Integrated Dual-Polarization Kramers-Kronig Receiver Architecture
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Solution Overview
Problem
Conventional polarization-diversity Kramers-Kronig heterodyne receivers have a large footprint due to the use of discrete polarization beam splitters and separate optical couplers, which increases the complexity and cost of the receiver architecture.
Innovation Solution
A dual-polarization Kramers-Kronig receiver architecture using two concatenated polarization-selective photodiodes without a polarization beam splitter, where the modulated optical data signal is optically mixed with an unmodulated local oscillator light, reducing the need for discrete components and integrating the photodetectors on a single chip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If discrete polarization beam splitters and separate optical couplers are used to separate polarization components, then the receiver can process dual-polarization signals, but the receiver footprint and device complexity increase
Solution Approach 1:
The patent combines the functions of polarization beam splitting and optical coupling into a single integrated photodetector component. The first photodetector is configured to detect one polarization component while the second photodetector detects the orthogonal polarization component, eliminating the need for separate discrete PBS and optical coupler components.
Solution Approach 2:
The integrated photodetector structure serves multiple functions simultaneously: it acts as both the polarization beam splitter and the optical coupler, while also performing the detection function. This multi-functionality reduces the overall component count and receiver footprint while maintaining dual-polarization processing capability.
2Adaptability or versatility
If discrete polarization beam splitters and separate optical couplers are used, then polarization components can be separated and processed, but the device complexity and cost increase
Solution Approach 1:
The patent merges multiple discrete components (polarization beam splitter, optical coupler, and photodetectors) into a single integrated photodetector assembly. This integration simplifies the receiver architecture by reducing the number of discrete components and their interconnections, thereby lowering device complexity and assembly cost.
Solution Approach 2:
While integrating components, the patent maintains functional segmentation by configuring the first photodetector to specifically detect one polarization component and the second photodetector to detect the orthogonal component. This functional segmentation preserves the polarization separation capability within the integrated structure.
3Reliability
If conventional discrete component architecture is used, then reliable polarization processing is achieved, but reception sensitivity is limited
Solution Approach 1:
By integrating the photodetectors and combining local oscillator light with signal light at the photodetector level, the patent achieves better signal mixing and detection efficiency. This integration improves reception sensitivity while maintaining reliable polarization processing through the configured photodetector arrangement.
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 significantly reduces the receiver footprint, enhances reception sensitivity, and maintains high bit-error ratio performance below the hard decision forward error correction threshold even after transmission over 120 km of standard single-mode fiber, while being cost-effective and polarization-robust.
Implementation Method 1
a first optical detector coupled to the input to receive the modulated optical data signal, wherein the first optical detector is polarization-selective or polarization-sensitive
Implementation Method 2
a second optical detector coupled to the first optical detector to receive from the first optical detector the components of the modulated optical data signal having the second polarization
Implementation Method 3
a processor, the processor configured to apply a Kramers-Kronig, KK, process to the first electrical signal and to the second electrical signal
Data Source
AI summary
An apparatus includes an input receiving a modulated optical data signal having components of at least first and second polarizations, a first optical detector receiving the data signal, the first optical detector being first polarization-selective or first polarization-sensitive, passing components of the data signal having the second polarization, and outputting a first electrical signal, a second optical detector coupled to the first optical detector to receive the components of the data signal having the second polarization, and outputting a second electrical signal, and a processor applying a Kramers-Kronig process to the first and second electrical signals, and outputting the data signal using the Kramers-Kronig processed first and second electrical signals. A combiner is connected between the input and the first optical detector and combines the data signal with an unmodulated optical signal such that the unmodulated optical signal serves as a Kramers-Kronig carrier for the first and second polarizations.