Fiber Grating Optical Filter for Mode Gain Equalization
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Solution Overview
Problem
Conventional optical fiber filters cannot implement gain equalization between multiple optical signal modes due to uncontrollable coupling of optical power across different signal modes, leading to unpredictable power adjustments.
Innovation Solution
An optical fiber filter design featuring a fiber core with progressively decreasing refractive indices and etched fiber gratings, where optical power is selectively coupled between specific first and second optical signal modes based on phase matching conditions, ensuring controlled power adjustment and equalization across different modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If optical power is coupled based on phase matching in conventional optical fiber filters, then optical power adjustment is achieved, but uncontrollable coupling to multiple optical signal modes occurs, preventing gain equalization
Solution Approach 1:
The invention segments the optical fiber structure into three distinct layers with different refractive indices: fiber core (highest), inner cladding (intermediate), and outer cladding (lowest). This segmentation creates separate transmission channels for different optical signal modes, allowing independent control of coupling between modes. The fiber grating is selectively applied only to the fiber core, enabling precise control over which modes are coupled while preventing unwanted coupling to other modes.
Solution Approach 2:
The invention applies local quality by creating spatially varying refractive indices within the fiber structure. The fiber core has the highest refractive index for transmitting signal modes, the inner cladding has an intermediate refractive index for transmitting specific modes, and the outer cladding has the lowest refractive index. This local differentiation allows selective coupling of optical power between specific modes while maintaining control and preventing uncontrollable multi-mode coupling.
2Productivity
If fiber core transmits multiple optical signal modes, then transmission capacity increases, but gain equalization between modes cannot be implemented due to uncontrollable power coupling
Solution Approach 1:
The segmented three-layer fiber structure enables simultaneous support for multiple optical signal modes in the fiber core while providing controlled coupling paths through the inner cladding. Each layer is optimized for specific mode transmission, allowing the system to maintain high transmission capacity through multi-mode support while achieving precise gain equalization through controlled inter-layer coupling at the fiber grating location.
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 solution enables precise and controlled adjustment of optical power, effectively achieving gain equalization between different optical signal modes with minimal interference, reducing the probability of signal transmission interruptions.
Implementation Method 1
at least part of optical power of a target first optical signal mode is coupled to only a target second optical signal mode at the fiber grating
Implementation Method 2
optical power of the target first optical signal mode is coupled to only a target second optical signal mode
Implementation Method 3
A refractive index of the fiber core, a refractive index of the inner cladding, and a refractive index of the outer cladding progressively decrease in sequence
Data Source
AI summary
An optical fiber filter includes a fiber core, inner cladding, and outer cladding. A refractive index of the fiber core, a refractive index of the inner cladding, and a refractive index of the outer cladding progressively decrease in sequence. The fiber core is configured to transmit at least two mutually different first optical signal modes, the inner cladding is configured to transmit at least two mutually different second optical signal modes, and at least one fiber grating is etched on the fiber core. At least part of optical power of a target first optical signal mode is coupled to only a target second optical signal mode at the fiber grating. The target first optical signal mode is one of the at least two first optical signal modes, and the target second optical signal mode is one of the at least two second optical signal modes.