DD148261A1 - CONVERSION PROCESS OF UNPOLARIZED LIGHT IN LINEAR POLARIZED LIGHT - Google Patents

Abstract

Optical communication techniques require non-reciprocal optical devices, but they require linearly polarized light for their function, which is generally not readily available. The aim is to achieve a high degree of conversion when converting unpolarized light into linearly polarized light. This is achieved by dividing the unpolarized light into two parts via a lens of optically anisotropic material, one part of which is bundled and the other part is parallelized. The bundled portion is then rotated in its polarization plane, for example via a lambda / 2 plate, so that it runs parallel to the first component and thus both components are now linearly polarized. The method makes the use of low-fidelity, non-reciprocal optical devices that are easy to manufacture available to the practice.

Description

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Berlin, 9.11.79 Ze / Ks 29170/333

Applicant Claus Renschen

Title: Transformation of unpolarized light into linearly polarized light

field of use

The invention relates to a method for converting unpolarized light into linearly polarized _light} which is used in optical communication systems, optical-Mei3 teohnik and the optical equipment construction.

Characteristic of known technical solutions

The optical information transmission line systems require, among others, non-reciprocal optical devices. However, these components, which are already known from radio-frequency technology, such as isolators and circulators, require linearly polarized electromagnetic waves for their function, that is to say those based on the optical range: linearly polarized light. However, linearly polarized light is generally not readily available in optical communications technology, so that it is known per se by use of the art

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Polarization filters or polarization prisms must be obtained from unpolarized light, either using dichroic or pleochroic materials, light of only one polarization direction unhindered passing such a polarization filter, while all other light is absorbed or by means of birefringent prisms, for example Nicoisches Prisma, Glan-Thomson -Prisma, Eoehon-Prisma et al., 'Two with respect to their polarization perpendicular to each other standing light components with different propagation sr ichtung generated, cf. IT.D. Shewandrow: The polarization of light, Akademie-Verlag, Berlin 1973. The use of the known polarizing filters thus causes a loss of interference of about 50 % · The use of polarizing prisms means a relatively high cost to exploit both with respect to their polarization perpendicular to each other standing light components or also calls a Intensitätsverl ust of ca. 50 % .

Object of the invention

The aim of the invention is to achieve a high degree of conversion in the conversion of unpolarized light into linearly polarized light, which allows the realization of non-reciprocal optical components with low intensity losses.

Explanation of the essence of the invention

It is an object of the invention in a method for converting unpolarized light in linearly polarized light to use simple lenses such that unpolarized light is almost completely converted into linearly polarized light of a propagation direction. This is achieved according to the invention in that unpolarized light is separated in two points by a lens of optically anisotropic material.

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is formed, that a portion of the light is focused and the other portion is parallelized so that the polarization of the light in these two points is perpendicular to each other, and in one of these points or near one of these points means for rotation of the polarization plane of the light are arranged and dimensioned so that the influence of the parallelized portion of the light, is relatively low and that in the vicinity of one of these points. Lenses are arranged from optically isotropic material such that both light components propagate with the same direction and / or the same angular divergence.

exemplary

Reference to a reproduced in the accompanying drawings embodiment, the invention is explained in detail. The drawing shows an arrangement for carrying out the method according to the invention by means of light emerging from an optical waveguide for the optical communication.

A arranged in a holder 9 Kalkspatlinse 2 .. _; '·· forms light emerging from the end face 4 of an optical waveguide 1, in two points.

The end surface 4 of the optical waveguide 1 is arranged at a distance 3 from the calcite lens 2, which is equal to the focal length of the calcspar lens 2 for light having a polarization direction (extraordinary proportion AS) parallel to the crystal axis 10 of the calcspar lens 2. One of the points mentioned here lies at infinity, that is, the extraordinary proportion AS of the light is parallelized behind the calcite lens 2. The light component with a polarization direction perpendicular to the crystal axis 10 of the calcspar lens 2, that is, the ordinary portion OS, is focused in the other point 8

 On a glass plate 5, a converging lens 6 is arranged in such a way.

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net, that the ordinary portion OS of the light is also parallelized and passes through the glass plate 5, on the other side of a λ / 2 plate 7 is arranged, which rotates the polarization direction of the ordinary portion OS by 90 °, so that this λ / 2-plate with respect to the crystal axis 10 leaves as an extraordinary proportion AS. The unpolarized light of the optical waveguide 1 has thus been almost completely converted into linearly polarized light, polarization direction perpendicular to the crystal axis 10. Conversely, parallel light waves of corresponding polarization can be coupled into the optical waveguide 1.

With the method according to the invention can be realized in conjunction with Λ / 2 plates, Faraday rotors and liquid crystals with natural rotation of the polarization plane low-attenuation, non-reciprocal optical components.

Claims (1)

_ ₅ _ '213034 invention claim A method of converting unpolarized light into linearly polarized light, characterized in that unpolarized light is imaged through a lens of optically anisotropic material at two points such that one portion is collimated and the other portion is collimated so that the polarization of the light in These two points are perpendicular to each other, and that in one of these points or in the vicinity of one of these points means for rotation of the plane of polarization of the light are arranged and dimensioned such that the influence of the parallelized portion of the light, is relatively small, and in that Are arranged near one of these points lenses of optically isotropic material such that both light components propagate with the same direction and / or the same angular divergence · A side , drawing. ,