System and method for receiving multi-polarized signals
Inventors
Jones, Nathaniel • Novak, Stephanie • Rowe, Edward
Assignees
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Publication Number
US-11050505-B1
Publication Date
2021-06-29
Expiration Date
Abstract
An optical communication system is configured to transmit and receive at least four multiplexed, differently-polarized, optically-transmitted signals. Each signal is associated with a predefined state of polarization. An optical transmitter is configured to transmit multiplexed, differently polarized, optically transmitted signals. An optical receiver is configured to receive the optically transmitted signals. The system includes a multi-polarization analyzer circuit configured to obtain an analyzed signal for each of the polarized signals in Stokes space. The analyzer circuit is configured to determine if the multiplexed signal has been transformed by extreme polarization-dependent loss (PDL), the receiver correcting for the extreme polarization-dependent loss.
Core Innovation
The invention relates to an optical receiver for at least four multiplexed, differently-polarized, optically-transmitted signals in which each optically-transmitted signal is associated with a predefined state of polarization. A multi-polarization analyzer circuit determines one of a rotation and a translation of the transmitted multiplexed signals in Stokes space. A compensation circuit converts at least one of the plurality of signals into Stokes space, calculates a plurality of Stokes vectors, and compensates for translation and rotation of induced polarization effects during transmission.
The compensation circuit returns each of the plurality of signals to a predefined state of polarization based on the calculated Stokes vectors. The compensation circuit calculates an offset vector that is indicative of the rotation and translation of the transmitted multiplexed signals in Stokes space in relation to a Poincaré sphere. The receiver circuit thereby enables polarization-induced rotation and translation compensation represented in Stokes space geometry relative to the Poincaré sphere.
The described approach further includes deriving a transfer matrix representation of the induced polarization effects, including unitary behavior for pure rotation versus non-unitary behavior for rotation and translation, and using the derived representation to demultiplex back to the predefined state of polarization. Stated implementations include coherent measurement using a coherent receiver and a centroid-shifted Stokes multi-polarization analyzer to measure and compensate polarization-induced rotation and translation in Stokes space.
Claims Coverage
The document provides three independent claims that collectively cover an optical receiver, an optical transmission system, and an optical communication system, with the common theme of Stokes-space compensation of polarization-induced translation and rotation using an offset vector relative to a Poincaré sphere.
Multi-polarization Stokes-space rotation/translation compensation with offset vector
An optical receiver receives at least four multiplexed, differently-polarized, optically-transmitted signals associated with a predefined state of polarization; determines rotation and translation of the transmitted multiplexed signals in Stokes space; converts at least one signal into Stokes space, calculates Stokes vectors, compensates translation and rotation of induced polarization effects during transmission, and returns each signal to a predefined state of polarization based on the calculated Stokes vectors, wherein the compensation circuit calculates an offset vector indicative of the rotation and translation in Stokes space in relation to a Poincaré sphere.
Stokes-space best-fit plane from multiplexed signal locations for translation/rotation compensation
An optical transmission system transmits a plurality of signals including at least four multiplexed, differently-polarized, optically-transmitted signals; a receiver receives the plurality of signals with at least one signal comprising data in Stokes space; and a compensation circuit converts at least one signal into Stokes space, calculates a plurality of Stokes vectors, compensates for translation and rotation during transmission, and returns each signal to a predefined state of polarization, wherein the compensation circuit determines at least four locations for the multiplexed signals in Stokes space and defines a best fit plane through the at least four locations.
Polarization demultiplexing and predefined-state transformation using Stokes-space offset vector
A system configured to communicate optically over a communication link includes an optical transmitter that generates and multiplexes a plurality of signals including at least four independent data signals with different states of polarization; an optical receiver with a demultiplexer for polarization demultiplexing the transmitted multiplexed signal into a plurality of polarized signals; and a compensation circuit that compensates translation and rotation of induced polarization effects during transmission and transforms each polarized signal to a predefined state of polarization, wherein the compensation circuit calculates an offset vector indicative of rotation and translation in Stokes space in relation to a Poincaré sphere.
Across the independent claims, the inventive coverage centers on compensating polarization-induced rotation and translation by converting signals to Stokes space, using Stokes vectors, calculating an offset vector relative to a Poincaré sphere, and returning signals to a predefined state of polarization. The transmission-system claim further specifies forming a best-fit plane from at least four Stokes-space locations, while the system claim includes polarization demultiplexing into polarized signals followed by compensation and predefined-state transformation.
Stated Advantages
Compensates for translation and rotation of induced polarization effects and returns signals to a predefined state of polarization.
Determines rotation and translation of transmitted multiplexed signals in Stokes space and uses an offset vector indicative of rotation and translation in relation to a Poincaré sphere.
Defines a best fit plane through at least four locations in Stokes space to enable compensation.
Documented Applications
Fiber links, free-space, integrated photonics, and active cables.
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