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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 15, Iss. 21 — Oct. 17, 2007
  • pp: 13519–13530

Design and realization of an all-fiber broadband tunable gain equalization filter for DWDM signals

R. K. Varshney, B. Nagaraju, A. Singh, B. P. Pal, and A. K. Kar  »View Author Affiliations

Optics Express, Vol. 15, Issue 21, pp. 13519-13530 (2007)

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Design and fabrication of a tunable gain equalization filter for dense wavelength division multiplexed (DWDM) signals through erbium doped fiber amplifiers (EDFA) is reported. It is based on a side-polished fiber (SPF) half-coupler block loaded with a displaceable tapered multimode overlay waveguide (MMOW). A simple and accurate normal mode analysis is employed to design this filtering device for its subsequent realization. Equalization of a typical EDFA gain spectrum in the C-band within ±0.35 dB or even less in the presence of various ITU standard C-band DWDM signal channels is demonstrated under varied operating conditions like add/drop of signals. Tunability of the filter notch is achieved through displacement of the SPF relative to the MMOW.

© 2007 Optical Society of America

OCIS Codes
(060.0060) Fiber optics and optical communications : Fiber optics and optical communications
(060.2310) Fiber optics and optical communications : Fiber optics
(060.2340) Fiber optics and optical communications : Fiber optics components
(060.2410) Fiber optics and optical communications : Fibers, erbium
(230.7408) Optical devices : Wavelength filtering devices

ToC Category:
Fiber Optics and Optical Communications

Original Manuscript: August 13, 2007
Revised Manuscript: September 24, 2007
Manuscript Accepted: September 24, 2007
Published: October 1, 2007

R. K. Varshney, B. Nagaraju, A. Singh, B. P. Pal, and A. K. Kar, "Design and realization of an all-fiber broadband tunable gain equalization filter for DWDM signals," Opt. Express 15, 13519-13530 (2007)

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  1. A. Srivastava and Y. Sun, Chapter 12 "Erbium doped fiber amplifiers for dynamic optical networks," in Guided wave optical components and devices: basics, technology and applications, B.P. Pal., ed. (Academic Press, Elsevier, Burlington, 2006), pp. 181-203
  2. C.G. Atkins, J.F. Massicott, J.R. Armitage, R. Wyatt, B.J. Ainslie, and S.P. Craig-Ryan, "High-gain, broad spectral bandwidth erbium-doped fiber amplifier pumped near 1.5 µm," Electron. Lett. 25, 910-911 (1989). [CrossRef]
  3. S. Yoshida, S. Kuwano, and K. Iwashita, "Gain-flattened EDFA with high Al concentration for multistage repeatered WDM transmission systems," Electron. Lett. 31, 1765-1767 (1995). [CrossRef]
  4. A. Mori, Y. Ohishi, M. Yamada, H. Ono, Y. Nishida, K. Oikawa, and S. Sudo, "1.5 ?m broadband amplification by tellurite-based EDFA’s," in Optical Fiber Communication conference, Technical Digest (Optical Society of America, 1997), post-deadline paper PD1.
  5. M. Yamada, H. Ono, A. Mori, T. Kanamori, S. Sudo, and Y. Ohishi, "Ultra-broadband and gain-flattened EDFA’s for WDM signals," in Optical Amplifiers and Their Applications, Technical Digest (Optical Society of America, 1997), paper MB1.
  6. M. Yamada, A. Mori, K. Kobayashi, H. Ono, T. Kanamori, K. Oikawa, Y. Nishida, and Y. Ohishi, "Gain-Flattened Tellurite-Based EDFA with a Flat Amplification Bandwidth of 76 nm," IEEE Photon. Technol. Lett. 10, 1244-1246 (1998). [CrossRef]
  7. J. Y. Pan, M. A. Ali, A. F. Elrefaie, and R. E. Wagner, "Multiwavelength fiber-amplifier cascades with equalization employing Mach-Zehnder optical filter," IEEE Photon. Technol. Lett. 7, 1501-1503 (1995). [CrossRef]
  8. H.S. Kim, S.H. Yun, H. K. Kim, N. Park, and B.Y. Kim, "Actively Gain-flattened erbium-doped fiber amplifier over 35 nm by using all-fiber acousto-optic tunable filters," IEEE Photon. Technol. Lett. 10, 790 -792 (1998). [CrossRef]
  9. B.Y. Kim, S.H. Yun, and B.W. Lee, "Acousto-optic filter", US Patent No. 6,532,323 B2 (2003).
  10. S. Li, K. S. Chiang, and W. A. Gambling, "Gain flattening of an erbium doped fiber amplifier using a high-birefringence fiber loop mirror," IEEE Photon. Technol. Lett. 13, 942-944 (2001). [CrossRef]
  11. N. Kumar, M.R. Shenoy, and B.P. Pal, "A standard fiber-based loop mirror as a gain-flattening filter for erbium-doped fiber amplifiers," IEEE Photon. Technol. Lett. 17, 2056-2058 (2005). [CrossRef]
  12. M. Lelic, G.J. Cowley, and N. Menon, "Dynamic controller for a multichannel optical amplifier," US Patent No. 6,535,330 (2003).
  13. R. Kashyap, R.  Wyatt, and P.F. McKee, "Wavelength flattened saturated erbium amplifier using multiple side-tap Bragg gratings," Electron. Lett. 29, 1025-1026 (1993). [CrossRef]
  14. C.R. Giles, "Lightwave applications of fiber Bragg gratings," IEEE J. Lightwave Technol. 15, 1391-1404 (1997). [CrossRef]
  15. J-C. Dung, S. Chi, and S. Wen, "Gain flattening of erbium-doped fiber amplifier using fiber Bragg gratings," Electron. Lett. 34, 555-556 (1998). [CrossRef]
  16. A. M. Vengsarkar, P. J. Lemaire, J. B. Judkins, V. Bhatia, T. Erdogan, and J. E. Sipe, "Long-period fiber gratings as band-rejection filters," IEEE J. Lightwave Technol. 14, 58-64 (1996). [CrossRef]
  17. J.R. Qian and H.F. Chen, "Gain flattening fiber filters using phase shifted long period fiber gratings," Electron. Lett. 34, 1132-1133 (1998). [CrossRef]
  18. Y. Liu, J.A.R. Williams, L. Zhang, and I. Bennion, "Phase shifted and cascaded long-period fiber gratings," Opt. Commun. 164, 27-31 (1999). [CrossRef]
  19. P.D. Greene and H.N. Rourke, "Tailoring long period optical fiber gratings for flattening EDFA gain spectra," Electron. Lett. 35, 1373-1374 (1999). [CrossRef]
  20. M. Harumoto, M. Shigehara, and H. Suganuma, "Gain-flattening filter using long-period fiber gratings," IEEE J. Lightwave Technol. 20, 1027-1033 (2002). [CrossRef]
  21. Y.J. Rao, A.Z. Hu, and Y.C. Niu, "A novel dynamic LPFG gain equalizer written in a bend-insensitive fiber," Opt. Commun. 244, 137 -140 (2005). [CrossRef]
  22. J.K. Bae, J. Bae, S.H. Kim, N. Park, and S.B. Lee, "Dynamic EDFA gain-flattening filter using two LPFGs with divided coil heaters," IEEE Photon. Technol. Lett. 17, 1226-1228 (2005). [CrossRef]
  23. M.K. Pandit, K.S. Chiang, Z.H. Chen, and S.P. Li, "Tunable Long-Period Fiber Gratings for EDFA gain and ASE equalization," Microwave and Opt. Technol. Lett. 25, 181-184 (2000). [CrossRef]
  24. I.B. Sohn, J.G. Baek, N.K. Lee, H.W. Kwon, and J.W. Song, "Gain flattened and improved EDFA using microbending long-period fiber gratings," Electron. Lett. 38, 1324-325 (2002). [CrossRef]
  25. R.A. Bergh, G. Kotler, and H.J. Shaw, "Single-mode fiber optic directional coupler," Electron. Lett. 16, 260-261 (1980). [CrossRef]
  26. C.A. Millar, M. C. Brierley, and S.R. Mallinson, "Exposed-core single-mode-fiber channel-dropping filter using a high-index overlay waveguide," Opt. Lett. 12, 284-286 (1987). [CrossRef] [PubMed]
  27. D.G. Moodie and W. Johnstone, "Wavelength tunability of components based on the evanescent coupling from a side-polished fiber to a high-index-overlay waveguide," Opt. Lett. 18, 1025 - 1027 (1993). [CrossRef] [PubMed]
  28. W.V. Sorin, "Broadband tunable in-line filter for fiber optics," US Patent no. 4.986,623 (1991).
  29. R.B. Charters, A.P. Kuczyhski, S.E. Stakes, R.P. Tatam, and G.J. Ashwell, "In-line fiber optic channel dropping filter using Langmuir-Blodgett films," Electron. Lett. 30, 594-595 (1994). [CrossRef]
  30. R. D. Pechstedt and P. St. J. Russell, "Narrow-band in-line fiber filter using surface-guided Bloch modes supported by dielectric multilayer stacks," IEEE J. Lightwave Technol. 14, 1541-1545 (1996). [CrossRef]
  31. S. Zhao and B. Pi, "Mach-Zehnder interferometers and applications based on evanescent couplings through side-polished fiber coupling ports," US Patent no. 6,501,875 B2, (2002).
  32. K. McCallion, W. Johnstone, and G. Fawcett, "Tunable fiber optic in-line bandpass filter," Opt. Lett. 19, 542-544 (1994). [CrossRef] [PubMed]
  33. B.P. Pal, G. Raizada, and R.K. Varshney, "Modelling a Fiber Half-block with Multimode Overlay Waveguide," J. Opt. Commun. 17, 179-83 (1996).
  34. G. Raizada, B.P. Pal, and R.K. Varshney, "Estimating performance of fiber optic modulators/switches with multimode electro-optic overlay/interlay waveguide," Opt. Fib. Tech. 2, 89-97 (1996). [CrossRef]
  35. R.K. Varshney, "Side-polished fiber coupler half block and devices," in Guided Wave Optics, A. Sharma, ed. (Viva Books Pvt. Ltd., New Delhi, India, 2005), pp. 110-121.
  36. W. Johnstone, "Side polished evanescently coupled optical fiber overlay devices: a review," in Guided wave optical components and devices: basics, technology and applications, B.P. Pal., ed. (Academic Press, Elsevier, Burlington, 2006), pp. 225-232.
  37. R.K. Varshney, A. Singh, K. Pande, and B.P. Pal, "Side-polished fiber-based gain-flattening filter for erbium doped fiber amplifiers," Opt. Commun. 271, 441- 444 (2007). [CrossRef]
  38. B.P. Pal, "All-fiber guided wave components," in Electromagnetic fields in unconventional structures and materials, A. Lakhtakia and O.N. Singh, eds. (John Wiley, New York, 2000), pp. 359-432.
  39. K. T. Kim, S. Hwangbo, J. P. Mah, and K. R. Sohn, "Widely tunable filter based on coupling between a side-polished fiber and a tapered planar waveguide," IEEE Photon. Technol. Lett. 17, 142-144 (2005). [CrossRef]
  40. A. Sharma, J. Kompella, and P.K. Mishra, "Analysis of fiber directional couplers and coupler half-blocks using a new simple model for single-mode fibers,"IEEE J. Lightwave Technol. 8, 143-151 (1990). [CrossRef]
  41. A.K. Ghatak, K. Thyagarajan, and M.R. Shenoy, "Numerical analysis of planar optical waveguides using matrix approach," IEEE J. Lightwave Technol. 5, 660-667 (1987). [CrossRef]
  42. M.J.F. Digonnet, J.R. Feth, L.F. Stokes, and H.J. Shaw, "Measurement of the core proximity in polished fiber substrates and couplers," Opt. Lett. 10, 463-465 (1985). [CrossRef] [PubMed]

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