PIC Optical Amplifier With Shared Pump Coupling and Isolators
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Solution Overview
Problem
Semiconductor optical amplifiers (SOA) face challenges due to slow response times, sensitivity issues, nonlinear effects, and high junction losses, making them less practical than Erbium-Doped Fiber Amplifiers (EDFA), while EDFA components are difficult to integrate into small form factors like QSFP or QSFP-DD.
Innovation Solution
Integration of passive optical components, including optical isolators, couplers, and photodiodes, onto a Photonics Integrated Circuit (PIC) chip, with shared pump light sources for preamp and booster amplifiers, and optional doped-fiber amplifiers outside the chip, to create compact optical amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discrete EDFA components are used, then amplification performance is improved, but device size and integration difficulty increase
Solution Approach 1:
The patent integrates multiple discrete EDFA components (pump lasers, isolators, couplers, doped fiber amplifiers) onto a single PIC chip, merging previously separate components into one integrated device. This resolves the contradiction by achieving both improved amplification performance through EDFA technology and reduced integration complexity through monolithic integration.
Solution Approach 2:
The PIC chip serves multiple functions simultaneously: it acts as a preamplifier, booster amplifier, and includes integrated pump sources and isolation functionality. This multi-functionality allows the single integrated device to replace multiple discrete components, improving performance while simplifying integration.
2Volume of moving object
If SOA is used, then device size is reduced, but response time and performance deteriorate
Solution Approach 1:
The patent combines the compact PIC platform with EDFA technology rather than using SOA alone. The integration merges the size advantages of photonic integration with the superior performance of EDFA, achieving both small device size and fast response time simultaneously.
3Device complexity
If passive components are integrated onto PIC chip, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent merges all passive components (isolators, couplers, waveguides) and active components (pump lasers, amplifiers) into a single monolithic PIC structure. This integration reduces overall device complexity while the standardized PIC manufacturing process manages precision requirements through established fabrication techniques.
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 enables compact, efficient optical amplification with improved response times and reduced complexity, facilitating integration with coherent transceivers in small form factors.
Implementation Method 1
A first optical isolator is formed on the substrate in the path of the first optical waveguide to receive light input into the first end of the first optical waveguide. The first optical isolator is operative for allowing the passage of the light input into the first end of the first optical waveguide and to avoid or prevent a reflection of the light back to the first end of the first optical waveguide
Implementation Method 2
A coupler is formed on the substrate in the path of the first optical waveguide after the first optical isolator. The coupler is operative for combining the light from the first optical isolator with light from a pump light source positioned off of the substrate
Implementation Method 3
Semiconductor optical amplifiers (SOA) of compact size can be used to amplify optical signals. The use of prior art SOA's is hampered by their lack of relatively quick response.
Implementation Method 4
one or more tap or monitor photodiodes for monitoring signal light propagating on or through one or more optical waveguides formed on the PIC chip
Data Source
AI summary
A photonics integrated circuit chip includes first and second optical waveguides formed on a semiconductor substrate. Light input into the first optical waveguide passes through a first optical isolator and a coupler formed on the substrate. The coupler outputs light from the first optical isolator combined with light from an off-substrate pump light source to an off-substrate optical fiber which outputs the combined light into the second optical waveguide for passage through a second optical isolator formed on the substrate. The substrate may also include third and fourth optical waveguides. Light input into the third optical waveguide passes through a third optical isolator and a second coupler formed on the substrate. The second coupler outputs light from the second optical isolator combined with light from the pump light source to an off-substrate second optical fiber which outputs the combined light into the fourth optical waveguide for passage through a fourth optical isolator formed on the substrate.