Wavelength Conversion Using Segmented Nonlinear Media
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Solution Overview
Problem
Current optical communication systems face limitations in expanding transmission capacity due to phase mismatch and polarization rotation issues during wavelength conversion, leading to decreased conversion efficiency, especially when trying to utilize the C, S, and L bands simultaneously.
Innovation Solution
The use of nonlinear optical media with different properties, such as clockwise and counterclockwise polarization rotation, and positive and negative dispersion values, are combined to compensate for wavelength dispersion and frequency-dependent polarization rotation, maintaining phase match and reducing polarization mismatch, thereby enhancing wavelength conversion efficiency over a wide band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single nonlinear optical medium is used for wavelength conversion, then the device structure is simple, but phase mismatch and polarization rotation cause decreased conversion efficiency
Solution Approach 1:
The patent divides the nonlinear optical medium into multiple segments (first and second nonlinear optical media) with different dispersion properties. This segmentation allows each segment to contribute differently to the wavelength conversion process, compensating for phase mismatch and polarization rotation effects that would occur in a single uniform medium, thereby maintaining high conversion efficiency across a wide wavelength band.
Solution Approach 2:
The patent changes the dispersion parameters of the nonlinear optical media by selecting materials with different dispersion characteristics (different dispersion slopes). This parameter change enables compensation for the wavelength-dependent phase mismatch and polarization rotation, allowing efficient wavelength conversion across a broad spectral range without requiring a single complex medium.
2Productivity
If wavelength conversion is performed across a wide band, then transmission capacity is expanded, but phase mismatch and polarization rotation increase, reducing conversion efficiency
Solution Approach 1:
By segmenting the nonlinear optical medium into multiple sections with different dispersion properties, the patent enables wideband wavelength conversion while maintaining efficiency. Each segment handles different portions of the wavelength spectrum, compensating for the increased phase mismatch and polarization rotation that occur when operating across a wide bandwidth.
Solution Approach 2:
The patent uses composite nonlinear optical media with different dispersion characteristics to achieve wideband efficient wavelength conversion. The combination of materials with different properties creates a composite structure that compensates for wavelength-dependent effects, enabling high conversion efficiency across the entire wide bandwidth required for expanded transmission capacity.
3Productivity
If the number of optical fiber cores is increased to expand transmission capacity, then transmission capacity increases, but the cost of laying optical fibers increases
Solution Approach 1:
The patent changes the wavelength parameter of existing optical signals through efficient wavelength conversion. By using the segmented nonlinear optical media to convert wavelengths across C, L, and S bands, the system can multiplex more channels on existing single-core or few-core optical fibers, expanding transmission capacity without proportionally increasing the number of fiber cores required.
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 configuration allows for high-efficiency wavelength conversion across a wide band, suppressing spectrum degradation and polarization crosstalk, and maintaining conversion efficiency even when polarization rotation per unit length is twice as large as in existing systems.
Implementation Method 1
Wavelength conversions with a single wavelength of excitation light using a four-wave mixing
Implementation Method 2
frequency-dependent polarization rotation cause the conversion efficiency to decrease
Implementation Method 3
phase mismatch due to the wavelength dispersion
Data Source
AI summary
An optical communication device includes an excitation light source that outputs excitation light, a multiplexer that multiplexes signal light and the excitation light outputted from the excitation light source, a first nonlinear optical medium into which the multiplexed excitation light and the signal light are inputted, and a second nonlinear optical medium that is coupled to the first nonlinear optical medium in series and has an optical property different from that of the first nonlinear optical medium.