Integrated Photonic Microwave Bandpass Filter Incorporating a Polymer Microring Resonator

폴리머 마이크로링 공진기를 이용한 광학적 마이크로웨이브 대역통과 필터

  • Chin, Won-Jun (Department of Electronic Engineering, Kwangwoon University) ;
  • Kim, Do-Hwan (Department of Electronic Engineering, Kwangwoon University) ;
  • Song, Ju-Han (Department of Electronic Engineering, Kwangwoon University) ;
  • Lee, Sang-Shin (Department of Electronic Engineering, Kwangwoon University)
  • Published : 2005.10.01


An integrated photonic microwave bandpass filter has been proposed and demonstrated incorporating a coherently coupled microring resonator in low-loss polymers. The proposed device may feature compact site, simple structure, tuning via the thermooptic and electrooptic effect, and flexible integration with other electrical and optical devices. The resonator was designed to have an extremely small bandwidth so that it could be used to selectively pass the optical signal carrying the microwave signal to attain efficient bandpass filtering. We made and tested two resonators with a single ring and double rings, and performed a theoretical fitting of their measured transfer curves to predict the performance of the microwave filters based on them precisely. It was found that as the number of the rings used for the resonator increases, the bandwidth gets smaller, the rolloff sharper, and the band rejection higher. Finally our filter exhibited the center frequency of 10GHz, the 3-dB bandwidth of 1.0GHz, the corresponding quality (Q) factor of 10, and the rejection outside of the passband of more than 25dB.

본 논문에서는 코히런트하게 결합되는 폴리머 마이크로링 공진기를 이용한 광학적 방식의 마이크로웨이브 대역통과 필터를 제안하고 구현하였다. 제안된 소자는 소형이며 구조가 간단하고, 열광학 및 전기광학 효과를 통한 중심주파수 변화가 용이하고, 그리고 다른 전기소자나 광소자와의 집적성 등이 뛰어나다. 특히, 이 공진기는 마이크로웨이브 신호를 수반하는 광신호를 효과적으로 필터링하기 위해 아주 작은 대역폭을 갖도록 설계되었다. 본 논문에서는 한 개의 링과 두 개의 링으로 구성된 공진기를 각각 제작하여 특성을 확인하였다. 링 공진기의 측정된 전달 특성을 이론적으로 fitting하였으며, 이로부터 제안된 마이크로웨이브 필터의 특성을 정확하게 예측하였다. 공진기의 링 수가 증가할수록 대역폭은 감소하고 롤오(roll-off) 특성이 향상되며 대역 소멸비가 증가함을 알 수 있었다. 측정된 대역통과 필터의 중심주파수는 $\~10GHz$였고 3-dB 대역폭은 $\~0GHz$였다. 그리고 Q값(quality factor)은 $\~10$이었고 통과대역의 소멸비는 약 25dB였다.


  1. D. B. Hunter and R. A. Minasian, 'Tunable microwave fiber-optic bandpass filters,' IEEE Photon. Technol. Lett., vol. 11, no. 7, pp. 874-876, 1999
  2. D. B. Hunter and R. A. Minasian, 'Photonic signal processing of microwave signals using an active-fiber Bragggrating-pair structure,' IEEE Trans. Microwave Theory Tech., vol. 45, no. 8, pp. 1463-1466, 1997
  3. D. B. Hunter and R. A. Minasian, 'Microwave optical filters using in-fiber Bragg grating arrays,' IEEE Microwave Guided Wave Lett., vol. 6, no. 2, pp. 103-105, 1996
  4. F. Zeng and J. Yao, 'All-optical microwave mixing and bandpass filtering in a radio-over-fiber link,' IEEE Photon. Technol. Lett., vol. 17, no. 4, pp. 899-901, 2005
  5. M. Y. Frankel and R. D. Esman, 'Fiber-optic tunable microwave transversal filter,' IEEE Photon. Technol. Lett., vol. 7, no. 2, pp. 191-193, 1995
  6. B. Vidal, V. Polo, J. L. Corral, and J. Marti, 'Efficient architecture for WDM photonic microwave filters,' IEEE Photon. Technol. Lett., vol. 16, no. 12, pp. 257-259, 2004
  7. F. Coppinger, C. K. Madsen, and B. Jalali, 'Photonic microwave filtering using coherently coupled integrated ring resonators,' Microwave and Optical Technology Letters, vol. 21, no. 2, pp. 90-93, 1999<90::AID-MOP4>3.0.CO;2-V
  8. P. Rabiei, W. H. Steier, C. Zhang, and L. R. Dalton, 'Polymer micro-ring filters and modulators,' J. Lightwave Technol., vol. 20, no. 11, pp. 1968-1975, 2002
  9. D. H. Kim, J. G. Im, S. S. Lee, S. W. Ahn, and K. D. Lee, 'Polymer microring resonator using nanoimprint technique based on a stamp incorporating a smoothing buffer layer,' IEEE Photon. Technol. Lett, to be published, 2005
  10. Myung-Hyun Lee, Jung Jin Ju, Suntak Park, Jung Yun Do, and Seung Koo Park, 'Polymer-based devices for optical communications,' ETRI J. vol. 24, no. 4, August 2002
  11. Jin Tae Kim, Choon-Gi Choi, and Hee-Kyung Sung, 'Polymer planaer-Iigntwave-circuit-type variable optical attenuator fabricated by hot embossing process,' ETRI J. vol. 27, no. 1, February 2005
  12. Chung-Yen Chao and L. Jay Guo, 'Thermal-flow technique for reducing surface roughness and controlling gap size in polymer microring resonator,' Appl. Phys. Lett., vol. 84, no. 14, pp. 2479-2481, 2004
  13. A. Yariv, 'Universal relations for coupling of optical power between microresonators and dielectric waveguides,' Electron. Lett., vol. 36, no. 4, pp. 321-322, 2000
  14. D. Marcuse, 'Bending losses of the asymmetric slab waveguide,' Bell System Technical J, vol. 50, no. 8, pp. 2551-2563, 1971
  15. C. K. Madsen and J. H. Zhao, 'A general planar waveguide autoregressive optical filter,' J. Lightwave Technol., vol. 14, no. 3, pp. 437-447, 1996
  16. T. Ito and Y. Kokubun, 'Nondestructive measurement of propagation loss and coupling efficiency in microring resonator filters using filter response,' Jap. J. Appl. Phys., vol. 43, no. 3, pp. 1002-1005, 2004