DE2911129A1 - RING INTERFEROMETER WITH A SINGLE-MODE LIGHT-WAVE GUIDE WINDED TO A COIL - Google Patents

Description

SIEMENS AKTIENGESELLSCHAFT Our mark
Berlin and Munich VPA 79 P 7 O 4 O BRO

Ring interferometer with one wound into a coil Single mode fiber optic cable

The present invention relates to a ring interferometer having a coil wound
Single mode fiber optic cable.

Ring interferometers of the type mentioned are based on the Sagnac effect, which occurs when the known The arrangement in relation to a reference system generates non-reciprocal running time differences in the coil, which can be determined interferometrically. A typical application of such a ring interferometer is in the field of navigation.

It has been observed that a birefringent property of a single mode optical waveguide used
can lead to difficulties. In order to remedy such difficulties, it has previously been suggested that
between the ends of the single-mode optical fiber

and receiving photodetectors polarizing filters
whose polarization planes are parallel to each other (see older patent applications
Ed 1 Sti / 21.3.79 _{0300A2 / O018}

3 -r- VPA 79 ρ? 04 O FRG

P 28 04 103.4 (VPA 78 P 7005), P 28 04 119.2 (VPA 78 P 7006) and P 28 14 476.5 (VPA 78 P 7035)).

It is the object of the present invention to provide a ring interferometer of the type mentioned at the beginning, which works without such polarization filters, but with birefringent properties of Optical fibers can still not lead to difficulties.

The object is achieved in that the single-mode optical waveguide and / or additionally present optical waveguides coupled to the single-mode optical waveguide is or are formed with one or more optical waveguides which have only one polarization state can lead or can and / or that for coupling together existing optical waveguides Directional couplers are used that can only couple one polarization state.

Through this surprisingly simple-appearing solution idea, the difficulties, -those through Birefringence can be caused suddenly and easily eliminated.

A fiber or a strip conductor can be used as an optical waveguide that can only carry one polarization state be used. Such optical waveguides, which can only carry one state of polarization, are from Appl. Phys. Lett. 33 (1978) 814-816 and Appl. Phys. Lett. 33 (1978) 699-701 known.

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The teaching given by the label of the claim applies to all ring interferometers, regardless of theirs Construction can be used.

For example, it can be used for all the embodiments of those specified in the earlier patent applications mentioned Embodiments are applied. In embodiments in which the light is in free beam paths is fed to the coil or continued from it, the fiber optic cable of the coil may of necessity lead only one polarization state. This is the case, for example, with older patent applications P 28 04 103.4 (VPA 78 P 7005) and P 28 14 476.5 (VPA 78 P 7035) Figures 1 to 3.

The light is fed to the coil in an optical circuit in additional optical waveguides or continued by it, it is useful if these additional optical waveguides are present can only lead one polarization state. Such an optical circuit is for example in Embodiment of the earlier patent application P 28 04 119.2 (VPA 78 P 7006) as well as in both other patent applications indicated in FIG.

This circuit also contains optical directional couplers. It is then useful if these optical directional couplers can only couple one polarization state.

The three alternative options can be used individually or in any combination, as can be seen from the label of the claim.

It is clear that the fiber optic cable (s) that

030042/0016

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can only lead one polarization state or the directional coupler (s) that can only couple over one polarization state, according to the
Structure of the ring interferometer can be used in such a way that
that they achieve the same effect as is achieved with the polarization filters in the subjects of the earlier patent applications mentioned. In the subject of the earlier patent application P 28 04 119.2
(VPA 78 P 7006) this effect is achieved with certainty if both existing directional couplers can only couple one and the same polarization state and / or if all of the optical waveguides of the optical circuit that are also present in addition to the coil, with which the directional couplers are also constructed, only have one and can lead the same polarization state. Even
the optical waveguide of the coil itself can be such an optical waveguide. If the optical waveguides of the optical circuit are ordinary optical waveguides and their structure is designed in such a way, for example with small curvatures and short length, so that no significant disruptive effects become effective in them, it is also sufficient if only the optical waveguide of the coil is an optical waveguide, the only
can lead to a polarization state.

1 claim

030042/0016

Claims (1)

79 P 7 O 4 O BRO Claim Ring interferometer with one wound into a coil Single-mode optical waveguide, characterized in that the single-mode optical waveguide and / or additionally existing optical waveguides coupled to the single-mode optical waveguide one or more optical waveguides is or are formed, which or which only have one polarization state can lead or can and / or that optical directional couplers for coupling together existing optical waveguides are used that can only couple one polarization state. 0300A2 / 0016 ORIGINAL INSPECTED