# 편광상이 고리 구조 기반 Lyot형 고차 광섬유 빗살 필터의 출력 편광 분석에 관한 연구

• Accepted : 2015.08.23
• Published : 2015.10.30
• 15 52

#### Abstract

In this paper, we investigated the output polarization of a Lyot-type optical fiber comb filter based on a polarization-diversity loop structure. It was found that the output state of polarization (SOP) of the filter made a wavelength-dependent evolution, and the spectral periods of the output SOP variation in flat-top and lossy flat-top band modes were the channel separation of the filter and its half, respectively. For a certain input SOP, the filter could pass or reject specific spectral sections by adding and controlling an output analyzer. In particular, it was theoretically anticipated that the filter with the output polarizer could provide the fine continuous tuning of its pass band center in a wavelength range corresponding to the ${\pm}9.5%$ of channel spacing(0.8nm) when the input SOP was properly adjusted. It is expected that this tuning function can be effectively applied to suppress unwanted spectral portions in modulated optical signals.

#### Keywords

Polarization-Maintaining Fiber;Birefringence;Lyot Filter;Polarization

#### References

1. T. Hasegawa, K. Inoue, and K. Oda, "Polarization independent frequency conversion by fiber four-wave mixing with a polarization diversity technique," IEEE Photonics Technology Letters, vol. 5, pp. 947-949, 1993. https://doi.org/10.1109/68.238264
2. X. Fang, and R. O. Claus, "Polarization-independent all-fiber wavelength-division multiplexer based on a Sagnac interferometer," Optics Letters, vol. 20, pp. 2146-2148, 1995. https://doi.org/10.1364/OL.20.002146
3. Y. W. Lee, K. J. Han, B. Lee and J. Jung, "Polarization-independent all-fiber multiwavelengthswitchable filter based on a polarization-diversity loop configuration," Optics Express, vol. 11, pp. 3359-3364, 2003. https://doi.org/10.1364/OE.11.003359
4. I. Solc, "Birefringent chain filters," Journal of the Optical Society of America, vol. 55, pp. 621-625, 1965. https://doi.org/10.1364/JOSA.55.000621
5. Y. W. Lee, H.-T. Kim, J. Jung, and B. Lee, "Wavelength-switchable flat-top fiber comb filter based on a Solc type birefringence combination," Optics Express, vol. 13, pp. 1039-1048, 2005. https://doi.org/10.1364/OPEX.13.001039
6. Y. W. Lee, H.-T. Kim, and Y. W. Lee, "Second-order all-fiber comb filter based on polarization-diversity loop configuration," Optics Express, vol. 16, pp. 3871-3876, 2008. https://doi.org/10.1364/OE.16.003871
7. S. Jo, K. Park, and Y. W. Lee, "Lyot-type flat-top fibre multiwavelength filter based on polarisation-diversity loop structure," Micro & Nano Letters, vol. 9, pp. 858-861, 2014. https://doi.org/10.1049/mnl.2014.0386

#### Acknowledgement

Supported by : 한국연구재단