US 6,856,401 B1 · Elimination of polarization fading in unbalanced optical measuring interferometers

Abstract

Method and assembly for sustained elimination or reduction of polarization induced signal fading in optical interferometer networks comprising at least two optical paths from an input port to an output port, the transmission delays of the paths differing by τ, an interrogation arrangement interrogating the optical phase differences between the paths, containing at least one optical source launching optical power into a port, a detector arrangement converting the optical power from an output port into electrical detector signals, and a control and signal processing unit capable of processing detector signals to determine the phase difference. The method comprising the steps of: altering the input polarization state produced by the source with a modulation frequency that is comparable to or higher than 1/(4τ) receiving the optical signals at the detector arrangement providing a detector signal; processing the detector signal determining the phase difference between the optical signals.

Claims13

Dependent claims

A method of reducing polarization induced signal fading in an optical interferometer network, comprising:

providing a first and a second optical path from an input port to an output port, wherein transmission delays of the first and second optical paths differ by an amount of time τ,
inputting an input signal into the input port;
altering a polarization state of the input signal to switch between a first state of polarization (SOP0A) during a first portion of a polarization switching period and a second state of polarization (SOP0B) during a second portion of the polarization switching period, wherein the polarization state is altered with a modulation frequency that is a multiple of 1/(4τ);
receiving an interference signal from the output port, the interference signal caused by interference between a first output signal having passed through the first optical path and a second output signal having passed through the second optical path;
and
processing the interference signal to determine a phase difference between the first and second output signals.

3 more elements

An assembly for reducing polarization induced signal fading in an optical interferometer network, comprising:

a first and a second optical path from an input port to an output port, wherein transmission delays of the first and second optical paths differ by an amount of time τ,
an optical source for launching optical power into the input port, the optical source having a polarization modulator that switches a polarization state between a first state of polarization (SOP0A) during a first portion of a polarization switching period and a second state of polarization (SOP0B) during a second portion of the polarization switching period, wherein the polarization state is altered with a modulation frequency that is a multiple of 1/(4τ);
a detector for converting the optical power received from the output port into electrical detector signals;
and
a control and signal processing unit for processing the detector signals to determine a phase difference induced between optical waves having traveled the first and second paths.

2 more elements

Dependencies are inferred from the claim text.

Elimination of polarization fading in unbalanced optical measuring interferometers

Life of this patent

Elimination of polarization fading in unbalanced optical measuring interferometers

Life of this patent

Abstract

Claims13