## Largely tunable CFBG-based dispersion compensator with fixed center wavelength

Optics Express, Vol. 11, Issue 22, pp. 2970-2974 (2003)

http://dx.doi.org/10.1364/OE.11.002970

Acrobat PDF (105 KB)

### Abstract

A largely tunable chirped fiber Bragg grating (CFBG)-based dispersion compensator with fixed center wavelength is demonstrated. Tunable dispersion ranging from 178 to 2126 ps/nm, corresponding to a large range of 3-db bandwidth from 0.42 to 5.04 nm, is realized by using a 10 cm-long CFBG with an original bandwidth of 1.61 nm. The variation in center wavelength is less than 0.2 nm.

© 2003 Optical Society of America

## 1. Introduction

2. R. Kashyap, H.-G. Froehlich, A. Swanton, and D. J. Armes, “1.3 m long super-step-chirped fibre Bragg grating with a continuous delay of 13.5 ns and bandwidth 10 nm for broadband dispersion compensation,” Electron. Lett. **32**, 1807–1809 (1996). [CrossRef]

3. M. K. Durkin, M. Ibsen, M. J. Cole, and R. I. Laming, “1 m long continuously-written fibre Bragg gratings for combined second- and third-order dispersion compensation,” Electron. Lett. **33**, 1891–1893 (1997). [CrossRef]

4. J. Lauzon, S. Thibault, J. Martin, and F. Ouelletter, “Implementation and characterization of fiber Bragg grating linearly chirped by a temperature-gradient,” Opt. Lett. **19**, 2027–2029 (1994). [CrossRef] [PubMed]

9. N. Q. Ngo, S. Y. Li, R. T. Zheng, S. C. Tjin, and P. Shum, “Electrically tunable dispersion compensator with fixed center wavelength using fiber Bragg grating,” J. Lightwave Technol. **21**, 1568–1575 (2003). [CrossRef]

10. X. Dong, B.-O. Guan, S. Yuan, X. Dong, and H.-Y. Tam, “Strain gradient chirp of fiber Bragg grating without shift of central Bragg wavelength,” Opt. Commun. **202**, 91–95 (2002). [CrossRef]

## 2. Design and principle

*L*=18 cm, width at the fixed end

*b*

_{0}=3 cm, and thickness

*h*=0.8 cm. The CFBG, which was deeply written in a H

_{2}-loaded single-mode fiber, has a reflectivity higher than 0.999. The original 3-dB bandwidth and center wavelength of the CFBG are 1.61 nm and 1562.5 nm, respectively. The angle between the axis of the CFBG and the central axis of the lateral side of the beam is

*θ*=4.5°.

10. X. Dong, B.-O. Guan, S. Yuan, X. Dong, and H.-Y. Tam, “Strain gradient chirp of fiber Bragg grating without shift of central Bragg wavelength,” Opt. Commun. **202**, 91–95 (2002). [CrossRef]

10. X. Dong, B.-O. Guan, S. Yuan, X. Dong, and H.-Y. Tam, “Strain gradient chirp of fiber Bragg grating without shift of central Bragg wavelength,” Opt. Commun. **202**, 91–95 (2002). [CrossRef]

**202**, 91–95 (2002). [CrossRef]

**202**, 91–95 (2002). [CrossRef]

*x*(0<

*x*<

*L*), can be given by

*M*(

*x*) and

*I*(

*x*) are the bending moment and the moment of inertia of the beam cross section at

*x*,

*E*the Young modulus,

*F*and

*f*, the force and displacement at the free end of the beam, respectively.

*Δλ*(

_{B}*λ*denotes the Bragg wavelength), for any segment of the grating is directly proportional to the local axial strain along the grating (

_{B}*ε*) [10

_{ax}**202**, 91–95 (2002). [CrossRef]

**202**, 91–95 (2002). [CrossRef]

*κ*and the grating length from the given segment to the cross point of grating and the neutral layer of the beam,

*l*(-0.5

*L*<

_{g}*l*<0.5

*L*), where

_{g}*L*is the total length of the CFBG. Therefore, the final description of variation in Bragg wavelength at a given grating segment with

_{g}*l*can be described as [10

**202**, 91–95 (2002). [CrossRef]

*C*(0<

*C*<1) is a constant introduced to describe the efficiency of strain transfer from the beam to the grating, and

*p*the effective photoelastic constant (~0.22) of the fiber material. The bandwidth variation thus can be described as

_{e}*A*≅0.5

*C*(1-

*p*)

_{e}*λ*sin(2

_{Bc}L_{g}*θ*), is a constant.

*λ*is the center wavelength of the CFBG.

_{Bc}*x*, i.e.,

*κ*is uniform along the beam. That is the main improvement in our modified method since it is dependent on

*x*for the simple supported beam used in Ref. 10

**202**, 91–95 (2002). [CrossRef]

*x*for the grating was much shorter than the beam. A uniform curvature in the beam is very important for keeping a linear chirp in the grating as shown by Eq. (2), and a linear chirp means linear time delay and uniform dispersion in the grating. The above equations show that the bandwidth of the grating, i.e., the dispersion of the dispersion compensator, can be linearly tuned by applying force or displacement at the free end of the cantilever beam.

**202**, 91–95 (2002). [CrossRef]

*C*=0.9, and the curvatures of the beam at the center of the grating is 0.2 m

^{-1}. It is obviously shown that the tuning efficiency and linearity of the CFBG are greatly enhanced by using the modified method.

## 3. Results and discussion

**202**, 91–95 (2002). [CrossRef]

*R*-squared value of the linear fit to the experimental data is 0.9991, which shows a good linearity in tuning of bandwidth. The factor of

*C*, inferred from the tuning rate and the other experimental parameters, is 0.83, which is much better than that (~0.55) achieved in Ref. [10

**202**, 91–95 (2002). [CrossRef]

## 4. Summary

## References and Links

1. | V. Gusmeroli and D. Scarano, “Fiber grating dispersion compensator,” OFC (Optical Society of America, Washington, D.C., 1999) 4, 11–13. |

2. | R. Kashyap, H.-G. Froehlich, A. Swanton, and D. J. Armes, “1.3 m long super-step-chirped fibre Bragg grating with a continuous delay of 13.5 ns and bandwidth 10 nm for broadband dispersion compensation,” Electron. Lett. |

3. | M. K. Durkin, M. Ibsen, M. J. Cole, and R. I. Laming, “1 m long continuously-written fibre Bragg gratings for combined second- and third-order dispersion compensation,” Electron. Lett. |

4. | J. Lauzon, S. Thibault, J. Martin, and F. Ouelletter, “Implementation and characterization of fiber Bragg grating linearly chirped by a temperature-gradient,” Opt. Lett. |

5. | M.L. Blanc, S. Y. Huang, M. M. Ohn, and R. M. Measures, “Tunable chirping of a fibre Bragg grating using a tapered cantilever bed,” Electron. Lett. |

6. | M. M. Ohn, A. t. Alavie, R. Maaskant, M. G. Xu, F. Bilodeau, and K. O. Hill., “Dispersion variable fibre Bragg grating using a piezoelectric stack,” Electron. Lett. |

7. | B. J. Eggleton, J. A. Rogers, P. S. Westbook, and T. A. Strasser, “Electrically tunable power efficient dispersion compensation fiber Bragg grating,” IEEE Photon. Technol. Lett. |

8. | J. L. Cruz, A. Diez, M. V. Andres, A. Segura, B. Ortega, and L. Dong, “Fibre Bragg gratings tuned and chirped using magnetic fields,” Electron. Lett. |

9. | N. Q. Ngo, S. Y. Li, R. T. Zheng, S. C. Tjin, and P. Shum, “Electrically tunable dispersion compensator with fixed center wavelength using fiber Bragg grating,” J. Lightwave Technol. |

10. | X. Dong, B.-O. Guan, S. Yuan, X. Dong, and H.-Y. Tam, “Strain gradient chirp of fiber Bragg grating without shift of central Bragg wavelength,” Opt. Commun. |

**OCIS Codes**

(060.2340) Fiber optics and optical communications : Fiber optics components

(060.4510) Fiber optics and optical communications : Optical communications

(230.1480) Optical devices : Bragg reflectors

**ToC Category:**

Research Papers

**History**

Original Manuscript: August 26, 2003

Revised Manuscript: October 28, 2003

Published: November 3, 2003

**Citation**

Xinyong Dong, P. Shum, N. Ngo, C. Chan, Jun Ng, and Chunliu Zhao, "A largely tunable CFBG-based dispersion compensator with fixed center wavelength," Opt. Express **11**, 2970-2974 (2003)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-11-22-2970

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### References

- V. Gusmeroli, D. Scarano, �??Fiber grating dispersion compensator,�?? OFC (Optical Society of America, Washington, D.C., 1999) 4, 11-13.
- R. Kashyap, H.-G. Froehlich, A. Swanton, D. J. Armes, �??1.3 m long super-step-chirped fibre Bragg grating with a continuous delay of 13.5 ns and bandwidth 10 nm for broadband dispersion compensation,�?? Electron. Lett. 32, 1807-1809 (1996). [CrossRef]
- M. K. Durkin, M. Ibsen, M. J. Cole, and R. I. Laming, �??1 m long continuously-written fibre Bragg gratings for combined second- and third-order dispersion compensation,�?? Electron. Lett. 33, 1891-1893 (1997). [CrossRef]
- J. Lauzon, S. Thibault, J. Martin, and F. Ouelletter, �??Implementation and characterization of fiber Bragg grating linearly chirped by a temperature-gradient,�?? Opt. Lett. 19, 2027-2029 (1994). [CrossRef] [PubMed]
- M.L. Blanc, S. Y. Huang, M. M. Ohn and R. M. Measures, �??Tunable chirping of a fibre Bragg grating using a tapered cantilever bed,�?? Electron. Lett. 30, 2163-2165 (1994). [CrossRef]
- M. M. Ohn, A. t. Alavie, R. Maaskant, M. G. Xu, F. Bilodeau, K. O. Hill., �??Dispersion variable fibre Bragg grating using a piezoelectric stack,�?? Electron. Lett. 32, 2000-2001, (1996). [CrossRef]
- B. J. Eggleton, J. A. Rogers, P. S. Westbook, and T. A. Strasser, �??Electrically tunable power efficient dispersion compensation fiber Bragg grating,�?? IEEE Photon. Technol. Lett. 11, 854-856 (1999). [CrossRef]
- J. L. Cruz, A. Diez, M. V. Andres, A. Segura, B. Ortega, L. Dong, �??Fibre Bragg gratings tuned and chirped using magnetic fields,�?? Electron. Lett. 33, 235-236 (1997). [CrossRef]
- N. Q. Ngo, S. Y. Li, R. T. Zheng, S. C. Tjin, and P. Shum, �??Electrically tunable dispersion compensator with fixed center wavelength using fiber Bragg grating,�?? J. Lightwave Technol. 21, 1568-1575 (2003). [CrossRef]
- X. Dong, B.-O. Guan, S. Yuan, X. Dong, H.-Y. Tam, �??Strain gradient chirp of fiber Bragg grating without shift of central Bragg wavelength,�?? Opt. Commun. 202, 91-95 (2002). [CrossRef]

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