Reflective Dual-Band ASE Source for Compact C+L Band Coverage
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Solution Overview
Problem
Conventional ASE sources require multiple components and significant space to cover both C-band and L-band wavelength ranges, leading to power fluctuations and increased complexity in optical communication networks, especially when upgrading to include additional channels beyond the C-band.
Innovation Solution
A dual-band ASE source utilizing reflective elements and doped fiber to extend the optical path length, reducing the physical length of doped fiber required and incorporating optical circulators to efficiently direct pump beams and ASE, allowing ASE generation across the C+L band without the need for excessive fiber length or specialty fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional ASE sources use multiple discrete components to cover C-band and L-band wavelength ranges, then the wavelength coverage is achieved, but the device size and component count increase significantly
Solution Approach 1:
The patent combines C-band and L-band ASE generation into a single integrated source by using a reflective topology where a single pass through the doped fiber generates C-band ASE and the reflected light passes through the same fiber again to generate L-band ASE, eliminating the need for separate ASE sources for each band
Solution Approach 2:
The patent extends the optical path length by folding the light path using a reflective element, allowing the same physical fiber to be traversed multiple times. This dimensional change in light propagation enables extended wavelength coverage without increasing physical device size
2Adaptability or versatility
If separate ASE sources are used for C-band and L-band, then complete wavelength coverage is achieved, but the complexity and cost of the ROADM card increase
Solution Approach 1:
The patent makes a single ASE source perform multiple functions by generating both C-band and L-band wavelengths through the reflective topology, eliminating the need for separate dedicated sources for each band and reducing overall system complexity
Solution Approach 2:
The patent merges the functionality of two separate ASE sources into one integrated source that simultaneously provides C-band and L-band coverage, reducing component count and simplifying the ROADM card architecture
3Adaptability or versatility
If ROADM cards integrate more optical functions, then network functionality improves, but the available space on the card decreases
Solution Approach 1:
The patent merges multiple optical functions (C-band ASE generation, L-band ASE generation, and wavelength-dependent gain) into a single compact source, freeing up card space for additional optical functions
Solution Approach 2:
The patent uses optical path folding to extend the effective interaction length within a compact physical footprint, enabling enhanced functionality without increasing the space required on the ROADM card
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
The solution provides a compact, efficient ASE source that spans the C+L band, reducing component count and size, and enabling seamless integration on ROADM cards while maintaining uniform gain profiles across all channels, thus addressing power fluctuations and network upgrade challenges.
Implementation Method 1
A reflective element is disposed at a far-end termination of a section of doped fiber and is used to re-direct initially-generated ASE to propagate through the doped fiber a second time
Implementation Method 2
The pump beam passes through a section of rare-earth doped fiber (typically, erbium-doped fiber (EDF)) where the interaction of the pump with the dopant first promotes spontaneous emission within the fiber, followed by amplification of the spontaneous emission
Implementation Method 3
followed by amplification of the spontaneous emission
Data Source
AI summary
An arrangement for generating amplified spontaneous emission (ASE) over the combination of the C-band and L-band wavelength ranges is proposed, based on a reflective topology that reduces the number of individual components (compared with separate C-band and L-band ASE sources) required to generate the broadband ASE output. A pair of ASE generators are used, where at least one of the generators is configured to include a reflective element at a termination of the included gain fiber. The inclusion of the reflective element allows for the generated emission to pass through the gain fiber twice (emulating the operation of a conventional dual-stage ASE source). A long wavelength portion of the ASE created by a first ASE generator may be used as a seed input by the remaining ASE generator of the pair to further increase the efficiency of extending the ASE along the L-band wavelength range.