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EMI Shielding for High Performance Optoelectronic Transceiver through Utilization of Electrically Conductive Gasket and Laser Welding

IP.com Disclosure Number: IPCOM000112845D
Original Publication Date: 1994-Jun-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Bernier, WE: AUTHOR [+3]

Abstract

Electromagnetic interference is a particularly critical design consideration for optoelectronic devices, especially when both the light emitting source and high sensitivity receiver are incorporated in a single optoelectronic module. Effective shielding is required to isolate the Transmitter Optical Subassembly (TOSA) from the Receiver Optical Subassembly (ROSA) so that transmitted signals do not reduce the sensitivity of the receiver photo diode. The transmitted signals may originate not only from the TOSA but also from external sources in the operating environment. High voltage discharges also create a secondary concern since they may cause damage to TOSA and ROSA circuitry.

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EMI Shielding for High Performance Optoelectronic Transceiver through
Utilization of Electrically Conductive Gasket and Laser Welding

      Electromagnetic interference is a particularly critical design
consideration for optoelectronic devices, especially when both the
light emitting source and high sensitivity receiver are incorporated
in a single optoelectronic module.  Effective shielding is required
to isolate the Transmitter Optical Subassembly (TOSA) from the
Receiver Optical Subassembly (ROSA) so that transmitted signals do
not reduce the sensitivity of the receiver photo diode.  The
transmitted signals may originate not only from the TOSA but also
from external sources in the operating environment.  High voltage
discharges also create a secondary concern since they may cause
damage to TOSA and ROSA circuitry.  The shielding provided by gasket
material filled with silver plated aluminum particles under
compression provides an effective ground path between ROSA and the
module lid and between TOSA and module lid at the front of the
module.  The housing is laser welded to the module lid providing
ground path through the entire module housing and TOSA/ROSA housings.

      Fig. 1(a) illustrates the lid.  It has a groove in it for
insertion of the electrically conductive gasket.  Fig. 1(b)
illustrates the housing with a groove in the center section to
accommodate the gasket.  Fig. 2 illustrates the gasket which fits in
the ROSA and TOSA wells of the lid. ...