Adaptive Injection Current Controller for Optical Burst Amplitude Equalization
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Solution Overview
Problem
Current passive optical network (PON) systems face challenges in maintaining consistent optical burst signal amplitudes, leading to DC voltage offset variations that hinder optical receivers' ability to distinguish between '0' and '1' symbols, especially at higher data rates, and existing solutions like 8b10b code and optical power equalization using gain clamped Semiconductor Optical Amplifiers (SOAs) become less efficient with increased burst amplitude differences.
Innovation Solution
An adaptive injection current (AIC) controller is used to adjust the amplitude of optical burst signals by converting them into voltage signals, calculating amplitude correction values, inverting and adjusting these signals, and converting them back into current signals to inject into Optical Amplifiers (OAs), ensuring equal power amplification and reduced DC offset variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical power equalization using gain clamped Semiconductor Optical Amplifiers (SOAs) is implemented, then DC offset variations in optical receivers are reduced, but the solution becomes less efficient when burst amplitude difference in optical burst signals increases
Solution Approach 1:
The patent implements dynamic adaptation by using a delay line to store previous burst signals and comparing them with current bursts to calculate amplitude correction values. This dynamic adjustment mechanism allows the system to adapt to varying burst amplitude differences in real-time, resolving the contradiction between maintaining DC offset stability and handling amplitude variations efficiently
Solution Approach 2:
The system employs feedback control by detecting the amplitude of incoming optical bursts, comparing it with stored reference bursts, calculating correction values, and applying these corrections through adaptive injection current control. This closed-loop feedback mechanism enables the system to maintain reliability across varying burst amplitude conditions
2Productivity
If 8b10b code is implemented to relax optical receiver time requirements, then detection capability at high data rates is improved, but bandwidth overhead increases by about 25 percent
Solution Approach 1:
The patent applies preliminary action by pre-calculating amplitude correction values based on stored reference burst signals before the actual detection process. This preparation reduces the time required for level recovery during high-speed detection, improving productivity without requiring bandwidth overhead for coding
Solution Approach 2:
The system replaces the mechanical/coding-based approach (8b10b code) with an optical/electrical signal processing approach using delay lines, photodetectors, and voltage-to-current converters. This substitution achieves high-speed detection capability without the 25% bandwidth overhead associated with 8b10b encoding
3Speed
If optical burst signal rates are increased from 1.25 Gbps to 2.5 Gbps and 10 Gbps, then network capacity is improved, but level recovery time in optical receivers increases excessively
Solution Approach 1:
The system performs preliminary action by pre-processing optical burst signals through amplitude equalization using stored reference bursts before they reach the optical receiver. This preliminary adjustment reduces the level recovery time required at the receiver, enabling high-speed operation at 2.5 Gbps and 10 Gbps without excessive recovery delays
Solution Approach 2:
The patent introduces an intermediary system consisting of delay lines, photodetectors, and amplitude correction circuits that process optical burst signals before they reach the final receiver. This intermediary equalization stage prepares the signals in advance, reducing the time burden on the main receiver and enabling higher data rates
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces DC offset variations in optical receivers, enabling efficient detection of optical burst signals at higher rates (up to 10 Gbps) and compensating for signal losses over long distances in PONs with multiple ONUs, thereby enhancing the overall performance of optical receivers.
Implementation Method 1
an optical power splitter
Implementation Method 2
an optical delay line coupled to the optical power splitter
Implementation Method 3
converting an optical signal into a voltage signal
Implementation Method 4
converting the adjusted voltage signal into a current signal
Implementation Method 5
an OA coupled to the optical delay line, and an adaptive injection current (AIC) controller coupled to the optical power splitter and the OA
Data Source
AI summary
An apparatus comprising an optical power splitter, an optical delay line coupled to the optical power splitter, an optical amplifier (OA) coupled to the optical delay line, and an adaptive injection current (AIC) controller coupled to the optical power splitter and the OA. Also disclosed is an apparatus comprising at least one component configured to implement a method comprising converting an optical signal into a voltage signal, calculating an amplitude correction value for the voltage signal, inverting an amplitude of the voltage signal, adjusting the amplitude of the inverted voltage signal according to the amplitude correction value, and converting the adjusted voltage signal into a current signal. Included is a network comprising an optical line terminal (OLT) comprising an optical receiver and an AIC controlled OA coupled to the optical receiver, wherein the AIC controlled OA provides optical power equalization for any upstream optical signals.