Abstract
In this paper, we did a study of the transmission characteristics of the
acousto-optic tunable filter (AOTF) operating with ultra-short light
pulses (2 ps). Initially one considers the performance of the device.
with several lengths, operating in the non-linear regime without loss,
It was observed that the effect of dispersion and non-linearity has
strong influence on the pulse propagation when one increases the length
of the AOTF, For shorter length of the device the switched pulse is
presenting time broadening for soliton and non-soliton profiles. For
higher length of the device, pulse break-up was observed for non-soliton
profile and time displacement for the soliton profile. Considering the
AOTF with 4 dB/mm. of loss, one considers the device of length 0.25 mm
constructed with several increasing non-linearity profiles. In this
paper, we compare five simple coefficients of self phase modulation
(SPM) profiles, namely linear, Gaussian, exponential, logarithm and
constant. One can observe that there is always an optimum value for beta
(final value of the profile Q(xi) of the non-linearity) that one can
obtain a switched pulse with the same time duration of the input pulse,
Comparing the soliton and non-soliton pulse propagation, one can say
that the constant profile present the lowest value for beta comparing
with the other profiles. This value is around 1.53 and 1.79 for the
non-soliton and soliton propagation, respectively, One can also say that
one can operate the AOTF in a configuration that one can avoid the pulse
break-up and have a switched pulse with the same time duration compared
with the lossy AOTF. With the increase of the beta parameter the pulse
is showing break-up even for the constant profile, One concludes that is
possible to operate the AOTF in a soliton and non-soliton input
profiles. The study of the AOTF operating with ultra-short optical
pulses provides possibilities for achieving, high efficiency in
ultra-fast all-optical signal processing, especially for optical
switches, filters and optical transistors. The AOTF has attracted great
attention in recent years, in part because it appears to be a suitable
basis for multi-wavelength optical cross-connects. It is probably the
only known tunable filter that is capable of selecting several
wavelengths simultaneously, This capability can be used to construct a
multi-wavelength router. (C) 2002 Elsevier Science B.V. All rights
reserved.
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