Optical Receiver Training Sequences for Fast Polarization Alignment
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Solution Overview
Problem
Optical communication networks face limitations in increasing bandwidth due to dispersion and power budget constraints in intensity modulation with direct detection (IM-DD) PONs, and using multiple wavelengths and dual-polarization can help, but require fast polarization alignment in burst mode upstream communications to minimize overhead.
Innovation Solution
A transmitter and receiver system configured for dual-polarization communications, where a first portion of the data segment is transmitted using a first polarization and a second portion using both polarizations, enabling fast alignment and continuous tracking of polarization at the receiver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple wavelengths are stacked to enable higher bandwidths, then bandwidth capacity is improved, but non-linearities cause large penalties and wavelength window occupancy increases
Solution Approach 1:
The patent transitions from single-polarization to dual-polarization dimension, effectively doubling the bandwidth capacity without adding more wavelengths. By utilizing both horizontal and vertical polarizations of light, the system achieves higher productivity while avoiding the non-linear penalties associated with multi-wavelength operation.
2Measurement precision
If polarization alignment is performed using traditional methods in burst mode, then alignment is achieved, but overhead increases and alignment speed decreases
Solution Approach 1:
The patent applies preliminary action by pre-configuring the dual-polarization transmission format with known training sequences in both polarization states. This allows the receiver to perform fast polarization alignment using predetermined reference signals, reducing both alignment time and overhead compared to traditional trial-and-error methods.
Solution Approach 2:
The patent changes the transmission parameter from single-polarization to dual-polarization format, enabling the receiver to track polarization state changes more efficiently. By transmitting known patterns in both polarization dimensions, the system achieves faster and more accurate polarization alignment while minimizing overhead.
3Productivity
If IM-DD PONs increase bit-rate to meet bandwidth demand, then data capacity is improved, but dispersion cannot be completely mitigated and power budget is limited
Solution Approach 1:
The patent resolves the contradiction by adding the polarization dimension to the transmission system. Instead of continuously increasing bit-rate which degrades signal quality due to dispersion, the system doubles capacity by utilizing both polarization states, thereby improving productivity while maintaining signal quality and reliability.
Data Source
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AI summary
Various example embodiments for supporting optical communications in an optical communication system may be configured to support dual-polarization alignment for dual-polarization communications within an optical communication network. Various example embodiments for supporting dual-polarization alignment, within an optical communication network supporting optical communications from a transmitter (121, 200, 510) to a receiver (111, 300, 400, 520) based on dual polarizations including a first polarization and a second polarization, may be configured to support dual-polarization alignment to the dual polarizations at the receiver based on communication of a data segment such that a first portion of the data segment is communicated based on the first polarization and a second portion of the data segment is communicated based on the first polarization and the second polarization.