SMF to MMF Coupler Using Hollow Core Photonic Crystal Fiber
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Solution Overview
Problem
Current technologies face challenges in efficiently transitioning from multimode fiber networks to single mode networks due to mode mismatch, modal dispersion, and increased noise when trying to operate multimode fibers with single mode transceivers.
Innovation Solution
A fiber optic patch cord design that includes a photonic crystal fiber with a hollow core, optimizing the mode field diameter between 16 to 19 microns, to enhance coupling between single mode and multimode fibers, thereby minimizing signal degradation and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single mode transceivers are used to operate over multimode fibers, then data transmission capability is improved, but mode mismatch and modal dispersion increase causing signal degradation
Solution Approach 1:
The patent introduces a mode conditioning cable as an intermediary device between the single mode transceiver and the multimode fiber. This cable contains a mode conditioning section that transforms the single mode field distribution into a multimode field distribution, enabling efficient coupling and reducing modal dispersion while maintaining high data transmission capability
Solution Approach 2:
The patent changes the physical parameters of the optical field by using a mode conditioning section with specific refractive index profile and length. This transforms the mode field diameter and numerical aperture parameters to match between single mode and multimode fibers, resolving the mode mismatch problem
2Adaptability or versatility
If single mode transceivers operate over multimode fibers, then wavelength compatibility is improved, but modal noise and attenuation increase
Solution Approach 1:
The mode conditioning cable acts as a mediator that conditions the optical mode before it enters the multimode fiber. By controlling the mode field distribution at the interface, it reduces the excitation of higher order modes that cause modal noise, while maintaining wavelength compatibility
Solution Approach 2:
The mode conditioning section performs preliminary action by pre-conditioning the optical field before it propagates through the multimode fiber. This preliminary mode transformation prevents the generation of modal noise and reduces attenuation from the outset
3Device complexity
If direct coupling between single mode and multimode fibers is used, then device complexity is reduced, but coupling efficiency decreases
Solution Approach 1:
The mode conditioning cable serves as an intermediary coupling device that, while adding a component to the system, actually simplifies the overall coupling structure by providing a standardized interface. The mode conditioning section enables efficient power transfer by matching mode fields, reducing coupling loss
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 solution achieves efficient coupling between single mode and multimode fibers, reducing modal noise and signal attenuation, thereby enabling reliable high-speed data transmission across different fiber types.
Implementation Method 1
a photonic crystal fiber (PCF) with a hollow core placed between the SMF and MMF
Implementation Method 2
A mode field diameter (MFD) of the PCF hollow core section is in the range of 16 to 19 microns, the length of the PCF is between 1 cm to 10 cm, the MMF has 50±2 microns core diameter, the SMF has a 6-9 microns core diameter, and the coupling between the PCF mode to the MMF fundamental mode is maximized
Data Source
AI summary
A patch cord for transmitting between a single mode fiber (SMF) and a multi-mode fiber (MMFs) has a MMF, SMF, and a photonic crystal fiber (PCF) with a hollow core placed between the SMF and MMF. A mode field diameter (MFD) of the PCF hollow core section is in the range of 16 to 19 microns, the length of the PCF is between 1 cm to 10 cm, the MMF has 50±2 microns core diameter, the SMF has a 6-9 microns core diameter, and the coupling between the PCF mode to the MMF fundamental mode is maximized.