Optical Receiver Phase Retrieval for Chromatic Dispersion
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Solution Overview
Problem
Current methods for mitigating chromatic dispersion in high data rate optical networks are costly, complex, and require additional hardware or complex signal processing, limiting the reach of optical signals and introducing interference.
Innovation Solution
A receiver with a control unit that iteratively determines the amplitude and phase of received optical signals using measured values, inverse and transmission functions, allowing for chromatic dispersion compensation without additional hardware and reducing algorithmic complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dispersion compensation fibers (DCF) or fiber Bragg gratings (FBG) are used to compensate chromatic dispersion, then chromatic dispersion-induced inter-symbol interference is mitigated, but additional optical hardware is required and signal loss increases by a few dB
Solution Approach 1:
The patent replaces physical optical compensation hardware (DCF, FBG) with a digital signal processing approach. The receiver uses a control unit to perform iterative phase retrieval and chromatic dispersion compensation through mathematical calculations based on measured amplitude values and transmission channel characteristics, eliminating the need for additional optical components.
Solution Approach 2:
The patent introduces an intermediate computational process between signal reception and compensation. The control unit calculates transmission functions and inverse transmission functions of the optical channel, using these as intermediaries to retrieve phase information and compensate chromatic dispersion without direct physical intervention.
2Reliability
If optical phase conjugation (OPC) is applied to restore chromatic dispersion-induced inter-symbol interference, then signal quality is improved, but hardware complexity and computational power requirements increase significantly
Solution Approach 1:
The patent substitutes complex optical phase conjugation hardware with a computational algorithm. The control unit performs iterative phase retrieval by calculating the phase of the sent optical signal from the amplitude of the received signal using the inverse transmission function, achieving signal restoration without physical phase conjugation devices.
Solution Approach 2:
The patent creates a computational model (transmission function and inverse transmission function) that replicates the behavior of the optical channel. This mathematical copy allows the system to simulate and reverse the chromatic dispersion effects without physically recreating the optical conditions.
3Reliability
If pre-distortion is applied at the transmitter to compensate chromatic dispersion, then dispersion compensation is achieved, but the electrical field exhibits varying phase requiring more expensive modulators
Solution Approach 1:
Instead of applying pre-distortion at the transmitter that modifies the phase of the electrical field, the patent inverts the approach by performing compensation at the receiver. The control unit calculates the phase that was present at the transmitter by using the inverse transmission function, thereby avoiding the need for expensive phase-modulating modulators at the TX side.
Solution Approach 2:
The receiver performs self-service by autonomously determining the transmitted signal's phase and amplitude characteristics through iterative calculations. The control unit uses the measured received signal amplitude and the known transmission channel properties to reconstruct the original signal parameters without requiring complex TX-side modifications.
4Device complexity
If direct-detection receivers are used to reduce complexity, then receiver structure is simplified, but phase information of the received optical signal cannot be directly obtained
Solution Approach 1:
The patent introduces computational intermediaries (transmission function and inverse transmission function) that enable phase retrieval from amplitude-only measurements. The control unit uses these mathematical tools to bridge the gap between direct-detection capability and phase information requirement, calculating the phase as an intermediate step in the compensation process.
Solution Approach 2:
The patent replaces physical phase detection hardware (which would be required in coherent receivers) with a computational phase retrieval algorithm. The control unit calculates the phase information through mathematical operations on the amplitude data and transmission channel characteristics, substituting physical measurement with computational derivation.
Data Source
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AI summary
A receiver (300) is provided which is configured for receiving optical signals via an optical transmission channel (200). The receiver comprises a control unit (310) configured to determine an amplitude and a phase of a received optical signal.