Open AccessWavelength switchable flat-top all-fiber comb filter based on a double-loop Mach-Zehnder interferometer
Author(s) -
Aiping Luo,
ZhiChao Luo,
WenCheng Xu,
ChiChang Hu
Publication year - 2010
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.18.006056
Subject(s) - optics , comb filter , interferometry , polarization controller , passband , channel spacing , wavelength , polarizer , bandwidth (computing) , physics , materials science , mach–zehnder interferometer , wavelength division multiplexing , band pass filter , fiber laser , telecommunications , birefringence , computer science
A wavelength switchable all-fiber comb filter with flat-top spectral response based on a double-loop Mach-Zehnder (M-Z) interferometer is proposed and demonstrated. The proposed flat-top filter consists of a rotatable polarizer and a double-loop M-Z interferometer composed of two fiber couplers with a polarization controller (PC) in the first loop. In the theoretical analysis, when the second coupler of the M-Z interferometer is a non-3dB one, with proper settings of the polarization state of the input light and the PC, the wavelength switchable comb filter with flat-top passband can be obtained. Theoretical prediction was verified by experimental demonstration. The measured 1 dB bandwidth was 0.51 nm with a channel spacing of 0.98 nm, indicating that the flat-top passband of 1 dB bandwidth extends to about 50% of the comb spacing.