Polarization Multiplexed Receiver Reference Light Segmentation
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Solution Overview
Problem
In polarization multiplexed optical transmission systems, changes in temperature or mechanical conditions can cause the polarization axis of reference lights to coincide with one of the polarized components, leading to incomplete demodulation and reduced transmission quality due to the heterodyne method's reliance on intermediate angle polarization axes.
Innovation Solution
The system employs reference lights with different frequencies for each polarized component, ensuring that the polarization directions of the reference lights remain distinct from the polarized components even under changes, preventing coincidence and maintaining proper demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the heterodyne method uses intermediate angle polarization axes for reference lights, then demodulation can be performed under normal conditions, but transmission quality deteriorates when polarization axes coincide with polarized components under temperature or mechanical changes
Solution Approach 1:
The system segments the reference light into multiple reference lights with different polarization axes. Instead of using a single reference light, the patent employs at least two reference lights with distinct polarization directions, allowing the system to maintain demodulation capability even when one reference light's polarization axis coincides with a polarized component due to environmental changes.
Solution Approach 2:
The multiple reference lights serve multiple functions simultaneously - each reference light can independently demodulate one of the polarized components. This multi-functionality ensures that the system can adapt to different polarization states caused by temperature or mechanical changes, maintaining reliable transmission quality under varying conditions.
2Device complexity
If a single reference light is used for polarization multiplexed transmission, then the system structure remains simple, but incomplete demodulation occurs when polarization axis coincidence happens under abnormal conditions
Solution Approach 1:
The reference light is segmented into multiple reference lights with different polarization characteristics. This segmentation allows the system to cover a broader range of polarization states, ensuring complete demodulation of both polarized components even when environmental changes cause polarization axis misalignment.
Solution Approach 2:
The system changes the polarization parameter of the reference lights by using at least two reference lights with different polarization axes. This parameter diversification ensures that at least one reference light maintains an appropriate angle with each polarized component, preventing incomplete demodulation under abnormal conditions while keeping the structural increase manageable.
3Reliability
If reference lights with different frequencies are employed for each polarized component, then polarization direction coincidence is prevented under all conditions, but system complexity and cost increase
Solution Approach 1:
The patent applies local quality by assigning different frequencies specifically to the reference lights coupled with different polarized components. Each reference light has a frequency tailored to its associated polarized component, ensuring that polarization direction coincidence is prevented locally at each demodulation path without requiring all optical components in the system to be different or more complex.
Solution Approach 2:
The system changes the frequency parameter of the reference lights to differentiate them for each polarized component. By using frequency as a distinguishing parameter, the system prevents polarization direction coincidence and ensures continuous demodulation reliability while managing overall system complexity through targeted parameter differentiation rather than universal component complexity.
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 effectively reduces transmission quality deterioration by ensuring continuous demodulation of signals, even under abnormal conditions, without requiring costly optical components for frequency differentiation.
Implementation Method 1
a first photodetector configured to convert the first polarized light to a first electrical signal; a second photodetector configured to convert the second polarized light to a second electrical signal
Implementation Method 2
a first frequency shift unit configured to generate a first shift signal by shifting a frequency of the first electrical signal based on a frequency of the first reference light, and generate a second shift signal by shifting the frequency of the first electrical signal based on a frequency of the second reference light
Data Source
AI summary
A transmitter transmitting a polarization multiplexed optical signal, includes: a light source; a generating unit configured to split a light of the light source into first and second polarized lights, optically modulate the first and second polarized lights based on an electric data signal, and multiplex the first polarized light optically-modulated and the second polarized light optically-modulated to generate the polarization multiplexed optical signal; and a coupling unit configured to couple a first reference light having a frequency different from a frequency of the light of the light source with the first polarized light and couple a second reference light having a frequency different from the frequency of the light of the light source with the second polarized light, wherein the first reference light and the second reference light have different frequencies.