CA2315006A1 - Temperature insensitive mach-zehnder interferometer - Google Patents
Temperature insensitive mach-zehnder interferometer Download PDFInfo
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- CA2315006A1 CA2315006A1 CA 2315006 CA2315006A CA2315006A1 CA 2315006 A1 CA2315006 A1 CA 2315006A1 CA 2315006 CA2315006 CA 2315006 CA 2315006 A CA2315006 A CA 2315006A CA 2315006 A1 CA2315006 A1 CA 2315006A1
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- fiber
- temperature
- length
- optical
- coat
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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
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29346—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by wave or beam interference
- G02B6/2935—Mach-Zehnder configuration, i.e. comprising separate splitting and combining means
- G02B6/29352—Mach-Zehnder configuration, i.e. comprising separate splitting and combining means in a light guide
-
- 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
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29379—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means characterised by the function or use of the complete device
- G02B6/29398—Temperature insensitivity
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Light Guides In General And Applications Therefor (AREA)
Abstract
A Mach-Zehnder interferometer comprising two optical couplers intercommunicated by two optical fibers. One of the optical fibers has a predeterminded portion of its length surrounded by a coat. The material of the coat has a coeffiecient of thermal expansion which, in combination with the dimensions of the coat, influences the characteristics of the fiber to render it temperature insensitive. In this temperature insensitive fiber, temperature induced changes in the geometrical length and refracture index of the fiber offset each other whereby the optical path length of the fiber is unaffected by change in temperature.
Also included is an optical fiber of specific length and having such a coat over a predetermined portion of its length to render the fiber temperature insensitive.
Also included is an optical fiber of specific length and having such a coat over a predetermined portion of its length to render the fiber temperature insensitive.
Description
TEMPERATURE INSENSITIVE MACH-ZEHNDER INTERFEROMETER
This invention generally relates to optical communication systems and more particularly optical interleavers and interferometers.
The most favorite way to utilize the large bandwidth of optical fibers is to use optical wavelength division multiplexing (WDM) scheme. In this technique, the available bandwidth is partitioned amongst a number of parallel wavelength (frequency) channels where each channel carries up to a maximum rate accessible to electronic interfaces. Furthermore, different protocols and framing lay be used on different channels.
In the transmitter side of a WDM system, there are a number of different laser sources with di#~erent wavelengths. Each data channel is modulated on one of the wavelength channels and aII the wavelength channels are multiplexed and sent to the same ~ica1 fiber. In the receiving end, each channel must be demultiplexed from the set of wavelength channels. An optical receiver, then, will demodulate data from each channel. It is obvious that multiplexers, ~rnultiplexes, and filters in general are the very essential components of such a system.
The cap~ity of a WDM system increases as more wavelength channels are established. If the total wavelength window remains fixed, the only way to increase the number of channels is to decrease channel spacing, i.e. tighter channel sets. As a matter of fact, in order to exploit the total available bandwidth in ~tical fiber, we need to increase the number of channels, decrease the channel spacing and increase the total wavelength window.
In order to use channels that are spaced tighter, sharper and more precise filters are needed. There are a number of techniques to make optical filters, such as thin film, fiber brag grating and Asymmetric Mach-Zehnder I~ferometer (MZI) based sclurmes. The latter is known to offer the sharpest and simplest of ail.
Asymmetric MZI consists of two optical couplers (or Y branches) connected by two waveguides, i.e. optical fibers, of different length. The differential delay contributes to the interference and consequently forms the filtering function. One can control the channel spacing by changing the length difference of an Asymmetric MZI. A
typical MZI is slmwn in Figure 1.
Asymmetric MZI has a periodic sinusoidal wavelength response. One example is shown in Figure 2. Its transfer function for output light intensity versus input light intensity follows the following periodic function.
F(Jl) = lfi (1 + exp(j.
This invention generally relates to optical communication systems and more particularly optical interleavers and interferometers.
The most favorite way to utilize the large bandwidth of optical fibers is to use optical wavelength division multiplexing (WDM) scheme. In this technique, the available bandwidth is partitioned amongst a number of parallel wavelength (frequency) channels where each channel carries up to a maximum rate accessible to electronic interfaces. Furthermore, different protocols and framing lay be used on different channels.
In the transmitter side of a WDM system, there are a number of different laser sources with di#~erent wavelengths. Each data channel is modulated on one of the wavelength channels and aII the wavelength channels are multiplexed and sent to the same ~ica1 fiber. In the receiving end, each channel must be demultiplexed from the set of wavelength channels. An optical receiver, then, will demodulate data from each channel. It is obvious that multiplexers, ~rnultiplexes, and filters in general are the very essential components of such a system.
The cap~ity of a WDM system increases as more wavelength channels are established. If the total wavelength window remains fixed, the only way to increase the number of channels is to decrease channel spacing, i.e. tighter channel sets. As a matter of fact, in order to exploit the total available bandwidth in ~tical fiber, we need to increase the number of channels, decrease the channel spacing and increase the total wavelength window.
In order to use channels that are spaced tighter, sharper and more precise filters are needed. There are a number of techniques to make optical filters, such as thin film, fiber brag grating and Asymmetric Mach-Zehnder I~ferometer (MZI) based sclurmes. The latter is known to offer the sharpest and simplest of ail.
Asymmetric MZI consists of two optical couplers (or Y branches) connected by two waveguides, i.e. optical fibers, of different length. The differential delay contributes to the interference and consequently forms the filtering function. One can control the channel spacing by changing the length difference of an Asymmetric MZI. A
typical MZI is slmwn in Figure 1.
Asymmetric MZI has a periodic sinusoidal wavelength response. One example is shown in Figure 2. Its transfer function for output light intensity versus input light intensity follows the following periodic function.
F(Jl) = lfi (1 + exp(j.
2~~L~,, In this equation, 3t is the average refractive index of the media that light is propagating, ~, is the wavelength of the light and oL~,, is the free space optical path length difference between the two arms. The MZI can be used as the building block in an optical wavelength multiplexerldemultiplexer. As shown in the above equation, MZI characteristic mainly depends on the oL~,,. Unfortunately, this factor changes with temperature. In fact, MZI suffers from its sever sensitivity to temperature.
The optical path length is a function of index of refraction of the fiber as well as its geometric length. In the prior art, active methods are mostly used to compensate for the variation in the optical length. In one active method, a piezoelectric stretcher is used to control the fiber length based on the ambient temperature so that tile optical path length of the fibex remains the same: In other designs, the temperature of the device is kit above the ambient temperature to provide a constant working temperature.
a In passive temperature compensation techniques, a mechanical stretching mechanism is mostly used. In some of these schemes, the fiber arms are pre-stretched so that with the temperature raise the tension is released and the length stays the same.
These methods, however, highly depend on a mechanical compensation system that could be temperature sensitive and difficult to fine tune.
In this invention, the physical characteristics of the fiber and a coating material are used to provi~ intrinsic temperature compensation. This technique does not need any fiutl~ adjustments or control once it is applied.
A novel design is proposed in this invention to remove the sensitivity of the Mach-Zehnder Interferometer (MZn to enable its use in forming very sharp filters for systems with very tight channel spacing. In this technique, a layer of a poly selected material is deposited onto a small section of one arm or both arms of the MZI to compensate for the temperature-~ variations. An important point about this invention is that the temperature compensation method used is a passive method and no active control is .
Figure i presents the general stcvcture of the asymmetric Mach-Zxhnder Interferometer (MZI).
Figure 2 illustrates the transfer fiu~ction of the MZI periodic filter.
Figures 3 snd 4 show typical single c~pticai fiber cross-sections.
Figures 5, 6 and 7 show the temperature compensation technique of depositing a coating Layer onto the fiber imroduced in this invention.
Figures 8 aed 9 display the length of the coating section for the example discussed in detail.
The optical path length is a function of index of refraction of the fiber as well as its geometric length. In the prior art, active methods are mostly used to compensate for the variation in the optical length. In one active method, a piezoelectric stretcher is used to control the fiber length based on the ambient temperature so that tile optical path length of the fibex remains the same: In other designs, the temperature of the device is kit above the ambient temperature to provide a constant working temperature.
a In passive temperature compensation techniques, a mechanical stretching mechanism is mostly used. In some of these schemes, the fiber arms are pre-stretched so that with the temperature raise the tension is released and the length stays the same.
These methods, however, highly depend on a mechanical compensation system that could be temperature sensitive and difficult to fine tune.
In this invention, the physical characteristics of the fiber and a coating material are used to provi~ intrinsic temperature compensation. This technique does not need any fiutl~ adjustments or control once it is applied.
A novel design is proposed in this invention to remove the sensitivity of the Mach-Zehnder Interferometer (MZn to enable its use in forming very sharp filters for systems with very tight channel spacing. In this technique, a layer of a poly selected material is deposited onto a small section of one arm or both arms of the MZI to compensate for the temperature-~ variations. An important point about this invention is that the temperature compensation method used is a passive method and no active control is .
Figure i presents the general stcvcture of the asymmetric Mach-Zxhnder Interferometer (MZI).
Figure 2 illustrates the transfer fiu~ction of the MZI periodic filter.
Figures 3 snd 4 show typical single c~pticai fiber cross-sections.
Figures 5, 6 and 7 show the temperature compensation technique of depositing a coating Layer onto the fiber imroduced in this invention.
Figures 8 aed 9 display the length of the coating section for the example discussed in detail.
This invention introduces a novel temperature insensitive Mach-Zehnder Interferometer (MZI) design. This structure could be used in many other optical systems that use MZI. This is particularly significant in Dense Wavelength Division Multiplexing (DWDM) subsystems such as optical interleaver, multiplexer/demultiplexer and f lters which are based on MZI. This architecture also enables very tightly spaced periodic MZI filters with very sharp response.
Asymmetric MZI consists of two optical (50:50) couplers connected with two fiber arms having different optical path lengths. This is shown in Figure 1. As shown in the figure, one arm is longer than the other one by oL. Once the temperature changes, the lengths of the optical path of the two arms also change. Since two arms do not have the same length, one experiences more changes than the other one.
It shcmld be noted, however, that the temperature dependency is not only because of the geometric path length expansion or contraction but also because of the change of the refraction index of the fiber. In this invention, a novel method is introduced to compensate for both effects and consequently the changes caused by temperature variation.
A typical optical fiber is depicted in Figures 3 and 4. In the f gores, the fiber core radius is indicated by ~ and the cladding radius by Rte. The Coefficient of Thermal Expansi~ (C'I'E) of the core material is a~ and that of the cladding material is ate. The effective CTE of the optical fiber is a,~ _ (a~"~ A~ + aA!(A~ + Ate, Eq. 1 where A~", and Aare the cross-sectional areas of the core and cladding, respectively. The above formula is simply a weighted average of the two coefficients of rherm$1 expansion.
Asymmetric MZI consists of two optical (50:50) couplers connected with two fiber arms having different optical path lengths. This is shown in Figure 1. As shown in the figure, one arm is longer than the other one by oL. Once the temperature changes, the lengths of the optical path of the two arms also change. Since two arms do not have the same length, one experiences more changes than the other one.
It shcmld be noted, however, that the temperature dependency is not only because of the geometric path length expansion or contraction but also because of the change of the refraction index of the fiber. In this invention, a novel method is introduced to compensate for both effects and consequently the changes caused by temperature variation.
A typical optical fiber is depicted in Figures 3 and 4. In the f gores, the fiber core radius is indicated by ~ and the cladding radius by Rte. The Coefficient of Thermal Expansi~ (C'I'E) of the core material is a~ and that of the cladding material is ate. The effective CTE of the optical fiber is a,~ _ (a~"~ A~ + aA!(A~ + Ate, Eq. 1 where A~", and Aare the cross-sectional areas of the core and cladding, respectively. The above formula is simply a weighted average of the two coefficients of rherm$1 expansion.
Replacing A~ by ~~2 and Aby ar(R2- R,~,r2) we get to «,~,. _ (~/ R~,~)2 («~ - «+ «,. Eq. 2 The optical path L~ of an optical fiber of geometric length L,~ and index refraction of n is 1~ = nL~. Eq. 3 Consequently, the change of the refractive index or geoic length can affect the optical path length as shown in the following.
~L~ _ ~n~ L,,o + n ~ ~L"o Eq. 4 In this equation, Qn is the thermal change in the refractive index for a temperature change of oT degrees, which is equal to (dnldTj4T. Similarly,OL,~ indicates the thermal expansion or contraction of the geometric length of the fiber for ~T, i.e.
01.~ _ (dL~IdTj~T . R~lacing them in the above equation, we can get ~L~ _ [L~(dnldTj+ n(dl,,~IdTj]aT Eq. 5 We also know that in the linear region of the thermal expansion of the geometric length of the fiber dl,,~IdT = a,~L~. Therefore, DLL _ [(dnldTj + na,~]L~d T. Eq. 6 From the above equation,if (dnldT) + n«"~ = 0, or (dnldTj= -na~,then L~ = 0, i.e. optical path lengtfi does not change with temperature. The typical values for a"~
are in the range of 10-' (C-'), while typical values for dnldT are usually negative in the range of -10~ (C-'). Therefore, there is a chance to select some of the parameters S
of the fiber, such as the core or cladding radius, core or cladding material, and so on, to make it as temperature insensitive fiber. in this invention, however, a simpler method is used to fix the temperature sensitivity of the asymmetric MZI.
In the scheme proposed in this invention, a lays of a properly selected material is deposited onto a small portion of optical fiber constituting one arm or both arms of the MZI. There are a number of advantages to this method; some of them are discussed below. This method eliminates all the complexity of the specialty fiber r~nufacturing needed for the temperature insensitive fiber. Secondly, the d~osited material can be selected from a wider range of materials by properly calculating the thickness of the deposition layer. Thirdly, this method is not as complicated as the fabrication of the specialty temperature insensitive fiber. Finally, the method can be easily adapted to different fiber types.
Figures 5, 6 and 7 show the general case where a layer of a properly selected material is deposited onto each arm of the MZI. For the spotter arm, the length of the coating region is shown by 1,, the radius of the resulting cross-s~tional radius and area by Rl and A1, respectively. Similarly, l2, RZ and A2 show the length, resulting cross-sectional radius and area for the longer arm. The CTE for the coating material on the shorter arm is a.~,a,~ and a~~ for the longer arm. The effective C'fE for these regions can be calculated by «, = (c~~ A~ + aA~ + a~,~ Al)l(A~ + A+ A,), Eq. 7 where i = 1,2. In the above equation, a, and a2 are the effective CTE for the dated region of the shorter and longer arm, respectively. Again replacing the cross-sectional areas we get to ai = (~~ROi (ate -aa.aaa~ + (~aaa~ ~Rr)2 (a~.uawa -a~.cc~) + a~ecnv Eq. 8 and 1 = 1,2.
Now assume the geometric length of the shorter arm of the MZI to be L,,, a~
the longer arm to be Lø = 1,~, + ~ . As discussed before, in order to compensate for the temperature changes the following condition must satisfy.
oL,~ _ ~L~ Eq. 9 Replacing each side for a D T temperature change, we find (dnldt + na"~.)(1,~, -l,)~T + (dnfdT + na,)11~T =
(dnldT + na~)(La, + to - lz)4T + (dnldT + na2)h Fsq. 10 If we rearrange and simplify the equation, we can write it as (a, - a~)nl, =(a2 - a~)n12 + (dn/dT + na,~,)~. Eq. 11 If we assume the coating length on one of the arms, the above equation gives the coating length on the other arm of the MZI. For the simplest case, we deposit on only one arm. In that case, we set the Iength of the coating region on of the arms to zero.
If the coating section is one the shorter arm, then (dnldT + na"~,.)lo l,= ,12=0 Eq.l2-1 n(a2 -a,~«) If the coating section is on the longer arm, then -(dn/dT + na,~)~
h = 0, l2 = Eq.l3-2 n(az -~) a~,.=a~=5.6X10-'(/~G~
a~~ = 2 X 10'6 (/' G') R~ = 8 micrometer R= 125 micrometer RZ = ( 125 + 50) = 175 micrometer az = 1.27 x 10'6 (/~ G~
IZ = 9.92 mm dl = 0 If we increase the thickness of the coating layer to 0.1 mm (100 micrometer), 0.5 mm (500 micrometer), and 1 mm (1000 micrometer), we obtain the following results.
Coating R2 = ( 125 + 100) = 225 micrometer thickness a2 = 1.56 x 10'6 (/ ~ G'~
0.1 mm l2 = 7.04 mm Coating RZ = (125 + 500) = 625 micrometer thickness a2 = 1.94 X 10'~ (/ ~ G~
O.Smm IZ=5.llmm Coating RZ = ( 125 + 1000) = 1125 micrometer thickness az = 1.98 X 10~ (/ ~ G') 1 mm h = 4.96 mm In Figure 8, l2 values for different coating thickness values are plotted for the above parameters. We see that for thick layers of coating, the length of the coating region gets to a limit, which is around 4.92 for the above example. Figure 9 shows the above results for different coating materials with different CTEs.
Similar calculations can be carried out to find thickness and length of the coating section for the case of the d~ositian on the shorter arm of the MZI. It is apparent that a combination of deposition on both arms can also be done. In this case, the length of coating on one of the arms depends on the other one. BAs a result, one of the lenghts (i.e. h or lZ) is the free parameter.
~L~ _ ~n~ L,,o + n ~ ~L"o Eq. 4 In this equation, Qn is the thermal change in the refractive index for a temperature change of oT degrees, which is equal to (dnldTj4T. Similarly,OL,~ indicates the thermal expansion or contraction of the geometric length of the fiber for ~T, i.e.
01.~ _ (dL~IdTj~T . R~lacing them in the above equation, we can get ~L~ _ [L~(dnldTj+ n(dl,,~IdTj]aT Eq. 5 We also know that in the linear region of the thermal expansion of the geometric length of the fiber dl,,~IdT = a,~L~. Therefore, DLL _ [(dnldTj + na,~]L~d T. Eq. 6 From the above equation,if (dnldT) + n«"~ = 0, or (dnldTj= -na~,then L~ = 0, i.e. optical path lengtfi does not change with temperature. The typical values for a"~
are in the range of 10-' (C-'), while typical values for dnldT are usually negative in the range of -10~ (C-'). Therefore, there is a chance to select some of the parameters S
of the fiber, such as the core or cladding radius, core or cladding material, and so on, to make it as temperature insensitive fiber. in this invention, however, a simpler method is used to fix the temperature sensitivity of the asymmetric MZI.
In the scheme proposed in this invention, a lays of a properly selected material is deposited onto a small portion of optical fiber constituting one arm or both arms of the MZI. There are a number of advantages to this method; some of them are discussed below. This method eliminates all the complexity of the specialty fiber r~nufacturing needed for the temperature insensitive fiber. Secondly, the d~osited material can be selected from a wider range of materials by properly calculating the thickness of the deposition layer. Thirdly, this method is not as complicated as the fabrication of the specialty temperature insensitive fiber. Finally, the method can be easily adapted to different fiber types.
Figures 5, 6 and 7 show the general case where a layer of a properly selected material is deposited onto each arm of the MZI. For the spotter arm, the length of the coating region is shown by 1,, the radius of the resulting cross-s~tional radius and area by Rl and A1, respectively. Similarly, l2, RZ and A2 show the length, resulting cross-sectional radius and area for the longer arm. The CTE for the coating material on the shorter arm is a.~,a,~ and a~~ for the longer arm. The effective C'fE for these regions can be calculated by «, = (c~~ A~ + aA~ + a~,~ Al)l(A~ + A+ A,), Eq. 7 where i = 1,2. In the above equation, a, and a2 are the effective CTE for the dated region of the shorter and longer arm, respectively. Again replacing the cross-sectional areas we get to ai = (~~ROi (ate -aa.aaa~ + (~aaa~ ~Rr)2 (a~.uawa -a~.cc~) + a~ecnv Eq. 8 and 1 = 1,2.
Now assume the geometric length of the shorter arm of the MZI to be L,,, a~
the longer arm to be Lø = 1,~, + ~ . As discussed before, in order to compensate for the temperature changes the following condition must satisfy.
oL,~ _ ~L~ Eq. 9 Replacing each side for a D T temperature change, we find (dnldt + na"~.)(1,~, -l,)~T + (dnfdT + na,)11~T =
(dnldT + na~)(La, + to - lz)4T + (dnldT + na2)h Fsq. 10 If we rearrange and simplify the equation, we can write it as (a, - a~)nl, =(a2 - a~)n12 + (dn/dT + na,~,)~. Eq. 11 If we assume the coating length on one of the arms, the above equation gives the coating length on the other arm of the MZI. For the simplest case, we deposit on only one arm. In that case, we set the Iength of the coating region on of the arms to zero.
If the coating section is one the shorter arm, then (dnldT + na"~,.)lo l,= ,12=0 Eq.l2-1 n(a2 -a,~«) If the coating section is on the longer arm, then -(dn/dT + na,~)~
h = 0, l2 = Eq.l3-2 n(az -~) a~,.=a~=5.6X10-'(/~G~
a~~ = 2 X 10'6 (/' G') R~ = 8 micrometer R= 125 micrometer RZ = ( 125 + 50) = 175 micrometer az = 1.27 x 10'6 (/~ G~
IZ = 9.92 mm dl = 0 If we increase the thickness of the coating layer to 0.1 mm (100 micrometer), 0.5 mm (500 micrometer), and 1 mm (1000 micrometer), we obtain the following results.
Coating R2 = ( 125 + 100) = 225 micrometer thickness a2 = 1.56 x 10'6 (/ ~ G'~
0.1 mm l2 = 7.04 mm Coating RZ = (125 + 500) = 625 micrometer thickness a2 = 1.94 X 10'~ (/ ~ G~
O.Smm IZ=5.llmm Coating RZ = ( 125 + 1000) = 1125 micrometer thickness az = 1.98 X 10~ (/ ~ G') 1 mm h = 4.96 mm In Figure 8, l2 values for different coating thickness values are plotted for the above parameters. We see that for thick layers of coating, the length of the coating region gets to a limit, which is around 4.92 for the above example. Figure 9 shows the above results for different coating materials with different CTEs.
Similar calculations can be carried out to find thickness and length of the coating section for the case of the d~ositian on the shorter arm of the MZI. It is apparent that a combination of deposition on both arms can also be done. In this case, the length of coating on one of the arms depends on the other one. BAs a result, one of the lenghts (i.e. h or lZ) is the free parameter.
Claims (5)
1. A Mach-Zehnder interferometer comprising two optical couplers intercommunicated together by two optical fibers one of which has a predetermined portion of its length surrounded by a coat of a material having a coefficient of thermal expansion which, in combination with the dimensions of the coat, influences the characteristics of the fiber to render it temperature insensitive in which temperature induced changes in the geometrical length and refractive index of the temperature insensitive fiber offset each other whereby the optical path length of the temperature insensitive fiber is unaffected by change in temperature.
2. A Mach-Zehnder interferometer according to Claim 1 wherein the temperature insensitive fiber is shorter than the other fiber.
3. A Mach-Zehnder interferometer according to Claim 1 wherein the temperature insensitive fiber is longer than the other fiber.
4. An optical fiber of specific length and having a predetermined portion of its length surrounded by a coat of a material having a coefficient of thermal expansion which, in combination with the dimensions of the coat, influences the characteristics of the fiber to render it temperature insensitive in which temperature induced changes in geometrical length and refractive index of the temperature insensitive fiber offset each other whereby the optical path of the temperature insensitive fiber is unaffected by change in temperature.
5. A Dense Wavelength Division Multiplexing system comprising a Mach-Zehnder interferometer comprising two optical couplers intercommunicated together by two optical fibers one of which has a predetermined portion of its length surrounded by a coat of a material having coefficient of thermal expansion which, in combination with dimensions of the coat, influences the characteristics of the fiber to render it temperature insensitive in which temperature induced changes in the geometrical length and refractive index of the temperature insensitive fiber offset each other whereby the optical path length of the temperature insensitive fiber is unaffected by change in temperature.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2315006 CA2315006A1 (en) | 2000-08-03 | 2000-08-03 | Temperature insensitive mach-zehnder interferometer |
| US09/920,050 US6778278B2 (en) | 2000-08-03 | 2001-08-02 | Temperature insensitive Mach-Zehnder interferometers and devices |
| CA 2354752 CA2354752A1 (en) | 2000-08-03 | 2001-08-03 | Temperature insensitive mach-zehnder interferometers and devices |
| US10/886,553 US6900898B2 (en) | 2000-08-03 | 2004-07-09 | Temperature insensitive Mach-Zehnder interferometers and devices |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2315006 CA2315006A1 (en) | 2000-08-03 | 2000-08-03 | Temperature insensitive mach-zehnder interferometer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2315006A1 true CA2315006A1 (en) | 2002-02-03 |
Family
ID=4166836
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2315006 Abandoned CA2315006A1 (en) | 2000-08-03 | 2000-08-03 | Temperature insensitive mach-zehnder interferometer |
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| Country | Link |
|---|---|
| CA (1) | CA2315006A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016018508A3 (en) * | 2014-06-03 | 2016-08-04 | Nikon Metrology Nv | Thermally compensated fiber interferomoeter assembly |
| CN116299869A (en) * | 2023-05-17 | 2023-06-23 | 国开启科量子技术(北京)有限公司 | Optical fiber interference device and quantum communication equipment |
-
2000
- 2000-08-03 CA CA 2315006 patent/CA2315006A1/en not_active Abandoned
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2016018508A3 (en) * | 2014-06-03 | 2016-08-04 | Nikon Metrology Nv | Thermally compensated fiber interferomoeter assembly |
| US10989879B2 (en) | 2014-06-03 | 2021-04-27 | Nikon Metrology Nv | Thermally compensated fiber interferometer assembly |
| CN116299869A (en) * | 2023-05-17 | 2023-06-23 | 国开启科量子技术(北京)有限公司 | Optical fiber interference device and quantum communication equipment |
| CN116299869B (en) * | 2023-05-17 | 2023-10-03 | 国开启科量子技术(北京)有限公司 | Optical fiber interference device and quantum communication equipment |
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