Dense-Comb Redundant Ring Laser Array for Optical Reliability
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Solution Overview
Problem
Existing optical networking systems rely on group III-V compound semiconductor devices for lasers, which are the least reliable components and lack guaranteed long-term reliability, necessitating a solution for redundancy in these systems.
Innovation Solution
A dense-comb redundant ring laser array is designed with reflective silicon optical amplifiers (RSOAs) and ring-resonator filters, featuring a shared ring resonator and symmetric power splitter for redundancy and increased reliability, allowing for failover of RSOAs and reduced encroachment between resonance frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If group III-V compound semiconductor devices are used for lasers, then laser functionality is achieved, but long-term reliability deteriorates
Solution Approach 1:
The patent implements a redundant array of reflective silicon optical amplifiers where each amplifier has backup capability. The system is designed beforehand with redundant components that can take over if primary components fail, cushioning against reliability issues before they manifest as system failures.
Solution Approach 2:
The invention transitions from group III-V compound semiconductor materials to silicon-based materials for the laser amplifiers. This parameter change in material composition fundamentally improves long-term reliability while maintaining laser functionality, as silicon devices are known for their stability and longevity.
2Reliability
If redundant RSOA components are added, then reliability improves, but device complexity increases
Solution Approach 1:
The patent designs a universal redundant array architecture where RSOA components can serve multiple functions: primary laser amplification, backup amplification, and wavelength-selective filtering through integrated ring resonators. This multi-functionality reduces the need for separate dedicated backup components, thereby limiting the increase in device complexity.
Solution Approach 2:
The invention merges the amplifier function and wavelength-selective filter function into a single integrated RSOA-ring resonator structure. This combining of functions reduces the total number of discrete components needed, limiting complexity increase while achieving redundancy through the array architecture.
3Reliability
If ring-resonator filters are used instead of DBRs, then reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs uniform ring-resonator filter designs that can be fabricated using standardized processes. The homogeneous structure and geometry of the ring resonators allow for consistent manufacturing across the array, reducing the impact of precision variations and improving overall reliability compared to traditional DBR structures.
4Productivity
If dense-comb laser array is implemented, then bandwidth increases, but cavity length decreases
Solution Approach 1:
The patent achieves dense-comb laser operation by transitioning from longitudinal cavity modes to transverse resonance modes in ring resonators. This dimensional change in the resonance mechanism allows for high spectral density (dense comb) without requiring long cavity lengths, as the resonance condition is determined by the ring perimeter rather than the linear cavity length.
Solution Approach 2:
The invention changes the fundamental resonance parameter from linear cavity length to ring resonator perimeter. By controlling the ring radius and number of resonators rather than extending linear cavity length, the system achieves high bandwidth dense-comb output with compact dimensions.
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 enhances the reliability of optical networking systems by providing redundancy for RSOAs, reducing link downtime, and eliminating the need for additional switching or multiplexing elements, while doubling the density of comb lines and reducing cavity length.
Implementation Method 1
a symmetric power splitter comprising a reciprocal network having a first port, a second port, a third port and a fourth port, wherein light entering the first port is approximately equally split with a 90-degree phase difference between the third port and the fourth port
Implementation Method 2
a set of ring-resonator filters, including a first subset of ring-resonator filters associated with the first subset of RSOAs, and a second subset of ring-resonator filters associated with the second subset of RSOAs
Implementation Method 3
a set of reflective silicon optical amplifiers (RSOAs), including a first subset of RSOAs and a second subset of RSOAs
Implementation Method 4
each intermediate waveguide is attached to an RSOA in the set of RSOAs, and channels light in proximity to an associated ring-resonator filter in the set of ring-resonator filters
Data Source
AI summary
The disclosed embodiments relate to the design of a hybrid laser comprising a shared ring mirror coupled to a pair of buses by a 3 dB coupler (also referred to as a “symmetric splitter”), which is described in more detail below. Each bus is also coupled to an array of ring filters, wherein each ring filter couples an associated reflective silicon optical amplifier (RSOA) to the shared ring mirror and in doing so forms a Verniered ring pair with the shared ring mirror. The resulting system provides a comb source with redundant channels that can provide individual outputs or a shared output. This hybrid laser provides a significant improvement over existing comb-based lasers by providing redundancy for at least one laser channel.