M. Sharma et al., OPTICAL CIRCUITS FOR EQUALIZING GROUP DELAY DISPERSION OF OPTICAL FIBERS, Journal of lightwave technology, 12(10), 1994, pp. 1759-1765
Optical circuits are synthesized for equalizing the group delay disper
sion of single-mode fibers. The transfer function of the equalizing ci
rcuits are given by Chebyshev polynomials of the second kind. The vari
ous realization methods for the group delay equalizer are shown, inclu
ding periodic structures using birefringent crystals, birefringent fib
ers, and Mach-Zehnder interferometric planar optical circuits. An opti
cal equalizer employing TiO2 birefringent crystals was fabricated and
evaluated by using an optical network analyzer, which operates by maki
ng modulation-envelope phase and amplitude measurements while scanning
the optical carrier frequency. The measured optical equalizer charact
eristics show excellent agreement with the simulation analysis. The ef
fectiveness of the equalizer for substantial reduction of the dispersi
on penalty for a 10 Gb/s signal transmitted over 30 km of normal dispe
rsion fiber was demonstrated. The periodicity of the equalizer results
in periodic dispersion-free bands, and hence, the equalizer is suitab
le for use in future multichannel FDM systems.