Integrated Optical Multiplexer With Polarization Stage for Low Insertion Loss
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Solution Overview
Problem
Existing multiplexers in optical communications suffer from excessive insertion loss due to misalignment of signal wavelengths with transmission peaks and variations in laser and multiplexer passbands, particularly in photonic integrated circuits, leading to degraded transmission links and the need for higher optical power from lasers.
Innovation Solution
Incorporating a polarization beam splitter and rotator in a multi-stage multiplexer design, where each stage combines signals by wavelength and the last stage combines by polarization, using mach-zehnder interferometers with higher-order delay elements to achieve a flattened passband and reduce insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional multiplexers are used in optical communications, then signal multiplexing can be achieved, but excessive insertion loss occurs due to misalignment of signal wavelengths with transmission peaks
Solution Approach 1:
The multiplexer is divided into multiple stages, with wavelength stages using mach-zehnder interferometers for wavelength-based signal combination and a final polarization stage for polarization-based combination. This segmentation allows each stage to operate independently with optimized passband characteristics, reducing overall insertion loss.
Solution Approach 2:
The patent transitions from traditional single-dimension wavelength multiplexing to multi-dimensional multiplexing by adding polarization multiplexing as an additional dimension. This allows signals to be combined not only by wavelength but also by polarization state, effectively broadening the passband and reducing wavelength-dependent losses.
2Reliability
If conventional multiplexer designs are used, then device complexity can be controlled, but transmission link performance degrades due to higher optical power requirements
Solution Approach 1:
The patent employs dynamically adjustable polarization controllers and phase shifters that allow the multiplexer to adapt to varying input conditions. This dynamic adjustment optimizes the alignment between signal wavelengths and transmission peaks in real-time, improving transmission link performance without requiring excessive optical power.
3Productivity
If multi-stage multiplexing is implemented, then wavelength combination efficiency improves, but device complexity increases
Solution Approach 1:
The patent merges wavelength-based multiplexing and polarization-based multiplexing into a unified multi-stage architecture. By combining these two multiplexing dimensions, the system achieves high signal combination efficiency while sharing common structural elements such as waveguides and couplers across stages, thereby managing device complexity.
Solution Approach 2:
The mach-zehnder interferometers used in the wavelength stages serve multiple functions: they perform wavelength-based signal combination while also providing phase control capabilities that are later utilized in the polarization stage. This multi-functionality reduces the need for separate dedicated components, managing overall device 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
The proposed design significantly reduces insertion loss by ensuring broad passbands and minimizing wavelength-dependent losses, enhancing the performance of optical multiplexers in photonic integrated circuits.
Implementation Method 1
the last stage combines input optical signals by polarization using a polarization beam combiner
Implementation Method 2
the polarization beam combiner may also include the polarization rotating function on a second subset of the input signals
Implementation Method 3
each of the wavelength stages incorporate one or more mach-zehnder interferometers
Data Source
AI summary
In part, in one aspect, the disclosure relates to a system including an integrated optical multiplexer. The integrated optical multiplexer may include a plurality of optical inputs configured and constructed to receive input optical signals; two or more stages of multiplexing in a cascading configuration, wherein the two or more stages of multiplexing are divided into wavelength stages and a last stage, wherein each of the wavelength stages combine subsets of input optical signals by wavelength, the last stage combines input optical signals by polarization using a polarization beam combiner, and at a combined output of the integrated optical multiplexer a first subset of the input optical signals have a different polarization than a second subset of the input optical signals.