US 12,674,823 B2 · Passive optical Sagnac interferometer for current sensing

Abstract

Passive optical Sagnac interferometers for current sensing, method of using the same and method of constructing the same. In one embodiment, the passive optical Sagnac interferometer for current sensing comprises an N×N fibre coupler, wherein N>=3; and a fibre coil disposed on a first side of the N×N fibre coupler, a first port of the N×N fibre coupler coupled to a first end of the fibre coil via a first linear polariser and a second port of the N×N fibre coupler coupled to a second end of the fibre coil via a second linear polariser; wherein the fibre coil is configured to support only one elliptical polarisation state in counter-propagating light signals in the fibre coil.

Claims20

Dependent claims

A passive optical Sagnac interferometer for current sensing comprising:

an N×N fibre coupler, wherein N≥3;
and
a fibre coil disposed on a first side of the N×N fibre coupler, a first port of the N×N fibre coupler coupled to a first end of the fibre coil via a first linear polariser and a second port of the N×N fibre coupler coupled to a second end of the fibre coil via a second linear polariser;
wherein the fibre coil is configured to support only one elliptical polarisation state in counter-propagating light signals in the fibre coil, such that a first light signal propagating in a first direction through the fibre coil has a same handedness as a second light signal propagating through the fibre coil in a second direction opposite to the first direction.

1 more element

A passive optical Sagnac interferometer for current sensing comprising:

an N×N fibre coupler;
a fibre cable coupled to the N×N fibre coupler, a first output port of the N×N fibre coupler coupled to a first end of a first fibre of the fibre cable and a second output port of the N×N fibre coupler coupled to a first end of a second fibre of the fibre cable;
and
first and second at least approximately circular polarisers, wherein the first circular polariser is coupled between the first port of the N×N fibre coupler and the first end of the first fibre and the second circular polariser is coupled between the second port of the N×N fibre coupler and the first end of the second fibre, and wherein respective second ends of the first fibre and the second fibre are coupled to each other;
wherein the fibre cable is configured to be wound into a coil;
and
wherein the first fibre comprises non-polarising spun elliptically birefringent optical fibre and the second fibre comprises unspun highly birefringent optical fibre.

4 more elements

A passive optical Sagnac interferometer for current sensing comprising:

an N×N polarisation maintaining fibre coupler;
a fibre cable coupled to the N×N fibre coupler, a first output port of the N×N fibre coupler coupled to a first end of a first fibre of the fibre cable and a second output port of the N×N fibre coupler coupled to a first end of a second fibre of the fibre cable;
and
first and second linear polarisers, wherein the first linear polariser is coupled between the first port of the N×N polarisation maintaining fibre coupler and the first end of the first fibre and the second linear polariser is coupled between the second port of the N×N polarisation maintaining fibre coupler and the first end of the second fibre, and wherein respective second ends of the first fibre and the second fibre are coupled to each other;
wherein the fibre cable is configured to be wound into a coil;
and
wherein the first fibre comprises spun elliptically birefringent polarising optical fibre and the second fibre comprises unspun highly birefringent optical fibre.

4 more elements

Dependencies are inferred from the claim text.

Passive optical Sagnac interferometer for current sensing

Life of this patent

Passive optical Sagnac interferometer for current sensing

Life of this patent

Abstract

Claims20