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A strain-fiber actuator by use of shape memory alloy spring
ARTICLE IN PRESS
Optik
Optics
Optik 120 (2009) 818–823 www.elsevier.de/ijleo
A strain-fiber actuator by use of shape memory alloy spring Chi-Feng Chena,, Rui-Ting Zhengb, Tsu-Te Kungc,d, Chang-Neng Shauoe, Hsiou-Jeng Shye a
Department of Mechanical Engineering, Institute of Opto-Mechatronics Engineering, National Central University, Jhongli 32054, Taiwan, ROC b Mechanical Industry Research Laboratories, Industrial Technology Research Institute, Taiwan, ROC c Department of Mechanical Engineering, National Central University, Jhongli 32054, Taiwan, ROC d Department of Electro-Optical Engineering, National United University, Miaoli 36003, Taiwan, ROC e Materials & Electro-Optics Research Division, Chung Shan Institute of Science and Technology, P.O. Box. 90008-8-8, Lung-Tan, Tao-Yuan, 325 Taiwan, ROC Received 30 November 2007; accepted 12 March 2008
Abstract A strain-fiber actuator by use of shape memory alloy spring is proposed and experimentally investigated. The shape memory alloy actuator with a diameter of 0.3 mm and length of 2 mm was driven by a DC power supply of 7 V to persist for 5 s. The deformation and the strain ratio were found to be 60 mm and 3%, respectively. To apply the actuator to strain a fiber Bragg grating, we obtained a tunable spectrum width of 50 nm around the wavelength of 1550 nm for optical communication. r 2008 Elsevier GmbH. All rights reserved. Keywords: Shape memory alloy; Shape memory alloy actuator; Fiber Bragg grating; FBG; Strain-tunable FBG
1. Introduction The fiber Bragg grating (FBG) with the advantages of high spectral selectivity, high reflectivity, and low cost become an important element for selectively controlling specific wavelength of light within an optical fiber [1]. FBG can be used in a variety of applications, such as filtering of wavelength, stabilizing of semiconductor lasers, reflecting of pump energy in fiber amplifier, and compensating for fiber dispersion. A typical FBG consists of a length of optical fiber including a plurality of perturbations in the index of refraction which is substantially equally spaced along the fiber length. Corresponding author. Tel.: +886 3 4267308; fax: +886 3 4254501.
E-mail address: [email protected] (C.-F. Chen). 0030-4026/$ - see front matter r 2008 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijleo.2008.03.021
A conventional fiber grating filters out only a fixed wavelength. Each grating selectively reflects a narrow bandwidth of the light. However, in many applications, it is desirable to have a tunable grating whose wavelength response can be controllably altered. A tunable FBG realized by thermal–optical method [2,3] and strain– optical methods [4–11] have been researched. Strainoptical methods based on strain mechanisms, such as piezoelectric, magnetic, electro-optical, and magnetostrictive devices, are mechanically induced strain to extend or compress the grating period. A nearly linear shift of the Bragg wavelength is obtained in conjunction with the refractive index change in the grating. Fiber-to-the-home (FTTH) systems have been expected to be the key infrastructure for broadband access systems because of huge capacity, small size and
ARTICLE IN PRESS C.-F. Chen et al. / Optik 120 (2009) 818–823
lightness, and immunity to electromagnetic interference of optical fibers [12]. FTTH systems provide various kinds of advanced services such as voice, video, and data over the optical fiber and connect to the customer sides. In order to achieve FTTH realization, a key condition that is further cost reduction of the fiber-optic access network must be satisfied. A key issue for FTTH is the availability of inexpensive optical devices such as beam splitter, MUX/DEMUX, OADM, etc. As a result, a cost-effective and efficient way to fabricate those optical devices becomes rather critical and in great demand. Due to the merits of large driving force, large driving displacement, and low cost, the shape memory alloy (SMA) can be used as a source of driving force. In this study, we investigate the feasibility of a tunable optical fiber grating with the quasi-active and low-cost SMA spring as an actuator. We fabricate the device and measure the driving force and displacement of the SMA actuator.
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fixer is bound on the substrate and the position matcher is variably locked by the positioner. It is obvious that the extension of the fiber depends on the fixed position of position the matcher. By this concept, Fig. 2 shows the photo of the setup for the test platform of the fiber with the SMA tunable platform which comprises the SMA device of two stages. Fig. 3 is the photo of the fiber with a SMA actuator arranged into the SMA tunable platform. In this study,
2. Experimental process The experimental setup is shown in Fig. 1. The tunable FBG comprises by the actuator with a SMA spring to strain the grating. The SMA is a function material that can memorize its original shape. When the operation temperature is higher than the threshold temperature of a SMA, the deformed SMA will recover its original shape by the shape memory effect. On the basis of this character, we use the Ni–Ti alloy of a SMA material to fabricate the actuator with a SMA spring. The SMA spring, which served as the actuator, has the advantages of large driving force, large driving displacement, and low cost. However, some disadvantages like low positional precision and poor repeatability restrain the application range of the SMA. To overcome the shortcomings, we design a device that is constituted by a SMA spring, a recover spring, and a positioner. As the fiber is driven by the SMA actuator, the recover spring will return the fiber to its original position. The positioner controls the stop position and determines the precision for the driven fiber. The positioner comprises a series of stages. The strain mechanism can tune the fiber through the stage-mode. The number of stage-modes depends on the number of state of the positioner. Such a strain device belongs to a quasi-active driving. A brief of the operation procedures of this device are described. First, an intended pulse voltage adds on the SMA spring actuators to generate a hot resistance. The shape memory effect of such actuator leads to a driving force. After the voltage is turned off, the driving forces disappear, and then the stress of recovery spring will recover the SMA spring in a moment. It is seen from Fig. 1 that the SMA spring, recovery spring, and fiber are fixed between the fixer and position matcher. The
Fig. 1. Schematic illustration of the tunable optical fiber grating using a SMA actuator.
Fig. 2. Test platform of a fiber with the SMA device of two stages.
Fig. 3. Photo of a fiber with a SMA actuator.
ARTICLE IN PRESS 820
C.-F. Chen et al. / Optik 120 (2009) 818–823
we mainly investigate the feasibility of a tunable optical fiber grating using a SMA actuator. Accordingly, we need to test and measure the functions of the driving force and displacement of the SMA actuators. Fig. 4 is the schematic illustration of the measurement setup of the driving force of SMA. We measure the SMA driving force from the load cell as functions of tuning voltage and persisting time of power supply. The driving force relating with the driving voltage and actuating time is obtained. Fig. 5 shows the schematic flowchart to measure the displacement of the fiber device.
Load Cell
DC power supply
Acrate
10 mm 20 mm
2.5 mm
Fig. 4. Schematic illustration of the measurement setup of the SMA driving force.
3. Experimental result First, to confirm the bonding strength among the fiber, SMA actuator, and recover spring, we used three types of UV curing epoxy resins to bond fibers A and B, and then tested their bonding strength. Here types A, B, and C are Norland optical adhesive 81 fast bonding, Norland optical adhesive 81 fast bonding, and DYMAX Ultra-fast adhesive, respectively. The schematic illustration of the experimental setup is shown in Fig. 6. The test results of the bonding strength for three types of UV curing epoxy resins are shown in Fig. 7. The maximum forces of types A, B, and C are 3.430, 2.690, and 1.1891 kg, respectively. The test tension rate is 5 mm/ min. Fig. 8 shows the SEM images of upper and lower sections for epoxy resins of types A, B, and C, respectively. One can see that types A and B are brittle destruction and type C is ductile destruction. It is found that the UV curing epoxy resin of Norland optical adhesive 61 strong bonding has very strong bonding strength. In other words, this UV curing epoxy resin can provide a suitable bonding among the elements. To study the feasibility of an actuator straining fiber by use of SMA spring is our main objective. On the other hand, FBGs are much more expensive than general fibers. Thus, we replace the general fiber with FBG to reduce the experimental cost. Then we explore the suitable parameters of the SMA actuator. The driving forces and driving displacements of SMA actuators are measured and discussed. Figs. 9 and 10 show the driving force of the actuator with SMA filament diameters of 0.3 and 1 mm, respectively, for different driving voltages as a function of time. One can see that the saturation phenomenon is easily obtained for the high driving voltage of 7 V.
Fig. 5. Schematic illustration of the measurement setup of the SMA displacement.
Fig. 6. Schematic illustration of the setup of the bonding strength test.
Fig. 7. Test results of the bonding strength for three types of UV curing epoxy resins.
ARTICLE IN PRESS C.-F. Chen et al. / Optik 120 (2009) 818–823
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Fig. 9. Driving force of the actuator with the SMA filament diameter of 0.3 mm for different driving voltages as a function of time.
Fig. 10. Driving force of the actuator with the SMA filament diameter of 1 mm for different driving voltages as a function of time.
Fig. 8. SEM images of upper and lower sections for epoxy resins of (a) type A, (b) type B, and (c) type C.
Finally, we measure its driving displacement. To measure the varied fiber length strained by the SMA actuator, we define the scale that is determined by a standard length. We take two images as the conditions before and after the fiber devices are strained. Comparing these two images, the displacement can be obtained by the margin of the fiber device. Figs. 11(a) and (b) show the images by CCD with the conditions before and after the fiber devices are strained, respectively. In Table 1, the measured results for several actuators under different driving conditions are shown. It is seen that the SMA actuator with 0.3 mm diameter and 2 mm length is driven by a voltage of 7 V to persist for 5 s. The
ARTICLE IN PRESS 822
Table 1.
C.-F. Chen et al. / Optik 120 (2009) 818–823
Measured results for several SMA actuators under different driving conditions
Actuator specification
Driving voltage (V)
Filament diameter of 0.3 mm and actuator length of 2 mm Filament diameter of 0.3 mm and actuator length of 2 mm Filament diameter of 1 mm and actuator length of 2 mm Filament diameter of 1 mm and actuator length of 2 mm
5
Driving time (s)
Driving displacement (mm)
Strain ratio (%)
Driving stage
7
40
2
Two stages
7
5
60
3
Two stages
5
7
50
2.5
Two stages
7
11
80
4
Two stages
5 s. Then, the deformation and the strain ratio were found to be 60 mm and 3%, respectively. To extend the application of the SMA actuator to a tunable FBG, we applied the actuator to strain a FBG and obtained a tunable spectrum width of 50 nm around the wavelength of 1550 nm for optical communication.
Acknowledgments The authors would like to thank Dr. T.C. Wu at MIRL of ITRI, Taiwan, for their guidance and assistance.
References
Fig. 11. Images with the conditions (a) before and (b) after the fiber device is driven by the SMA actuator.
deformation and the strain ratio were found to be 60 mm and 3%, respectively.
4. Conclusion A quasi-active driving and inexpensive strain-fiber actuator by use of a SMA spring is experimentally investigated to be practicable. The UV curing epoxy resin of Norland optical adhesive 61 strong bonding was found to provide a strong bonding strength among the fiber, SMA actuator, and recover spring. The obtained SMA actuator with 0.3 mm diameter and 2 mm length was driven by a DC power supply of 7 V to persist for
[1] K.O. Hill, G. Meltz, Fiber Bragg grating technology fundamentals and overview, J. Lightwave Technol. 15 (1997) 1263–1276. [2] H. Okayama, Y. Ozeki, T. Kunii, Dynamic wavelength selective add/drop node comprising tunable gratings, Electron. Lett. 33 (1997) 881–882. [3] H.G. Limberger, N.H. Ky, D.M. Costantini, R.P. Salathe, C.A.P. Muller, G.R. Fox, Efficient miniature fiber-optic tunable filter based on intracore Bragg grating and electrically resistive coating, IEEE Photon. Technol. Lett. 10 (1998) 361–363. [4] A. Iocco, H.G. Limberger, R.P. Salathe, Bragg grating fast tunable filter, Electron. Lett. 33 (1997) 2147–2148. [5] J.L. Cruz, A. Diez, M.V. Andres, A. Segura, B. Ortega, L. Dong, Fiber Bragg gratings tuned and chirped using magnetic fields, Electron. Lett. 33 (1997) 235–236. [6] S. Jin, R.P. Espindola, H. Mavoori, T.A. Strasser, J.J. DeMarco, Magnetically programmable fiber Bragg gratings, Electron. Lett. 34 (1998) 2158–2159. [7] A.M. Glass, S. Jin, P.J. Lemaire, T.A. Strasser, Magnetorstrictively Tunable Optical Fiber Gratings, United States Patent, 5812711, 1998. [8] C.S. Goh, S.Y. Set, K. Kikuchi, Widely tunable optical filters based on fiber Bragg gratings, IEEE Photon. Technol. Lett. 14 (2002) 1306–1308.
ARTICLE IN PRESS C.-F. Chen et al. / Optik 120 (2009) 818–823
[9] B. Srinivasan, R.K. Jain, First demonstration of thermally poled electrooptically tunable fiber Bragg gratings, IEEE Photon. Technol. Lett. 12 (2000) 170–172. [10] T. Inui, T. Komukai, M. Nakazawa, Highly efficient tunable fiber Bragg grating filters using multiplayer piezoelectric transducers, Opt. Commun. 190 (2002) 1–4.
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[11] A. Iocco, H.G. Limberger, R.P. Salathe, L.A. Everall, K.E. Chisholm, J.A.R. Williams, I. Bennion, Bragg grating fast tunable filter for wavelength division multiplexing, J. Lightwave Technol. 17 (1999) 1217–1221. [12] I. Yamashita, T. Matsumoto, N. Shibata, Fiber-to-thehome based on a PDS architecture, Opt. Fiber Technol. 4 (1998) 189–203.
Optik
Optics
Optik 120 (2009) 818–823 www.elsevier.de/ijleo
A strain-fiber actuator by use of shape memory alloy spring Chi-Feng Chena,, Rui-Ting Zhengb, Tsu-Te Kungc,d, Chang-Neng Shauoe, Hsiou-Jeng Shye a
Department of Mechanical Engineering, Institute of Opto-Mechatronics Engineering, National Central University, Jhongli 32054, Taiwan, ROC b Mechanical Industry Research Laboratories, Industrial Technology Research Institute, Taiwan, ROC c Department of Mechanical Engineering, National Central University, Jhongli 32054, Taiwan, ROC d Department of Electro-Optical Engineering, National United University, Miaoli 36003, Taiwan, ROC e Materials & Electro-Optics Research Division, Chung Shan Institute of Science and Technology, P.O. Box. 90008-8-8, Lung-Tan, Tao-Yuan, 325 Taiwan, ROC Received 30 November 2007; accepted 12 March 2008
Abstract A strain-fiber actuator by use of shape memory alloy spring is proposed and experimentally investigated. The shape memory alloy actuator with a diameter of 0.3 mm and length of 2 mm was driven by a DC power supply of 7 V to persist for 5 s. The deformation and the strain ratio were found to be 60 mm and 3%, respectively. To apply the actuator to strain a fiber Bragg grating, we obtained a tunable spectrum width of 50 nm around the wavelength of 1550 nm for optical communication. r 2008 Elsevier GmbH. All rights reserved. Keywords: Shape memory alloy; Shape memory alloy actuator; Fiber Bragg grating; FBG; Strain-tunable FBG
1. Introduction The fiber Bragg grating (FBG) with the advantages of high spectral selectivity, high reflectivity, and low cost become an important element for selectively controlling specific wavelength of light within an optical fiber [1]. FBG can be used in a variety of applications, such as filtering of wavelength, stabilizing of semiconductor lasers, reflecting of pump energy in fiber amplifier, and compensating for fiber dispersion. A typical FBG consists of a length of optical fiber including a plurality of perturbations in the index of refraction which is substantially equally spaced along the fiber length. Corresponding author. Tel.: +886 3 4267308; fax: +886 3 4254501.
E-mail address: [email protected] (C.-F. Chen). 0030-4026/$ - see front matter r 2008 Elsevier GmbH. All rights reserved. doi:10.1016/j.ijleo.2008.03.021
A conventional fiber grating filters out only a fixed wavelength. Each grating selectively reflects a narrow bandwidth of the light. However, in many applications, it is desirable to have a tunable grating whose wavelength response can be controllably altered. A tunable FBG realized by thermal–optical method [2,3] and strain– optical methods [4–11] have been researched. Strainoptical methods based on strain mechanisms, such as piezoelectric, magnetic, electro-optical, and magnetostrictive devices, are mechanically induced strain to extend or compress the grating period. A nearly linear shift of the Bragg wavelength is obtained in conjunction with the refractive index change in the grating. Fiber-to-the-home (FTTH) systems have been expected to be the key infrastructure for broadband access systems because of huge capacity, small size and
ARTICLE IN PRESS C.-F. Chen et al. / Optik 120 (2009) 818–823
lightness, and immunity to electromagnetic interference of optical fibers [12]. FTTH systems provide various kinds of advanced services such as voice, video, and data over the optical fiber and connect to the customer sides. In order to achieve FTTH realization, a key condition that is further cost reduction of the fiber-optic access network must be satisfied. A key issue for FTTH is the availability of inexpensive optical devices such as beam splitter, MUX/DEMUX, OADM, etc. As a result, a cost-effective and efficient way to fabricate those optical devices becomes rather critical and in great demand. Due to the merits of large driving force, large driving displacement, and low cost, the shape memory alloy (SMA) can be used as a source of driving force. In this study, we investigate the feasibility of a tunable optical fiber grating with the quasi-active and low-cost SMA spring as an actuator. We fabricate the device and measure the driving force and displacement of the SMA actuator.
819
fixer is bound on the substrate and the position matcher is variably locked by the positioner. It is obvious that the extension of the fiber depends on the fixed position of position the matcher. By this concept, Fig. 2 shows the photo of the setup for the test platform of the fiber with the SMA tunable platform which comprises the SMA device of two stages. Fig. 3 is the photo of the fiber with a SMA actuator arranged into the SMA tunable platform. In this study,
2. Experimental process The experimental setup is shown in Fig. 1. The tunable FBG comprises by the actuator with a SMA spring to strain the grating. The SMA is a function material that can memorize its original shape. When the operation temperature is higher than the threshold temperature of a SMA, the deformed SMA will recover its original shape by the shape memory effect. On the basis of this character, we use the Ni–Ti alloy of a SMA material to fabricate the actuator with a SMA spring. The SMA spring, which served as the actuator, has the advantages of large driving force, large driving displacement, and low cost. However, some disadvantages like low positional precision and poor repeatability restrain the application range of the SMA. To overcome the shortcomings, we design a device that is constituted by a SMA spring, a recover spring, and a positioner. As the fiber is driven by the SMA actuator, the recover spring will return the fiber to its original position. The positioner controls the stop position and determines the precision for the driven fiber. The positioner comprises a series of stages. The strain mechanism can tune the fiber through the stage-mode. The number of stage-modes depends on the number of state of the positioner. Such a strain device belongs to a quasi-active driving. A brief of the operation procedures of this device are described. First, an intended pulse voltage adds on the SMA spring actuators to generate a hot resistance. The shape memory effect of such actuator leads to a driving force. After the voltage is turned off, the driving forces disappear, and then the stress of recovery spring will recover the SMA spring in a moment. It is seen from Fig. 1 that the SMA spring, recovery spring, and fiber are fixed between the fixer and position matcher. The
Fig. 1. Schematic illustration of the tunable optical fiber grating using a SMA actuator.
Fig. 2. Test platform of a fiber with the SMA device of two stages.
Fig. 3. Photo of a fiber with a SMA actuator.
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C.-F. Chen et al. / Optik 120 (2009) 818–823
we mainly investigate the feasibility of a tunable optical fiber grating using a SMA actuator. Accordingly, we need to test and measure the functions of the driving force and displacement of the SMA actuators. Fig. 4 is the schematic illustration of the measurement setup of the driving force of SMA. We measure the SMA driving force from the load cell as functions of tuning voltage and persisting time of power supply. The driving force relating with the driving voltage and actuating time is obtained. Fig. 5 shows the schematic flowchart to measure the displacement of the fiber device.
Load Cell
DC power supply
Acrate
10 mm 20 mm
2.5 mm
Fig. 4. Schematic illustration of the measurement setup of the SMA driving force.
3. Experimental result First, to confirm the bonding strength among the fiber, SMA actuator, and recover spring, we used three types of UV curing epoxy resins to bond fibers A and B, and then tested their bonding strength. Here types A, B, and C are Norland optical adhesive 81 fast bonding, Norland optical adhesive 81 fast bonding, and DYMAX Ultra-fast adhesive, respectively. The schematic illustration of the experimental setup is shown in Fig. 6. The test results of the bonding strength for three types of UV curing epoxy resins are shown in Fig. 7. The maximum forces of types A, B, and C are 3.430, 2.690, and 1.1891 kg, respectively. The test tension rate is 5 mm/ min. Fig. 8 shows the SEM images of upper and lower sections for epoxy resins of types A, B, and C, respectively. One can see that types A and B are brittle destruction and type C is ductile destruction. It is found that the UV curing epoxy resin of Norland optical adhesive 61 strong bonding has very strong bonding strength. In other words, this UV curing epoxy resin can provide a suitable bonding among the elements. To study the feasibility of an actuator straining fiber by use of SMA spring is our main objective. On the other hand, FBGs are much more expensive than general fibers. Thus, we replace the general fiber with FBG to reduce the experimental cost. Then we explore the suitable parameters of the SMA actuator. The driving forces and driving displacements of SMA actuators are measured and discussed. Figs. 9 and 10 show the driving force of the actuator with SMA filament diameters of 0.3 and 1 mm, respectively, for different driving voltages as a function of time. One can see that the saturation phenomenon is easily obtained for the high driving voltage of 7 V.
Fig. 5. Schematic illustration of the measurement setup of the SMA displacement.
Fig. 6. Schematic illustration of the setup of the bonding strength test.
Fig. 7. Test results of the bonding strength for three types of UV curing epoxy resins.
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Fig. 9. Driving force of the actuator with the SMA filament diameter of 0.3 mm for different driving voltages as a function of time.
Fig. 10. Driving force of the actuator with the SMA filament diameter of 1 mm for different driving voltages as a function of time.
Fig. 8. SEM images of upper and lower sections for epoxy resins of (a) type A, (b) type B, and (c) type C.
Finally, we measure its driving displacement. To measure the varied fiber length strained by the SMA actuator, we define the scale that is determined by a standard length. We take two images as the conditions before and after the fiber devices are strained. Comparing these two images, the displacement can be obtained by the margin of the fiber device. Figs. 11(a) and (b) show the images by CCD with the conditions before and after the fiber devices are strained, respectively. In Table 1, the measured results for several actuators under different driving conditions are shown. It is seen that the SMA actuator with 0.3 mm diameter and 2 mm length is driven by a voltage of 7 V to persist for 5 s. The
ARTICLE IN PRESS 822
Table 1.
C.-F. Chen et al. / Optik 120 (2009) 818–823
Measured results for several SMA actuators under different driving conditions
Actuator specification
Driving voltage (V)
Filament diameter of 0.3 mm and actuator length of 2 mm Filament diameter of 0.3 mm and actuator length of 2 mm Filament diameter of 1 mm and actuator length of 2 mm Filament diameter of 1 mm and actuator length of 2 mm
5
Driving time (s)
Driving displacement (mm)
Strain ratio (%)
Driving stage
7
40
2
Two stages
7
5
60
3
Two stages
5
7
50
2.5
Two stages
7
11
80
4
Two stages
5 s. Then, the deformation and the strain ratio were found to be 60 mm and 3%, respectively. To extend the application of the SMA actuator to a tunable FBG, we applied the actuator to strain a FBG and obtained a tunable spectrum width of 50 nm around the wavelength of 1550 nm for optical communication.
Acknowledgments The authors would like to thank Dr. T.C. Wu at MIRL of ITRI, Taiwan, for their guidance and assistance.
References
Fig. 11. Images with the conditions (a) before and (b) after the fiber device is driven by the SMA actuator.
deformation and the strain ratio were found to be 60 mm and 3%, respectively.
4. Conclusion A quasi-active driving and inexpensive strain-fiber actuator by use of a SMA spring is experimentally investigated to be practicable. The UV curing epoxy resin of Norland optical adhesive 61 strong bonding was found to provide a strong bonding strength among the fiber, SMA actuator, and recover spring. The obtained SMA actuator with 0.3 mm diameter and 2 mm length was driven by a DC power supply of 7 V to persist for
[1] K.O. Hill, G. Meltz, Fiber Bragg grating technology fundamentals and overview, J. Lightwave Technol. 15 (1997) 1263–1276. [2] H. Okayama, Y. Ozeki, T. Kunii, Dynamic wavelength selective add/drop node comprising tunable gratings, Electron. Lett. 33 (1997) 881–882. [3] H.G. Limberger, N.H. Ky, D.M. Costantini, R.P. Salathe, C.A.P. Muller, G.R. Fox, Efficient miniature fiber-optic tunable filter based on intracore Bragg grating and electrically resistive coating, IEEE Photon. Technol. Lett. 10 (1998) 361–363. [4] A. Iocco, H.G. Limberger, R.P. Salathe, Bragg grating fast tunable filter, Electron. Lett. 33 (1997) 2147–2148. [5] J.L. Cruz, A. Diez, M.V. Andres, A. Segura, B. Ortega, L. Dong, Fiber Bragg gratings tuned and chirped using magnetic fields, Electron. Lett. 33 (1997) 235–236. [6] S. Jin, R.P. Espindola, H. Mavoori, T.A. Strasser, J.J. DeMarco, Magnetically programmable fiber Bragg gratings, Electron. Lett. 34 (1998) 2158–2159. [7] A.M. Glass, S. Jin, P.J. Lemaire, T.A. Strasser, Magnetorstrictively Tunable Optical Fiber Gratings, United States Patent, 5812711, 1998. [8] C.S. Goh, S.Y. Set, K. Kikuchi, Widely tunable optical filters based on fiber Bragg gratings, IEEE Photon. Technol. Lett. 14 (2002) 1306–1308.
ARTICLE IN PRESS C.-F. Chen et al. / Optik 120 (2009) 818–823
[9] B. Srinivasan, R.K. Jain, First demonstration of thermally poled electrooptically tunable fiber Bragg gratings, IEEE Photon. Technol. Lett. 12 (2000) 170–172. [10] T. Inui, T. Komukai, M. Nakazawa, Highly efficient tunable fiber Bragg grating filters using multiplayer piezoelectric transducers, Opt. Commun. 190 (2002) 1–4.
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[11] A. Iocco, H.G. Limberger, R.P. Salathe, L.A. Everall, K.E. Chisholm, J.A.R. Williams, I. Bennion, Bragg grating fast tunable filter for wavelength division multiplexing, J. Lightwave Technol. 17 (1999) 1217–1221. [12] I. Yamashita, T. Matsumoto, N. Shibata, Fiber-to-thehome based on a PDS architecture, Opt. Fiber Technol. 4 (1998) 189–203.