Browse Prior Art Database

Optical Waveguides Built into Modules

IP.com Disclosure Number: IPCOM000088611D
Original Publication Date: 1977-Jul-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Archey, WB: AUTHOR

Abstract

This article relates to packaging applications wherein optical cables are used to communicate between two more electronic functions which are remote from one another. Typically, the light-emitting diodes at one end of the cable transmit signal pulses in the 10/-6/ meter wavelength reflections to the detectors at the opposite end of the cable. In such typical prior art it is usually required that the respective cable ends either contact or be in very close proximity to the emitters and the detectors. Specifically, this article teaches that optical signals can be brought from devices in a package to the package periphery without having additional discrete optical fibers installed through the package wall, thus avoiding mechanical assembly, rework or replacement problems usually attendant with the optical fiber approach.

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Optical Waveguides Built into Modules

This article relates to packaging applications wherein optical cables are used to communicate between two more electronic functions which are remote from one another. Typically, the light-emitting diodes at one end of the cable transmit signal pulses in the 10/-6/ meter wavelength reflections to the detectors at the opposite end of the cable. In such typical prior art it is usually required that the respective cable ends either contact or be in very close proximity to the emitters and the detectors. Specifically, this article teaches that optical signals can be brought from devices in a package to the package periphery without having additional discrete optical fibers installed through the package wall, thus avoiding mechanical assembly, rework or replacement problems usually attendant with the optical fiber approach.

The preferred method of achieving this, shown in the figure, employs utilization of strips 10 of polyimide dielectric layers so that optical, as well as electrical, paths can be simultaneously or sequentially fabricated. Polyimide, as the light-conducting medium, has the advantage of low absorption near one micron wavelength while the evaporated metal, layer 11, covering the waveguides, assures total internal light reflections for minimum loss of light within the polyimide. The metal coating also eliminates crosstalk between channels.

Requirements for the optical waveguide cross-sectional dimensions are few, but it is necessary that when a rectangular shape is used that the minimum dimension be greater than one half of the wavelen...