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Acousto-Optically Tuned Angle Etalon

IP.com Disclosure Number: IPCOM000100289D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Liu, K: AUTHOR [+2]

Abstract

Tunable optical filters for use in wavelength-division multiplexed optical communications generally fall into two categories: mechanical tuning which is slow but independent of optical polarization, or acousto- or electro-optic which is fast but usually polarization dependent. This invention uses acousto-optics to replace mechanical tuning in a hybrid scheme to avoid both problems.

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Acousto-Optically Tuned Angle Etalon

       Tunable optical filters for use in wavelength-division
multiplexed optical communications generally fall into two
categories: mechanical tuning which is slow but independent of
optical polarization, or acousto- or electro-optic which is fast but
usually polarization dependent.  This invention uses acousto-optics
to replace mechanical tuning in a hybrid scheme to avoid both
problems.

      Etalons have long been used as wavelength selective filters in
optical systems.  The simplest form is a Fabry-Perot cavity formed by
two parallel mirror surfaces. The passband of the optical filter
depends on the optical path through the etalon, which, in turn,
depends on the angle at which the beam is incident.  Tilting such
etalons to tune them is a standard technique.

      However, the speed at which such mechanical tuning can be
achieved is limited to sub-kHz. In optics, fast tuning (in micro- or
nano-seconds) is usually done with acousto-optics or electro-optics.
Tunable filters made with these mechanisms usually can work only on a
single specified polarization.  However, acousto-optic beam
deflectors (as opposed to filters) can be and have been constructed
to be polarization-independent.  That is, the angle of deflection
does not depend on polarization.  For some devices, the efficiency of
deflection is also insensitive to polarization.  The angle of
deflection can be varied by changing the acoustic frequency.  This
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