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Fast Wave Optical Guide Couplers Using Holographic Elements

IP.com Disclosure Number: IPCOM000073652D
Original Publication Date: 1971-Jan-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Pennington, K: AUTHOR [+2]

Abstract

An important element in the use of optical waveguides is the provision of efficient input and output couplers. One known class of couplers is based on the principle of "fast wave leakage" wherein the guide velocity in a localized region is made to exceed the velocity in the surrounding medium so that its energy will radiate out of the guide. The improvement is illustrated by reference to this class of coupler, but as will appear has a wider scope of application.

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Fast Wave Optical Guide Couplers Using Holographic Elements

An important element in the use of optical waveguides is the provision of efficient input and output couplers. One known class of couplers is based on the principle of "fast wave leakage" wherein the guide velocity in a localized region is made to exceed the velocity in the surrounding medium so that its energy will radiate out of the guide. The improvement is illustrated by reference to this class of coupler, but as will appear has a wider scope of application.

An example of a fast wave coupler is shown in drawing A. This output coupler is, in principle, one hundred percent efficient. The emerging beam has an unstable profile in the sense that unlike a Gaussian beam, its form as well as its diameter will change with distance and may, therefore, be hard to use in some specific optical arrangements.

The same device can be used as an input coupler, and if a beam could be obtained having the same profile as that of the output beam indicated in A, the coupler would be in principle one hundred percent efficient. An optical mode transformer that will transform a Gaussian profile into the profile required for the coupler can be effected with high efficiency, using a phase hologram. A plate is prepared having a density profile matching the amplitude profile of the required beam and used as the object in constructing the phase hologram, with a Gaussian reference beam. The input coupler would then take the form in...