3. The system consisl.s of 78 layers of a total thickness of approximately 27 Nm.
Fig. 7 shows the refractive-value path of the system according to Fig. 6.
Figure 2 shows the refractive-value path of a system, according to the invention, that closely reflects the path of the first desired transmission curve, and which comprises a great number of layers the optical thickness of which deviates from ~,I4 or ~,/2. The system consists of 112 layers in total with the following build-up:
0.6505H, 034L 0.4243H 0.9405L 1.0015H 1.0113L "1.0043H 0.9935L
0.9838H 0.9778L 0.9776H 0.9831 L 0.9904H 0.99541_ 0.9971 H
0.9979L 1.0004H 4,0062L 1.0023H 1.0L 0.9982H 0.9966L 0.995H
0.9933L 0.9913H 0.9891 L 0.9869H 0.985L 0.9839H 0.9846L 0.9883H
0.9975L 1.0122H 09155L 0.0706H 0.1537L, 0.3915H, 0.2603L 0.7195H
1.0316L 1.0139H 0.9991 L 0.989H 0.9837L 0.9824H 0.9835L 0.9857H
0.9878L 0.9894H 0.9915L 0.9947H 0.9988L 1.0034H 4.0106L
1.0013H 0.9948L 0.9911 H 0.9893L 0.9883H 0.98771_ 0.9874H
0.9875L 0.9879H 0.9886L 0.9897H 0.9913L 0.9939f-~ 0.9981 L
0.8754H 0.0574L 0.1429H 0.8937L 0.0675H 0.1481 L. 0.3561 H
0.2993L 0.6967H 1.0004L 0.9846H 0.9745L 0.96971-I 0.9695L
0.9731 H 0.979L 0.9851 H 0.99L 0.9932H 0.9959L 0.9992H 1.0015L
1.0012H 4.0026L 0.9999H 1.0014L 1.0053H 1.009L 1.0065H
0.9933L 0.9723H 0.9523L 0.9413H 0.9428L 0.95451-I 0.9657L
0.9541 H 0.8887L 0.6238H 0.2241 L 0.1628H 0.6552L_ 0.0941 H
0.0149L
In this connection H refers to a layer with a high refracti~re index nH , and L
denotes a layer with a low index of refraction n~_ Prefer<~bly Nb205, Ti02, Ta 20 5, Zr0 2 as well as Hf02 are used as materials for vrhe high-refractive-index layers. The use of nioboxide is particularly preferred for the high-refractive layer, whereas silica is especially preferred for the low-refrac-tive-index layer. The optical thickness of layer is standardized as follows:
1,000=n~d=~,/4 which means a value of 1,000 corresponds to an optical thickness of layer of exactly ~, /4; for example, a value of 0.9956 of an optical thickness of layer that is slightly less than 7~ 14 and, for example, a value of 1.0043 of an optical thickness of layer that is slightly greater than x,14.
In Fig. 2 a second desired characteristic for a narrow-bind interference filter is specified.
Figures 4 and 5 show interference filters, according to the invention, that fulfill to a large extent the required transmission path in conformity with the second desired characteristic as specified in Figure 3. I=figure 4 shows the actual transmission path of an interference filter, according to the invention. As can be seen from the comparison between Figure 3 and Figure 4, the actual transmission path corresponds to s~ large extent to the specified one, according to the second desired characteristic. The total thickness of layer of the system, according to Fig. 4 and 5, is almost 50%
lower than the total thickness of layer of a system that is exclusively comprised of 7~I4 and x,12 layers. Figure 5 shows the refractive path of the invented system to fulfill the second desired characteristic. The system, as shown in Fig. 5, consists of a total of 66 individual ladders with the following build-up:
s 0.5486H 0.007L 0.5289H 1.1718L 1.2095H 1.1575L 1.0469H 0.9728L
0.971 H 1.0217L 1.0764H 1.0379L 0.9368H 0.9652L 1.0171 H 0.9912L
0.945H 4.0895L 0.9593H 1.0102L 0.895H 0.9771 L 1.0412H 1.005L
0.9303H 0.8977L 0.9442H 1.0036L 1.032H 1.0729L 1.1511 H 1.175L
1.0713H 0.8283L 1.1149H 1.5524L 0.7855H 1.0895L_ 1.0185H 1.008L
1.0233H 1.0482L 1.0739H 1.1208L 1.2156H 0.93591_ 1.0174H
0.8977L 1.2226H 3.974L 0.8322H 0.986L 1.0412H 'I .1036L 0.9771 H
0.8995L 0.872H 0.8306L 0.8384H 0.928L1.0438H 1.115L 1.132H
1.1647L 1.2208H 1.3793L
The designations of the layered system are identical to those of the system shown in Figure 1; this means L refers to layers of a low refractive index and H refers to layers of a high refractive index. In the examples given the refractive index of the high-index layer is n~= 1.43 and the refractive index of the low-refractive-index layer is nH = ~'_.3. The material of the high-refractive-index layer is preferably comprised of Nb20 5, and the material of the low-refractive-index layer preferably consists of Si02. Figure 5 shows the refractive-index path in relation to the thickness of layer. The alternation between high and low-refractive-index layers, as well as the total of 2 spacer-like layers is clearly recognizable.
Figure 6 shows the transmission curve of a so-called three-cavity filter, according to the state of the art, that is comprised exclusively of a,14 and ~,/2 layers, as well as multiples thereof. In this case stacks 1, 2, 5 and 6 are built up identically, and stacks 3 and 4 have mirror coatings consisting of 3/4 7~-layers. A stack denotes a large number of a,14 I;~yers (or multiples thereof) of alternating high and low-refractive-index materials. A cavity comprises two stacks that are separated by spacer layers as, for example, a x,12 layer made of high or low-refractive-index material. The coupling 5 layers between the individual cavities, for example, can be low-refractive -index ~./4 layers.
The design, according to the state of the art, likewise shows a good approximation to the specified, second desired characteristic, as can be seen from the comparison between Figure 3 and Figure 6.
As shown by the refractive-value path of the three-cavit~r filter, illustrated in Figure 7, the individual layers, as well as the two spacer layers are clearly thicker in construction. This leads to an almost 50% greater total thickness of layer in the state of the art, as compared to the design, according to the invention.
Another advantage of the invention is the great edge stE:epness, as well as a greater transmission in the passband width.
The illustrated, layered systems of an altered optical thickness are produced preferably with the help of the plasma-activat~sd CVD process as, for example, by applying an atomic monolayer or less per plasma pulse and by counting the pulses as described above.
Alternatively, the optical thickness of layer can be altered by changing the process parameters during the pulse interval that is variably adjustable.
The advantage of using the plasma-activated CVD process is the achievement of a very effective change-over and the possibility within the layered system to produce, in a simple way, layers of an optical thickness that deviates from x,14. In current continuous CVD proccases this is not possible without a change-over.
The very narrow-band ialters, produced according to the invention, whose 5 edge steepness is adjustable in a very controlled manner, can be used as edge-type filters of extreme edge steepness or as very slat gain-flattening filters. Furthermore, the introduced narrowband filters are suitable, due to io their precisely controllable transmission path, for multiplexers or demultiplexers in WDM (Wavelength-Division-Multiplex) or in DWDM (Dense-Wavelength-Division-Multiplex) systems of telecommunications engineering. A special advantage of this invenstion is the greatly reduced total thickness of layer as compared to the conventional design.
m
The problem is solved, according to the invention, by the fact that in an interference-optical narrowband filter for a wavelength crf ~,o a number of layers of a multilayered system have an optical thickness of layer that deviates from 7~I2 or 714.
Such optical narrowband filter comprises, therefore, altE:rnately arranged dielectric layers consisting, for example, of materials such as titanium dioxide and silica, preferably nioboxide and silica, and wherein the optical thickness of the individual layers can be any fraction or multiple of ~,/4.
Such design, according to the invention, has the advantage that at a smaller total thickness than in designs consisting only of ~,/4 layers, a respective transmission characteristic that conforms to predetermined specifications can be achieved.
Preferred materials to be used for high-refractive-index layers are Nb20 5, Ti0 2, Ta 20 5, Zr02 as well as Hf02.
For designs, according to the state of the art, with mirror coatings of (HL)-stacks (H: coating made of a high-refractive-index material, L: coating made of a low-refractive-index material), as well as spacer layers consisting of n*~,/2 layers for which the coating materials have been specified, it is not possible to adapt at will the transmission characteristic to predetermined specifications since the ratio of the rE:fractive values, the minimum reflection of the mirror coatings and the position of the band-pass on the wavelength scale are very limited.
The designs, according to the invention, overcome this disadvantage.
Furthermore, by using layers whose optic thickness deviates from x,14 or multiples thereof, the so-called non-x,14 layers, it is possible to vary and particularly to minimize recesses in the transmission characteristic of the band-pass filter, the so-called "ripples".
Provision has been made in a preferred embodiment of the invention to the effect that the optical thickness of layers that deviatE: from ~,/4 or from x,12 is selected in such a way that the total thickness of layer of the interference-optical narrowband filter is minimized when the transmission characteristic is specified.
It is especially preferable if the interference-optical narrowband filter has a great number of stacks with several alternating high and low-refractive -index layers. In a first embodiment provision can have been made for the arrangement of a large number of reflecting ~,/4 layers in a stack and for at least one layer whose optical layer of thickness deviate:> from x.14 or 7~,I2.
It is also possible to provide a stack in which the optical thickness of almost all layers deviates from ~,/4.
In a particular embodiment spacer layers have been prcwided between the stacks that can comprise one or several ?~/2 layers but ~~Iso layers of an optical thickness that deviates from 7~I2.
Since the designs, according to the invention, are produced in production processes, using customary measuring methods, such ~~s optical moni-toring or the extreme-value turn-off, and thus lack the required accuracy, a process is also indicated that makes the production of such narrowband filters possible. According to the invention, a plasma-activated CVD
(PICVD) process is used for this purpose wherein the production parameters are selected in such a way that per microwave pulse, on average, clearly less than one monolayer of the dielectric layer is deposited on a substrate. Thus, by counting the pulses it is possible to set a specified thickness of layer.
In such plasma-activated CDV process, for example, it is possible to de-termine first of all the number N of the plasma pulses in order to obtain a x,14 or x,12 layer. Furthermore, to produce a layer of an optical thickness that deviates from ~,/4 or ~,,I2 , the number of plasma pulses in relation to the predetermined number N can be increased or decreased by n, so that a slightly thicker or thinner layer than a ~./4 layer is creai:ed.
Alternatively to this, the material used for the production of a 714 layer in a plasma-activated CVD process can be replaced by a material with slightly deviating optical constants in order to produce a layer o~f a thickness that deviates from ~,/4 and without negatively affecting the edge steepness of the filter since, the change-over to the other material can be made during a pulse interval.
It is especially preferable when per plasma pulse, on average, clearly less than one monolayer of the dielectric layer is deposited. A specified thick ness of layer can then be very precisely set by counting the pulses.
A modification of the optical thickness of layer is possible by changing the process parameters, such as the temperature of the substrate and/or the gas pressure of the process or the coating rate.
By changing the temperature of the substrate andlor the. gas pressure of the process or the coating rate, differences in refractive values of 0.05 and more can be obtained.
Described below are exemplified embodiments of Fabry-Perot narrow-band filters that comprise one or several layers of a thiclkness deviating from x,14.
Figure 1 shows a first, desired transmission curve of a layered system.
Figure 2 shows the refractive-value path of a system that fulfills the first, desired transmission curve with a total of 112 layers, including a great number of layers whose ~nptical thickness of layer deviates from x,14.
Figure 3 shows a second, desired transmission curve for a narrow-band interference filter.
Figure 4 shows a transmission curve with a layered system of a total of 66 layers, including a great numbE:r of layers whose thickness of layer deviates from 7,.I4, and Having a total thickness of approximately 16 pm, which almost meets the desired values according to Figure 3.
Figure 5 shows the refractive-value path of the sysi:em according to Figure 4.
Fig. 6 shows the transmission curve of a layered system based on ~,/4 and ~./2 layers which almost meets the desired values according to Figure 3. The system consisl.s of 78 layers of a total thickness of approximately 27 Nm.
Fig. 7 shows the refractive-value path of the system according to Fig. 6.
Figure 2 shows the refractive-value path of a system, according to the invention, that closely reflects the path of the first desired transmission curve, and which comprises a great number of layers the optical thickness of which deviates from ~,I4 or ~,/2. The system consists of 112 layers in total with the following build-up:
0.6505H, 034L 0.4243H 0.9405L 1.0015H 1.0113L "1.0043H 0.9935L
0.9838H 0.9778L 0.9776H 0.9831 L 0.9904H 0.99541_ 0.9971 H
0.9979L 1.0004H 4,0062L 1.0023H 1.0L 0.9982H 0.9966L 0.995H
0.9933L 0.9913H 0.9891 L 0.9869H 0.985L 0.9839H 0.9846L 0.9883H
0.9975L 1.0122H 09155L 0.0706H 0.1537L, 0.3915H, 0.2603L 0.7195H
1.0316L 1.0139H 0.9991 L 0.989H 0.9837L 0.9824H 0.9835L 0.9857H
0.9878L 0.9894H 0.9915L 0.9947H 0.9988L 1.0034H 4.0106L
1.0013H 0.9948L 0.9911 H 0.9893L 0.9883H 0.98771_ 0.9874H
0.9875L 0.9879H 0.9886L 0.9897H 0.9913L 0.9939f-~ 0.9981 L
0.8754H 0.0574L 0.1429H 0.8937L 0.0675H 0.1481 L. 0.3561 H
0.2993L 0.6967H 1.0004L 0.9846H 0.9745L 0.96971-I 0.9695L
0.9731 H 0.979L 0.9851 H 0.99L 0.9932H 0.9959L 0.9992H 1.0015L
1.0012H 4.0026L 0.9999H 1.0014L 1.0053H 1.009L 1.0065H
0.9933L 0.9723H 0.9523L 0.9413H 0.9428L 0.95451-I 0.9657L
0.9541 H 0.8887L 0.6238H 0.2241 L 0.1628H 0.6552L_ 0.0941 H
0.0149L
In this connection H refers to a layer with a high refracti~re index nH , and L
denotes a layer with a low index of refraction n~_ Prefer<~bly Nb205, Ti02, Ta 20 5, Zr0 2 as well as Hf02 are used as materials for vrhe high-refractive-index layers. The use of nioboxide is particularly preferred for the high-refractive layer, whereas silica is especially preferred for the low-refrac-tive-index layer. The optical thickness of layer is standardized as follows:
1,000=n~d=~,/4 which means a value of 1,000 corresponds to an optical thickness of layer of exactly ~, /4; for example, a value of 0.9956 of an optical thickness of layer that is slightly less than 7~ 14 and, for example, a value of 1.0043 of an optical thickness of layer that is slightly greater than x,14.
In Fig. 2 a second desired characteristic for a narrow-bind interference filter is specified.
Figures 4 and 5 show interference filters, according to the invention, that fulfill to a large extent the required transmission path in conformity with the second desired characteristic as specified in Figure 3. I=figure 4 shows the actual transmission path of an interference filter, according to the invention. As can be seen from the comparison between Figure 3 and Figure 4, the actual transmission path corresponds to s~ large extent to the specified one, according to the second desired characteristic. The total thickness of layer of the system, according to Fig. 4 and 5, is almost 50%
lower than the total thickness of layer of a system that is exclusively comprised of 7~I4 and x,12 layers. Figure 5 shows the refractive path of the invented system to fulfill the second desired characteristic. The system, as shown in Fig. 5, consists of a total of 66 individual ladders with the following build-up:
s 0.5486H 0.007L 0.5289H 1.1718L 1.2095H 1.1575L 1.0469H 0.9728L
0.971 H 1.0217L 1.0764H 1.0379L 0.9368H 0.9652L 1.0171 H 0.9912L
0.945H 4.0895L 0.9593H 1.0102L 0.895H 0.9771 L 1.0412H 1.005L
0.9303H 0.8977L 0.9442H 1.0036L 1.032H 1.0729L 1.1511 H 1.175L
1.0713H 0.8283L 1.1149H 1.5524L 0.7855H 1.0895L_ 1.0185H 1.008L
1.0233H 1.0482L 1.0739H 1.1208L 1.2156H 0.93591_ 1.0174H
0.8977L 1.2226H 3.974L 0.8322H 0.986L 1.0412H 'I .1036L 0.9771 H
0.8995L 0.872H 0.8306L 0.8384H 0.928L1.0438H 1.115L 1.132H
1.1647L 1.2208H 1.3793L
The designations of the layered system are identical to those of the system shown in Figure 1; this means L refers to layers of a low refractive index and H refers to layers of a high refractive index. In the examples given the refractive index of the high-index layer is n~= 1.43 and the refractive index of the low-refractive-index layer is nH = ~'_.3. The material of the high-refractive-index layer is preferably comprised of Nb20 5, and the material of the low-refractive-index layer preferably consists of Si02. Figure 5 shows the refractive-index path in relation to the thickness of layer. The alternation between high and low-refractive-index layers, as well as the total of 2 spacer-like layers is clearly recognizable.
Figure 6 shows the transmission curve of a so-called three-cavity filter, according to the state of the art, that is comprised exclusively of a,14 and ~,/2 layers, as well as multiples thereof. In this case stacks 1, 2, 5 and 6 are built up identically, and stacks 3 and 4 have mirror coatings consisting of 3/4 7~-layers. A stack denotes a large number of a,14 I;~yers (or multiples thereof) of alternating high and low-refractive-index materials. A cavity comprises two stacks that are separated by spacer layers as, for example, a x,12 layer made of high or low-refractive-index material. The coupling 5 layers between the individual cavities, for example, can be low-refractive -index ~./4 layers.
The design, according to the state of the art, likewise shows a good approximation to the specified, second desired characteristic, as can be seen from the comparison between Figure 3 and Figure 6.
As shown by the refractive-value path of the three-cavit~r filter, illustrated in Figure 7, the individual layers, as well as the two spacer layers are clearly thicker in construction. This leads to an almost 50% greater total thickness of layer in the state of the art, as compared to the design, according to the invention.
Another advantage of the invention is the great edge stE:epness, as well as a greater transmission in the passband width.
The illustrated, layered systems of an altered optical thickness are produced preferably with the help of the plasma-activat~sd CVD process as, for example, by applying an atomic monolayer or less per plasma pulse and by counting the pulses as described above.
Alternatively, the optical thickness of layer can be altered by changing the process parameters during the pulse interval that is variably adjustable.
The advantage of using the plasma-activated CVD process is the achievement of a very effective change-over and the possibility within the layered system to produce, in a simple way, layers of an optical thickness that deviates from x,14. In current continuous CVD proccases this is not possible without a change-over.
The very narrow-band ialters, produced according to the invention, whose 5 edge steepness is adjustable in a very controlled manner, can be used as edge-type filters of extreme edge steepness or as very slat gain-flattening filters. Furthermore, the introduced narrowband filters are suitable, due to io their precisely controllable transmission path, for multiplexers or demultiplexers in WDM (Wavelength-Division-Multiplex) or in DWDM (Dense-Wavelength-Division-Multiplex) systems of telecommunications engineering. A special advantage of this invenstion is the greatly reduced total thickness of layer as compared to the conventional design.
m
Claims
1. A process, as set forth in Claim 1, is characterized by determining the number N of the plasma pulses in order to obtain a .lambda./4 or .lambda./2 layer, and that in order to produce a thickness of layer that deviates from .lambda./4 or .lambda./2, the number N of the plasma pulses in relation to N is increased or decreased by n whilst N is always >n.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE1999132082 DE19932082A1 (en) | 1999-07-12 | 1999-07-12 | Interference optical narrow band filter |
| DE19932082.9 | 1999-07-12 | ||
| PCT/EP2000/006518 WO2001004668A1 (en) | 1999-07-12 | 2000-07-10 | Narrow-band optical interference filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2379077A1 true CA2379077A1 (en) | 2001-01-18 |
Family
ID=7914238
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002379077A Abandoned CA2379077A1 (en) | 1999-07-12 | 2000-07-10 | Narrow-band optical interference filter |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP1194799A1 (en) |
| CN (1) | CN1360681A (en) |
| AU (2) | AU5826800A (en) |
| CA (1) | CA2379077A1 (en) |
| DE (1) | DE19932082A1 (en) |
| TW (1) | TW452666B (en) |
| WO (2) | WO2001004669A1 (en) |
Families Citing this family (23)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10143145C1 (en) * | 2001-09-03 | 2002-10-31 | Fraunhofer Ges Forschung | Production of layer system used for optical precision components comprises depositing individual layers on substrate in vacuum deposition chamber using pulsed magnetron sputtering stations at prescribed speed |
| US20080037127A1 (en) * | 2006-03-31 | 2008-02-14 | 3M Innovative Properties Company | Wide angle mirror system |
| US9545360B2 (en) | 2009-05-13 | 2017-01-17 | Sio2 Medical Products, Inc. | Saccharide protective coating for pharmaceutical package |
| ES2513866T3 (en) | 2009-05-13 | 2014-10-27 | Sio2 Medical Products, Inc. | Container coating and inspection |
| US9458536B2 (en) | 2009-07-02 | 2016-10-04 | Sio2 Medical Products, Inc. | PECVD coating methods for capped syringes, cartridges and other articles |
| US11624115B2 (en) | 2010-05-12 | 2023-04-11 | Sio2 Medical Products, Inc. | Syringe with PECVD lubrication |
| US9878101B2 (en) | 2010-11-12 | 2018-01-30 | Sio2 Medical Products, Inc. | Cyclic olefin polymer vessels and vessel coating methods |
| US9272095B2 (en) | 2011-04-01 | 2016-03-01 | Sio2 Medical Products, Inc. | Vessels, contact surfaces, and coating and inspection apparatus and methods |
| US11116695B2 (en) | 2011-11-11 | 2021-09-14 | Sio2 Medical Products, Inc. | Blood sample collection tube |
| JP6095678B2 (en) | 2011-11-11 | 2017-03-15 | エスアイオーツー・メディカル・プロダクツ・インコーポレイテッド | Passivation, pH protection or slippery coatings for pharmaceutical packages, coating processes and equipment |
| CN102759768B (en) * | 2012-07-31 | 2014-12-31 | 杭州科汀光学技术有限公司 | Optical filter |
| WO2014071061A1 (en) | 2012-11-01 | 2014-05-08 | Sio2 Medical Products, Inc. | Coating inspection method |
| EP2920567B1 (en) | 2012-11-16 | 2020-08-19 | SiO2 Medical Products, Inc. | Method and apparatus for detecting rapid barrier coating integrity characteristics |
| US9764093B2 (en) | 2012-11-30 | 2017-09-19 | Sio2 Medical Products, Inc. | Controlling the uniformity of PECVD deposition |
| EP2925903B1 (en) | 2012-11-30 | 2022-04-13 | Si02 Medical Products, Inc. | Controlling the uniformity of pecvd deposition on medical syringes, cartridges, and the like |
| EP2961858B1 (en) | 2013-03-01 | 2022-09-07 | Si02 Medical Products, Inc. | Coated syringe. |
| EP2971228B1 (en) | 2013-03-11 | 2023-06-21 | Si02 Medical Products, Inc. | Coated packaging |
| US9937099B2 (en) | 2013-03-11 | 2018-04-10 | Sio2 Medical Products, Inc. | Trilayer coated pharmaceutical packaging with low oxygen transmission rate |
| US9863042B2 (en) | 2013-03-15 | 2018-01-09 | Sio2 Medical Products, Inc. | PECVD lubricity vessel coating, coating process and apparatus providing different power levels in two phases |
| EP3693493A1 (en) | 2014-03-28 | 2020-08-12 | SiO2 Medical Products, Inc. | Antistatic coatings for plastic vessels |
| CN116982977A (en) | 2015-08-18 | 2023-11-03 | Sio2医药产品公司 | Medicaments and other packages with low oxygen transmission rate |
| CN106597591B (en) * | 2017-01-25 | 2022-07-26 | 杭州科汀光学技术有限公司 | Quasi-rectangular narrow-band filter with high cut-off and low ripple |
| CN111399104B (en) * | 2020-04-26 | 2021-02-09 | 腾景科技股份有限公司 | Double-peak ultra-narrow-band steep optical interference filter and manufacturing method thereof |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CH557546A (en) * | 1972-10-19 | 1974-12-31 | Balzers Patent Beteilig Ag | A REFLECTION-REDUCING COVERING COMPOSED OF A MULTIPLE OR COMPOSITE (LAMBDA) / 4-LAYERS. |
| US4373782A (en) * | 1980-06-03 | 1983-02-15 | Optical Coating Laboratory, Inc. | Non-polarizing thin film edge filter |
| SU1125588A1 (en) * | 1982-01-27 | 1984-11-23 | Киевское Научно-Производственное Объединение "Аналитприбор" | Interferention cutting filter |
| JPS619604A (en) * | 1984-06-23 | 1986-01-17 | Koshin Kogaku:Kk | Multi-layered dielectric film filter |
| US4793669A (en) * | 1987-09-11 | 1988-12-27 | Coherent, Inc. | Multilayer optical filter for producing colored reflected light and neutral transmission |
| US4896928A (en) * | 1988-08-29 | 1990-01-30 | Coherent, Inc. | Chromatically invariant multilayer dielectric thin film coating |
| EP0753082B1 (en) * | 1994-03-29 | 1999-07-07 | Schott Glas | Pcvd process and device for coating domed substrates |
| DE4445427C2 (en) * | 1994-12-20 | 1997-04-30 | Schott Glaswerke | Plasma CVD method for producing a gradient layer |
| US6011652A (en) * | 1997-12-23 | 2000-01-04 | Cushing; David Henry | Multilayer thin film dielectric bandpass filter |
-
1999
- 1999-07-12 DE DE1999132082 patent/DE19932082A1/en not_active Withdrawn
-
2000
- 2000-07-10 WO PCT/EP2000/006519 patent/WO2001004669A1/en active Application Filing
- 2000-07-10 EP EP00944023A patent/EP1194799A1/en not_active Withdrawn
- 2000-07-10 AU AU58268/00A patent/AU5826800A/en not_active Abandoned
- 2000-07-10 WO PCT/EP2000/006518 patent/WO2001004668A1/en not_active Application Discontinuation
- 2000-07-10 CN CN 00810229 patent/CN1360681A/en active Pending
- 2000-07-10 AU AU66906/00A patent/AU6690600A/en not_active Abandoned
- 2000-07-10 CA CA002379077A patent/CA2379077A1/en not_active Abandoned
- 2000-08-17 TW TW89113814A patent/TW452666B/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| TW452666B (en) | 2001-09-01 |
| WO2001004668A1 (en) | 2001-01-18 |
| DE19932082A1 (en) | 2001-01-18 |
| CN1360681A (en) | 2002-07-24 |
| AU5826800A (en) | 2001-01-30 |
| EP1194799A1 (en) | 2002-04-10 |
| WO2001004669A1 (en) | 2001-01-18 |
| AU6690600A (en) | 2001-01-30 |
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