Browse Prior Art Database

Parallel Injection Acousto Optical Tunable Filter

IP.com Disclosure Number: IPCOM000109329D
Original Publication Date: 1992-Aug-01
Included in the Prior Art Database: 2005-Mar-23
Document File: 2 page(s) / 93K

Publishing Venue

IBM

Related People

Choy, MM: AUTHOR [+4]

Abstract

Disclosed is a scheme using parallel acoustic wave injection to speed up the process of filling the entire filter and one to two order of magnitude tuning speed increase can be expected from this scheme.

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Parallel Injection Acousto Optical Tunable Filter

       Disclosed  is  a  scheme using parallel acoustic wave
injection to speed up the process of filling the entire filter and
one to two order of magnitude tuning speed increase can be expected
from this scheme.

      The reconfiguration speed of an acousto-optical device is
primarily limited by the sound velocity in the material, for example,
LiNbO3 and GaAs.  In particular, the acousto-optic tunable filter
performance is limited by the inherent trade-off between the tuning
speed and the filter resolution since the filter bandwidth is
inversely proportional to the length of active area (*).  The tuning
speed is given by the time it takes to fill this length with acoustic
waves at the new frequency.  For a typical required optical bandwidth
on the order of several nanometers, this time constant is on the
order of several microseconds.  This speed needs to be improved for
gigabit packet switching applications which may require
submicrosecond tuning time.

      In this article, we propose to divide an acousto-optic tunable
filter (AOTF) into multiple sections and each section has its own RF
transducer and the RF signals are injected into all of the
transducers simultaneously.  Coherent phase continuity between
adjacent transducers has to be maintained to ensure constructive
generation of the three-wave phase matched interaction.  The proposed
multi-section AOTF (MS-AOTF) is shown in the figure.  An acoustic
absorber is placed at the end of each section for the following two
reasons:
o   t...