@InProceedings{Supelec609,
author = {Xunqui Wu and Joel Jacquet and Guang-Hua Duan},
title = {{Steep and flat bandpass filter using linearly chirped and apodized fiber Bragg grating}},
year = {2010},
booktitle = {{Proceedings of SPIE (Optical Components and Materials VII)}},
volume = {7598},
number = {1Y},
month = {jan},
note = {(Poster)},
address = {San Francisco (USA)},
url = {http://dx.doi.org/10.1117/12.842689},
doi = {10.1117/12.842689},
abstract = {The development of new optical systems requires the design of
novel components that fulfill the market constraints. In
particular, low loss, high optical rejection and low cost
narrowband filters can play an important role for the
introduction of the Wavelength Division Multiplexing (WDM)
technology in the local network. So, a novel fiber filter is
proposed in this article, with a special combined apodized
Linearly Chirped Fiber Bragg Grating (LCFBG) which presents the
preferable flat-top and steep-edge characteristics. In the
design, we use a continuum cavity condition which is obtained
when the effective round-trip phase of oscillated wavelength band
is kept identical over the whole Bragg wavelength range. And the
transmission spectra are calculated by the reconstruction of the
matrixes with the continuum oscillation condition. Therefore, our
works show that the ideal square shaped filter is obtained with a
lower chirp value relatively together with symmetric reflectivity
on both mirrors. The coupling coefficient of the FBG is adjusted
to get the same reflectivity values and then to get a
transmission filter close to unity. We have then introduced an
apodization function of the filter to get a flatter transfer
function. Various apodizations schemes have been tested. In this
paper, we design and analyze a type of continuum fiber filter
with the cavity formed between mirror and apodized LCFBG as
reflectors. We calculate firstly the reflectivity, the
transmissivity and the group time delay of LCFBG modeled by a
simple and practical Transfer Matrix Method (TMM), and then the
cavity is reconstructed by TMM, the length of the oscillated
cavity is calculated by the continuum oscillation condition, so
the output of transmission from the side of LCFBG is continuous
in the corresponded reflected bandwidth of LCFBG. We obtain the
results and discuss some characteristics of this type of
continuum fiber filter.}
}