Mode Controller With Twisted Step-Index and Graded-Index Fibers
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Solution Overview
Problem
Existing mode controllers fail to produce a near-field pattern (NFP) of light that complies with the encircled flux boundary conditions specified in IEC 61300-1, as they do not effectively convert the propagation mode of light to a low-order mode distribution.
Innovation Solution
A mode controller configuration that includes a step-index fiber and a graded-index fiber wound around separate pairs of bobbins, with the light propagating through the step-index fiber and then converted to a low-order mode in the graded-index fiber by twisting, causing leakage at the core-cladding boundary, thus achieving compliance with IEC 61300-1 boundary conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If light propagates through a conventional single-type optical fiber in existing mode controllers, then the structure remains simple, but the propagation mode cannot be converted to a low-order mode distribution compliant with IEC 61300-1 boundary conditions
Solution Approach 1:
The optical fiber is divided into two distinct segments: a step-index fiber portion and a graded-index fiber portion. Each segment performs a specific function - the step-index fiber converts light to equilibrium mode distribution, while the graded-index fiber converts it to low-order mode distribution. This segmentation resolves the contradiction by achieving precise mode control through functional division rather than using a single complex fiber type.
Solution Approach 2:
The invention uses a composite optical fiber structure combining two different fiber types (step-index and graded-index) with distinct refractive index profiles. This composite structure enables the system to achieve IEC 61300-1 compliance by leveraging the complementary properties of both fiber types, resolving the contradiction between manufacturing precision and device complexity.
2Manufacturing precision
If the optical fiber is wound around bobbins and twisted to form helical areas, then mode conversion is achieved, but the structural complexity increases
Solution Approach 1:
The bobbin system is segmented into multiple bobbins, each responsible for winding a specific portion of the optical fiber. This allows independent control of twisting parameters for different fiber sections, enabling effective mode conversion while managing structural complexity through modular configuration.
Solution Approach 2:
The optical fiber is wound into helical (curved) paths around the bobbins, creating controlled curvature and torsion. This curvature-induced twisting is essential for converting the propagation mode from equilibrium distribution to low-order mode distribution, directly addressing the mode conversion requirement while the modular bobbin design manages the resulting structural 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 mode controller successfully converts the propagation mode of light to a low-order mode distribution, ensuring compliance with IEC 61300-1 encircled flux boundary conditions and allowing for efficient light emission with a simple and cost-effective structure.
Implementation Method 1
propagation mode of the light launched into the graded-index fiber is converted to a low-order mode
Implementation Method 2
causing leakage at the core-cladding boundary
Data Source
AI summary
Provided is a mode controller which includes an optical fiber coupled body and at least one pair of bobbins, and the mode controller is configured so that: the one pair of bobbins includes two bobbins arranged, spaced from one another; the optical fiber coupled body includes a step-index fiber and a graded-index fiber, which are coupled with each other; the step-index fiber and/or the graded-index fiber is/are wound around the at least one pair of bobbins, and twisted to form a helical area(s); light is launched into the step-index fiber, propagates through the step-index fiber, is emitted from the step-index fiber, and is launched into the graded-index fiber; propagation mode of the light is converted to an equilibrium mode distribution during the propagation of the light through the step-index fiber; and the propagation mode of the light launched into the graded-index fiber is converted to a low-order mode.