Increasing the free spectral range of silica waveguide rings for filter applications. Academic Article uri icon


  • Ring resonators are promising building blocks for developing compact optical filters with arbitrary functions; however, a major challenge for planar waveguide filter implementations is to overcome the limited free spectral range (FSR) for a given core-to-cladding refractive-index difference (D) while maintaining low loss and a large range of coupling ratios. The loss and coupling of rings operating in the whispering-gallery-mode regime were investigated by use of Ge-doped silica waveguides with a low refractive-index difference (D=0.75%) . A FSR of 12 GHz with a loss of 0.36 dB/cm was demonstrated with coupling ratios of 30% (41% optimum).

published proceedings

  • Opt Lett

altmetric score

  • 3

author list (cited authors)

  • Madsen, C. K., & Zhao, J. H.

citation count

  • 5

complete list of authors

  • Madsen, CK||Zhao, JH

publication date

  • January 1998