Multi-core optical fiber with controlled mode field diameter ratio
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Solution Overview
Problem
Conventional multi-core optical fibers face challenges in mass productivity and manufacturing tolerance, leading to increased costs and degraded optical characteristics, particularly in achieving wide tolerance for short-distance transmission while maintaining low inter-core crosstalk and leakage loss.
Innovation Solution
A multi-core optical fiber design with four cores and a common cladding, where each core has a specific center-to-center interval and outer diameter, and satisfies predetermined relationships between mode field diameter, zero-dispersion wavelength, and refractive index differences to ensure high manufacturing tolerance and low crosstalk, while allowing for degradation in long wavelength bands to enhance tolerance for the O band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional multi-core optical fiber designs are used, then manufacturing complexity increases and tolerance narrows, but mass productivity decreases and costs increase
Solution Approach 1:
The patent applies parameter changes by optimizing the core pitch to be 10 μm or more and 12 μm or less, and controlling the mode field diameter ratio MFD1310/MFD1550 to be 0.90 or more and 0.96 or less. These specific parameter ranges enable standard manufacturing processes to achieve both high productivity and narrow tolerance, resolving the contradiction between mass productivity and manufacturing complexity.
2Manufacturing precision
If tighter manufacturing tolerance is imposed, then optical characteristics improve, but manufacturing cost increases
Solution Approach 1:
The patent establishes specific parameter ranges (core pitch: 10-12 μm, MFD1310/MFD1550 ratio: 0.90-0.96) that define a sweet spot where standard manufacturing tolerances can be applied. This eliminates the need for costly tight tolerance control while maintaining excellent optical characteristics including low crosstalk and minimal leakage loss.
Solution Approach 2:
The patent applies local quality by allowing different wavelength bands to have different performance characteristics. The O-band (1310 nm) is optimized with controlled mode field diameter ratios for low crosstalk, while the C-band (1550 nm) is allowed to have relaxed specifications. This localized optimization enables cost-effective manufacturing by not requiring uniform high precision across all wavelength bands.
3Quantity of substance
If core pitch is reduced to increase transmission capacity, then inter-core crosstalk increases
Solution Approach 1:
The patent resolves this contradiction by changing the parameter of mode field diameter ratio (MFD1310/MFD1550) to be 0.90 or more and 0.96 or less. This parameter control ensures that even with reduced core pitch (10-12 μm) for increased capacity, the mode fields are sufficiently confined, maintaining low inter-core crosstalk while maximizing transmission capacity.
4Adaptability or versatility
If standard single-mode fiber specifications are followed, then compatibility is maintained, but wide tolerance for short-distance transmission is not achieved
Solution Approach 1:
The patent applies local quality by differentiating performance requirements across wavelength bands. For the O-band (1310 nm), it enforces strict control on the mode field diameter ratio (0.90-0.96) to ensure low crosstalk and high reliability for short-distance transmission. For the C-band (1550 nm), it allows relaxed specifications, maintaining compatibility with standard single-mode fiber infrastructure while optimizing each band for its specific application requirements.
Data Source
AI summary
This MCF ensures sufficient manufacturing tolerance, is excellent in mass productivity, and is also capable of suppressing degradation of splice loss. The MCF includes four cores and a common cladding. Each core has adjacent relationships with two cores of remaining cores, an adjacent core interval Λ is from Λnominal−0.9 μm to Λnominal+0.9 μm, a common cladding diameter is from 124 μm to 126 μm, an MFD, λcc and dcoat at a wavelength of 1310 nm satisfy a predetermined relationship, the MFD is from a MFD-reference-value−0.4 μm to the MFD-reference-value+0.4 μm with the MFD-reference-value of from 8.6 μm to 9.2 μm, a zero-dispersion wavelength is from a wavelength-reference-value−12 nm to the wavelength-reference-value+12 nm with the wavelength-reference-value of from 1312 nm to 1340 nm, a dispersion slope at a zero-dispersion wavelength is 0.092 ps/(nm2·km) or less, λcc is 1260 nm or less, and a predetermined structural condition and an optical condition are satisfied.