Abstract

Third-order add-drop filters based on series-coupled microring resonators were fabricated in silicon-rich silicon nitride with accurate dimensional control and negligible sidewall roughness. For the first time, a low 3 dB drop loss is demonstrated with a wide 24 nm free-spectral-range in a high-order microring filter without using the Vernier effect. The spectral response is matched by rigorous numerical simulation, and non-idealities in the drop- and through-port responses are shown to be of design origin and to be correctable.

© 2004 Optical Society of America

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References

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  1. B.E. Little, S.T. Chu, H.A. Haus, J.S. Foresi and J.-P. Laine, �??Microring resonator channel dropping filters,�?? J. Lightwave Technol. 15, 998-1005 (1997).
    [CrossRef]
  2. B.E. Little, �??Advances in microring resonators,�?? presented at the Integrated Photonics Research Conference, Washington, DC, USA, 16-20 Jun. 2003.
  3. Y. Yanagase, S. Suzuki, Y. Kokubun and S.T. Chu, �??Box-like filter response and expansion of FSR by a vertically triple coupled microring resonator filter,�?? J. Lightwave Technol. 20, 1525-1529 (2002).
    [CrossRef]
  4. J.V. Hryniewicz, P.P. Absil, B.E. Little, R.A. Wilson and P.-T. Ho, �??Higher order filter response in coupled microring resonators,�?? IEEE Photon. Technol. Lett. 12, 320-322 (2000).
    [CrossRef]
  5. B.E. Little, �??A VLSI Photonic Platform,�?? in Proceedings of Optical Fiber Communication Conference, (Optical Society of America, Washington, DC, 2003), vol. 2, pp. 444-445.
  6. M. R. Watts, �??Wavelength switching and routing through evanescently induced absorption,�?? MS Thesis, Dept. of Electrical Eng. and Computer Sc., Massachusetts Institute of Technology, Cambridge MA, 2001.
  7. T. Barwicz and H.I Smith, �??Evolution of line-edge-roughness during fabrication of high index-contrast microphotonic devices,�?? J. Vac. Sci. Technol. B 21, 2892-2896 (2003).
    [CrossRef]
  8. C. Manolatou, M.A. Popovic, P.T. Rakich, T. Barwicz, H.A. Haus and E.P. Ippen, �??Spectral anomalies due to coupling-induced frequency shifts in dielectric coupled resonator filters,�?? presented at the Optical Fiber Communication Conference, Los Angeles, CA, USA, 22-27 Feb. 2004.
  9. R. Grover, V. Van, T. A. Ibrahim, P. P. Absil, L. C. Calhoun, F. G. Johnson, J. V. Hryniewicz, and P.-T. Ho, �??Parallel-cascaded semiconductor microring resonators for high-order and wide-FSR filters,�?? J. Lightwave Technol. 20, 900-905 (2002).
    [CrossRef]
  10. B.E. Little, S.T. Chu, J.V. Hryniewicz and P.P. Absil, �??Filter synthesis for periodically coupled microring resonators,�?? Opt. Lett. 25, 344-346 (2000).
    [CrossRef]

IEEE Photon. Technol. Lett. (1)

J.V. Hryniewicz, P.P. Absil, B.E. Little, R.A. Wilson and P.-T. Ho, �??Higher order filter response in coupled microring resonators,�?? IEEE Photon. Technol. Lett. 12, 320-322 (2000).
[CrossRef]

J. Lightwave Technol. (3)

B.E. Little, S.T. Chu, H.A. Haus, J.S. Foresi and J.-P. Laine, �??Microring resonator channel dropping filters,�?? J. Lightwave Technol. 15, 998-1005 (1997).
[CrossRef]

R. Grover, V. Van, T. A. Ibrahim, P. P. Absil, L. C. Calhoun, F. G. Johnson, J. V. Hryniewicz, and P.-T. Ho, �??Parallel-cascaded semiconductor microring resonators for high-order and wide-FSR filters,�?? J. Lightwave Technol. 20, 900-905 (2002).
[CrossRef]

Y. Yanagase, S. Suzuki, Y. Kokubun and S.T. Chu, �??Box-like filter response and expansion of FSR by a vertically triple coupled microring resonator filter,�?? J. Lightwave Technol. 20, 1525-1529 (2002).
[CrossRef]

J. Vac. Sci. Technol. B (1)

T. Barwicz and H.I Smith, �??Evolution of line-edge-roughness during fabrication of high index-contrast microphotonic devices,�?? J. Vac. Sci. Technol. B 21, 2892-2896 (2003).
[CrossRef]

OFC 2003 (1)

B.E. Little, �??A VLSI Photonic Platform,�?? in Proceedings of Optical Fiber Communication Conference, (Optical Society of America, Washington, DC, 2003), vol. 2, pp. 444-445.

OFC 2004 (1)

C. Manolatou, M.A. Popovic, P.T. Rakich, T. Barwicz, H.A. Haus and E.P. Ippen, �??Spectral anomalies due to coupling-induced frequency shifts in dielectric coupled resonator filters,�?? presented at the Optical Fiber Communication Conference, Los Angeles, CA, USA, 22-27 Feb. 2004.

Opt. Lett. (1)

Other (2)

M. R. Watts, �??Wavelength switching and routing through evanescently induced absorption,�?? MS Thesis, Dept. of Electrical Eng. and Computer Sc., Massachusetts Institute of Technology, Cambridge MA, 2001.

B.E. Little, �??Advances in microring resonators,�?? presented at the Integrated Photonics Research Conference, Washington, DC, USA, 16-20 Jun. 2003.

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Figures (3)

Fig. 1.
Fig. 1.

Cross-section of a waveguide. See Table 1 for waveguide parameters.

Fig. 2.
Fig. 2.

Third-order add-drop filter based on series-coupled microring resonators. The rings’ outer radius is 7.3 µm. The ring-to-bus gap is 60 nm and the ring-to-ring gap is 268 nm. (a) Scanning-electron micrograph. (b) Schematic of the chip layout used in the experiment. To ensure a reliable drop-loss measurement, the drop and the through waveguides traverse equivalent paths.

Fig. 3.
Fig. 3.

Measured and simulated response of the third-order microring filter. The spectral asymmetry is due to frequency mismatch of resonators and can be compensated. Input-to-drop loss is dominated by scattering at the 60-nm-wide ring-bus coupler gaps. The narrow peak on the right of the drop spectrum is a measurement artifact. The inset shows several resonances and the free-spectral-range.

Tables (1)

Tables Icon

Table 1. Waveguide Parameters

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