CA2291385A1 - Tunable optical fiber gratings device - Google Patents
Tunable optical fiber gratings device Download PDFInfo
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- CA2291385A1 CA2291385A1 CA 2291385 CA2291385A CA2291385A1 CA 2291385 A1 CA2291385 A1 CA 2291385A1 CA 2291385 CA2291385 CA 2291385 CA 2291385 A CA2291385 A CA 2291385A CA 2291385 A1 CA2291385 A1 CA 2291385A1
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- fiber
- neutral plane
- beam member
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- grating area
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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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02057—Optical fibres with cladding with or without a coating comprising gratings
- G02B6/02076—Refractive index modulation gratings, e.g. Bragg gratings
- G02B6/02195—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for tuning the grating
- G02B6/022—Refractive index modulation gratings, e.g. Bragg gratings characterised by means for tuning the grating using mechanical stress, e.g. tuning by compression or elongation, special geometrical shapes such as "dog-bone" or taper
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- Optics & Photonics (AREA)
- Mechanical Light Control Or Optical Switches (AREA)
Abstract
A tunable optical fiber grating device for tuning optical characteristic responses of an optical grating area of an optical fiber includes an elongated beam member defining a neutral plane with a first and a second ends and adapted to receive the fiber' therealong. A securing member continuously secures the grating area all along the beam member between its ends and generally parallel to the neutral plane to allow for transmission of a bend of the beam member about the neutral plane to the grating area. A fixed support member has a screw for releasably securing the first end of the beam member within the neutral plane, and a mobile support member has a slotted element to slidably receive the second end of the beam member within the neutral plane.
The mobile support member displaces the second end relative to the first end substantially perpendicularly to the neutral plane to bending the beam, thereby stretching or compressing the grating area for tuning the optical characteristic responses of the optical fiber depending on the direction of the bend.
The mobile support member displaces the second end relative to the first end substantially perpendicularly to the neutral plane to bending the beam, thereby stretching or compressing the grating area for tuning the optical characteristic responses of the optical fiber depending on the direction of the bend.
Description
Patent name: Tunable optical fiber gratings Background:
UV light can induce a permanent refractive index change in some kind optical fibers and optical wave-guides. The photosensitivity of the certain kind optical fiber waveguide can be used to make Bragg grating and long period gratings, which is a permanent, spatially periodic refractive index modulation along the length of the photosensitive core of the optical fiber or optic wave guide. Fiber Bragg gratings can selectively reflect specific wavelengths of light within an optical fiber. The selective reflected wavelength is equal to the twice the periods of the Bragg grating times the effective refractive index of the propagation mode. Fiber grating have many applications including band rejection filter, semiconductor laser stabilizer, fiber laser wavelength selector, fiber amplifier reflector, fiber dispersion compensation, DWDM filter, WDM add and drop multiplex, light pulse shape reforming, optical fiber switch, optical sensor. '1'-'6>
There is a demand to alter the periodic spacing of fiber refractive index perturbations in fiber core (or both core and cladding) to have tunable fiber grating whose wavelength can be controllable. The applications like tunable DWDM filter, dynamic DWDM add and drop multiplexes, tunable fiber laser, tunable wavelength selective switch are requiring tunable fiber Bragg gratings.
One attempt to make a tunable fiber grating uses a piezoelectric element to strain the grating. See Quetel et al., 1996 Technical Digest Series, Conf. on Optical Fiber Communication, San Jose, Calif., Feb. 25-Mar. 1, 1996, Vol. 2, p. 120, paper No. WF6.
The difficulty with this approach is that the strain produced by piezoelectric actuation is relatively small, limiting the tuning range of the device. Moreover, it requires a continuous application of relatively high voltage, e.g., approximately 100 volts for 1 nm strain. Accordingly, there is a need for a tunable fiber grating having an enhanced tuning range and no requirement for continuous power.
Another attempt is to use magnatostrictive strain for tuning the fiber grating (US patent 5812711). The disadvantages of this approach is that the size of large magnetostrictive component is not small and the cost of the device is relatively high.
G.A.Ball and W.W.Morey used compression-tuned approach to tune fiber Bragg grating over 32 run range. See G.A.Ball and W.W.Morey Optics Letters, Vol. 19, pp.
1979(1994). This approach needs very precisely grounded ceramic ferrules, and very high accurate alignment.
Benjamin L. Eggleton, John A. Rogers, Paul S. Westbrook and Thomas A. Strasser from Bell Lab, Lucent Technologies coated fiber with two metal layers, one uniform metal layer and one variable thickness metal layer along the fiber grating, to tune the fiber grating center wavelength and chirp independently. It is very complicated and costly to coate fiber with two different metal layers.
/.
Accordingly, there is a need for a tunable fiber grating having simple tuning mechanism and low cost.
Invention In the present invention, a tunable fiber grating comprises a fiber grating, a rotation stage and a cantilever beam. The fiber grating is secured on the cantilever beam by epoxy, welding or other approaches. The cantilever beam has one end fixed and another end free, which is pushed back and forth with a small groove mounted on the rotation stage. The cantilever beam is an uniform density and thickness, triangle shape made of metal or other materials. Both ends of the cantilever beam were mounted with thicker rectangle shape blocks to make sure that the bending length of the cantilever beam is fixed. The triangle shape of the cantilever beam is to serve the purpose that the bending angle is uniform along the cantilever beam. When the rotation stage turns, the groove on the rotation stage will push the free end of the cantilever beam and the cantilever beam will be bent. Since the fiber grating is secured on one surface of the cantilever beam, bending the cantilever beam in different directions will stretch or suppress the fiber grating. By compressing and stretching fiber grating, the invention has a large tunable wavelength range.
Brief Description of the drawings The advantages, nature and additional features of the invention will appear more fully upon consideration of the illustrative embodiments described in the accompanying drawings. In the drawings Figure 1 schematically illustrates a embodiment of a tunable fiber grating.
Figure 2 schematically illustrates a triangle shape cantilever beam with both ends mounted with thick metal blocks.
Figure 3 schematically illustrates a fiber with an optical grating is fixed on a cantilever beam with epoxy or other approach Figure 4 schematically illustrates a fiber with an optical grating is fixed on a v-groove of a cantilever beam with epoxy or other approach Figure 5 schematically illustrates a different curve shape of a cantilever beam with both ends mounted with thick metal blocks.
Figure 6 schematically illustrates another different curve shape of a cantilever beam with both ends mounted with thick metal blocks.
Figure 7 schematically illustrates using some bearings between the groove and the block to smooth the movement between the groove and the block.
Figure 8 schematically illustrates a tunable fiber grating driving with a motorized stage Figure 9 schematically illustrates a tunable fiber laser with two tunable fiber gratings Figure 10 schematically illustrates a tunable grating with a circulator to drop one wavelength It is to be understood that these drawings are for purpose of illustrating the concepts of the invention and are not to scale.
Detailed description Referring to the drawings, FIG.l schematically illustrates a tunable fiber grating 8 comprising a fiber 6 having a fiber grating 3 secured on a cantilever beam 9, one block 4 which is free (movable), one block 5 which can not be moved, a rotation stage
UV light can induce a permanent refractive index change in some kind optical fibers and optical wave-guides. The photosensitivity of the certain kind optical fiber waveguide can be used to make Bragg grating and long period gratings, which is a permanent, spatially periodic refractive index modulation along the length of the photosensitive core of the optical fiber or optic wave guide. Fiber Bragg gratings can selectively reflect specific wavelengths of light within an optical fiber. The selective reflected wavelength is equal to the twice the periods of the Bragg grating times the effective refractive index of the propagation mode. Fiber grating have many applications including band rejection filter, semiconductor laser stabilizer, fiber laser wavelength selector, fiber amplifier reflector, fiber dispersion compensation, DWDM filter, WDM add and drop multiplex, light pulse shape reforming, optical fiber switch, optical sensor. '1'-'6>
There is a demand to alter the periodic spacing of fiber refractive index perturbations in fiber core (or both core and cladding) to have tunable fiber grating whose wavelength can be controllable. The applications like tunable DWDM filter, dynamic DWDM add and drop multiplexes, tunable fiber laser, tunable wavelength selective switch are requiring tunable fiber Bragg gratings.
One attempt to make a tunable fiber grating uses a piezoelectric element to strain the grating. See Quetel et al., 1996 Technical Digest Series, Conf. on Optical Fiber Communication, San Jose, Calif., Feb. 25-Mar. 1, 1996, Vol. 2, p. 120, paper No. WF6.
The difficulty with this approach is that the strain produced by piezoelectric actuation is relatively small, limiting the tuning range of the device. Moreover, it requires a continuous application of relatively high voltage, e.g., approximately 100 volts for 1 nm strain. Accordingly, there is a need for a tunable fiber grating having an enhanced tuning range and no requirement for continuous power.
Another attempt is to use magnatostrictive strain for tuning the fiber grating (US patent 5812711). The disadvantages of this approach is that the size of large magnetostrictive component is not small and the cost of the device is relatively high.
G.A.Ball and W.W.Morey used compression-tuned approach to tune fiber Bragg grating over 32 run range. See G.A.Ball and W.W.Morey Optics Letters, Vol. 19, pp.
1979(1994). This approach needs very precisely grounded ceramic ferrules, and very high accurate alignment.
Benjamin L. Eggleton, John A. Rogers, Paul S. Westbrook and Thomas A. Strasser from Bell Lab, Lucent Technologies coated fiber with two metal layers, one uniform metal layer and one variable thickness metal layer along the fiber grating, to tune the fiber grating center wavelength and chirp independently. It is very complicated and costly to coate fiber with two different metal layers.
/.
Accordingly, there is a need for a tunable fiber grating having simple tuning mechanism and low cost.
Invention In the present invention, a tunable fiber grating comprises a fiber grating, a rotation stage and a cantilever beam. The fiber grating is secured on the cantilever beam by epoxy, welding or other approaches. The cantilever beam has one end fixed and another end free, which is pushed back and forth with a small groove mounted on the rotation stage. The cantilever beam is an uniform density and thickness, triangle shape made of metal or other materials. Both ends of the cantilever beam were mounted with thicker rectangle shape blocks to make sure that the bending length of the cantilever beam is fixed. The triangle shape of the cantilever beam is to serve the purpose that the bending angle is uniform along the cantilever beam. When the rotation stage turns, the groove on the rotation stage will push the free end of the cantilever beam and the cantilever beam will be bent. Since the fiber grating is secured on one surface of the cantilever beam, bending the cantilever beam in different directions will stretch or suppress the fiber grating. By compressing and stretching fiber grating, the invention has a large tunable wavelength range.
Brief Description of the drawings The advantages, nature and additional features of the invention will appear more fully upon consideration of the illustrative embodiments described in the accompanying drawings. In the drawings Figure 1 schematically illustrates a embodiment of a tunable fiber grating.
Figure 2 schematically illustrates a triangle shape cantilever beam with both ends mounted with thick metal blocks.
Figure 3 schematically illustrates a fiber with an optical grating is fixed on a cantilever beam with epoxy or other approach Figure 4 schematically illustrates a fiber with an optical grating is fixed on a v-groove of a cantilever beam with epoxy or other approach Figure 5 schematically illustrates a different curve shape of a cantilever beam with both ends mounted with thick metal blocks.
Figure 6 schematically illustrates another different curve shape of a cantilever beam with both ends mounted with thick metal blocks.
Figure 7 schematically illustrates using some bearings between the groove and the block to smooth the movement between the groove and the block.
Figure 8 schematically illustrates a tunable fiber grating driving with a motorized stage Figure 9 schematically illustrates a tunable fiber laser with two tunable fiber gratings Figure 10 schematically illustrates a tunable grating with a circulator to drop one wavelength It is to be understood that these drawings are for purpose of illustrating the concepts of the invention and are not to scale.
Detailed description Referring to the drawings, FIG.l schematically illustrates a tunable fiber grating 8 comprising a fiber 6 having a fiber grating 3 secured on a cantilever beam 9, one block 4 which is free (movable), one block 5 which can not be moved, a rotation stage
2 (rotated manually , or motorized), a groove 10 fixed on the rotation stage 2, and a base 1 for the rotation stage 2. The fiber grating 3 is attached on the cantilever 9, with glue or epoxy for example. One end of the cantilever 9 with block 5 is fixed on the rotation stage base 1. The another end of the cantilever 9 with block 4 is free and can be pushed back and forth. When the rotation stage 2 turns, the groove 10 will push the block 4 and the cantilever beam 9 will be bent. The bending of the cantilever beam 9 will compress or stretch the fiber grating 8 for changing the center wavelength of the fiber grating. In FIG. 1, the fiber grating is attached on the right side of the cantilever beam 9, bending the cantilever beam 9 on the right direction will compress the fiber grating 8, and bending the cantilever beam 9 on the left direction will stretch the fiber grating 8. Two blocks 4 and 5 are much thicker than the cantilever beam 9 so they can be considered as rigid and can not be bent. The cantilever beam 9 has a fixed length between these two blocks 4 and 5.
The material of the cantilever beam could be metal, plastic, polymer or other materials.
The shape of the cantilever beam 9 could be in a triangle shape shown in FIG.
2, or in a curved shape shown in FIGS and FIG.6. Of course, the cantilever beam 9 can be in a rectangle shape. One reason of using different shape other than the rectangle shape is to make the bending angle of the cantilever beam 9 very uniform from the position close to fixed point to far from the fixed point, so the fiber grating 8 will be compressed or stretched uniformly to have linear shift of the center wavelength and to have no chirped tuning.
The fiber grating can be stick on one surface of the cantilever beam 9 with glue or epoxy as shown in FIG. 3. The surface of the cantilever 9 can have a v-groove on its surface which the fiber grating is fixed as shown in FIG. 4. When the rotation stage 2 turns right (clockwise) as shown in FIG. 1, the cantilever beam 9 is bent and the fiber grating 8 is compressed. When the rotation stage 2 turns left (anti clock wise), the cantilever beam 9 is bent in opposite direction and the fiber grating 8 is stretched.
Combination of compression and stretch of the fiber grating 8, a large tuning range can be obtained.
Two blocks 4 and 5 have two functions: the first function is to fix the length of the cantilever beam 9 since the two blocks are much thicker than the cantilever beam 9 does and they can be treated as rigid. When the free block 4 is moving along the groove, the length of the cantilever beam 9, which can be bent, is constant. The second function of them is to lead the fiber out of the cantilever beam 9 and to prevent the fiber by touch from the groove 10 as shown in FIG. 3 and FIG 4.
To keep the bending angle of the cantilever 9 uniform everywhere during the increasing of the bending angle of the cantilever 9, the end of the cantilever beam 9 will not be traveling in a circular curve. The contact point of the groove 10 on the cantilever beam 9 will be slightly changed because the groove 10 is mounted on the rotation stage 2 and it travels on a circular track. The block 4 is fixed at the free end of the cantilever beam 9.
The contact point of the groove 10 is on the block 4, which is rigid and can not be bent, not on the end of the cantilever beam 9 directly. A small gap between the groove 10
The material of the cantilever beam could be metal, plastic, polymer or other materials.
The shape of the cantilever beam 9 could be in a triangle shape shown in FIG.
2, or in a curved shape shown in FIGS and FIG.6. Of course, the cantilever beam 9 can be in a rectangle shape. One reason of using different shape other than the rectangle shape is to make the bending angle of the cantilever beam 9 very uniform from the position close to fixed point to far from the fixed point, so the fiber grating 8 will be compressed or stretched uniformly to have linear shift of the center wavelength and to have no chirped tuning.
The fiber grating can be stick on one surface of the cantilever beam 9 with glue or epoxy as shown in FIG. 3. The surface of the cantilever 9 can have a v-groove on its surface which the fiber grating is fixed as shown in FIG. 4. When the rotation stage 2 turns right (clockwise) as shown in FIG. 1, the cantilever beam 9 is bent and the fiber grating 8 is compressed. When the rotation stage 2 turns left (anti clock wise), the cantilever beam 9 is bent in opposite direction and the fiber grating 8 is stretched.
Combination of compression and stretch of the fiber grating 8, a large tuning range can be obtained.
Two blocks 4 and 5 have two functions: the first function is to fix the length of the cantilever beam 9 since the two blocks are much thicker than the cantilever beam 9 does and they can be treated as rigid. When the free block 4 is moving along the groove, the length of the cantilever beam 9, which can be bent, is constant. The second function of them is to lead the fiber out of the cantilever beam 9 and to prevent the fiber by touch from the groove 10 as shown in FIG. 3 and FIG 4.
To keep the bending angle of the cantilever 9 uniform everywhere during the increasing of the bending angle of the cantilever 9, the end of the cantilever beam 9 will not be traveling in a circular curve. The contact point of the groove 10 on the cantilever beam 9 will be slightly changed because the groove 10 is mounted on the rotation stage 2 and it travels on a circular track. The block 4 is fixed at the free end of the cantilever beam 9.
The contact point of the groove 10 is on the block 4, which is rigid and can not be bent, not on the end of the cantilever beam 9 directly. A small gap between the groove 10
3 and the block 4 will allow the contact point of the groove 10 on the block 4 , which is fixed at the end of the cantilever beam 9, slightly shift. The shift of contact point on block 4 will not increase or decrease the cantilever length as we said before it is rigid.
Since the block 4 is rigid, only the cantilever beam will be bent. In this way the total length of the cantilever beam is fixed. The cantilever 9 will have the same bending angle along its length during its bending angle increasing. In this way we can achieve two goals at the same time: 1. the cantilever beam 9 always has a fixed length for the purpose of uniform bending angle along its length when the bending angle increase; 2. The act point on the end of the cantilever beam 9(here is the block 4) is slight shifted when the groove 10, which is fixed on the rotation stage 2, is moving in a circular track (using the groove on the rotation stage 2 to push the block 4). This very simple structure of the tunable fiber grating will be low cost and high accuracy for a wide tuning range.
The groove 10 mounted on the rotation stage 2 has a narrow slot to allow the cantilever slightly move back and forth inside it. The narrow slot of the groove 10, which is little bit wider than the cantilever beam thickness, can also reduce the backlash when it push the cantilever beam 9(here is the block 4) into opposite direction. To allow the block 4 move smoothly inside the groove 10 and to reduce the friction between the groove 10 and the block 4, some bearings can be installed on the slot of the groove 10 as shown in figure 7.
FIG. 8 is another example of the tunable fiber grating. The rotation stage 2 is driving by step motor or do motor 7. Because the step motor can be turned in a very small step, such as 0.001° degree, a high tuning resolution of the tunable fiber grating can be obtained.
Fiber grating can be used as wavelength selector (or formed a cavity) in a fiber laser.
Tunable fiber grating of course can be used for tunable fiber laser application. FIG. 9 is another example of applications of our tunable fiber grating. FGl and FG2 are both tunable fiber gratings. EDF is Erbium doped fiber or other doped fiber. By tuning the FG1 and FG2 simultaneously we could get different wavelength output from the fiber laser.
FIG. 10 is another example of application of our tunable fiber grating.
Combined a three-port circulator with our tunable fiber grating, we can make a tunable WDM drop multiplexer/demultiplexer.
In the invention a tunable optical fiber grating device comprising:
A length of optical fiber including an optical grating along a portion of this length;
A cantilever beam with said fiber secured on one surface;
A rotation stage for moving said cantilever beam to be bent in different direction, thereby compressing or stretching said optical fiber grating to alter its wavelength response;
In the invention, said optical grating is a Bragg grating;
In the invention, said optical grating is a tilted Bragg grating;
In the invention, said optical grating is a long period grating;
In the invention, said optical fiber is secured on one surface of said cantilever by glue, or epoxy, or metal welding, or other approaches;
In the invention, the cantilever beam can be rectangle shape, triangle shape, curve shape.
One purpose of using different shape is to make sure that the cantilever beam can be bent uniformly (every where along the length of the cantilever has a same bending angle).
In the invention, the cantilever beam material can be metal, plastic, or other materials.
In the invention, both ends of the cantilever beam have fixed with blocks which are rigid. The first purpose of the two blocks will make sure that the length of the cantilever beam will be constant and the second purpose of the two blocks is to protect the fiber lead from a touch of the groove and to lead the fiber to outside from the cantilever beam.
In the invention, a rotation stage is used to move one end of the cantilever back and forth.
A groove is fixed on the rotation to push the block on the free end of the cantilever beam in different direction so the cantilever beam will be bend in different direction. The groove also allows the block on the free end of the cantilever beam has slightly relative move within the groove to keep the cantilever beam bending uniformly along its length when the bending angle of the cantilever beam increases.
In the invention, one end of the cantilever beam is fixed on a base with a block, another end of the cantilever beam bends when the groove on the rotation stage pushes it through the block at its end.
In the invention, there is a small gap between the groove which will push the block, and the block which is fixed with the free end of the cantilever beam to allow the block move slightly relatively to the groove when the groove travels in a circular track.
The small gap between the groove and the block can also reduce the backlash when the rotation direction of the rotation stage changes.
In the invention, two bearings can be installed in the groove to allow the block move smoothly inside the groove.
In the invention, the fiber with an optical grating on it is stick on one surface of the cantilever beam. When the cantilever beam bends in different directions, the optical grating will be compressed or stretched accordingly.
In the invention, the rotation stage is fixed on one base so it can be turned relatively with the base. One end of the cantilever beam is fixed on the base through a rigid block and another end of the cantilever beam is pushed back and forth by the groove on the rotation stage.
In the invention, the rotation stage can be rotated manually through a driving knob.
In the invention, the rotation stage can be rotated through a step motor or do motor. In this case we can electrically control the rotation with high resolution.
In the invention, the tunable fiber grating can incorporate with a circular to form a tunable transmission filter.
In the invention, the tunable fiber grating can be used in dynamic add and drop module for WDM (wavelength division multiplex) system.
In the invention, the tunable fiber grating can be used for fiber laser to tune the output wavelength of the fiber laser.
In the invention, the tunable fiber grating can be used to form a external cavity of semiconductor laser to select the wavelength of the semiconductor.
8, References:
<1>. Morey W.M., Ball G.A., and Metlz G.:" Photoinduced Bragg Gratings in Optical fibers", Optics and Photonics News, February 1994, pp.8-14 <2>. G.A. Ball, W.W.Morey, and W.H. Glenn, :"Standing-Wave Monomode Erbium Fiber Laser", IEEE Photonics Technology Letters, vol. 3, pp.613-615(1991) <3>. K. O. Hill and G. Meltz, "Fiber Bragg Grating Technology Fundamentals and Overview", Journal of Lightwave Technology, vol. 15, pp. 1263-1276(1997) <4>. K.O. Hill, Y. Fujii, D.C. Hohnson, and B.S. Kawasaki, "photo-sensitivity in optical fiber waveguides: Application to reflection filter fabrication, " Appl. Phys.
Lett., Vol. 32, pp. 647-649(1978).
<5>. G. Meltz, W.W. Morey and W.H. Glenn, "Formation of Bragg Gratings in optical fibers by transverse holographic method", Optics Letters, vol. 14, pp.823-825(1989) <6>. Mark Krol and Jaymin Amin, "Components and architectures for fixed and reconfigurable optical add/drop multiplexers", Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides'99, Stuart, Florida, p. 4(1999) 6.
Since the block 4 is rigid, only the cantilever beam will be bent. In this way the total length of the cantilever beam is fixed. The cantilever 9 will have the same bending angle along its length during its bending angle increasing. In this way we can achieve two goals at the same time: 1. the cantilever beam 9 always has a fixed length for the purpose of uniform bending angle along its length when the bending angle increase; 2. The act point on the end of the cantilever beam 9(here is the block 4) is slight shifted when the groove 10, which is fixed on the rotation stage 2, is moving in a circular track (using the groove on the rotation stage 2 to push the block 4). This very simple structure of the tunable fiber grating will be low cost and high accuracy for a wide tuning range.
The groove 10 mounted on the rotation stage 2 has a narrow slot to allow the cantilever slightly move back and forth inside it. The narrow slot of the groove 10, which is little bit wider than the cantilever beam thickness, can also reduce the backlash when it push the cantilever beam 9(here is the block 4) into opposite direction. To allow the block 4 move smoothly inside the groove 10 and to reduce the friction between the groove 10 and the block 4, some bearings can be installed on the slot of the groove 10 as shown in figure 7.
FIG. 8 is another example of the tunable fiber grating. The rotation stage 2 is driving by step motor or do motor 7. Because the step motor can be turned in a very small step, such as 0.001° degree, a high tuning resolution of the tunable fiber grating can be obtained.
Fiber grating can be used as wavelength selector (or formed a cavity) in a fiber laser.
Tunable fiber grating of course can be used for tunable fiber laser application. FIG. 9 is another example of applications of our tunable fiber grating. FGl and FG2 are both tunable fiber gratings. EDF is Erbium doped fiber or other doped fiber. By tuning the FG1 and FG2 simultaneously we could get different wavelength output from the fiber laser.
FIG. 10 is another example of application of our tunable fiber grating.
Combined a three-port circulator with our tunable fiber grating, we can make a tunable WDM drop multiplexer/demultiplexer.
In the invention a tunable optical fiber grating device comprising:
A length of optical fiber including an optical grating along a portion of this length;
A cantilever beam with said fiber secured on one surface;
A rotation stage for moving said cantilever beam to be bent in different direction, thereby compressing or stretching said optical fiber grating to alter its wavelength response;
In the invention, said optical grating is a Bragg grating;
In the invention, said optical grating is a tilted Bragg grating;
In the invention, said optical grating is a long period grating;
In the invention, said optical fiber is secured on one surface of said cantilever by glue, or epoxy, or metal welding, or other approaches;
In the invention, the cantilever beam can be rectangle shape, triangle shape, curve shape.
One purpose of using different shape is to make sure that the cantilever beam can be bent uniformly (every where along the length of the cantilever has a same bending angle).
In the invention, the cantilever beam material can be metal, plastic, or other materials.
In the invention, both ends of the cantilever beam have fixed with blocks which are rigid. The first purpose of the two blocks will make sure that the length of the cantilever beam will be constant and the second purpose of the two blocks is to protect the fiber lead from a touch of the groove and to lead the fiber to outside from the cantilever beam.
In the invention, a rotation stage is used to move one end of the cantilever back and forth.
A groove is fixed on the rotation to push the block on the free end of the cantilever beam in different direction so the cantilever beam will be bend in different direction. The groove also allows the block on the free end of the cantilever beam has slightly relative move within the groove to keep the cantilever beam bending uniformly along its length when the bending angle of the cantilever beam increases.
In the invention, one end of the cantilever beam is fixed on a base with a block, another end of the cantilever beam bends when the groove on the rotation stage pushes it through the block at its end.
In the invention, there is a small gap between the groove which will push the block, and the block which is fixed with the free end of the cantilever beam to allow the block move slightly relatively to the groove when the groove travels in a circular track.
The small gap between the groove and the block can also reduce the backlash when the rotation direction of the rotation stage changes.
In the invention, two bearings can be installed in the groove to allow the block move smoothly inside the groove.
In the invention, the fiber with an optical grating on it is stick on one surface of the cantilever beam. When the cantilever beam bends in different directions, the optical grating will be compressed or stretched accordingly.
In the invention, the rotation stage is fixed on one base so it can be turned relatively with the base. One end of the cantilever beam is fixed on the base through a rigid block and another end of the cantilever beam is pushed back and forth by the groove on the rotation stage.
In the invention, the rotation stage can be rotated manually through a driving knob.
In the invention, the rotation stage can be rotated through a step motor or do motor. In this case we can electrically control the rotation with high resolution.
In the invention, the tunable fiber grating can incorporate with a circular to form a tunable transmission filter.
In the invention, the tunable fiber grating can be used in dynamic add and drop module for WDM (wavelength division multiplex) system.
In the invention, the tunable fiber grating can be used for fiber laser to tune the output wavelength of the fiber laser.
In the invention, the tunable fiber grating can be used to form a external cavity of semiconductor laser to select the wavelength of the semiconductor.
8, References:
<1>. Morey W.M., Ball G.A., and Metlz G.:" Photoinduced Bragg Gratings in Optical fibers", Optics and Photonics News, February 1994, pp.8-14 <2>. G.A. Ball, W.W.Morey, and W.H. Glenn, :"Standing-Wave Monomode Erbium Fiber Laser", IEEE Photonics Technology Letters, vol. 3, pp.613-615(1991) <3>. K. O. Hill and G. Meltz, "Fiber Bragg Grating Technology Fundamentals and Overview", Journal of Lightwave Technology, vol. 15, pp. 1263-1276(1997) <4>. K.O. Hill, Y. Fujii, D.C. Hohnson, and B.S. Kawasaki, "photo-sensitivity in optical fiber waveguides: Application to reflection filter fabrication, " Appl. Phys.
Lett., Vol. 32, pp. 647-649(1978).
<5>. G. Meltz, W.W. Morey and W.H. Glenn, "Formation of Bragg Gratings in optical fibers by transverse holographic method", Optics Letters, vol. 14, pp.823-825(1989) <6>. Mark Krol and Jaymin Amin, "Components and architectures for fixed and reconfigurable optical add/drop multiplexers", Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides'99, Stuart, Florida, p. 4(1999) 6.
Claims (15)
1. A tunable optical fiber gratings device for tuning optical characteristic responses of a longitudinal optical grating area of an optical fiber, said device comprising an elongated beam member defining a neutral plane with a first and a second ends and adapted to receive said fiber therealong, a securing member for continuously securing said optical grating area all along said beam member between said first and second ends and generally parallel to said neutral plane to allow for transmission of a bend of said beam member about said neutral plane to said optical grating area, a fixed support member having a clamping means for releasably securing said first end of said beam member within said neutral plane, and a mobile support member having a directing means for slidably receiving said second end of said beam member within said neutral plane, said mobile support member displacing said second end relative to said first end substantially perpendicularly to said neutral plane and bending the same, thereby stretching or compressing said grating area of said fiber for tuning said optical characteristic responses of said optical fiber depending on a direction of said bend.
2. A device as defined in claim 1, wherein said grating area of said optical fiber being a combination of at least one doped fiber zone and at least one fiber grating zone, said zones being adjacent to each other.
3. A device as defined in claim 1, wherein said beam member preferably having a uniform cross-section perpendicular to said neutral plane between said first and second ends.
4. A device as defined in claim 1, wherein said beam member having a generally polygonal shape within said neutral plane for providing a non chirped tuning of said fiber.
5. A device as defined in claim 1, wherein said beam member having at least one guiding member extending between said first and second ends and adapted for guiding said optical grating area of said fiber therealong.
6. A device as defined in claim 1, wherein said first end of said beam member having at least one abutment member adjacent to said securing member and said fiber to be in abutting position with said clamping means for preventing said optical grating area and said securing member from being strained by said clamping means.
7. A device as defined in claim 6, wherein said second end of said beam member having at least one abutment member adjacent to said securing member and said fiber to be in abutting position with said directing means for preventing said optical grating area and said securing member from being strained by said directing means.
8. A device as defined in claim 1, wherein said clamping means having at least one abutment member to be in abutting position with said first end of said beam member adjacent to said securing member for preventing said optical grating area and said securing member from being strained by said clamping means.
9. A device as defined in claim 8, wherein said directing means having at least one abutment member to be in abutting position with said second end of said beam member adjacent to said securing member for preventing said optical grating area and said securing member from being strained by said directing means.
10. A device as defined in claim 1, further comprising a driving mechanism connected to said mobile support member for displacing said second end relative to said first end of said beam member substantially perpendicularly to said neutral plane via said directing means mounted on said mobile support member.
11. A device as defined in claim 10, wherein said mobile support member including a sliding gauge for measuring displacement of said second end of said beam member relative to said first end.
12. A device as defined in claim 10, further comprising a controller connected to said driving mechanism for controlling said bend of said beam member, thereby controlling of said optical characteristic responses of said grating area of said optical fiber.
13. A device as defined in claim 1, wherein said fiber being a first fiber located at a first determined distance from said neutral plane, said beam member being adapted to receive a second longitudinal optical grating area of a second optical fiber therealong, said device further comprising a second securing member for continuously securing said second grating area all along said beam member between said first and second ends and generally parallel to said neutral plane at a second distance from the same.
14. A device as defined in claim 13, wherein said second fiber being secured on an opposite side of said neutral plane relative to said first fiber.
15. A device as defined in claim 14, wherein said first and second distances are approximately equal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2291385 CA2291385A1 (en) | 1999-11-25 | 1999-11-25 | Tunable optical fiber gratings device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2291385 CA2291385A1 (en) | 1999-11-25 | 1999-11-25 | Tunable optical fiber gratings device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2291385A1 true CA2291385A1 (en) | 2001-05-25 |
Family
ID=4164772
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2291385 Abandoned CA2291385A1 (en) | 1999-11-25 | 1999-11-25 | Tunable optical fiber gratings device |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2291385A1 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003029044A (en) * | 2001-07-11 | 2003-01-29 | Sumitomo Electric Ind Ltd | Optical parts, optical module, optical amplifier and optical communication system |
| EP1413902A1 (en) * | 2001-07-11 | 2004-04-28 | Sumitomo Electric Industries, Ltd. | Optical component, optical module, optical amplifier, and optical communication system |
| CN109078815A (en) * | 2018-02-06 | 2018-12-25 | 上海光栅信息技术有限公司 | A kind of fiber grating adhesive curing technique |
-
1999
- 1999-11-25 CA CA 2291385 patent/CA2291385A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2003029044A (en) * | 2001-07-11 | 2003-01-29 | Sumitomo Electric Ind Ltd | Optical parts, optical module, optical amplifier and optical communication system |
| EP1413902A1 (en) * | 2001-07-11 | 2004-04-28 | Sumitomo Electric Industries, Ltd. | Optical component, optical module, optical amplifier, and optical communication system |
| EP1413902A4 (en) * | 2001-07-11 | 2005-06-01 | Sumitomo Electric Industries | Optical component, optical module, optical amplifier, and optical communication system |
| JP4696413B2 (en) * | 2001-07-11 | 2011-06-08 | 住友電気工業株式会社 | Optical component, optical module, optical amplifier, and optical communication system |
| CN109078815A (en) * | 2018-02-06 | 2018-12-25 | 上海光栅信息技术有限公司 | A kind of fiber grating adhesive curing technique |
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