Proposed is a Lyot-type flat-top fibre multiwavelength filter based on a polarisation-diversity loop structure, which has flat-top and lossy flat-top passbands and multiwavelength switching capability. The proposed filter is composed of a polarisation beam splitter, two half-wave plates (HWPs) and two polarisation-maintaining fibre (PMF) loops concatenated with a 60° offset between their principal axes. One of the two PMF loops is two times longer than the other. It is able to operate in a flat-top or a lossy flat-top band mode at the selected combination of the azimuthal orientation angles of two HWPs. In particular, through the adjustment of the orientation angles of the two HWPs, its multiwavelength channels can be interleaved in each mode, which cannot be realised in a previously reported Lyot-Sagnac comb filter based on a fibre coupler. In addition to the channel interleaving capability, it provides narrower passbands compared with previous fibre multiwavelength filters with the same order. To make a quantitative comparison between the passband bandwidths of the proposed filter and other filters, both −1 and −3 dB passband bandwidths of a conventional zeroth-order, a Solc-type first-order and the proposed multiwavelength filters were considered and compared with each other.

References

1. 1)
  - 6. Fang, X., Demarest, K., Ji, H., Allen, C., Pelz, L.: ‘A subnanosecond polarization-independent tunable filter/wavelength router using a Sagnac interferometer’, IEEE Photonics Technol. Lett., 1997, 9, pp. 1490–1492 (doi: 10.1109/68.634718).
2. 2)
  - 4. Lee, Y.W., Han, K.J., Lee, B., Jung, J.: ‘Polarization-independent all-fiber multiwavelength-switchable filter based on a polarization-diversity loop configuration’, Opt. Express, 2003, 11, pp. 3359–3364 (doi: 10.1364/OE.11.003359).
3. 3)
  - 17. Özgören, K., Ilday, F.Ö.: ‘All-fiber all-normal dispersion laser with a fiber-based Lyot filter’, Opt. Lett., 2010, 35, pp. 1296–1298 (doi: 10.1364/OL.35.001296).
4. 4)
  - 8. Yoon, I., Lee, Y.W., Jung, J., Lee, B.: ‘Tunable multiwavelength fiber laser employing a comb filter based on a polarization-diversity loop configuration’, J. Lightwave Technol., 2006, 12, pp. 1805–1811 (doi: 10.1109/JLT.2006.871013).
5. 5)
  - 9. Kim, C.S., Kang, J.U.: ‘Multiwavelength switching of Raman fiber ring laser incorporating composite polarization-maintaining fiber Lyot-Sagnac filter’, Appl. Opt., 2004, 43, pp. 3151–3157 (doi: 10.1364/AO.43.003151).
6. 6)
  - 14. Fang, X., Claus, R.O.: ‘Polarization-independent all-fiber wavelength-division multiplexer based on a Sagnac interferometer’, Opt. Lett., 1995, 20, pp. 2146–2148 (doi: 10.1364/OL.20.002146).
7. 7)
  - 19. Solc, I.: ‘Birefringent chain filters’, J. Opt. Soc. Am., 1965, 55, pp. 621–625 (doi: 10.1364/JOSA.55.000621).
8. 8)
  - 18. Yan, Z., Mou, C., Wang, H., et al: ‘All-fiber polarization interference filters based on 45°-tilted fiber gratings’, Opt. Lett., 2012, 37, pp. 353–355 (doi: 10.1364/OL.37.000353).
9. 9)
  - 11. Ryu, C.-H., Jung, S.-Y., Koo, J.-Y., Yeon, M.-S.: ‘An application of the novel techniques detecting partial discharge employable to GIS using optical fiber’, KIEE J. Electr. Eng. Technol., 2007, 2, pp. 396–400 (doi: 10.5370/JEET.2007.2.3.396).
10. 10)
  - 10. Lee, Y.W., Jung, J., Lee, B.: ‘Multiwavelength-switchable SOA-fiber ring laser based on polarization-maintaining fiber loop mirror and polarization beam splitter’, IEEE Photonics Technol. Lett., 2004, 16, pp. 54–56 (doi: 10.1109/LPT.2003.819414).
11. 11)
  - 3. Lee, Y.W., Han, K.J., Jung, J., Lee, B.: ‘Polarization-independent tunable fiber comb filter’, IEEE Photonics Technol. Lett., 2004, 16, pp. 2066–2068 (doi: 10.1109/LPT.2004.832601).
12. 12)
  - 20. Kim, Y., Lee, Y.W.: ‘Study on spectral deviations of high-order optical fiber comb filter based on polarization-diversity loop configuration’, Opt. Commun., 2013, 301–302, pp. 159–163 (doi: 10.1016/j.optcom.2013.03.017).
13. 13)
  - 15. Lee, Y.W., Kim, H.-T., Jung, J., Lee, B.: ‘Wavelength-switchable flat-top fiber comb filter based on a Solc type birefringence combination’, Opt. Express, 2005, 13, pp. 1039–1048 (doi: 10.1364/OPEX.13.001039).
14. 14)
  - G. Rossi , O. Jerphagnon , B.-E. Olsson , D.J. Blumenthal . Optical SCM data extraction using a fiber-loop mirror for WDM network systems. IEEE Photonics Technol. Lett. , 897 - 899
15. 15)
  - 5. Zhu, G., Wang, Q., Chen, H., Dong, H., Dutta, N.K.: ‘High-quality optical pulse train generation at 80 Gb/s using a modified regenerative-type mode-locked fiber laser’, IEEE J. Quantum Electron., 2004, 40, pp. 721–725 (doi: 10.1109/JQE.2004.828266).
16. 16)
  - 2. Lee, Y.W.: ‘Polarization-independent multiwavelength-switchable filter based on polarization beam splitter and fiber coupler’, KIEE J. Electr. Eng. Technol., 2009, 4, pp. 405–409 (doi: 10.5370/JEET.2009.4.3.405).
17. 17)
  - 12. Ryu, H.-S., Han, G.-H., Yoon, N.-S.: ‘The method of determining stress levels regarding the electrical ALT through optical temperature sensor’, KIEE J. Electr. Eng. Technol., 2008, 3, pp. 184–191 (doi: 10.5370/JEET.2008.3.2.184).
18. 18)
  - 16. Jia, Z., Chen, M., Xie, S.: ‘Label erasing technique employing Lyot-Sagnac filter’, Electron. Lett., 2002, 38, pp. 1563–1564 (doi: 10.1049/el:20021029).
19. 19)
  - 13. Jung, H., Kim, J.-Y., Chang, K.-T., Jung, C.-S.: ‘Slope movement detection using ubiquitous sensor network’, KIEE J. Electr. Eng. Technol., 2009, 4, pp. 143–148 (doi: 10.5370/JEET.2009.4.1.143).
20. 20)
  - T. Hasegawa , K. Inoue , K. Oda . Polarization independent frequency conversion by fiber four-wave mixing with a polarization diversity technique. IEEE Photonics Technol. Lett. , 8 , 947 - 949

Lyot-type flat-top fibre multiwavelength filter based on polarisation-diversity loop structure

References

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