Bidirectional Optical Amplifier Array for PON Systems
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Solution Overview
Problem
In optical PON systems, high splitting factors lead to significant attenuation losses, and existing unidirectional EDFAs struggle to maintain constant amplification for burst-like upstream signals due to long time gaps and amplitude variations, requiring additional control mechanisms and potentially increased transmission power.
Innovation Solution
A bidirectional optical amplifier arrangement using two-stage amplification with a unidirectional EDFA for downstream signals and a bidirectional EDFA for both directions, optimized with power monitors and regenerators to maintain constant inversion and output power, reducing the need for additional pump lasers and enhancing noise figure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If unidirectional EDFAs are used for amplification, then amplification can be achieved, but constant amplification for burst-like upstream signals cannot be maintained due to long time gaps and amplitude variations
Solution Approach 1:
The patent combines upstream and downstream signal amplification into a single bidirectional EDFA device. The upstream and downstream signals are amplified simultaneously in the same erbium-doped fiber medium, allowing the downstream continuous signal to maintain constant inversion while the upstream burst signals receive stable amplification without requiring separate control mechanisms for each direction.
Solution Approach 2:
The bidirectional EDFA performs multiple functions: it amplifies both upstream burst signals and downstream continuous signals simultaneously using a single device. This multi-functional approach eliminates the need for separate unidirectional amplifiers and their associated control systems, reducing overall device complexity while maintaining reliable constant amplification for both signal types.
2Productivity
If high splitting factors are used to increase participants, then network capacity increases, but attenuation losses increase sharply
Solution Approach 1:
The bidirectional EDFA provides continuous amplification for both upstream and downstream signals simultaneously. The downstream continuous signal maintains constant inversion in the erbium-doped fiber, which in turn provides stable amplification for upstream burst signals. This continuous amplification action compensates for the high attenuation losses caused by high splitting factors, enabling networks to support more participants without signal degradation.
3Reliability
If additional pump lasers are added to maintain constant inversion, then amplification stability improves, but device complexity and cost increase
Solution Approach 1:
The bidirectional EDFA configuration allows the downstream continuous signal to serve a dual purpose: it is both the signal to be transmitted and the means to maintain constant inversion in the erbium-doped fiber. The downstream signal's continuous presence automatically sustains the inversion level needed for amplifying upstream burst signals, eliminating the need for additional pump lasers or complex control systems to maintain inversion stability.
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 configuration ensures constant amplification of upstream signals, reduces noise, and minimizes the need for additional amplification stages, achieving cost-effective and efficient signal amplification while maintaining high data rates and low attenuation.
Implementation Method 1
the optical signals are amplified in both directions in a single amplifying fiber
Implementation Method 2
a first WDM coupler for separating/combining the upstream and downstream optical signals
Implementation Method 3
optical isolators which ensure bidirectional amplification for optical signals
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
The invention relates to a bidirectional optical amplifier array (VA) which is preferably used in a passive optical network (PON) system, is disposed between a first line termination (OLT) and a second line termination (ONU), and is penetrated by an optical downstream signal (OSD) in one direction and an optical upstream signal (OSD) in the opposite direction. Said optical amplifier array is composed of a first part with two branching and combining units (D1 and D2), a unidirectional optical amplifier (E1), and a transponder (T) in which the optical downstream signals and upstream signals (OSU and OSD) are separately amplified. The two signals (OSU and OSD) that run in opposite directions are amplified in a bidirectional amplifier (E2) in a second part. A constant gain is maintained in the bidirectional optical amplifier (E2) by means of the continuous downstream signal (OSD) such that the amplifier can be operated in stable conditions for the upstream signal (OSU) regardless of occurring bursts. In another embodiment, a splitter (S1) is integrated into the inventive amplifier array (VA).